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Source: https://theconversation.com/us/topics/astronomy-50/articles.atom

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6.  <title>Astronomy – The Conversation</title>
7.  <updated>2025-04-21T09:09:14Z</updated>
8.  <entry>
9.    <id>tag:theconversation.com,2011:article/243022</id>
10.    <published>2025-04-21T09:09:14Z</published>
11.    <updated>2025-04-21T09:09:14Z</updated>
12.    <link rel="alternate" type="text/html" href="https://theconversation.com/twinkling-star-reveals-the-shocking-secrets-of-turbulent-plasma-in-our-cosmic-neighbourhood-243022"/>
13.    <title>Twinkling star reveals the shocking secrets of turbulent plasma in our cosmic neighbourhood</title>
14.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/661914/original/file-20250415-56-2gaikj.jpg?ixlib=rb-4.1.0&amp;amp;rect=0%2C0%2C7680%2C4311&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;Artist&amp;#39;s impression of a pulsar bow shock scattering a radio beam.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;span class="source"&gt;Carl Knox/Swinburne/OzGrav&lt;/span&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;With the most powerful radio telescope in the southern hemisphere, we have observed a twinkling star and discovered an abundance of mysterious plasma structures in our cosmic neighbourhood.&lt;/p&gt;
15.  
16. <p>The plasma structures we see are variations in density or turbulence, akin to interstellar cyclones stirred up by energetic events in the galaxy.</p>
17.  
18. <p>The study, <a href="https://www.nature.com/articles/s41550-025-02534-6">published today</a> in Nature Astronomy, also describes the first measurements of plasma layers within an interstellar shock wave that surrounds a pulsar. </p>
19.  
20. <p>We now realise our local interstellar medium is filled with these structures and our findings also include a rare phenomenon that will challenge theories of pulsar shock waves.</p>
21.  
22. <h2>What’s a pulsar and why does it have a shock wave?</h2>
23.  
24. <p>Our observations honed in on the nearby fast-spinning pulsar, J0437-4715, which is 512 light-years away from Earth. A pulsar is a <a href="https://theconversation.com/explainer-what-is-a-neutron-star-29341">neutron star</a>, a super-dense stellar remnant that produces beams of radio waves and an energetic “wind” of particles.</p>
25.  
26. <p>The pulsar and its wind move with supersonic speed through the interstellar medium – the stuff (gas, dust and plasma) between the stars. This creates a bow shock: a shock wave of heated gas that glows red. </p>
27.  
28. <figure>
29.            <iframe width="440" height="260" src="https://www.youtube.com/embed/gjLk_72V9Bw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
30.            
31.          </figure>
32.  
33. <p>The interstellar plasma is turbulent and scatters pulsar radio waves slightly away from a direct, straight line path. The scattered waves create a pattern of bright and dim patches that drifts over our radio telescopes as Earth, the pulsar and plasma all move through space.</p>
34.  
35. <p>From our vantage point, this causes the pulsar to twinkle, or “scintillate”. The effect is similar to how turbulence in Earth’s atmosphere <a href="https://theconversation.com/curious-kids-why-do-stars-twinkle-81188">makes stars twinkle</a> in the night sky. </p>
36.  
37. <p>Pulsar scintillation gives us unique information about plasma structures that are too small and faint to be detected in any other way.</p>
38.  
39. <h2>Twinkling little radio star</h2>
40.  
41. <p>To the naked eye, the twinkling of a star might appear random. But for pulsars at least, there are hidden patterns.</p>
42.  
43. <p>With the right techniques, we can uncover ordered shapes from the interference pattern, called scintillation arcs. They detail the locations and velocities of compact structures in the interstellar plasma. Studying scintillation arcs is like performing a CT scan of the interstellar medium – each arc reveals a thin layer of plasma.</p>
44.  
45. <p>Usually, scintillation arc studies uncover just one, or at most a handful of these arcs, giving a view of only the most extreme (densest or most turbulent) plasma structures in our galaxy. </p>
46.  
47. <p>Our scintillation arc study broke new ground by unveiling an unprecedented 25 scintillation arcs, the most plasma structures observed for any pulsar to date.</p>
48.  
49. <p>The sensitivity of our study was only possible because of the close proximity of the pulsar (it’s our <a href="https://theconversation.com/what-happens-when-matter-is-squashed-to-the-brink-of-collapse-we-weighed-a-neutron-star-to-help-nasa-find-out-229813">nearest millisecond pulsar neighbour</a>) and the large collecting area of the <a href="https://www.sarao.ac.za/science/meerkat/about-meerkat/">MeerKAT radio telescope in South Africa</a>.</p>
50.  
51. <figure class="align-center ">
52.            <img alt="" src="https://images.theconversation.com/files/662138/original/file-20250416-56-tnbkoc.gif?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/662138/original/file-20250416-56-tnbkoc.gif?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=700&fit=crop&dpr=1 600w, https://images.theconversation.com/files/662138/original/file-20250416-56-tnbkoc.gif?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=700&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/662138/original/file-20250416-56-tnbkoc.gif?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=700&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/662138/original/file-20250416-56-tnbkoc.gif?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=879&fit=crop&dpr=1 754w, https://images.theconversation.com/files/662138/original/file-20250416-56-tnbkoc.gif?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=879&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/662138/original/file-20250416-56-tnbkoc.gif?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=879&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
53.            <figcaption>
54.              <span class="caption">Animation of 25 scintillation arcs changing in curvature with time according to the changing velocity of the pulsar. Each frame of the animation shows the scintillation arcs measured on one day, for six consecutive days. The inset scintillation arcs originate from the pulsar bow shock.</span>
55.              <span class="attribution"><a class="source" href="https://www.nature.com/articles/s41550-025-02534-6">Reardon et al., Nature Astronomy</a></span>
56.            </figcaption>
57.          </figure>
58.  
59. <h2>A Local Bubble surprise</h2>
60.  
61. <p>Of the 25 scintillation arcs we found, 21 revealed structures in the interstellar medium. This was surprising because the pulsar – like our own Solar System – is located in a relatively quiet region of our galaxy called the Local Bubble.</p>
62.  
63. <p>About <a href="https://www.nature.com/articles/s41586-021-04286-5">14 million years ago</a>, this part of our galaxy was lit up by stellar explosions that swept up material in the interstellar medium and inflated a hot void. Today, this bubble is still expanding and now extends up to 1,000 light-years from us. </p>
64.  
65. <p>Our new scintillation arc discoveries reveal that the Local Bubble is not as empty as previously thought. It is filled with compact plasma structures that could only be sustained if the bubble has cooled, at least in some areas, from millions of degrees down to a mild 10,000 degrees Celsius.</p>
66.  
67. <h2>Shock discoveries</h2>
68.  
69. <p>As the animation below shows, the pulsar is surrounded by its bow shock, which glows red with <a href="https://theconversation.com/explainer-seeing-the-universe-through-spectroscopic-eyes-37759">light from energised hydrogen atoms</a>.</p>
70.  
71. <figure>
72.            <iframe width="440" height="260" src="https://www.youtube.com/embed/G6UAvud6qVE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
73.            <figcaption><span class="caption">Artist’s animation of the bow shock scattering the pulsar beam. Carl Knox/Swinburne/OzGrav.</span></figcaption>
74.          </figure>
75.  
76. <p>While most pulsars are thought to produce bow shocks, only a handful have ever been observed because they are faint objects. Until now, none had been studied using scintillation.</p>
77.  
78. <p>We traced the remaining four scintillation arcs to plasma structures <em>inside</em> the pulsar bow shock, marking the first time astronomers have peered inside one of these shock waves.</p>
79.  
80. <p>This gave us a CT-like view of the different layers of plasma. Using these arcs together with an optical image we constructed a new three-dimensional model of the shock, which appears to be tilted slightly away from us because of the motion of the pulsar through space.  </p>
81.  
82. <p>The scintillation arcs also gave us the velocities of the plasma layers. Far from being as expected, we discovered that one inner plasma structure is moving towards the shock front against the flow of the shocked material in the opposite direction. </p>
83.  
84. <p>While such back flows can appear in simulations, they are rare. This finding will drive new models for this bow shock.</p>
85.  
86.  
87.  
88. <h2>Scintillating science</h2>
89.  
90. <p>With new and more sensitive radio telescopes being built around the world, we can expect to see scintillation from more pulsar bow shocks and other events in the interstellar medium.</p>
91.  
92. <p>This will uncover more about the energetic processes in our galaxy that create these otherwise invisible plasma structures.</p>
93.  
94. <p>The scintillation of this pulsar neighbour revealed unexpected plasma structures inside our Local Bubble and allowed us to map and measure the speed of plasma within a bow shock. It’s amazing what a twinkling little star can do.</p><img src="https://counter.theconversation.com/content/243022/count.gif" alt="The Conversation" width="1" height="1" />
95. <p class="fine-print"><em><span>Daniel Reardon receives funding from the Australian Research Council Centre of Excellence for Gravitational Wave Discovery (OzGrav).
96.  
97. &lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
98.    <summary>For the first time, astronomers have measured the plasma layers of a shock wave surrounding a pulsar.</summary>
99.    <author>
100.      <name>Daniel Reardon, Postdoctoral Researcher, Pulsar Timing and Gravitational Waves, Swinburne University of Technology</name>
101.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/daniel-reardon-1418102"/>
102.    </author>
103.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
104.  </entry>
105.  <entry>
106.    <id>tag:theconversation.com,2011:article/254900</id>
107.    <published>2025-04-18T22:44:39Z</published>
108.    <updated>2025-04-18T22:44:39Z</updated>
109.    <link rel="alternate" type="text/html" href="https://theconversation.com/scientists-found-a-potential-sign-of-life-on-a-distant-planet-an-astronomer-explains-why-many-are-still-skeptical-254900"/>
110.    <title>Scientists found a potential sign of life on a distant planet – an astronomer explains why many are still skeptical</title>
111.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/662692/original/file-20250418-56-at0887.jpg?ixlib=rb-4.1.0&amp;amp;rect=0%2C0%2C1280%2C718&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;An illustration of the exoplanet K2-18b, which some research suggests may be covered by deep oceans. &lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://webbtelescope.org/contents/media/images/2023/139/01H9R88HG8YXRMARWZ5B1YDT27"&gt;NASA, ESA, CSA, Joseph Olmsted (STScI)&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;A team of astronomers announced on April 16, 2025, that in the process of studying a planet around another star, &lt;a href="https://doi.org/10.3847/2041-8213/adc1c8"&gt;they had found evidence&lt;/a&gt; for an unexpected atmospheric gas. On Earth, that gas – called dimethyl sulfide – is mostly produced by living organisms. &lt;/p&gt;
112.  
113. <p>In April 2024, the <a href="https://science.nasa.gov/mission/webb/">James Webb Space Telescope</a> stared at the host star of the <a href="https://science.nasa.gov/exoplanet-catalog/k2-18-b/">planet K2-18b</a> for nearly six hours. During that time, the orbiting planet passed in front of the star. Starlight filtered through its atmosphere, carrying the fingerprints of atmospheric molecules <a href="https://theconversation.com/to-search-for-alien-life-astronomers-will-look-for-clues-in-the-atmospheres-of-distant-planets-and-the-james-webb-space-telescope-just-proved-its-possible-to-do-so-184828">to the telescope</a>. </p>
114.  
115. <figure class="align-center zoomable">
116.            <a href="https://images.theconversation.com/files/662693/original/file-20250418-56-afn8ji.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing planets and stars emitting light, which goes through JWST detectors, where it's split into different wavelengths to make a spectrum. Each spectrum suggests the presence of a different element." src="https://images.theconversation.com/files/662693/original/file-20250418-56-afn8ji.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/662693/original/file-20250418-56-afn8ji.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/662693/original/file-20250418-56-afn8ji.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/662693/original/file-20250418-56-afn8ji.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/662693/original/file-20250418-56-afn8ji.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/662693/original/file-20250418-56-afn8ji.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/662693/original/file-20250418-56-afn8ji.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
117.            <figcaption>
118.              <span class="caption">JWST’s cameras can detect molecules in the atmosphere of a planet by looking at light that passed through that atmosphere.</span>
119.              <span class="attribution"><a class="source" href="https://www.esa.int/ESA_Multimedia/Images/2021/06/Spectroscopy_with_Webb">European Space Agency</a></span>
120.            </figcaption>
121.          </figure>
122.  
123. <p>By comparing those fingerprints to 20 different molecules that they would potentially expect to observe in the atmosphere, the astronomers concluded that the most probable match was a gas that, on Earth, is a good indicator of life. </p>
124.  
125. <p><a href="https://scholar.google.com/citations?user=2SCIYjIAAAAJ&hl=en">I am an astronomer and astrobiologist</a> who studies planets around other stars and their atmospheres. In my work, I try to understand which nearby planets may be suitable for life. </p>
126.  
127. <h2>K2-18b, a mysterious world</h2>
128.  
129. <p>To understand what this discovery means, let’s start with the bizarre world it was found in. The planet’s name is K2-18b, meaning it is the first planet in the 18th planetary system found by the extended <a href="https://science.nasa.gov/mission/kepler/">NASA Kepler mission</a>, K2. Astronomers assign the “b” label to the first planet in the system, not “a,” to avoid possible confusion with the star. </p>
130.  
131. <p>K2-18b is a little over 120 light-years from Earth – on a galactic scale, this world is practically in our backyard.</p>
132.  
133. <p>Although astronomers know very little about K2-18b, we do know that it is very unlike Earth. To start, it is about <a href="https://exoplanetarchive.ipac.caltech.edu/overview/K2-18b">eight times more massive than Earth</a>, and it has a volume that’s about 18 times larger. This means that it’s only about half as dense as Earth. In other words, it must have a lot of water, which isn’t very dense, or a very big atmosphere, which is even less dense. </p>
134.  
135. <p>Astronomers think that this world could either be a smaller version of our solar system’s ice giant Neptune, called <a href="https://www.planetary.org/articles/the-skies-of-mini-neptunes">a mini-Neptune</a>, or perhaps a rocky planet with no water but a massive hydrogen atmosphere, called <a href="https://www.space.com/26087-gas-dwarf-alien-planets-aas224.html">a gas dwarf</a>. </p>
136.  
137. <p>Another option, as <a href="https://scholar.google.co.uk/citations?user=UVxRllsAAAAJ&hl=en">University of Cambridge astronomer Nikku Madhusudhan</a> recently proposed, is that the planet is a “<a href="https://doi.org/10.3847/1538-4357/abfd9c">hycean world</a>.”</p>
138.  
139. <p>That term means hydrogen-over-ocean, since astronomers predict that hycean worlds are planets with global oceans many times deeper than Earth’s oceans, and without any continents. These oceans are covered by massive hydrogen atmospheres that are thousands of miles high. </p>
140.  
141. <p>Astronomers do not know yet for certain that hycean worlds exist, but models for what those would look like match the limited data JWST and other telescopes have collected on K2-18b.  </p>
142.  
143. <p>This is where the story becomes exciting. Mini-Neptunes and gas dwarfs are unlikely to be hospitable for life, because they probably don’t have liquid water, and their interior surfaces have <a href="https://royalsocietypublishing.org/doi/10.1098/rsta.2019.0474">enormous pressures</a>. But a hycean planet would have a large and likely temperate ocean. So could the oceans of <a href="https://earthsky.org/space/hycean-planets-exoplanets-habitability/">hycean worlds be habitable</a> – or even inhabited? </p>
144.  
145. <h2>Detecting DMS</h2>
146.  
147. <p>In 2023, Madhusudhan and his colleagues used the <a href="https://science.nasa.gov/mission/webb/nircam/">James Webb Space Telescope’s short-wavelength infrared camera</a> to inspect starlight that filtered through K2-18b’s atmosphere for the first time. </p>
148.  
149. <p>They found evidence for the <a href="https://doi.org/10.3847/2041-8213/acf577">presence of two simple carbon-bearing molecules</a> – carbon monoxide and methane – and showed that the planet’s upper atmosphere lacked water vapor. This atmospheric composition supported, but did not prove, the idea that K2-18b could be a hycean world. In a hycean world, water would be <a href="https://doi.org/10.3847/1538-4357/abfd9c">trapped in the deeper and warmer atmosphere</a>, closer to the oceans than the upper atmosphere probed by JWST observations.</p>
150.  
151. <p>Intriguingly, the data also showed an additional, very weak signal. The team found that this weak signal matched a gas called <a href="https://www.astronomy.com/science/k2-18-b-could-have-dimethyl-sulfide-in-its-air-but-is-it-a-sign-of-life/">dimethyl sulfide</a>, or DMS. On Earth, DMS is produced in <a href="https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/dimethyl-sulfide">large quantities by marine algae</a>. It has very few, if any, nonbiological sources. </p>
152.  
153. <p>This signal made the initial detection exciting: on a planet that may have a massive ocean, there is likely a gas that is, on Earth, emitted by biological organisms. </p>
154.  
155. <figure class="align-center zoomable">
156.            <a href="https://images.theconversation.com/files/662696/original/file-20250418-56-fwtd80.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An illustration of what scientists imagine K2-18b to look like, which looks a little like Earth, with clouds and a translucent surface." src="https://images.theconversation.com/files/662696/original/file-20250418-56-fwtd80.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/662696/original/file-20250418-56-fwtd80.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=394&fit=crop&dpr=1 600w, https://images.theconversation.com/files/662696/original/file-20250418-56-fwtd80.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=394&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/662696/original/file-20250418-56-fwtd80.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=394&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/662696/original/file-20250418-56-fwtd80.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=495&fit=crop&dpr=1 754w, https://images.theconversation.com/files/662696/original/file-20250418-56-fwtd80.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=495&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/662696/original/file-20250418-56-fwtd80.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=495&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
157.            <figcaption>
158.              <span class="caption">K2-18b could have a deep ocean spanning the planet, and a hydrogen atmosphere.</span>
159.              <span class="attribution"><a class="source" href="https://www.cam.ac.uk/stories/carbon-found-in-habitable-zone-exoplanet">Amanda Smith, Nikku Madhusudhan (University of Cambridge)</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
160.            </figcaption>
161.          </figure>
162.  
163. <p>Scientists had a <a href="https://bigthink.com/starts-with-a-bang/k2-18b-inhabited/">mixed response</a> to this initial announcement. While the findings were exciting, some astronomers pointed out that the DMS signal seen was weak and that the hycean nature of K2-18b is very uncertain. </p>
164.  
165. <p>To address these concerns, Mashusudhan’s team turned JWST <a href="https://www.npr.org/2025/04/16/nx-s1-5364805/signs-life-alien-planet-biosignatures-exoplanet">back to K2-18b</a> a year later. This time, they <a href="https://science.nasa.gov/mission/webb/mid-infrared-instrument-miri/">used another camera</a> on JWST that looks for another range of wavelengths of light. <a href="https://doi.org/10.3847/2041-8213/adc1c8">The new results</a> – announced on April 16, 2025 – supported their initial findings. </p>
166.  
167. <p>These new data show a stronger – but still relatively weak – signal that the team attributes to DMS or a very similar molecule. The fact that the DMS signal showed up on another camera during another set of observations made the interpretation of DMS in the atmosphere stronger. </p>
168.  
169. <p>Madhusudhan’s <a href="https://doi.org/10.3847/2041-8213/adc1c8">team also presented</a> a very detailed analysis of the uncertainties in the data and interpretation. In real-life measurements, there are always some uncertainties. They found that these uncertainties are unlikely to account for the signal in the data, further supporting the DMS interpretation. As an astronomer, I find that analysis exciting. </p>
170.  
171. <h2>Is life out there?</h2>
172.  
173. <p>Does this mean that scientists have found life on another world? Perhaps – but we still cannot be sure. </p>
174.  
175. <p>First, does K2-18b really have an ocean deep beneath its thick atmosphere? Astronomers should test this. </p>
176.  
177. <p>Second, is the signal seen in two cameras two years apart really from dimethyl sulfide? Scientists will need more sensitive measurements and more observations of the planet’s atmosphere to be sure. </p>
178.  
179. <p>Third, if it is indeed DMS, does this mean that there is life? This may be the most difficult question to answer. Life itself is not detectable with existing technology. Astronomers will need to evaluate and exclude all other potential options to build their confidence in this possibility. </p>
180.  
181. <p>The new measurements may lead researchers toward a historic discovery. However, important uncertainties remain. Astrobiologists will need a much deeper understanding of K2-18b and similar worlds before they can be confident in the presence of DMS and its interpretation as a signature of life. </p>
182.  
183. <p>Scientists around the world are <a href="https://www.npr.org/2025/04/16/nx-s1-5364805/signs-life-alien-planet-biosignatures-exoplanet">already scrutinizing the published study</a> and will work on new tests of the findings, since independent verification is at the heart of science. </p>
184.  
185. <p>Moving forward, K2-18b is going to be an important target for JWST, the world’s most sensitive telescope. JWST may soon observe other potential hycean worlds to see if the signal appears in the atmospheres of those planets, too. </p>
186.  
187. <p>With more data, these tentative conclusions may not stand the test of time. But for now, just the prospect that astronomers may have detected gasses emitted by an alien ecosystem that bubbled up in a dark, blue-hued alien ocean is an incredibly fascinating possibility. </p>
188.  
189. <p>Regardless of the true nature of K2-18b, the new results show how <a href="https://blogs.nasa.gov/webb/2024/06/05/reconnaissance-of-potentially-habitable-worlds-with-nasas-webb/">using the JWST</a> to survey other worlds for clues of alien life will guarantee that the next years will be thrilling for astrobiologists.</p><img src="https://counter.theconversation.com/content/254900/count.gif" alt="The Conversation" width="1" height="1" />
190. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Daniel Apai receives funding for astrobiology research from NASA, the Heising-Simons Foundation, and the Gordon and Betty Moore Foundation. &lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
191.    <summary>The exoplanet K2-18b could harbor a massive ocean, but scientists will need to study the planet more to see if it’s really likely to host life.</summary>
192.    <author>
193.      <name>Daniel Apai, Associate Dean for Research and Professor of Astronomy and Planetary Sciences, University of Arizona</name>
194.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/daniel-apai-555353"/>
195.    </author>
196.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
197.  </entry>
198.  <entry>
199.    <id>tag:theconversation.com,2011:article/254404</id>
200.    <published>2025-04-15T12:41:08Z</published>
201.    <updated>2025-04-15T12:41:08Z</updated>
202.    <link rel="alternate" type="text/html" href="https://theconversation.com/mysterious-objects-from-other-stars-are-passing-through-our-solar-system-scientists-are-planning-missions-to-study-them-up-close-254404"/>
203.    <title>Mysterious objects from other stars are passing through our solar system. Scientists are planning missions to study them up close</title>
204.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/661267/original/file-20250411-62-d11epe.jpg?ixlib=rb-4.1.0&amp;amp;rect=0%2C110%2C1768%2C1009&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;&lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://www.nasa.gov/news-release/our-solar-systems-first-known-interstellar-object-gets-unexpected-speed-boost/"&gt;NASA/ESA/STScI&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;In late 2017, a mysterious object &lt;a href="https://science.nasa.gov/solar-system/comets/oumuamua/"&gt;tore through&lt;/a&gt; our solar system at breakneck speed. Astronomers scrambled to observe the fast moving body using the world’s most powerful telescopes. It was found to be one quarter mile (400m) long and very elongated – perhaps 10 times as long as it was wide. Researchers named it ‘Oumuamua, Hawaiian for “scout”. &lt;/p&gt;
205.  
206. <p>'Oumuamua was later confirmed to be the first object from another star known to have visited our solar system. While these interstellar objects (ISO) originate around a star, they end up as cosmic nomads, wandering through space. They are essentially <a href="https://www.aanda.org/articles/aa/full_html/2021/07/aa40587-21/aa40587-21.html">planetary shrapnel</a>, having been blasted out of their parent star systems by catastrophic events, such as giant collisions between planetary objects. </p>
207.  
208. <p>Astronomers say that 'Oumuamua could have been <a href="https://science.nasa.gov/solar-system/comets/oumuamua/">travelling through the Milky Way</a> for hundreds of millions of years before its encounter with our solar system. Just two years after this unexpected visit, a second ISO – <a href="https://science.nasa.gov/solar-system/comets/2i-borisov/">the Borisov Comet</a> – was spotted, this time by an amateur astronomer in Crimea. These celestial interlopers have given us tantalising glimpses of material from far beyond our solar system. </p>
209.  
210. <p>But what if we could do more than just watch them fly by?</p>
211.  
212. <p>Studying ISOs up close would offer scientists the rare opportunity to learn more about far off star systems, which are too distant to send missions to. </p>
213.  
214. <p>There may be <a href="https://www.annualreviews.org/content/journals/10.1146/annurev-astro-071221-054221">over 10 septillion</a> (or ten with 24 zeros) ISOs in the Milky Way
215. alone.  But if there are so many of them, why have we only seen two? Put simply, we cannot accurately predict when they will arrive. Large ISOs like 'Oumuamua, that are more easily detected, <a href="https://arxiv.org/abs/2502.03224">do not seem to visit</a> the solar system that often and they travel incredibly fast. </p>
216.  
217. <p>Ground- and space-based telescopes struggle to respond quickly to incoming ISOs, meaning that we are mostly looking at them <a href="https://www.astronomy.com/science/can-we-catch-oumuamua-interstellar-interloper/">after they pass through our cosmic neighbourhood</a>. However, innovative space missions could get us closer to objects like 'Oumuamua, by using breakthroughs in artificial intelligence (AI) to guide spacecraft safely to future visitors. Getting closer means we can get <a href="https://www.sciencedirect.com/science/article/pii/S003206332400014X">a better understanding</a> of their composition, geology, and activity – gaining insights into the conditions around other stars.</p>
218.  
219.  
220.  
221. <p>Emerging technologies being used to approach space debris could help to approach
222. other unpredictable objects, transforming these fleeting encounters into profound
223. scientific opportunities. So how do we get close? Speeding past Earth at an average of 32.14 km/s, ISOs give us less than a year for our spacecraft to try and intercept them <a href="https://www.astronomy.com/science/can-we-catch-oumuamua-interstellar-interloper/">after detection</a>. Catching up is not impossible – for example, it could be done via gravitational slingshot manoeuvres. However, it is difficult, costly and would take years to execute.</p>
224.  
225. <p>The good news is that the first wave of ISO-hunting missions is already in motion:
226. Nasa’s mission concept <a href="https://www.sciencedirect.com/science/article/abs/pii/S0032063320303500">is called Bridge</a> and the European Space Agency (Esa) has a mission called <a href="https://link.springer.com/article/10.1007/s11214-023-01035-0">Comet Interceptor</a>. Once an incoming ISO is identified, Bridge would
227. depart Earth to intercept it. However, launching from Earth currently requires a 30-day launch window after detection, which would cost valuable time.</p>
228.  
229. <figure class="align-center ">
230.            <img alt="Comet interceptor mission" src="https://images.theconversation.com/files/661268/original/file-20250411-56-3s9g0l.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/661268/original/file-20250411-56-3s9g0l.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/661268/original/file-20250411-56-3s9g0l.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/661268/original/file-20250411-56-3s9g0l.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/661268/original/file-20250411-56-3s9g0l.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/661268/original/file-20250411-56-3s9g0l.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/661268/original/file-20250411-56-3s9g0l.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
231.            <figcaption>
232.              <span class="caption">The Comet Interceptor mission is scheduled to launch in 2029.</span>
233.              <span class="attribution"><a class="source" href="https://www.esa.int/Science_Exploration/Space_Science/Comet_Interceptor/Top_five_questions_Comet_Interceptor_will_help_answer">ESA / Work performed by ATG under contract to ESA</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
234.            </figcaption>
235.          </figure>
236.  
237. <p>Comet Interceptor is scheduled for launch in 2029 and comprises a larger spacecraft and two smaller robotic probes. Once launched, it will lie in wait a million miles from Earth, waiting to ambush a long period comet (slower comets that come from further away) – or potentially an ISO. Placing spacecraft in a “storage orbit” allows for rapid deployment when a suitable ISO is detected.</p>
238.  
239. <p>Another proposal from the Institute for Interstellar Studies, Project Lyra, <a href="https://i4is.org/what-we-do/technical/project-lyra/">assessed the feasibility</a> of chasing down 'Oumuamua, which has already sped far beyond Neptune’s orbit. They found that it would be <a href="https://www.sciencedirect.com/science/article/abs/pii/S0094576518317004">possible in theory</a> to catch up with the object, but that this would also be very technically challenging.</p>
240.  
241. <h2>The fast and the curious</h2>
242.  
243. <p>These missions are a start, but, as described, <a href="https://www.universetoday.com/articles/vera-rubin-observatory-should-find-5-interstellar-objects-a-year-many-of-which-we-could-chase-down-with-spacecraft">their biggest limitation</a> is speed. To chase down ISOs like 'Oumuamua, we’ll need to move a lot faster – and think smarter. </p>
244.  
245. <p>Future missions <a href="https://www.space.com/space-exploration/tech/this-spacecraft-swarm-could-spot-interstellar-visitors-zipping-through-our-solar-system">may rely</a> on cutting-edge AI and related fields such as <a href="https://www.ibm.com/think/topics/deep-learning">deep learning</a> – which seeks to emulate the decision making power of the human brain – to identify and respond to incoming objects in real time. Researchers are already testing small spacecraft that operate in coordinated “swarms”, allowing them to image targets from multiple angles and adapt mid-flight. </p>
246.  
247. <p>At the <a href="https://rubinobservatory.org/">Vera C Rubin Observatory</a> in Chile, a 10-year survey of the night sky is due to begin soon. This astronomical survey is expected to find dozens of ISOs each year. Simulations suggest we may be on the cusp of a detection boom. </p>
248.  
249. <p>Any spacecraft would need to reach high speeds once an object is spotted and
250. ensure that its energy source doesn’t degrade, potentially after years waiting in
251. “storage orbit”. A number of missions have already utilised a form of propulsion called a solar sail. </p>
252.  
253. <p>These use sunlight on the lightweight, reflective sail to push the spacecraft through space. This <a href="https://www.space.com/25800-ikaros-solar-sail.html">would dispense</a> with the need for heavy fuel tanks. The next generation of solar sail spacecraft <a href="https://www.universetoday.com/articles/laser-powered-sails-would-be-great-for-exploring-the-solar-system-too">could use lasers</a> on the sails to reach even higher speeds, which would offer a nimble and low cost solution compared to other futuristic fuels, such as nuclear propulsion. </p>
254.  
255. <figure class="align-center ">
256.            <img alt="The Vera C. Rubin Observatory at dawn on Cerro Pachón in Chile." src="https://images.theconversation.com/files/661269/original/file-20250411-62-n2lfx3.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/661269/original/file-20250411-62-n2lfx3.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=290&fit=crop&dpr=1 600w, https://images.theconversation.com/files/661269/original/file-20250411-62-n2lfx3.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=290&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/661269/original/file-20250411-62-n2lfx3.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=290&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/661269/original/file-20250411-62-n2lfx3.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=365&fit=crop&dpr=1 754w, https://images.theconversation.com/files/661269/original/file-20250411-62-n2lfx3.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=365&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/661269/original/file-20250411-62-n2lfx3.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=365&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
257.            <figcaption>
258.              <span class="caption">The Vera Rubin Observatory in Chile should discover more interstellar objects.</span>
259.              <span class="attribution"><a class="source" href="https://noirlab.edu/public/images/rubin-Summit-Facility-at-Dawn/">RubinObs/NOIRLab/SLAC/NSF/DOE/AURA/Y. AlSayyad</a></span>
260.            </figcaption>
261.          </figure>
262.  
263. <p>A spacecraft approaching an ISO will also need to withstand high temperatures and possibly erosion from dust being ejected from the object as it moves. While traditional shielding materials can protect spacecraft, they add weight and may slow them down. </p>
264.  
265. <p>To address this, researchers are exploring novel technologies for lightweight, more durable and resistant materials, such as advanced carbon fibres. Some could even be 3D printed. They are also looking at innovative uses of traditional materials such as cork and ceramics.</p>
266.  
267. <p>A suite of different approaches is needed that involve ground-based telescopes and space based missions, working together to anticipate, chase down and observe ISOs. </p>
268.  
269. <p><a href="https://www.rand.org/pubs/research_reports/RRA3121-1.html">New technology</a> could allow the spacecraft itself to identify and predict the trajectories of incoming objects. However, <a href="https://arstechnica.com/space/2025/04/trump-white-house-budget-proposal-eviscerates-science-funding-at-nasa/">potential cuts</a> to space science in the US, including to observatories like the <a href="https://www.space.com/space-exploration/james-webb-space-telescope/nasa-james-webb-space-telescope-faces-20-percent-budget-cuts">James Webb Space Telescope</a>, threaten such progress. </p>
270.  
271. <p>Emerging technologies must be embraced to make an approach and rendezvous with an ISO a real possibility. Otherwise, we will be left scrabbling, taking pictures from afar as yet another cosmic wanderer speeds away.</p><img src="https://counter.theconversation.com/content/254404/count.gif" alt="The Conversation" width="1" height="1" />
272. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Billy Bryan works on projects at RAND Europe that are funded by the UK Space Agency and DG DEFIS. He is affiliated with RAND Europe&amp;#39;s Space Hub and is lead of the civil space theme, the University of Sussex Students&amp;#39; Union as a Trustee, and Rocket Science Ltd. as an advisor. &lt;/span&gt;&lt;/em&gt;&lt;/p&gt;&lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Chris Carter works on projects at RAND Europe that are funded by the UK Space Agency and DG DEFIS. He is affiliated with RAND Europe’s Space Hub and is a researcher in the civil space theme.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;&lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Theodora (Teddy) Ogden is a Senior Analyst at RAND Europe, where she works on defence and security issues in space. She was previously a fellow at Arizona State University, and before that was briefly at Nato.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
273.    <summary>Learning about these interstellar objects could give us insights into other star systems.</summary>
274.    <author>
275.      <name>Billy Bryan, Research Leader, RAND Europe</name>
276.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/billy-bryan-300235"/>
277.    </author>
278.    <author>
279.      <name>Chris Carter, Analyst, Science and Emerging Technology Team, RAND Europe</name>
280.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/chris-carter-2371623"/>
281.    </author>
282.    <author>
283.      <name>Theodora Ogden, Senior Analyst, Defence and Security Team, RAND Europe</name>
284.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/theodora-ogden-1339970"/>
285.    </author>
286.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
287.  </entry>
288.  <entry>
289.    <id>tag:theconversation.com,2011:article/253546</id>
290.    <published>2025-04-02T19:03:51Z</published>
291.    <updated>2025-04-02T19:03:51Z</updated>
292.    <link rel="alternate" type="text/html" href="https://theconversation.com/astronomers-listened-to-the-music-of-flickering-stars-and-discovered-an-unexpected-feature-253546"/>
293.    <title>Astronomers listened to the ‘music’ of flickering stars – and discovered an unexpected feature</title>
294.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/659189/original/file-20250402-56-zupvbf.jpg?ixlib=rb-4.1.0&amp;amp;rect=0%2C338%2C5651%2C3172&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;&lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://www.shutterstock.com/image-illustration/3d-illustration-active-big-sun-1632652363"&gt;Pavel Gabzdyl / Shutterstock&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;The “music” of starquakes – enormous vibrations caused by bursting bubbles of gas that ripple throughout the bodies of many stars – can reveal far more information about the stars’ histories and inner workings than scientists thought.&lt;/p&gt;
295.  
296. <p>In <a href="https://www.nature.com/articles/s41586-025-08760-2">new research published in Nature</a>, we analysed the frequency signatures of starquakes across a broad range of giant stars in the M67 star cluster, almost 3,000 light years from Earth. </p>
297.  
298. <p>Using observations from the Kepler space telescope’s K2 mission, we had a rare opportunity to track the evolution of stars during most of their journey through the giant phase of the stellar life cycle.</p>
299.  
300. <p>In doing so, we discovered that these stars get stuck “playing the same part of their tune” once their turbulent outer layer reaches a sensitive region deep inside.</p>
301.  
302. <p>This discovery reveals a new way to understand the history of stars – and of the entire galaxy.</p>
303.  
304. <h2>The sound of starquakes</h2>
305.  
306. <p>Starquakes happen in most stars (like our Sun) that have a bubbling outer layer, like a pot of boiling water. Bubbles of hot gas rise and burst at the surface, sending ripples through the entire star that cause it to vibrate in particular ways.</p>
307.  
308. <p>We can detect these vibrations, which occur at specific “resonant frequencies”, by looking for subtle variations in the brightness of the star. By studying the frequencies of each star in a group called a cluster, we can tune into the cluster’s unique “song”. </p>
309.  
310. <p>Our study challenges previous assumptions about resonant frequencies in giant stars, revealing they offer deeper insights into stellar interiors than previously thought. Moreover, our study has opened new ways to decipher the history of our Galaxy.</p>
311.  
312. <h2>The melody of a stellar cluster</h2>
313.  
314. <p>Astronomers have long sought to understand how stars like our Sun evolve over time. </p>
315.  
316. <p>One of the best ways to do this is by studying clusters – groups of stars that formed together and share the same age and composition. A cluster called M67 has attracted a lot of attention because it contains many stars with a similar chemical makeup to the Sun.</p>
317.  
318. <p>Just as earthquakes help us study Earth’s interior, starquakes reveal what lies beneath a star’s surface. Each star “sings” a melody, with frequencies determined by its internal structure and physical properties.</p>
319.  
320. <p>Larger stars produce deeper, slower vibrations, while smaller stars vibrate at higher pitches. And no star plays just one note – each one resonates with a full spectrum of sound from its interior.</p>
321.  
322. <h2>A surprising signature</h2>
323.  
324. <p>Among the key frequency signatures is the so-called small spacing – a group of resonant frequencies quite close together. In younger stars, such as the Sun, this signature can provide clues about how much hydrogen the star still has left to burn in its core.</p>
325.  
326. <p>In red giants the situation is different. These older stars have used up all the hydrogen in their cores, which are now inert. </p>
327.  
328. <p>However, hydrogen fusion continues in a shell surrounding the core. It was long assumed that the small spacings in such stars offered little new information.</p>
329.  
330. <h2>A stalled note</h2>
331.  
332. <p>When we measured the small spacings of stars in M67, we were surprised to see they revealed changes in the star’s internal fusion regions. </p>
333.  
334. <p>As the hydrogen-burning shell thickened, the spacings increased. When the shell moved inward, they shrank.</p>
335.  
336. <p>Then we found something else unexpected: at a certain stage, the small spacings stalled. It was like a record skipping on a note.</p>
337.  
338. <figure>
339.            <iframe width="440" height="260" src="https://www.youtube.com/embed/loxmLI0iAgg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
340.            
341.          </figure>
342.  
343. <p>We discovered that this stalling appears during a specific stage in the life of a giant star — when its outer envelope, the “boiling” layer that transports heat, grows so deep that it makes up about 80% of the star’s mass. At this point the inner boundary of the envelope reaches into a highly sensitive region of the star. </p>
344.  
345. <p>This boundary is extremely turbulent, and the speed of sound shifts steeply across it — and that steep change affects how sound waves travel through the star. We also found that the stalling frequency is distinctively determined by the star’s mass and chemical composition.</p>
346.  
347. <p>This gives us a new way to identify stars in this phase and estimate their ages with improved precision.</p>
348.  
349. <h2>The history of the galaxy</h2>
350.  
351. <p>Stars are like fossil records. They carry the imprint of the environments in which they formed, and studying them lets us piece together the story of our galaxy.</p>
352.  
353. <p>The Milky Way has grown by merging with smaller galaxies, forming stars at different times in different regions. Better age estimates across the galaxy help us reconstruct this history in greater detail.</p>
354.  
355. <p>Clusters like M67 also provide a glimpse into the future of our own Sun, offering insight into the changes it will experience over billions of years.</p>
356.  
357. <p>This discovery gives us a new tool – and a new reason to revisit data we already have. With years of seismic observations from across the Milky Way, we can now return to those stars and “listen” again, this time knowing what to listen for.</p><img src="https://counter.theconversation.com/content/253546/count.gif" alt="The Conversation" width="1" height="1" />
358. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Claudia Reyes does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
359.    <summary>Stars are constantly vibrating because of ‘starquakes’. Listening to their sound can reveal a surprising amount of information.</summary>
360.    <author>
361.      <name>Claudia Reyes, Postdoctoral Fellow, Research School of Astronomy &amp; Astrophysics, Australian National University</name>
362.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/claudia-reyes-2359825"/>
363.    </author>
364.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
365.  </entry>
366.  <entry>
367.    <id>tag:theconversation.com,2011:article/251560</id>
368.    <published>2025-03-31T12:15:10Z</published>
369.    <updated>2025-03-31T12:15:10Z</updated>
370.    <link rel="alternate" type="text/html" href="https://theconversation.com/jets-from-powerful-black-holes-can-point-astronomers-toward-where-and-where-not-to-look-for-life-in-the-universe-251560"/>
371.    <title>Jets from powerful black holes can point astronomers toward where − and where not − to look for life in the universe</title>
372.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/656716/original/file-20250320-56-5esaam.jpg?ixlib=rb-4.1.0&amp;amp;rect=0%2C0%2C1596%2C1062&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;Black holes, like the one in this illustration, can spray powerful jets.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://commons.wikimedia.org/wiki/File:Artist%E2%80%99s_impression_of_the_black_hole_in_the_M87_galaxy_and_its_powerful_jet_%28eso2305b%29.jpg"&gt;S. Dagnello (NRAO/AUI/NSF)&lt;/a&gt;, &lt;a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/"&gt;CC BY-SA&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;One of the most powerful objects in the universe is a &lt;a href="https://public.nrao.edu/radio-astronomy/quasars/"&gt;radio quasar&lt;/a&gt; – a spinning black hole spraying out highly energetic particles. Come too close to one, and you’d get sucked in by its gravitational pull, or burn up from the intense heat surrounding it. But ironically, studying black holes and their jets can give researchers insight into where potentially habitable worlds might be in the universe.&lt;/p&gt;
373.  
374. <p><a href="https://scholar.google.com/citations?user=4YxMlZUAAAAJ&hl=en">As an astrophysicist</a>, I’ve spent two decades modeling how black holes spin, how that creates jets, and how they affect the environment of space around them.</p>
375.  
376. <h2>What are black holes?</h2>
377.  
378. <p><a href="https://theconversation.com/the-scariest-things-in-the-universe-are-black-holes-and-here-are-3-reasons-148615">Black holes</a> are massive, astrophysical objects that use gravity to pull surrounding objects into them. Active black holes have a pancake-shaped structure around them called an <a href="https://science.nasa.gov/universe/black-holes/anatomy/">accretion disk</a>, which contains hot, electrically charged gas.</p>
379.  
380. <p>The plasma that makes up the accretion disk comes from farther out in the galaxy. When <a href="https://www.reuters.com/science/nasa-releases-webb-telescope-images-galactic-merger-2024-07-12/">two galaxies collide and merge</a>, gas is funneled into the central region of that merger. Some of that gas ends up getting close to the newly merged black hole and forms the accretion disk.</p>
381.  
382. <p>There is one <a href="https://theconversation.com/supermassive-black-holes-have-masses-of-more-than-a-million-suns-but-their-growth-has-slowed-as-the-universe-has-aged-233396">supermassive black hole</a> <a href="https://theconversation.com/powerful-black-holes-might-grow-up-in-bustling-galactic-neighborhoods-211326">at the heart</a> of every massive galaxy. </p>
383.  
384. <p>Black holes and their disks <a href="https://www.astronomy.com/science/what-is-black-hole-spin/">can rotate</a>, and when they do, they drag space and time with them – a concept that’s mind-boggling and very hard to grasp conceptually. But black holes are important to study because they produce enormous amounts of energy that can influence galaxies.</p>
385.  
386. <p>How energetic a black hole is depends on different factors, such as the mass of the black hole, whether it rotates rapidly, and whether lots of material falls onto it. Mergers fuel the most energetic black holes, but not all black holes are fed by gas from a merger. In <a href="https://esahubble.org/wordbank/spiral-galaxy/">spiral galaxies</a>, for example, less gas tends to fall into the center, and the central black hole tends to have less energy. </p>
387.  
388. <p>One of the ways they generate energy is through what scientists call “<a href="https://theconversation.com/astronomers-have-detected-one-of-the-biggest-black-hole-jets-in-the-sky-188357">jets” of highly energetic particles</a>. A black hole can pull in magnetic fields and energetic particles surrounding it, and then as the black hole rotates, the magnetic fields twist into a jet that sprays out highly energetic particles. </p>
389.  
390. <p>Magnetic fields twist around the black hole as it rotates to store energy – kind of like when you pull and twist a rubber band.  When you release the rubber band, it snaps forward. Similarly, the magnetic fields release their energy by producing these jets.</p>
391.  
392. <figure class="align-center zoomable">
393.            <a href="https://images.theconversation.com/files/656718/original/file-20250320-74-qcfffi.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing an accretion disk and black hole spraying out a jet of particles, surrounded by magnetic field lines." src="https://images.theconversation.com/files/656718/original/file-20250320-74-qcfffi.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/656718/original/file-20250320-74-qcfffi.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/656718/original/file-20250320-74-qcfffi.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/656718/original/file-20250320-74-qcfffi.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/656718/original/file-20250320-74-qcfffi.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/656718/original/file-20250320-74-qcfffi.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/656718/original/file-20250320-74-qcfffi.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
394.            <figcaption>
395.              <span class="caption">The accretion disk around a black hole can form a jet of hot, energetic particles surrounded by magnetic field lines.</span>
396.              <span class="attribution"><a class="source" href="https://esahubble.org/images/opo1332b/">NASA, ESA, and A. Feild (STScI)</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
397.            </figcaption>
398.          </figure>
399.  
400. <p>These jets can speed up or suppress the formation of stars in a galaxy, depending on how the energy is released into the black hole’s host galaxy.</p>
401.  
402. <h2>Rotating black holes</h2>
403.  
404. <p>Some black holes, however, rotate in a different direction than the accretion disk around them. This phenomenon is called counterrotation, and some <a href="https://doi.org/10.3390/galaxies11030066">studies my colleagues and I have conducted</a> suggest that it’s a key feature governing the behavior of one of the most powerful kinds of objects in the universe: the radio quasar. </p>
405.  
406. <p>Radio quasars are the subclass of black holes that produce the <a href="https://esahubble.org/wordbank/quasar/">most powerful energy and jets</a>. </p>
407.  
408. <p>You can imagine the black hole as a rotating sphere, and the accretion disk as a disk with a hole in the center. The black hole sits in that center hole and rotates one way, while the accretion disk rotates the other way. </p>
409.  
410. <p>This counterrotation forces the black hole to spin down and eventually up again in the other direction, called corotation. Imagine a basketball that spins one way, but you keep tapping it to rotate in the other. The tapping will spin the basketball down. If you continue to tap in the opposite direction, it will eventually spin up and rotate in the other direction. The accretion disk does the same thing.</p>
411.  
412. <p>Since the jets tap into the black hole’s rotational energy, they are powerful only when the black hole is spinning rapidly. The change from counterrotation to corotation takes at least 100 million years. Many initially counterrotating black holes take billions of years to become rapidly spinning corotating black holes.</p>
413.  
414. <p>So, these black holes would produce powerful jets both early and later in their lifetimes, with an interlude in the middle where the jets are either weak or nonexistent. </p>
415.  
416. <p>When the black hole spins in counterrotation with respect to its accretion disk, that motion produces strong jets that push molecules in the surrounding gas close together, <a href="https://doi.org/10.1088/1538-3873/ac8f70">which leads to</a> the <a href="https://www.cfa.harvard.edu/research/topic/star-formation">formation of stars</a>.</p>
417.  
418. <p>But later, in corotation, the jet tilts. This tilt makes it so that the jet impinges directly on the gas, heating it up and inhibiting star formation. In addition to that, the jet also <a href="https://theconversation.com/im-an-astrophysicist-mapping-the-universe-with-data-from-the-chandra-x-ray-observatory-clear-sharp-photos-help-me-study-energetic-black-holes-229668">sprays X-rays</a> across the galaxy. <a href="https://imagine.gsfc.nasa.gov/science/toolbox/xray_astronomy1.html">Cosmic X-rays</a> are bad for life because they can harm organic tissue. </p>
419.  
420. <p>For life to thrive, it most likely needs a planet with <a href="https://science.nasa.gov/exoplanets/habitable-zone/">a habitable ecosystem</a>, and clouds of hot gas saturated with X-rays don’t contain such planets. So, astronomers can instead look for galaxies without a tilted jet coming from its black hole. This idea is key to understanding where intelligence could potentially have emerged and matured in the universe. </p>
421.  
422. <h2>Black holes as a guide</h2>
423.  
424. <p>By early 2022, I had built <a href="https://doi.org/10.3390/galaxies11030066">a black hole model</a> to use as a guide. It could point out environments with the right kind of black holes to produce the greatest number of planets without spraying them with X-rays. Life in such environments could emerge to its full potential. </p>
425.  
426. <figure>
427.            <iframe width="440" height="260" src="https://www.youtube.com/embed/b7mTVX9IE0s?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
428.            <figcaption><span class="caption">Looking at black holes and their role in star formation could help scientists predict when and where life was most likely to form.</span></figcaption>
429.          </figure>
430.  
431. <p>Where are such conditions present? The answer is low-density environments where galaxies had merged about 11 billion years ago.</p>
432.  
433. <p>These environments had black holes whose powerful jets enhanced the rate of star formation, but they never experienced a bout of tilted jets in corotation. In short, <a href="https://doi.org/10.3390/galaxies11030066">my model suggested</a> that theoretically, the most advanced extraterrestrial civilization would have likely emerged on the cosmic scene <a href="https://phys.org/news/2023-05-advanced-life-peaked-billions-years.html">far away and billions of years ago</a>.</p><img src="https://counter.theconversation.com/content/251560/count.gif" alt="The Conversation" width="1" height="1" />
434. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;David Garofalo does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
435.    <summary>Whether a galactic environment has the right conditions for habitable planets to form could depend on how the black hole in that galaxy is rotating.</summary>
436.    <author>
437.      <name>David Garofalo, Professor of Physics, Kennesaw State University</name>
438.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/david-garofalo-2324507"/>
439.    </author>
440.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
441.  </entry>
442.  <entry>
443.    <id>tag:theconversation.com,2011:article/253343</id>
444.    <published>2025-03-31T03:19:40Z</published>
445.    <updated>2025-03-31T03:19:40Z</updated>
446.    <link rel="alternate" type="text/html" href="https://theconversation.com/the-best-space-telescope-you-never-heard-of-just-shut-down-253343"/>
447.    <title>The best space telescope you never heard of just shut down</title>
448.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/658592/original/file-20250331-56-6zm1s8.jpg?ixlib=rb-4.1.0&amp;amp;rect=904%2C0%2C4337%2C2436&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;&lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://www.esa.int/Science_Exploration/Space_Science/Gaia/Gaia_creates_richest_star_map_of_our_Galaxy_and_beyond"&gt;ESA / Gaia / DPAC&lt;/a&gt;, &lt;a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/"&gt;CC BY-SA&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;On Thursday 27 March, the European Space Agency &lt;a href="https://www.esa.int/"&gt;(ESA)&lt;/a&gt; sent its last messages to the &lt;a href="https://www.esa.int/Science_Exploration/Space_Science/Gaia"&gt;Gaia Spacecraft&lt;/a&gt;. They told Gaia to &lt;a href="https://www.esa.int/Enabling_Support/Operations/Farewell_Gaia!_Spacecraft_operations_come_to_an_end"&gt;shut down its communication systems and central computer&lt;/a&gt; and said goodbye to this amazing space telescope. &lt;/p&gt;
449.  
450. <p>Gaia has been the most successful ESA space mission ever, so why did they turn Gaia off? What did Gaia achieve? And perhaps most importantly, why was it my favourite space telescope?</p>
451.  
452.  
453.  
454. <h2>Running on empty</h2>
455.  
456. <p>Gaia was retired for a simple reason: after more than 11 years in space, it <a href="https://www.cosmos.esa.int/web/gaia/end-of-observations">ran out of the cold gas propellant</a> it needed to keep scanning the sky. </p>
457.  
458. <p>The telescope did its last observation on 15 January 2025. The ESA team then performed testing for a few weeks, before telling Gaia to leave its home at <a href="https://www.esa.int/Science_Exploration/Space_Science/Gaia_overview#:%7E:text=Gaia%20is%20mapping%20the%20stars,as%20we%20orbit%20the%20Sun">a point in space called L2</a> and start orbiting the Sun away from Earth.</p>
459.  
460. <p>L2 is one of five “Lagrangian points” around Earth and the Sun where gravitational conditions make for a nice, stable orbit. L2 is located 1.5 million kilometres from Earth on the “dark side”, opposite the Sun. </p>
461.  
462.  
463.  
464. <p>L2 is <a href="https://science.nasa.gov/solar-system/resources/faq/what-are-lagrange-points/">a highly prized location</a> because it’s a stable spot to orbit, it’s close enough to Earth for easy communication, and spacecraft can use the Sun behind them for solar power while looking away from the Sun out into space. </p>
465.  
466. <p>It’s also too far away from Earth to send anyone on a repair mission, so once your spacecraft gets there it’s on its own.</p>
467.  
468. <h2>Keeping L2 clear</h2>
469.  
470. <p>L2 currently hosts the <a href="https://science.nasa.gov/mission/webb/">James Webb Space Telescope</a> (operated by the USA, Europe and Canada), the European <a href="https://www.esa.int/Science_Exploration/Space_Science/Euclid">Euclid mission</a>, the Chinese <a href="https://spacenews.com/change-6-orbiter-turns-up-at-sun-earth-lagrange-point-after-moon-sampling-mission/">Chang’e 6 orbiter</a> and the <a href="https://www.eoportal.org/satellite-missions/spektrg-srg#background">joint Russian-German Spektr-RG</a> observatory. Since L2 is such a key location for space missions, it’s essential to keep it clear of debris and retired spacecraft.</p>
471.  
472. <figure class="align-center zoomable">
473.            <a href="https://images.theconversation.com/files/658600/original/file-20250331-56-9rh9cc.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="'Bye' appears in the status of Gaia's subsystems as the spacecraft is powered down and switched off for the final time" src="https://images.theconversation.com/files/658600/original/file-20250331-56-9rh9cc.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/658600/original/file-20250331-56-9rh9cc.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/658600/original/file-20250331-56-9rh9cc.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/658600/original/file-20250331-56-9rh9cc.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/658600/original/file-20250331-56-9rh9cc.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/658600/original/file-20250331-56-9rh9cc.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/658600/original/file-20250331-56-9rh9cc.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
474.            <figcaption>
475.              <span class="caption">A final status update from Gaia.</span>
476.              <span class="attribution"><a class="source" href="https://bsky.app/profile/operations.esa.int/post/3lldwldhjsk2n">ESA</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
477.            </figcaption>
478.          </figure>
479.  
480. <p>Gaia used its thrusters for the last time to push itself away from L2, and is now drifting around the Sun in a “retirement orbit” where it won’t get in anybody’s way. </p>
481.  
482. <p>As part of the retirement process, the Gaia team <a href="https://bsky.app/profile/operations.esa.int/post/3lldvduwgts2i">wrote farewell messages into the craft’s software</a> and sent it the names of around 1,500 people who worked on Gaia over the years.</p>
483.  
484. <h2>What is Gaia?</h2>
485.  
486. <p>Gaia looks a bit like a spinning top hat in space. Its main mission was to produce a detailed, <a href="https://astrobiology.nasa.gov/missions/gaia-space-observatory/#:%7E:text=Mission%20Overview,and%20evolution%20of%20the%20Galaxy.">three-dimensional map of our galaxy, the Milky Way</a>. </p>
487.  
488. <p>To do this, it measured the precise positions and motions of <a href="https://www.cosmos.esa.int/web/gaia/dr3">1.46 billion objects in space</a>. Gaia also measured brightnesses and variability and those data were used to provide temperatures, gravitational parameters, stellar types and more for millions of stars. One of the key pieces of information Gaia provided was the distance to millions of stars.</p>
489.  
490.  
491.  
492. <h2>A cosmic measuring tape</h2>
493.  
494. <p>I’m a radio astronomer, which means I use radio telescopes here on Earth to explore the Universe. Radio light is the longest wavelength of light, invisible to human eyes, and I use it to investigate magnetic stars. </p>
495.  
496. <p>But even though I’m a radio astronomer and Gaia was an optical telescope, looking at the same wavelengths of light our eyes can see, I use Gaia data almost every single day. </p>
497.  
498. <p>I used it today to find out how far away, how bright, and how fast a star was. Before Gaia, I would probably never have known how far away that star was. </p>
499.  
500. <p>This is essential for figuring out how bright <a href="https://ui.adsabs.harvard.edu/abs/2024PASA...41...84D/abstract">the stars I study</a> really are, which helps me understand the physics of what’s happening in and around them.</p>
501.  
502.  
503.  
504. <h2>A huge success</h2>
505.  
506. <p>Gaia has contributed to thousands of articles in astronomy journals. Papers released by the Gaia collaboration have been cited <a href="https://ui.adsabs.harvard.edu/search/q=docs(library%2Fgwvt3P9gSCSLw7rMseAE2w)&sort=citation_count%20desc%2C%20bibcode%20desc&p_=0">well over 20,000 times in total</a>.</p>
507.  
508. <p>Gaia has produced too many science results to share here. To take just one example, Gaia <a href="https://www.esa.int/ESA_Multimedia/Images/2025/01/The_best_Milky_Way_map_by_Gaia">improved our understanding of the structure of our own galaxy</a> by showing that it has multiple spiral arms that are less sharply defined than we previously thought.</p>
509.  
510.  
511.  
512. <h2>Not really the end for Gaia</h2>
513.  
514. <p>It’s difficult to express how revolutionary Gaia has been for astronomy, but we can let the numbers speak for themselves. Around five astronomy journal articles are published every day that use Gaia data, making Gaia <a href="https://phys.org/news/2025-02-mission-space-telescope-gaia.html">the most successful ESA mission ever</a>. And that won’t come to a complete stop when Gaia retires.</p>
515.  
516. <p>The Gaia collaboration has published three data releases so far. This is where the collaboration performs the processing and checks on the data, adds some important analysis and releases all of that in one big hit. </p>
517.  
518. <p>And luckily, there are <a href="https://www.cosmos.esa.int/web/gaia/release">two more big data releases</a> with even more information to come. The fourth data release is expected in mid to late 2026. The fifth and final data release, containing all of the Gaia data from the whole mission, will come out sometime in the 2030s.</p>
519.  
520. <p>This article is my own small tribute to a telescope that changed astronomy as we know it. So I will end by saying a huge thank you to everyone who has ever worked on this amazing space mission, whether it was engineering and operations, turning the data into the amazing resource it is, or any of the other many jobs that make a mission successful. And thank you to those who continue to work on the data as we speak. </p>
521.  
522. <p>Finally, thank you to my favourite space telescope. Goodbye, Gaia, I’ll miss you.</p><img src="https://counter.theconversation.com/content/253343/count.gif" alt="The Conversation" width="1" height="1" />
523. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Laura Nicole Driessen is an ambassador for the Orbit Centre of Imagination at the Rise and Shine Kindergarten, in Sydney&amp;#39;s Inner West.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
524.    <summary>An astronomer says goodbye to Gaia, the satellite that mapped the galaxy.</summary>
525.    <author>
526.      <name>Laura Nicole Driessen, Postdoctoral Researcher in Radio Astronomy, University of Sydney</name>
527.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/laura-nicole-driessen-892965"/>
528.    </author>
529.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
530.  </entry>
531.  <entry>
532.    <id>tag:theconversation.com,2011:article/252627</id>
533.    <published>2025-03-20T03:46:50Z</published>
534.    <updated>2025-03-20T03:46:50Z</updated>
535.    <link rel="alternate" type="text/html" href="https://theconversation.com/cosmic-dark-energy-may-be-weakening-astronomers-say-raising-questions-about-the-fate-of-the-universe-252627"/>
536.    <title>Cosmic dark energy may be weakening, astronomers say, raising questions about the fate of the universe</title>
537.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/656444/original/file-20250319-56-8gcr0a.jpeg?ixlib=rb-4.1.0&amp;amp;rect=0%2C5%2C3600%2C2387&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;&lt;/span&gt; &lt;span class="attribution"&gt;&lt;span class="source"&gt;KPNO / NOIRLab / NSF / AURAB / Tafreshi&lt;/span&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;The universe has been expanding ever since the Big Bang almost 14 billion years ago, and astronomers believe a kind of invisible force called dark energy is making it accelerate faster.&lt;/p&gt;
538.  
539. <p>However, <a href="https://data.desi.lbl.gov/doc/papers">new results</a> from the <a href="https://www.desi.lbl.gov/">Dark Energy Spectroscopic Instrument</a> (DESI), released today, suggest dark energy may be changing over time. </p>
540.  
541. <p>If the result is confirmed, it may overturn our current theories of cosmology – and have significant consequences for the eventual fate of the universe. In extreme scenarios, evolving dark energy could either accelerate the universe’s expansion to the point of tearing it apart in a “Big Rip” or cause it to collapse inward in a “Big Crunch”. </p>
542.  
543. <p>As a member of the DESI collaboration, which includes more than 900 researchers from 70 institutions worldwide, I have been involved in the analysis and interpretation of the dark energy results.</p>
544.  
545. <h2>A new picture of dark energy</h2>
546.  
547. <p><a href="https://iopscience.iop.org/article/10.1086/300499">First discovered in 1998</a>, dark energy is a kind of essence that seems to permeate space and make the universe expand at an ever-increasing rate. Cosmologists have generally assumed it is constant: it was the same in the past as it will be in the future.</p>
548.  
549. <p>The assumption of constant dark energy is baked into the widely accepted Lambda-CDM model of the universe. In this model, only 5% of the universe is made up of the ordinary matter we can see. Another 25% is invisible dark matter than can only be detected indirectly. And by far the bulk of the universe – a whopping 70% – is dark energy.</p>
550.  
551. <p>DESI’s results are not the only thing that gives us clues about dark energy. We can also look at evidence from a kind of exploding stars called Type Ia supernovae, and the way the path of light is warped as it travels through the universe (so-called weak gravitational lensing). </p>
552.  
553. <p>Measurements of the faint afterglow of the Big Bang (known as the cosmic microwave background) are also important. They do not directly measure dark energy or how it evolves, but they provide clues about the universe’s structure and energy content — helping to test dark energy models when combined with other data. </p>
554.  
555. <figure class="align-center zoomable">
556.            <a href="https://images.theconversation.com/files/656511/original/file-20250320-56-di81x6.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Oval image in splotches of blue, yellow and green." src="https://images.theconversation.com/files/656511/original/file-20250320-56-di81x6.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/656511/original/file-20250320-56-di81x6.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/656511/original/file-20250320-56-di81x6.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/656511/original/file-20250320-56-di81x6.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/656511/original/file-20250320-56-di81x6.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/656511/original/file-20250320-56-di81x6.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/656511/original/file-20250320-56-di81x6.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
557.            <figcaption>
558.              <span class="caption">The cosmic microwave background – the afterglow of the Big Bang – contains clues about the nature of dark energy.</span>
559.              <span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Cosmic_microwave_background#/media/File:WMAP_2012.png">WMAP / Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
560.            </figcaption>
561.          </figure>
562.  
563. <p>When the new DESI results are combined with all this cosmological data, we see hints that dark energy is more complicated than we thought. </p>
564.  
565. <p>It seems dark energy may have been stronger in the past and is now weakening. This result challenges the foundation of the Lambda-CDM model, and would have profound implications for the future of the universe. </p>
566.  
567. <h2>How DESI maps the universe</h2>
568.  
569. <p>The DESI project is based at the Kitt Peak National Observatory in Arizona. Its goal is to create the most extensive 3D map of the universe ever made. </p>
570.  
571. <p>To do this, it uses a powerful spectroscope to precisely measure the frequency of light coming from up to 5,000 distant galaxies at once. This lets astronomers determine how far away the galaxies are, and how fast they are moving.</p>
572.  
573. <p>By mapping galaxies, we can detect subtle patterns in their large-scale distribution called baryon acoustic oscillations. These patterns can be used as cosmic rulers to measure the history of the universe’s expansion. </p>
574.  
575. <figure class="align-center zoomable">
576.            <a href="https://images.theconversation.com/files/656507/original/file-20250320-62-de756b.jpeg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A large telescope with some kind of large black instrument attached to it." src="https://images.theconversation.com/files/656507/original/file-20250320-62-de756b.jpeg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/656507/original/file-20250320-62-de756b.jpeg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/656507/original/file-20250320-62-de756b.jpeg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/656507/original/file-20250320-62-de756b.jpeg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/656507/original/file-20250320-62-de756b.jpeg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/656507/original/file-20250320-62-de756b.jpeg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/656507/original/file-20250320-62-de756b.jpeg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
577.            <figcaption>
578.              <span class="caption">The Dark Energy Spectroscopic Instrument can analysed the frequency of light from up to 5,000 distant galaxies at a time.</span>
579.              <span class="attribution"><span class="source">Marilyn Sargent / Berkeley Lab</span></span>
580.            </figcaption>
581.          </figure>
582.  
583. <p>By tracking these patterns over time, DESI can map how the universe’s expansion rate has changed.</p>
584.  
585. <p>DESI is only halfway through a planned five-year survey of the universe, releasing data in batches as it goes. </p>
586.  
587. <p>The new results are based on the second batch of data, which includes measurements from more than 14 million galaxies and brightly glowing galactic cores called quasars. This dataset spans a cosmic time window of 11 billion years — from when the universe was just 2.8 billion years old to the present day.</p>
588.  
589. <h2>New data, new challenges</h2>
590.  
591. <p>The new DESI results represent a major step forward compared with what we saw in the first batch of data. The amount of data collected has more than doubled, which has improved the accuracy of the measurements and made the findings more reliable.</p>
592.  
593. <p>Results from the first batch of data gave a hint that dark energy might not behave like a simple cosmological constant — but it wasn’t strong enough to draw firm conclusions. Now, the second batch of data has made this evidence stronger.</p>
594.  
595. <p>The strength of the results depends on which other datasets it is combined with, particularly the type of supernova data included. However, no combination of data so far meets the typical “five sigma” statistical threshold physicists use as the marker of a confirmed new discovery.</p>
596.  
597. <h2>The fate of the universe</h2>
598.  
599. <p>Still, the fact this pattern is becoming clearer with more data suggests that something deeper might be going on. If there is no error in the data or the analysis, this could mean our understanding of dark energy – and perhaps the entire standard model of cosmology – needs to be revised.</p>
600.  
601. <p>If dark energy is changing over time, it could have profound implications for the ultimate fate of the universe. </p>
602.  
603. <p>If dark energy grows stronger over time, the universe could face a “Big Rip” scenario, where galaxies, stars, and even atoms are torn apart by the increasing expansion rate. If dark energy weakens or reverses, the expansion could eventually slow down or even reverse, leading to a “Big Crunch”.</p>
604.  
605. <h2>What’s next?</h2>
606.  
607. <p>DESI aims to collect data from a total of 40 million galaxies and quasars. The additional data will improve statistical precision and help refine the dark energy model even further.</p>
608.  
609. <p>Future DESI releases and independent cosmological experiments will be crucial in determining whether this represents a fundamental shift in our understanding of the universe.</p>
610.  
611. <p>Future data could confirm whether dark energy is indeed evolving – or whether the current hints are just a statistical anomaly. If dark energy is found to be dynamic, it could require new physics beyond Einstein’s theory of general relativity and open the door to new models of particle physics and quantum gravity.</p>
612.  
613. <figure>
614.            <iframe width="440" height="260" src="https://www.youtube.com/embed/fQkFS5yot5I?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
615.            
616.          </figure><img src="https://counter.theconversation.com/content/252627/count.gif" alt="The Conversation" width="1" height="1" />
617. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Rossana Ruggeri is part of the DESI Collaboration.  She receives funding from her ARC DECRA grant. She is affiliated with QUT and UQ. &lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
618.    <summary>A project to map galaxies across the universe may have spied cracks in the foundation of our understanding of the cosmos.</summary>
619.    <author>
620.      <name>Rossana Ruggeri, Lecturer and ARC DECRA Fellow, Queensland University of Technology</name>
621.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/rossana-ruggeri-1432957"/>
622.    </author>
623.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
624.  </entry>
625.  <entry>
626.    <id>tag:theconversation.com,2011:article/252382</id>
627.    <published>2025-03-17T19:10:48Z</published>
628.    <updated>2025-03-17T19:10:48Z</updated>
629.    <link rel="alternate" type="text/html" href="https://theconversation.com/less-than-1-of-the-worlds-biggest-radio-telescope-is-complete-but-its-first-image-reveals-a-sky-dotted-with-ancient-galaxies-252382"/>
630.    <title>Less than 1% of the world’s biggest radio telescope is complete – but its first image reveals a sky dotted with ancient galaxies</title>
631.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/655550/original/file-20250317-68-uad278.png?ixlib=rb-4.1.0&amp;amp;rect=42%2C649%2C2284%2C1390&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;The first image from an early working version of the SKA-Low telescope, showing around 85 galaxies.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;span class="source"&gt;SKAO&lt;/span&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;Part of the world’s biggest mega-science facility – the &lt;a href="https://www.skao.int/en"&gt;SKA Observatory&lt;/a&gt; – is being built in outback Western Australia. &lt;/p&gt;
632.  
633. <p>After decades of planning, countless hours of work, and more than a few setbacks, an early working version of the telescope has captured its first glimpse of the sky.</p>
634.  
635. <p>Using 1,024 of what will eventually be 131,072 radio antennas, the first <a href="https://www.skao.int/en/explore/telescopes/ska-low">SKA-Low</a> image shows a tiny sliver of sky dotted with ancient galaxies billions of light-years from Earth.</p>
636.  
637. <p>This first snapshot shows the system works, and will improve dramatically in the coming months and years – and starts a new chapter in our exploration of the universe. </p>
638.  
639. <h2>A glimpse of the universe</h2>
640.  
641. <p>The SKA-Low telescope is currently under construction on Wajarri Yamaji Country in Western Australia, around 600 kilometres north of Perth. Together with the SKA-Mid telescope (under construction in South Africa), the two telescopes will make up the world’s largest and most sensitive radio observatory.</p>
642.  
643. <p>SKA-Low will consist of thousands of antennas spread across a vast area. It is designed to detect low-frequency radio signals from some of the most distant and ancient objects in the universe.</p>
644.  
645. <p>The first image, made using just 1,024 of the planned 131,000 antennas, is remarkably clear, confirming that the complex systems for transmitting and processing data from the antennas are working properly. Now we can move on to more detailed observations to analyse and verify the telescope’s scientific output.</p>
646.  
647. <h2>Bright galaxies, billions of years old</h2>
648.  
649. <p>The image shows a patch of the sky, approximately 25 square degrees in area, as seen in radio waves.</p>
650.  
651. <p>Twenty-five square degrees is an area of sky that would fit 100 full Moons. For comparison, it would be about the area of sky that a small apple would cover if you held it at arm’s length.</p>
652.  
653. <figure class="align-center zoomable">
654.            <a href="https://images.theconversation.com/files/655550/original/file-20250317-68-uad278.png?ixlib=rb-4.1.0&rect=42%2C649%2C2284%2C1390&q=45&auto=format&w=1000&fit=clip"><img alt="Photo showing dots of white on a black background." src="https://images.theconversation.com/files/655550/original/file-20250317-68-uad278.png?ixlib=rb-4.1.0&rect=42%2C649%2C2284%2C1390&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/655550/original/file-20250317-68-uad278.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/655550/original/file-20250317-68-uad278.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/655550/original/file-20250317-68-uad278.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/655550/original/file-20250317-68-uad278.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/655550/original/file-20250317-68-uad278.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/655550/original/file-20250317-68-uad278.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
655.            <figcaption>
656.              <span class="caption">The first image from an early working version of the SKA-Low telescope, showing around 85 galaxies.</span>
657.              <span class="attribution"><span class="source">SKAO</span></span>
658.            </figcaption>
659.          </figure>
660.  
661. <p>The dots in the image look like stars, but are actually some of the brightest galaxies in the universe. These galaxies are billions of light-years away, so the galaxies we are seeing now were emitting this light when the universe was half its current age.</p>
662.  
663. <p>They are so bright because each of these distant galaxies contains a supermassive black hole. Gas orbiting around black holes is very hot and moves very quickly, emitting energy in X-rays and radio waves. SKA-Low can detect these radio waves that have travelled billions of light years across the universe to reach Earth.</p>
664.  
665. <h2>The world’s largest radio telescope</h2>
666.  
667. <p>SKA-Low and SKA-Mid are both being built by the SKAO, a global project to build cutting-edge telescopes that will revolutionise our understanding of the universe and deliver benefits to society. (SKA stands for “square kilometre array”, describing the initial estimated collecting area of all the antennas and radio dishes put together.)</p>
668.  
669. <p>My own involvement in the project began in 2014. Since then I, along with many local and international colleagues, have deployed and verified several prototype systems on the path to SKA-Low. To now be part of the team that is making the first images with the rapidly growing telescope is extremely satisfying.</p>
670.  
671. <h2>A complex system with no moving parts</h2>
672.  
673. <p>SKA-Low will be made up of 512 aperture arrays (or stations), each comprised of 256 antennas. </p>
674.  
675. <p>Unlike traditional telescopes, aperture arrays have no moving parts, which makes them easier to maintain. The individual antennas receive signals from all directions at once and – to produce images – we use complex mathematics to combine the signals from each individual antenna and “steer” the telescope. </p>
676.  
677. <figure class="align-center zoomable">
678.            <a href="https://images.theconversation.com/files/655560/original/file-20250317-56-fw31ny.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Photo of many Christmas-tree like antennas in an open field." src="https://images.theconversation.com/files/655560/original/file-20250317-56-fw31ny.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/655560/original/file-20250317-56-fw31ny.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/655560/original/file-20250317-56-fw31ny.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/655560/original/file-20250317-56-fw31ny.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/655560/original/file-20250317-56-fw31ny.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/655560/original/file-20250317-56-fw31ny.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/655560/original/file-20250317-56-fw31ny.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
679.            <figcaption>
680.              <span class="caption">The SKA-Low telescope uses arrays of radio antennas (called stations) to create images of the universe.</span>
681.              <span class="attribution"><span class="source">SKAO / Max Alexander</span></span>
682.            </figcaption>
683.          </figure>
684.  
685. <p>The advantages and flexibility of aperture arrays come at the cost of complex signal processing and software systems. Any errors in signal timing, calibration or processing can distort the final image or introduce noise.</p>
686.  
687. <p>For this reason, the successful production of the first image is a key validation – it can only happen if the entire system is working.</p>
688.  
689. <h2>The shape of the universe and beyond</h2>
690.  
691. <figure class="align-right zoomable">
692.            <a href="https://images.theconversation.com/files/655564/original/file-20250317-62-hp8r6r.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Images showing a patch of sky with increasingly more dots in it." src="https://images.theconversation.com/files/655564/original/file-20250317-62-hp8r6r.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/655564/original/file-20250317-62-hp8r6r.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=1800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/655564/original/file-20250317-62-hp8r6r.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=1800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/655564/original/file-20250317-62-hp8r6r.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=1800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/655564/original/file-20250317-62-hp8r6r.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=2262&fit=crop&dpr=1 754w, https://images.theconversation.com/files/655564/original/file-20250317-62-hp8r6r.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=2262&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/655564/original/file-20250317-62-hp8r6r.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=2262&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
693.            <figcaption>
694.              <span class="caption">As SKA-Low grows, it will see more detail. Simulations show the full telescope may detect up to 600,000 galaxies in the same patch of sky shown in the first test image.</span>
695.              <span class="attribution"><span class="source">SKAO</span></span>
696.            </figcaption>
697.          </figure>
698.  
699. <p>Once completed, SKA-Low promises to transform our understanding of the early universe. </p>
700.  
701. <p>The antennas of the full telescope will be spread across an area approximately 70 kilometres in diameter, making it the most sensitive low-frequency radio array ever built. </p>
702.  
703. <p>This unprecedented sensitivity to low-frequency radio signals will allow scientists to detect the faint signals from the first stars and galaxies that formed after the Big Bang – the so-called “cosmic dawn”. SKA-Low will be the first radio telescope capable of imaging this very early period of our universe.</p>
704.  
705. <p>It will also help map the large-scale structure of the universe. We expect the telescope will also provide new insights into cosmic magnetism, the behaviour of interstellar gas, and the mysterious nature of dark matter and dark energy.</p>
706.  
707. <p>The sensitivity and resolution of SKA-Low gives it a huge discovery potential. Seven out of the top 10 discoveries from the Hubble Space Telescope were not part of the original science motivation. Like the HST, SKA-Low promises to be a transformative telescope. Who knows what new discoveries await?</p>
708.  
709. <h2>What’s next</h2>
710.  
711. <p>SKA-Low’s commissioning process will ramp up over the course of the year, as more antenna arrays are installed and brought online. With each additional station, the sensitivity and resolution of the telescope will increase. This growth will also bring greater technical challenges in handling the growing complexity and data rates.</p>
712.  
713. <p>By the end of 2025, SKA-Low is expected to have 16 working stations. The increased volume of output data at this stage will be the next major test for the telescope’s software systems.</p>
714.  
715. <p>By the end of 2026, the array is planned to expand to 68 working stations at which point it will be the the most sensitive low-frequency radio telescope on Earth.</p>
716.  
717. <p>This phase will be the next big test of the end-to-end telescope system. When we get to this stage, the same field you see in the image above will be able to comprehensively map and detect up to 600,000 galaxies. I’m personally looking forward to helping bring it together.</p><img src="https://counter.theconversation.com/content/252382/count.gif" alt="The Conversation" width="1" height="1" />
718. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Randall Wayth does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
719.    <summary>The SKA-Low radio telescope in Western Australia is slowly coming online. It will probe the shape of the universe and study cosmic mysteries.</summary>
720.    <author>
721.      <name>Randall Wayth, SKA-Low Senior Commissioning Scientist and Adjunct Associate Professor, Curtin Institute of Radio Astronomy, Curtin University</name>
722.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/randall-wayth-213195"/>
723.    </author>
724.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
725.  </entry>
726.  <entry>
727.    <id>tag:theconversation.com,2011:article/244463</id>
728.    <published>2025-03-17T12:59:40Z</published>
729.    <updated>2025-03-17T12:59:40Z</updated>
730.    <link rel="alternate" type="text/html" href="https://theconversation.com/what-was-the-first-thing-scientists-discovered-a-historian-makes-the-case-for-babylonian-astronomy-244463"/>
731.    <title>What was the first thing scientists discovered? A historian makes the case for Babylonian astronomy</title>
732.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/651466/original/file-20250225-32-imdki5.jpg?ixlib=rb-4.1.0&amp;amp;rect=474%2C388%2C8702%2C4372&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;Ancient Babylonians looked to the skies to predict what would happen.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://www.gettyimages.com/detail/photo/old-engraved-illustration-of-ancient-babylonia-royalty-free-image/1470481552?adppopup=true"&gt;mikroman6/Moment via Getty Images&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;
733.  
734. <p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
735.  
736. <hr>
737.  
738. <blockquote>
739. <p><strong>What was the first thing scientists discovered? – Jacob, age 9, Santiago, Panama</strong></p>
740. </blockquote>
741.  
742. <hr>
743.  
744. <p>All societies have had ways of understanding nature based on their experiences of it. For example, farmers need to understand the seasons and weather to know when to plant and harvest their crops. Hunters need to understand the lives of animals to know how to hunt them.</p>
745.  
746. <p>This kind of understanding of the natural world isn’t quite the same as science though. <a href="https://spaceplace.nasa.gov/science/en/">Science</a> typically refers to knowledge that’s more organized and formal than that. It’s not just an explanation, but a system that uses observations and experiments to build theories that are recorded, passed on to others and built on.</p>
747.  
748. <p>With that idea in mind, as a historian of science, my best answer to the question of what the first scientists discovered is Babylonian astronomy.</p>
749.  
750. <p><a href="https://www.britannica.com/place/Babylonia">The Babylonians</a> lived from about 2,500 to 4,000 years ago in the area that’s now Iraq. What makes <a href="https://astrobites.org/2023/09/18/the-earliest-astronomers-a-brief-overview-of-babylonian-astronomy/">Babylonian astronomy</a> stand out as being especially scientific is the careful, organized way in which Babylonian scribes – their keepers of knowledge – observed, recorded and eventually mathematically predicted the ways that the Sun, Moon, stars and planets move in the skies.</p>
751.  
752. <h2>Babylonian astronomy was uniquely scientific</h2>
753.  
754. <p>Before clocks, observing the sky was how people knew the time. During the day you can see the Sun, and at night you can see the stars. Many calendars are based on the skies too. A month is about how long it takes the Moon to go through its phases. A year is one full revolution of the Earth around the Sun.</p>
755.  
756. <p>But keeping track of time wasn’t the only way the Babylonians used astronomy. Like today’s world, Babylonia could be both predictable and chaotic. The weather changed with the seasons; crops were planted and harvested; festivals were celebrated; people were born, aged and died, all predictably. But a bad harvest might cause high prices for grains and starvation; a king might die young, causing political upheaval; a disease might kill thousands, all unpredictably. </p>
757.  
758. <p>The stars and planets can seem like that, too. The stars are always in the same places in relation to one another, so you can identify constellations, and those constellations rise and set at regular times over the course of a year. But the planets move around – they’re not always in the same places, and <a href="https://www.sciencefocus.com/space/retrograde">sometimes they even seem to stop</a> and move backward in their paths. Sometimes even more spectacular events occur, such as <a href="https://theconversation.com/what-would-a-solar-eclipse-look-like-from-the-moon-an-astronomer-answers-that-and-other-total-eclipse-questions-81308">eclipses</a>.</p>
759.  
760. <figure class="align-center zoomable">
761.            <a href="https://images.theconversation.com/files/652387/original/file-20250228-32-sxgqjw.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="timelapse composite photo of the Moon passing over the Sun during an eclipse" src="https://images.theconversation.com/files/652387/original/file-20250228-32-sxgqjw.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/652387/original/file-20250228-32-sxgqjw.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=354&fit=crop&dpr=1 600w, https://images.theconversation.com/files/652387/original/file-20250228-32-sxgqjw.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=354&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/652387/original/file-20250228-32-sxgqjw.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=354&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/652387/original/file-20250228-32-sxgqjw.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=445&fit=crop&dpr=1 754w, https://images.theconversation.com/files/652387/original/file-20250228-32-sxgqjw.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=445&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/652387/original/file-20250228-32-sxgqjw.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=445&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
762.            <figcaption>
763.              <span class="caption">An eclipse might have seemed like a powerful omen of something that would happen next.</span>
764.              <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/in-this-composite-of-7-photographs-the-moon-passes-by-the-news-photo/2141956427">Josh Edelson/AFP via Getty Images</a></span>
765.            </figcaption>
766.          </figure>
767.  
768. <p>For the Babylonians, those ideas were linked. They saw changes in the motions of the planets or rare events such as eclipses as signs – omens – about what was going to happen on Earth. For example, they might think the shadow of the Earth moving over the Moon in a certain way during a lunar eclipse meant that a flood would also happen.</p>
769.  
770. <p>The scribes kept a book called <a href="https://brunelleschi.imss.fi.it/galileopalazzostrozzi/object/OmensBasedOnEclipses.html">Enūma Anu Enlil</a> listing omens and their meanings. So if the seemingly changing motions of the heavens could be predicted, maybe earthly events could be, too. This led the scribes to study astronomy.</p>
771.  
772. <h2>How Babylonian astronomy worked</h2>
773.  
774. <p>The foundation of Babylonian astronomy was kept in a book called <a href="https://brunelleschi.imss.fi.it/galileopalazzostrozzi/object/ThePloughStar.html">MUL.APIN</a>, meaning “The Plough Star,” the name of a constellation. It recorded the positions of the stars, when in the year they would first be visible, the paths of the Sun and Moon, the periods when the planets would be visible in the night sky, and other fundamental astronomical knowledge.</p>
775.  
776. <p>Later, Babylonian scribes began to keep their <a href="https://brunelleschi.imss.fi.it/galileopalazzostrozzi/object/AstronomicalDiary.html">Astronomical Diaries</a>, which contained detailed records of the positions of the Moon and planets along with events on Earth such as the weather and the price of grain. In other words, they recorded their observations of both astronomical omens and the events they might have predicted.</p>
777.  
778. <figure class="align-center zoomable">
779.            <a href="https://images.theconversation.com/files/652389/original/file-20250228-32-1zdnvh.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="columns of white notations on a black background" src="https://images.theconversation.com/files/652389/original/file-20250228-32-1zdnvh.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/652389/original/file-20250228-32-1zdnvh.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=266&fit=crop&dpr=1 600w, https://images.theconversation.com/files/652389/original/file-20250228-32-1zdnvh.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=266&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/652389/original/file-20250228-32-1zdnvh.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=266&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/652389/original/file-20250228-32-1zdnvh.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=334&fit=crop&dpr=1 754w, https://images.theconversation.com/files/652389/original/file-20250228-32-1zdnvh.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=334&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/652389/original/file-20250228-32-1zdnvh.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=334&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
780.            <figcaption>
781.              <span class="caption">Babylonian scribes used cuneiform to write down records of all kinds.</span>
782.              <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/old-engraved-illustration-of-ancient-babylonia-royalty-free-image/1470481641">mikroman6/Moment via Getty Images</a></span>
783.            </figcaption>
784.          </figure>
785.  
786. <p>This kind of careful observation and record-keeping is a major part of science. The Astronomical Diaries were kept for over 700 years, making them maybe the longest-running scientific project ever. </p>
787.  
788. <p>The records in the Astronomical Diaries helped Babylonian scribes take another scientific step: predicting astronomical events. One part of this was computing what the Babylonians called goal-years: the number of years it took for a planet to return to the same place on the same day. For example, they computed that the period for Venus was eight Babylonian years. So if Venus was somewhere on a particular day, it would be in the same place on the same day eight years later.</p>
789.  
790. <p>By around the fourth century B.C.E., the scribes developed this knowledge into a system of mathematically predicting astronomical events. They made tables called <a href="https://www.metmuseum.org/art/collection/search/321969">ephemerides</a> that showed when these events would happen in the future. So Babylonian scribes succeeded in their project: They made the motions of the Sun, Moon and planets predictable.</p>
791.  
792. <h2>Babylonian astronomy and you</h2>
793.  
794. <p>MUL.APIN, the Astronomical Diaries, the ephemerides and all of Babylonian astronomy had a major impact on later astronomers, one that continues to today. Greek astronomers used Babylonian observations to make geometric models of planetary motions, part of the long path toward modern astronomy. The ephemerides were the ancestors of astronomical tables, which still exist. For example, <a href="https://eclipse.gsfc.nasa.gov/SEcat5/catalog.html">NASA has a table of eclipses</a> online that goes to the year 3000.</p>
795.  
796. <figure class="align-right zoomable">
797.            <a href="https://images.theconversation.com/files/652390/original/file-20250228-32-uvrlas.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="analog clock mounted perpendicular to a wall" src="https://images.theconversation.com/files/652390/original/file-20250228-32-uvrlas.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/652390/original/file-20250228-32-uvrlas.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=792&fit=crop&dpr=1 600w, https://images.theconversation.com/files/652390/original/file-20250228-32-uvrlas.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=792&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/652390/original/file-20250228-32-uvrlas.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=792&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/652390/original/file-20250228-32-uvrlas.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=995&fit=crop&dpr=1 754w, https://images.theconversation.com/files/652390/original/file-20250228-32-uvrlas.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=995&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/652390/original/file-20250228-32-uvrlas.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=995&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
798.            <figcaption>
799.              <span class="caption">We tell time using the Babylonian system.</span>
800.              <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/old-fashioned-clock-in-urban-public-school-hallway-royalty-free-image/1205592295">Catherine McQueen/Moment via Getty Images</a></span>
801.            </figcaption>
802.          </figure>
803.  
804. <p>But the most familiar thing that comes from Babylonian astronomy is how we tell time. The Babylonians didn’t use a decimal system with units of 10 like we do. Instead, they <a href="https://www.nytimes.com/2013/07/09/science/60-behind-every-second-millenniums-of-history.html">used a sexagesimal system</a>, with units of 60. Babylonian observations were so important that later people kept Babylonian units for astronomy, even though they used a base 10 system for other things.</p>
805.  
806. <p>So if you’ve ever wondered why an hour has 60 minutes, and a minute has 60 seconds, it’s because we’ve kept that way of measuring from Babylonian astronomy. Whenever you tell the time, you’re using some of the very oldest science.</p>
807.  
808. <hr>
809.  
810. <p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>. Please tell us your name, age and the city where you live.</em></p>
811.  
812. <p><em>And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.</em></p><img src="https://counter.theconversation.com/content/244463/count.gif" alt="The Conversation" width="1" height="1" />
813. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;James Byrne does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
814.    <summary>Science uses careful, organized observations and tests to construct theories that are recorded, passed on to others and built on.</summary>
815.    <author>
816.      <name>James Byrne, Assistant Teaching Professor in the Herbst Program for Engineering, Ethics &amp; Society, University of Colorado Boulder</name>
817.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/james-byrne-2267808"/>
818.    </author>
819.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
820.  </entry>
821.  <entry>
822.    <id>tag:theconversation.com,2011:article/252170</id>
823.    <published>2025-03-17T10:03:59Z</published>
824.    <updated>2025-03-17T10:03:59Z</updated>
825.    <link rel="alternate" type="text/html" href="https://theconversation.com/youve-heard-of-the-big-bang-now-astronomers-have-discovered-the-big-wheel-heres-why-its-significant-252170"/>
826.    <title>You’ve heard of the Big Bang. Now astronomers have discovered the Big Wheel – here’s why it’s significant</title>
827.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/655018/original/file-20250313-56-cwv5zj.png?ixlib=rb-4.1.0&amp;amp;rect=147%2C188%2C1155%2C801&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;The Big Wheel alongside some of its neighbours. &lt;/span&gt; &lt;span class="attribution"&gt;&lt;span class="source"&gt;Weichen Wang et al. (2025)&lt;/span&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;Deep observations from the James Webb Space Telescope (JWST) have revealed an exceptionally large galaxy in the early universe. It’s a cosmic giant whose light has travelled over 12 billion years to reach us. We’ve dubbed it the Big Wheel, with our findings &lt;a href="https://www.nature.com/articles/s41550-025-02500-2"&gt;published today in Nature Astronomy&lt;/a&gt;. &lt;/p&gt;
828.  
829. <p>This giant disk galaxy existed within the first two billion years after the Big Bang, meaning it formed when the universe was just 15% of its current age. It challenges what we know about how galaxies form.</p>
830.  
831. <h2>What is a disk galaxy?</h2>
832.  
833. <p>Picture a galaxy like our own <a href="https://science.nasa.gov/resource/the-milky-way-galaxy">Milky Way</a>: a flat, rotating structure made up of stars, gas and dust, often surrounded by an extensive halo of unseen <a href="https://en.wikipedia.org/wiki/Dark_matter">dark matter</a>.</p>
834.  
835. <p>Disk galaxies typically have clear spiral arms extending outward from a dense central region. Our Milky Way itself is a disk galaxy, characterised by beautiful spiral arms that wrap around its centre. </p>
836.  
837. <figure>
838.            <iframe width="440" height="260" src="https://www.youtube.com/embed/cuKXQJgkeYg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
839.            <figcaption><span class="caption">An artist impression of the Milky Way showcasing the dusty spiral structures similar to The Big Wheel.</span></figcaption>
840.          </figure>
841.  
842. <p>Studying disk galaxies, like the Milky Way and the newly discovered Big Wheel, helps us uncover <a href="https://science.nasa.gov/universe/galaxies/evolution/">how galaxies form</a>, grow and evolve across billions of years.</p>
843.  
844. <p>These studies are especially significant, as understanding galaxies similar to our own can provide deeper insights into the cosmic history of our galactic home.</p>
845.  
846. <h2>A giant surprise</h2>
847.  
848. <p>We previously thought galaxy disks form gradually over a long period: either through gas smoothly flowing into galaxies from surrounding space, or by merging with smaller galaxies.</p>
849.  
850. <p>Usually, rapid mergers between galaxies would disrupt the delicate spiral structures, turning them into more chaotic shapes. However, the Big Wheel managed to quickly grow to a surprisingly large size without losing its distinctive spiral form. This challenges long-held ideas about the growth of giant galaxies.</p>
851.  
852. <p>Our detailed JWST observations show that the Big Wheel is comparable in size and rotational speed to the largest <a href="https://www.jpl.nasa.gov/news/astronomers-discover-colossal-super-spiral-galaxies/">“super-spiral” galaxies</a> in today’s universe. It is three times as big in size as comparable galaxies at that epoch and is one of the most massive galaxies observed in the early cosmos.</p>
853.  
854. <p>In fact, its rotation speed places it among galaxies at the high end of what’s called the <a href="https://en.wikipedia.org/wiki/Tully%E2%80%93Fisher_relation">Tully-Fisher relation</a>, a well-known link between a galaxy’s stellar mass and how fast it spins. </p>
855.  
856. <p>Remarkably, even though it’s unusually large, the Big Wheel is actively growing at a rate similar to other galaxies at the same cosmic age.</p>
857.  
858. <figure class="align-center zoomable">
859.            <a href="https://images.theconversation.com/files/655021/original/file-20250313-56-10dn99.png?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/655021/original/file-20250313-56-10dn99.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/655021/original/file-20250313-56-10dn99.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/655021/original/file-20250313-56-10dn99.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/655021/original/file-20250313-56-10dn99.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/655021/original/file-20250313-56-10dn99.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/655021/original/file-20250313-56-10dn99.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/655021/original/file-20250313-56-10dn99.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
860.            <figcaption>
861.              <span class="caption">The Big Wheel galaxy is seen at the centre. In striking contrast, the bright blue galaxy (upper right) is only about 1.5 billion light years away, making the Big Wheel roughly 50 times farther away. Although both appear a similar size, the enormous distance of the Big Wheel reveals its truly colossal physical scale.</span>
862.              <span class="attribution"><span class="source">JWST</span></span>
863.            </figcaption>
864.          </figure>
865.  
866. <h2>Unusually crowded part of space</h2>
867.  
868. <p>What makes this even more fascinating is the environment in which the Big Wheel formed.</p>
869.  
870. <p>It’s located in an unusually crowded region of space, where galaxies are packed closely together, ten times denser than typical areas of the universe. This dense environment likely provided ideal conditions for the galaxy to grow quickly. It probably experienced mergers that were gentle enough to let the galaxy maintain its spiral disk shape.</p>
871.  
872. <p>Additionally, the gas flowing into the galaxy must have aligned well with its rotation, allowing the disk to grow quickly without being disrupted. So, a perfect combination. </p>
873.  
874. <figure>
875.            <iframe width="440" height="260" src="https://www.youtube.com/embed/O674AZ_UKZk?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
876.            <figcaption><span class="caption">An illustration of how a massive spiral galaxy forms and evolves over billions of years. This evolutionary path is similar to real-world galaxies like Andromeda, our closest spiral galaxy neighbour, which also developed distinct spiral arms similar to the Big Wheel.</span></figcaption>
877.          </figure>
878.  
879. <h2>A fortunate finding</h2>
880.  
881. <p>Discovering a galaxy like the Big Wheel was incredibly unlikely. We had less than a 2% chance to find this in our survey, according to current galaxy formation models. </p>
882.  
883. <p>So, our finding was fortunate, probably because we observed it within an exceptionally dense region, quite different from typical cosmic environments.</p>
884.  
885. <p>Besides its mysterious formation, the ultimate fate of the Big Wheel is another intriguing question. Given the dense environment, future mergers might significantly alter its structure, potentially transforming it into a galaxy comparable in mass to the largest ones observed in nearby clusters, such as Virgo.</p>
886.  
887. <p>The Big Wheel’s discovery has revealed yet another mystery of the early universe, showing that our current models of galaxy evolution still need refinement.</p>
888.  
889. <p>With more observations and discoveries of massive, early galaxies like the Big Wheel, astronomers will be able to unlock more secrets about how the universe built the structures we see today.</p>
890.  
891. <hr>
892. <p>
893.  <em>
894.    <strong>
895.      Read more:
896.      <a href="https://theconversation.com/from-dead-galaxies-to-mysterious-red-dots-heres-what-the-james-webb-telescope-has-found-in-just-3-years-243592">From dead galaxies to mysterious red dots, here’s what the James Webb telescope has found in just 3 years</a>
897.    </strong>
898.  </em>
899. </p>
900. <hr>
901. <img src="https://counter.theconversation.com/content/252170/count.gif" alt="The Conversation" width="1" height="1" />
902. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Themiya Nanayakkara receives funding from Australian Research Council.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
903.    <summary>This enormous disk object formed soon after the Big Bang, challenging what we know about how galaxies grow.</summary>
904.    <author>
905.      <name>Themiya Nanayakkara, Lead Astronomer at the James Webb Australian Data Centre, Swinburne University of Technology</name>
906.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/themiya-nanayakkara-1324058"/>
907.    </author>
908.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
909.  </entry>
910.  <entry>
911.    <id>tag:theconversation.com,2011:article/252075</id>
912.    <published>2025-03-14T12:30:39Z</published>
913.    <updated>2025-03-14T12:30:39Z</updated>
914.    <link rel="alternate" type="text/html" href="https://theconversation.com/four-small-planets-discovered-around-one-of-the-closest-stars-to-earth-an-expert-explains-what-we-know-252075"/>
915.    <title>Four small planets discovered around one of the closest stars to Earth – an expert explains what we know</title>
916.    <content type="html">&lt;p&gt;Barnard’s Star is a small, dim star, of the type that astronomers call &lt;a href="https://www.britannica.com/science/red-dwarf-star"&gt;red dwarfs&lt;/a&gt;. Consequently, even though it is one of the closest stars to Earth, such that its light takes only six years to get here, it is too faint to be seen with the naked eye. Now, four small planets have &lt;a href="https://noirlab.edu/public/news/noirlab2510/"&gt;been found&lt;/a&gt; orbiting the star. Teams in America and Europe achieved this challenging detection by exploiting precision instruments on the world’s largest telescopes. &lt;/p&gt;
917.  
918. <p>Diminutive Barnard’s Star is closer in size to Jupiter than to the Sun. Only the three stars that make up the Alpha Centauri system lie closer to us. </p>
919.  
920. <p>The planets newly discovered around Barnard’s Star are much too faint to be seen directly, so how were they found? The answer lies in the effect of their gravity on the star. The mutual gravitational attraction keeps the planets in their orbits, but also tugs on the star, moving it in a rhythmic dance that can be detected by sensitive <a href="https://en.wikipedia.org/wiki/Optical_spectrometer">spectrograph</a> instruments. Spectrographs split up the star’s light into its component wavelengths. They can be used to <a href="https://www.nature.com/articles/nature13780">measure the</a> star’s motion. </p>
921.  
922. <p>A significant challenge for detection, however, is the star’s own behaviour. Stars are fluid, with the nuclear furnace at their core driving churning motions that generate a magnetic field (just as the churning of Earth’s molten core produces Earth’s magnetic field). The surfaces of red dwarf stars are rife with magnetic storms. <a href="https://link.springer.com/chapter/10.1007/3540313966_8">This activity</a> can mimic the signature of a planet when there isn’t one there.</p>
923.  
924.  
925.  
926. <p>The task of finding planets by this method starts with building highly sensitive spectrograph instruments. They are mounted on telescopes large enough to capture sufficient light from the star. The light is then sent to the spectrograph which records the data. The astronomers then observe a star over months or years. After carefully calibrating the resulting data, and accounting for stellar magnetic activity, one can then scrutinise the data for the tiny signals that reveal orbiting planets.</p>
927.  
928. <p>In 2024, a team led by Jonay González Hernández from the Canary Islands Astrophysics Institute <a href="https://ui.adsabs.harvard.edu/abs/2024A%26A...690A..79G/abstract">reported on</a> four years of monitoring of Barnard’s Star with the <a href="https://www.eso.org/sci/facilities/paranal/instruments/espresso.html">Espresso</a> spectrograph on the European Southern Observatory’s Very Large Telescope in Chile. They found one definite planet and reported tentative signals that indicated three more planets. </p>
929.  
930. <p>Now, a team led by Ritvik Basant from the University of Chicago in <a href="https://iopscience.iop.org/article/10.3847/2041-8213/adb8d5">a paper</a> just published in Astrophysical Journal Letters, have added in three years of monitoring with the <a href="https://www.gemini.edu/instrumentation/maroon-x">Maroon-X</a> instrument on the Gemini North telescope. Analysing their data confirmed the existence of three of the four planets, while combining both the datasets showed that all four planets are real.</p>
931.  
932. <p>Often in science, when detections push the limits of current capabilities, one needs to ponder the reliability of the findings. Are there spurious instrumental effects that the teams haven’t accounted for? Hence it is reassuring when independent teams, using different telescopes, instruments and computer codes, arrive at the same conclusions.  </p>
933.  
934. <figure class="align-center ">
935.            <img alt="Gemini North telescope." src="https://images.theconversation.com/files/654797/original/file-20250312-56-pjw8gy.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/654797/original/file-20250312-56-pjw8gy.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/654797/original/file-20250312-56-pjw8gy.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/654797/original/file-20250312-56-pjw8gy.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/654797/original/file-20250312-56-pjw8gy.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/654797/original/file-20250312-56-pjw8gy.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/654797/original/file-20250312-56-pjw8gy.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
936.            <figcaption>
937.              <span class="caption">The Gemini North telescope is located on Maunakea in Hawaii.</span>
938.              <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/gemini-north-observatory-on-top-mauna-2003813894">MarkoBeg / Shutterstock</a></span>
939.            </figcaption>
940.          </figure>
941.  
942. <p>The planets form a tightly packed, close-in system, having short orbital periods of between two and seven Earth days (for comparison, our Sun’s closest planet, Mercury, orbits in 88 days). It is likely they all have masses less than Earth’s. They’re probably rocky planets, with bare-rock surfaces blasted by their star’s radiation. They’ll be too hot to hold liquid water, and any atmosphere is likely to have been stripped away. </p>
943.  
944. <p>The teams looked for longer-period planets, further out in the star’s habitable zone, but didn’t find any. We don’t know much else about the new planets, such as their estimated sizes. The best way of figuring that out would be to watch for transits, when planets pass in front of their star, and then measure how much starlight they block. But the Barnard’s Star planets are not orientated in such a way that we see them “edge on” from our perspective. This means that the planets don’t transit, making them harder to study.</p>
945.  
946. <p>Nevertheless, the Barnard’s Star planets tell us about planetary formation. They’ll have formed in a <a href="https://www.aanda.org/articles/aa/full_html/2024/11/aa51388-24/aa51388-24.html">protoplanetary disk</a> of material that swirled around the star when it was young. Particles of dust will have stuck together, and gradually built up into rocks that aggregated into planets. Red dwarfs are the most common type of star, and most of them seem to have planets. Whenever we have sufficient observations of such stars we find planets, so there are likely to be far more planets in our galaxy than there are stars.</p>
947.  
948. <p>Most of the planets that have been discovered are close to their star, well inside the habitable zone (where liquid water could survive on the planet’s surface), but that’s largely because their proximity makes them much easier to find. Being closer in means that their gravitational tug is bigger, and it means that they have shorter orbital periods (so we don’t have to monitor the star for as long). It also increases their likelihood of transiting, and thus of being found in transit surveys. </p>
949.  
950. <p>The European Space Agency’s <a href="https://platomission.com/">Plato mission</a>, to be launched in 2026, is designed to find planets further from their stars. This should produce many more planets in their habitable zones, and should begin to tell us whether our own solar system, which has no close-in planets, is unusual.</p><img src="https://counter.theconversation.com/content/252075/count.gif" alt="The Conversation" width="1" height="1" />
951. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Coel Hellier has received research council grants for the discovery of exoplanets.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
952.    <summary>The small worlds were particularly challenging to discover.</summary>
953.    <author>
954.      <name>Coel Hellier, Professor of Astrophysics, Keele University</name>
955.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/coel-hellier-460658"/>
956.    </author>
957.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
958.  </entry>
959.  <entry>
960.    <id>tag:theconversation.com,2011:article/252033</id>
961.    <published>2025-03-14T03:24:42Z</published>
962.    <updated>2025-03-14T03:24:42Z</updated>
963.    <link rel="alternate" type="text/html" href="https://theconversation.com/saturn-now-has-274-moons-but-exactly-what-makes-something-a-moon-remains-unclear-252033"/>
964.    <title>Saturn now has 274 moons – but exactly what makes something a moon remains unclear</title>
965.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/655272/original/file-20250314-56-jhwds3.jpg?ixlib=rb-4.1.0&amp;amp;rect=0%2C273%2C2400%2C1548&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;Dione, one of Saturn&amp;#39;s 274 moons, viewed with Saturn and its rings in the background.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://photojournal.jpl.nasa.gov/catalog/PIA07744"&gt;NASA / JPL / Space Science Institute&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;Earlier this week, Saturn gained a whopping &lt;a href="https://www.nature.com/articles/d41586-025-00781-1"&gt;128 new official moons&lt;/a&gt;, as the International Astronomical Union &lt;a href="https://www.minorplanetcenter.net/mpec/RecentMPECs.html"&gt;recognised&lt;/a&gt; discoveries from a team of astronomers led by Edward Ashton at the Academia Sinica in Taiwan. The sixth planet from the Sun now has a grand total of 274 moons, the most of any planet in the Solar System.  &lt;/p&gt;
966.  
967. <p>The discovery has raised a lot of questions. How do you spot moons, and why hadn’t anybody seen these ones already? Doesn’t Jupiter have the most moons? What are they going to call all these moons? Are there more out there? And what exactly makes something a moon, anyway?</p>
968.  
969.  
970.  
971. <h1>Counting moons</h1>
972.  
973. <p>These new discoveries cement Saturn’s place as the winner of the Solar System’s moon competition, with more confirmed moons than all of the other planets combined. But it hasn’t always been this way.</p>
974.  
975. <p>Jupiter’s four largest moons – Io, Europa, Ganymede and Callisto – were the first ever discovered orbiting another planet. They were spotted by <a href="https://www.nasa.gov/history/410-years-ago-galileo-discovers-jupiters-moons/">Galileo Galilei more than 400 years ago, in 1610</a>. Saturn’s first known moon, <a href="https://science.nasa.gov/saturn/moons/titan/exploration/">Titan</a>, was discovered by Dutch astronomer Christiaan Huygens 45 years later.</p>
976.  
977.  
978.  
979. <p>The new batch of 128 moons was discovered by stacking images from the <a href="https://www.cfht.hawaii.edu/">Canada France Hawaii telescope</a>. Some of Saturn’s other moons were discovered by space voyages, and some during what are called “ring-plane crossings”. </p>
980.  
981. <p>When the <a href="https://science.nasa.gov/mission/voyager/voyager-1/">Voyager 1 spacecraft</a> passed by Saturn, it took images that were used to discover the moon <a href="https://science.nasa.gov/saturn/moons/atlas/">Atlas</a>. The <a href="https://science.nasa.gov/mission/cassini/">Cassini Mission</a> later discovered <a href="https://www.skyatnightmagazine.com/space-missions/cassini-mission">seven new Saturnian moons</a>.</p>
982.  
983. <p>A ring-crossing is where Saturn’s rings <a href="https://theconversation.com/will-saturns-rings-really-disappear-by-2025-an-astronomer-explains-217370">seem to disappear</a> from our point of view here on Earth. This is when Saturn is at just the right angle so we’re looking at the rings exactly side-on (that is, when we can only see the edge of the rings).</p>
984.  
985. <p>Titan was discovered during a ring-plane crossing, and so were <a href="https://hubblesite.org/contents/news-releases/1995/news-1995-25.html">12 other moons</a>. Saturn’s rings will be edge-on twice in 2025, in March and November.</p>
986.  
987.  
988.  
989. <h2>The moon race</h2>
990.  
991. <p>From 2019 to 2023, Jupiter and Saturn were fighting for first place in the moon race. </p>
992.  
993. <p>In 2019, Saturn surpassed Jupiter with the discovery of 20 new moons. This took the count to 82 for Saturn and 79 for Jupiter. </p>
994.  
995. <p>Just a few years later, in February 2023, Jupiter took the lead with <a href="https://www.astronomy.com/science/jupiter-now-has-92-moons-surpassing-saturn-for-record/">12 new moons</a>, beating Saturn’s 83 moons at the time. Only a short time later, still in 2023, the same astronomers who discovered the recent 128 moons discovered 62 moons orbiting Saturn. This placed the ringed planet firmly in the lead.</p>
996.  
997. <p>Elsewhere in the Solar System, Earth has one moon, Mars has two, Jupiter has 95, Uranus has 28 and Neptune has 16, for a total of 142 moons. We only need to discover ten more moons around Saturn to give it double the number of all the other planets combined.</p>
998.  
999. <h2>Regular or irregular?</h2>
1000.  
1001. <p>The newly discovered moons are all small. Each one is only a few kilometres across.  If something that small can be a moon, what really counts as a moon?</p>
1002.  
1003. <p><a href="https://science.nasa.gov/solar-system/moons/#:%7E:text=Naturally%2Dformed%20bodies%20that%20orbit,moons%20in%20our%20solar%20system.">NASA</a> tells us “naturally formed bodies that orbit planets are called moons”, but even asteroids can have moons. We <a href="https://science.nasa.gov/mission/dart/">crashed a spacecraft into an asteroid’s moon</a> in 2022. Earth has had <a href="https://theconversation.com/earth-is-getting-a-tiny-new-mini-moon-it-wont-be-the-first-or-the-last-239507">a few mini-moons</a>, some only a couple of metres in size. The line of what is and isn’t a moon is a bit hazy.</p>
1004.  
1005. <p>Moons orbiting planets in the Solar System can be either <a href="https://ui.adsabs.harvard.edu/abs/2025arXiv250307081A/abstract">“regular” or “irregular”</a>. The new moons are all irregular.</p>
1006.  
1007.  
1008.  
1009. <p>Regular moons are formed around a planet at the same time as the planet itself forms. Irregular moons are thought to be small planets (planetesimals) that are captured by a planet as it finishes forming. They are then broken into pieces by collisions. </p>
1010.  
1011. <p>Regular moons tend to orbit their planets in nice, circular orbits around the equator. Irregular moons typically orbit in big ovals further away from planets, and at a range of angles. Saturn has 24 regular moons and 250 irregular moons. </p>
1012.  
1013. <p>Studying these moons can tell us about how moons form, and reveal clues about <a href="https://ui.adsabs.harvard.edu/abs/2007AJ....133.1962N/abstract">how the Solar System formed and evolved</a>. </p>
1014.  
1015. <p>Saturn’s rings are made of small chunks of ice and rock. <a href="https://science.nasa.gov/saturn/facts/#:%7E:text=Space%20Science%20Institute-,Rings,other%20materials%20such%20as%20dust.">Astronomers think</a> they formed out of pieces of comets, asteroids and moons that were torn apart by Saturn’s gravity.</p>
1016.  
1017. <p>So for Saturn in particular, irregular moons can tell us more about the formation of <a href="https://theconversation.com/a-brief-astronomical-history-of-saturns-amazing-rings-120945">its beautiful rings</a>.</p>
1018.  
1019. <h2>What’s in a name?</h2>
1020.  
1021. <p>Names of astronomical objects are governed by the <a href="https://www.iau.org/public/themes/naming/">International Astronomical Union</a> (IAU). Originally, all moons in the Solar System were given names from Greco-Roman mythology. </p>
1022.  
1023. <p>But the large number of moons, particularly of Saturn and Jupiter, means the IAU has expanded to giants and gods from other mythology. And it’s all about the details. If binary moons are discovered, they are required to be given names of twins or siblings.</p>
1024.  
1025. <p>Saturn’s first seven moons were given <a href="https://pubs.aip.org/physicstoday/online/42281/The-controversial-origins-of-naming-moons">numbers instead of names</a>. In 1847, John Herschel named them after the <a href="https://www.britannica.com/topic/Titan-Greek-mythology">Greek Titans</a>. After they ran out of titans and Greek mythological giants, they expanded the naming system to include Inuit and Gallic gods and Norse giants.</p>
1026.  
1027. <p>Discoverers get to suggest names for moons, and the names they suggest are given priority by the IAU. In the past, there have been competitions to name new moons of <a href="https://www.iau.org/news/announcements/detail/ann19010/">Jupiter</a> and <a href="https://carnegiescience.edu/NameSaturnsMoons">Saturn</a>.</p>
1028.  
1029. <p>With 128 new moons for Saturn, it might take a while to come up with names that follow the IAU rules. Maybe we’ll even see the addition of different mythologies. We’ll have to wait and see. Until then, each moon has a name made of a string of numbers and letters, such as “S/2020 S 27”.</p>
1030.  
1031.  
1032.  
1033. <h2>Will we find more moons?</h2>
1034.  
1035. <p>Without a solid definition of what a moon is, it’s hard to say when (or if) we will ever finish finding them. Everyone agrees we shouldn’t call every single chunk of rock in Saturn’s rings a moon, but exactly where to draw the line isn’t clear.</p>
1036.  
1037. <p>That said, there is probably a limit to the number of moon-like objects astronomers are likely to want to add to the list. Edward Ashton, who led the discovery of the new moons, doesn’t think we’ll be finding too many new moons <a href="https://www.theguardian.com/science/2025/mar/11/astronomers-discover-128-new-moons-orbiting-saturn">until our technology improves</a>.</p><img src="https://counter.theconversation.com/content/252033/count.gif" alt="The Conversation" width="1" height="1" />
1038. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Laura Nicole Driessen is an ambassador for the Orbit Centre of Imagination at the Rise and Shine Kindergarten, in Sydney&amp;#39;s Inner West.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
1039.    <summary>The number of known moons in our Solar System has been rising for centuries, but astronomers say it has probably peaked – for now.</summary>
1040.    <author>
1041.      <name>Laura Nicole Driessen, Postdoctoral Researcher in Radio Astronomy, University of Sydney</name>
1042.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/laura-nicole-driessen-892965"/>
1043.    </author>
1044.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
1045.  </entry>
1046.  <entry>
1047.    <id>tag:theconversation.com,2011:article/251369</id>
1048.    <published>2025-03-13T00:20:42Z</published>
1049.    <updated>2025-03-13T00:20:42Z</updated>
1050.    <link rel="alternate" type="text/html" href="https://theconversation.com/a-lunar-eclipse-is-on-tomorrow-nz-and-parts-of-australia-are-in-for-a-spectacle-251369"/>
1051.    <title>A lunar eclipse is on tomorrow – NZ and parts of Australia are in for a spectacle</title>
1052.    <content type="html">&lt;p&gt;As the full moon rises tomorrow (Friday March 14), it will be a special sight for those in Aotearoa New Zealand. It will also be worth a look for people along the east coast of Australia. &lt;/p&gt;
1053.  
1054. <p>Rather than being full and bright, the Moon will be partway through a lunar eclipse, the first of two lunar eclipses to occur this year.</p>
1055.  
1056. <p>New Zealand is in for a treat as the Moon will rise during totality – when the Moon passes completely into Earth’s shadow. Instead of turning dark, the Moon takes on a reddish glow that’s colloquially referred to as a “blood moon”. </p>
1057.  
1058. <p>Along the east coast of Australia, totality will happen while the Moon is still below the horizon; by the time the Moon rises, it will be in part-shadow. </p>
1059.  
1060. <h2>A red Moon in Earth’s shadow</h2>
1061.  
1062. <p>When it’s a full moon, the Sun and the Moon are located on opposite sides of the sky. With Earth in the middle, it can cast a large shadow blocking the Sun’s light from reaching the Moon.</p>
1063.  
1064. <figure>
1065.            <iframe width="440" height="260" src="https://www.youtube.com/embed/kgY60MTURp0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
1066.            
1067.          </figure>
1068.  
1069. <p>However, during most full moons we don’t see an eclipse because the Moon’s orbit is slightly tilted – by just five degrees – compared to Earth’s orbit around the Sun. Most months the full moon passes either above or below Earth’s shadow. But twice a year, the path of the Moon takes it <em>through</em> the shadow instead. </p>
1070.  
1071. <p>When the Moon is fully immersed in shadow, the reason it turns red is entirely due to Earth’s atmosphere.  </p>
1072.  
1073. <h2>The first eclipse <em>from</em> the Moon</h2>
1074.  
1075. <p>The <a href="https://fireflyspace.com/missions/blue-ghost-mission-1/">Blue Ghost Mission 1</a>, which successfully landed on the Moon on March 2, will be the first to image an eclipse from the Moon. As we experience the lunar eclipse, the Blue Ghost 1 lander will see a total eclipse of the Sun thanks to Earth moving in front of it. </p>
1076.  
1077. <p>Being on the Moon during totality and looking up at the Earth, it should see the atmosphere lit up as a ring of red.</p>
1078.  
1079. <figure>
1080.            <iframe width="440" height="260" src="https://www.youtube.com/embed/j9BvZtwg2M4?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
1081.            
1082.          </figure>
1083.  
1084. <p>Only the low-wavelength red sunlight passes through the atmosphere because the bluer light is scattered away. This is also the reason why sunsets have red, orange and pink hues. </p>
1085.  
1086. <p>Importantly, the atmosphere also refracts or bends the light, redirecting it into Earth’s shadow and making the Moon appear red. </p>
1087.  
1088. <h2>When and where to look</h2>
1089.  
1090. <p>Lunar eclipses are brilliant to watch – they are perfectly safe and you don’t need special equipment. Since the Moon will be low in the sky, you will need a clear view of the eastern horizon, perhaps from somewhere high up. It’s a leisurely event, so it’s also great to have good company. </p>
1091.  
1092. <p>Since this eclipse happens at moonrise, you can use the website <a href="https://www.timeanddate.com/eclipse/lunar/2025-september-7">timeanddate.com</a> to check the moonrise time for your location and also to determine the eclipse magnitude, which is a measure of how much of the Moon is in shadow. </p>
1093.  
1094. <p>An eclipse magnitude of 1 or more means the Moon is fully in shadow or has reached totality.</p>
1095.  
1096. <p>If it is less than 1, it refers to the greatest fraction of the Moon’s diameter that is eclipsed. Imagine a diameter line across the Moon: where the edge of the shadow falls along that line will denote the magnitude of the eclipse. </p>
1097.  
1098. <figure class="align-center zoomable">
1099.            <a href="https://images.theconversation.com/files/654657/original/file-20250312-56-r3f8p5.png?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/654657/original/file-20250312-56-r3f8p5.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/654657/original/file-20250312-56-r3f8p5.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/654657/original/file-20250312-56-r3f8p5.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/654657/original/file-20250312-56-r3f8p5.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/654657/original/file-20250312-56-r3f8p5.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/654657/original/file-20250312-56-r3f8p5.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/654657/original/file-20250312-56-r3f8p5.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1100.            <figcaption>
1101.              <span class="caption">How lunar eclipse magnitude is measured: the fraction of an imaginary diameter that is in shadow. For Brisbane, it will be 57% of the line, therefore the magnitude is 0.57.</span>
1102.              <span class="attribution"><span class="source">Tanya Hill/The Conversation</span></span>
1103.            </figcaption>
1104.          </figure>
1105.  
1106. <p>Across New Zealand, the Moon will rise during totality. The farther north, the longer totality will be. By the time the Moon moves out of the shadow, twilight will have ended and the sky will be lovely and dark for the later part of the eclipse. </p>
1107.  
1108. <p><iframe id="K7l6s" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/K7l6s/1/" height="400px" width="100%" style="border: 0;" scrolling="no" frameborder="0"></iframe></p>
1109.  
1110. <p>On the east coast of Australia, the eclipse will be visible against the bright twilight sky. This will make it much harder to see from southern New South Wales, Victoria and Tasmania, since only a small part of the Moon will be in shadow. </p>
1111.  
1112. <p><iframe id="5zp5C" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/5zp5C/2/" height="400px" width="100%" style="border: 0;" scrolling="no" frameborder="0"></iframe></p>
1113.  
1114. <h2>Trick of the eye</h2>
1115.  
1116. <p>But wait, there’s more. Watching the Moon when it’s low on the horizon also creates an interesting effect called the Moon illusion. </p>
1117.  
1118. <p>Our brains trick us into thinking the Moon is much bigger than it usually is. But if you use your thumb to cover up the Moon when it’s low in the sky and then measure it again later in the evening when the Moon is up higher, you’ll see the Moon hasn’t really changed in size at all.</p>
1119.  
1120. <figure>
1121.            <iframe width="440" height="260" src="https://www.youtube.com/embed/49RztN4Bqu0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
1122.            
1123.          </figure>
1124.  
1125. <p>The illusion likely occurs because we instinctively think the <a href="https://www.pnas.org/doi/10.1073/pnas.97.1.500">sky is shaped like a dome</a> and that the Moon is closer to us when it’s overhead and farther away when it’s near the horizon. After all, that’s what happens when a bird flies off into the distance. </p>
1126.  
1127. <p>But the Moon is much farther away than a bird; its distance doesn’t change over the course of a night. </p>
1128.  
1129. <p>If our brains are telling us the Moon is farther away when it’s on the horizon, the Ponzo illusion demonstrates why we are tricked into thinking it appears bigger. In the image below the two moons are exactly the same size, but the perspective provided by the railway tracks makes us see the horizon one as larger. </p>
1130.  
1131.  
1132.  
1133. <p>If you aren’t able to see this eclipse, the second total lunar eclipse for 2025 will happen during the early hours of September 8.</p>
1134.  
1135. <p>It will be visible from across Australia, while New Zealand will see the eclipsed Moon setting at sunrise: almost an exact opposite to tomorrow’s eclipse.</p><img src="https://counter.theconversation.com/content/251369/count.gif" alt="The Conversation" width="1" height="1" />
1136. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Tanya Hill does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
1137.    <summary>A full moon, low on the horizon, tinted red – it’s a sight not to be missed.</summary>
1138.    <author>
1139.      <name>Tanya Hill, Honorary Fellow at University of Melbourne and Senior Curator (Astronomy), Museums Victoria Research Institute</name>
1140.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/tanya-hill-121214"/>
1141.    </author>
1142.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
1143.  </entry>
1144.  <entry>
1145.    <id>tag:theconversation.com,2011:article/250073</id>
1146.    <published>2025-03-12T14:14:31Z</published>
1147.    <updated>2025-03-12T14:14:31Z</updated>
1148.    <link rel="alternate" type="text/html" href="https://theconversation.com/black-holes-spew-out-powerful-jets-that-span-millions-of-light-years-were-trying-to-understand-their-whole-life-cycle-250073"/>
1149.    <title>Black holes spew out powerful jets that span millions of light-years – we’re trying to understand their whole life cycle</title>
1150.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/649434/original/file-20250217-38-e8vdw3.jpg?ixlib=rb-4.1.0&amp;amp;rect=0%2C0%2C5644%2C3572&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;An artistic representation of what a giant cosmic jet the size of the distance between the Milky Way and Andromeda could look like.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;span class="source"&gt;Author provided&lt;/span&gt;, &lt;a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/"&gt;CC BY-SA&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;There is a supermassive black hole at the centre of nearly every big galaxy – including ours, the Milky Way (it’s called &lt;a href="https://www.space.com/sagittarius-a"&gt;Sagittarius A*&lt;/a&gt;). Supermassive black holes are the densest objects in the universe, with masses reaching billions of times that of the Sun.&lt;/p&gt;
1151.  
1152. <p>Sometimes a galaxy’s supermassive black hole “wakes up” due to a sudden influx of gas and dust, most likely supplied from a neighbouring galaxy. It begins eating up lots of nearby gas and dust. This isn’t a calm, slow or passive process. As the black hole pulls in material, the material gets superheated on a scale of millions of degrees, far hotter than the surface temperature of our Sun, and is ejected from the galaxy at near-light speeds. This creates powerful jets that look like fountains in the cosmos. </p>
1153.  
1154. <p>The accelerated high-speed plasma matter prompts these “fountains” to emit radio signals that can only be detected by very powerful radio telescopes. This gives them their name: <a href="https://theconversation.com/radio-galaxies-the-mysterious-secretive-beasts-of-the-universe-64381">radio galaxies</a>. While black holes are common, radio galaxies are not. <a href="https://iopscience.iop.org/article/10.1088/0004-637X/740/1/20">Only between 10% and 20% of all galaxies</a> exhibit this phenomenon. </p>
1155.  
1156. <p>Giant radio galaxies are even less common. They account for only 5% of all radio galaxies and take their name from the fact that they reach enormous distances. Some radio galaxies’ jets reach <a href="https://www.aanda.org/articles/aa/full_html/2022/04/aa42778-21/aa42778-21.html">nearly 16 million light-years</a>. (That’s almost six times the distance between the Milky Way and the Andromeda galaxy.) The largest jet discovered <a href="https://www.nature.com/articles/s41586-024-07879-y">spans nearly 22 million light-years across</a>. </p>
1157.  
1158. <hr>
1159. <p>
1160.  <em>
1161.    <strong>
1162.      Read more:
1163.      <a href="https://theconversation.com/south-african-telescope-discovers-a-giant-galaxy-thats-32-times-bigger-than-earths-248023">South African telescope discovers a giant galaxy that's 32 times bigger than Earth's</a>
1164.    </strong>
1165.  </em>
1166. </p>
1167. <hr>
1168.  
1169.  
1170. <p>But how do these structures cover such enormous distances? To find out, I led a study in which <a href="https://www.aanda.org/articles/aa/full_html/2025/01/aa51812-24/aa51812-24.html">we used</a> modern supercomputers to develop models that simulated behaviour of giant cosmic jets within a mock universe, constructed on the basis of fundamental physical laws governing the cosmos.</p>
1171.  
1172. <p>This allowed us to observe how radio jets propagate over hundreds of millions of years – a process impossible to track directly in the real universe. These sophisticated simulations provide deeper insights into the life cycle of radio galaxies, highlighting the differences between their early, compact stages and their later, expansive forms. </p>
1173.  
1174. <p>Understanding the evolution of radio galaxies helps us unravel the broader processes that shape the universe.</p>
1175.  
1176. <h2>Supercomputing</h2>
1177.  
1178. <p>Cutting-edge technology was key to this study. </p>
1179.  
1180. <p>Sensitive observations from world-class radio telescopes like South Africa’s <a href="https://theconversation.com/meerkat-the-south-african-radio-telescope-thats-transformed-our-understanding-of-the-cosmos-227616">MeerKAT</a> and <a href="https://www.astron.nl/telescopes/lofar/">LOFAR</a> in the Netherlands have recently led to several discoveries of cosmic fountains. </p>
1181.  
1182. <hr>
1183. <p>
1184.  <em>
1185.    <strong>
1186.      Read more:
1187.      <a href="https://theconversation.com/meerkat-the-south-african-radio-telescope-thats-transformed-our-understanding-of-the-cosmos-227616">MeerKAT: the South African radio telescope that's transformed our understanding of the cosmos</a>
1188.    </strong>
1189.  </em>
1190. </p>
1191. <hr>
1192.  
1193.  
1194. <p>However, modelling their origins has been challenging. Tracking events over millions of years is impossible in real-time. </p>
1195.  
1196. <p>That’s where supercomputers come in. These high-performance computing systems are designed to process massive amounts of data. They can perform complex simulations at incredible speeds. In this study, their power was crucial for modelling the evolution of giant radio jets over millions of years. </p>
1197.  
1198. <p>The necessary supercomputing power was provided by South Africa’s <a href="https://idia.ac.za/">Inter-University Institute for Data Astronomy</a>, a network comprising the University of Pretoria, the University of Cape Town and the University of the Western Cape. </p>
1199.  
1200. <p>Our universe is governed by fundamental forces like gravity, which can be described through mathematical formulas. These formulas, essentially numbers, are fed into supercomputers to create a simulated “mock universe” that follows the same physical laws as the real cosmos. This allows scientists to experiment with how jets from supermassive black holes evolve over time. With their immense processing power, supercomputers can simulate millions of years of cosmic jet evolution in just a month.</p>
1201.  
1202. <h2>Key takeaways</h2>
1203.  
1204. <p>Gravity is the dominant force in the universe, pulling heavier matter and dragging nearby lighter matter. If gravity were the only force at play, the universe might have collapsed by now. Yet we see galaxies, galaxy clusters and even life itself thriving. We suspect that these cosmic fountains play a key role in solving the mystery of how this happens. </p>
1205.  
1206. <p>By releasing thermal and mechanical energy, they heat up the surrounding collapsing gas, counteracting gravity and maintaining a balance that sustains cosmic structures.</p>
1207.  
1208. <p>Our models also shed light on why some radio galaxies’ jets bend sharply, forming an “X” shape in radio waves instead of following a straight trajectory, and revealed the conditions under which giant fountains can continue growing even in dense cosmic environments (that is, in a galaxy cluster).</p>
1209.  
1210. <p>The study also suggests that giant radio galaxies may be statistically more common than previously believed. There are potentially thousands of undiscovered giant cosmic fountains. Thanks to world-class telescopes like MeerKAT and LOFAR – and the power of supercomputers – there’s plenty more to explore as we try to understand our universe.</p>
1211.  
1212. <p><em>The research on which this article is based required extensive collaboration with an international team, including Jacinta Delhaize from the University of Cape Town, Joydeep Bagchi from Christ University, India, and DJ Saikia from the Inter-University Centre for Astronomy and Astrophysics in India. Essential contributions by Kshitij Thorat and Roger Deane from the University of Pretoria also played a crucial role in shaping the study.</em></p><img src="https://counter.theconversation.com/content/250073/count.gif" alt="The Conversation" width="1" height="1" />
1213. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Gourab Giri does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
1214.    <summary>Understanding the evolution of radio galaxies is crucial for unravelling the broader processes that shape the universe.</summary>
1215.    <author>
1216.      <name>Gourab Giri, Postdoctoral researcher, University of Pretoria</name>
1217.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/gourab-giri-2328432"/>
1218.    </author>
1219.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
1220.  </entry>
1221.  <entry>
1222.    <id>tag:theconversation.com,2011:article/250251</id>
1223.    <published>2025-03-12T10:05:03Z</published>
1224.    <updated>2025-03-12T10:05:03Z</updated>
1225.    <link rel="alternate" type="text/html" href="https://theconversation.com/mysterious-radio-pulses-from-space-have-been-tracked-down-and-the-source-is-not-what-astronomers-expected-250251"/>
1226.    <title>Mysterious radio pulses from space have been tracked down – and the source is not what astronomers expected</title>
1227.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/651548/original/file-20250226-38-qyl5dt.jpg?ixlib=rb-4.1.0&amp;amp;rect=3%2C3%2C2649%2C1487&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;Artist&amp;#39;s impression of a red dwarf (left) and a white dwarf orbiting each other, resulting in radio pulses.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;span class="source"&gt;Daniëlle Futselaar/artsource.nl&lt;/span&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;In the past three years, astronomers have discovered a mysterious new type of radio source. We call these long period transients.&lt;/p&gt;
1228.  
1229. <p>These objects emit bright radio signals that repeat every few minutes to every few hours. We have found about a dozen examples, but we still don’t understand which type of star could emit radio pulses in this peculiar way.</p>
1230.  
1231. <p>In new research <a href="https://www.nature.com/articles/s41550-025-02491-0">published in Nature Astronomy</a> today, we have discovered a new long period transient. Furthermore, we identified the stars responsible for the mysterious radio flashes – a breakthrough never achieved before.</p>
1232.  
1233. <p>Spoiler alert: they’re not the typical “cosmic lighthouses” you might expect.</p>
1234.  
1235. <h2>What is a cosmic lighthouse?</h2>
1236.  
1237. <p>You may have heard of cosmic objects called pulsars – they’re a type of neutron star.</p>
1238.  
1239. <p>Neutron stars are the remnants of extremely massive stars when they’ve reached the end of their life. Pulsars are <em>rotating</em> neutron stars; as they spin, they emit a beam of radio emission that we can detect on Earth. This is why pulsars are often called <a href="https://www.space.com/32661-pulsars.html">cosmic lighthouses</a> – they “show” us a radio pulse on every rotation. We know of thousands of pulsars in our Milky Way galaxy. </p>
1240.  
1241. <p>You might think that sounds extremely similar to the mysterious long period transients I just described, and you’d be right.</p>
1242.  
1243. <p>However, the pulsars we know typically flash every second. These new objects show much slower repetition. According to theories about the evolution of neutron stars, pulsars that rotate this slowly shouldn’t exist.</p>
1244.  
1245. <p>So, is there another option?</p>
1246.  
1247. <p>White dwarfs are the other suggested source of long period transients. White dwarfs are the remnants of low-mass stars (like our Sun) at the end of their life, making them the smaller sibling of neutron stars. </p>
1248.  
1249. <figure class="align-center zoomable">
1250.            <a href="https://images.theconversation.com/files/651539/original/file-20250226-32-xheege.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/651539/original/file-20250226-32-xheege.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/651539/original/file-20250226-32-xheege.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/651539/original/file-20250226-32-xheege.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/651539/original/file-20250226-32-xheege.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/651539/original/file-20250226-32-xheege.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/651539/original/file-20250226-32-xheege.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/651539/original/file-20250226-32-xheege.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1251.            <figcaption>
1252.              <span class="caption">The central stations of the International LOFAR Telescope, a radio telescope in Europe.</span>
1253.              <span class="attribution"><a class="source" href="https://www.jb.man.ac.uk/news/2011/LOFAR-pulsars/">LOFAR/ASTRON</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
1254.            </figcaption>
1255.          </figure>
1256.  
1257. <h2>A cosmic detective hunt</h2>
1258.  
1259. <p>Using the international <a href="https://www.astron.nl/telescopes/lofar/">LOFAR</a> radio telescope in Europe, my colleagues and I discovered a new object: ILTJ1101+5521.</p>
1260.  
1261. <p><a href="https://academic.oup.com/mnras/article/531/4/4805/7691266">Ploughing through the LOFAR data</a>, we found seven bright pulses. Taking a closer look at the timing of these pulses, we found that they arrive every two hours (every 125.52978 ± 0.00002 minutes to be exact).</p>
1262.  
1263. <p>This made ILTJ1101 a new example of a long period transient.</p>
1264.  
1265.  
1266.  
1267. <p>We compared the location of the radio pulses to optical catalogues, which list stars and galaxies that telescopes have observed in visible light. And there it was – we found there was a faint red star exactly at the location of our radio pulses.</p>
1268.  
1269. <p>However, the properties of the radio pulses indicated these radio signals couldn’t be generated by this red star alone.</p>
1270.  
1271. <h2>A hidden companion</h2>
1272.  
1273. <p>Many stars have a stellar friend. The two stars are bound to each other and orbit each other. Known as binary stars, such pairings are incredibly common. About 50% of the stars with a mass similar to our Sun <a href="https://eos.org/articles/1-3-million-pairs-of-stars-surround-the-sun">have a binary companion</a>. </p>
1274.  
1275. <p>To investigate whether this was true for the red star at the location of our radio pulses, we took a spectrum. A spectrum shows how much light the star emits at each <a href="https://theconversation.com/explainer-what-is-the-electromagnetic-spectrum-8046">wavelength</a>.</p>
1276.  
1277. <p>Each type of star emits a unique spectral “<a href="https://en.wikipedia.org/wiki/Stellar_classification">fingerprint</a>”. Over different observations, we saw the fingerprint of the red star shift to slightly longer or shorter wavelengths. This effect is known as the <a href="https://theconversation.com/ive-calculated-santas-speed-on-christmas-eve-and-this-is-what-it-would-do-to-rudolphs-nose-245764">Doppler effect</a>, indicating that the star is moving away from us in one observation and moving towards us in the other. That’s similar to how the pitch of an ambulance siren changes as it moves towards you and then recedes in the distance.</p>
1278.  
1279. <p>The only way this type of movement can be achieved is if the red star is in a binary with another star. We found that the two stars orbit each other every two hours– that’s their orbital period.</p>
1280.  
1281. <p>It matches up perfectly with the puzzling slow repetition of the radio pulses we detected.</p>
1282.  
1283.  
1284.  
1285. <h2>What is the companion?</h2>
1286.  
1287. <p>Alongside spectra, we also had photometry measurements of ILTJ1101. Similar to the spectra, the photometry measurements show the amount of light the stars emit at different wavelengths. However, the spectra only covered a limited wavelength range, whereas the photometry measurements were taken over a much broader range of wavelengths.</p>
1288.  
1289. <p>From these photometry measurements we found a small excess of blue light. This light is not expected from the red star alone, and cannot be produced by a neutron star.</p>
1290.  
1291. <p>A white dwarf, however, perfectly fit the brief. </p>
1292.  
1293. <p>This is how we figured out that the radio pulses from ILTJ1101 are coming from a white dwarf in a binary system with a red star.</p>
1294.  
1295. <h2>Mystery solved? Not quite</h2>
1296.  
1297. <p>Does this mean all long period transients are white dwarf binaries? Probably not.</p>
1298.  
1299. <p>Some of these long period transients show very clear <a href="https://theconversation.com/a-strange-intermittent-radio-signal-from-space-has-astronomers-puzzled-231385">pulsar</a> <a href="https://theconversation.com/blinking-radio-pulses-from-space-hint-at-a-cosmic-object-that-shouldnt-exist-246663">characteristics</a>. Additionally, the periods of some long period transients are only <a href="https://theconversation.com/this-object-in-space-flashed-brilliantly-for-3-months-then-disappeared-astronomers-are-intrigued-175240">18 minutes</a>, which would be extremely short for an orbital period of a white dwarf binary. There is <a href="https://theconversation.com/astronomers-have-pinpointed-the-origin-of-mysterious-repeating-radio-bursts-from-space-244920">one other</a> long period transient that is likely to be associated with a white dwarf.</p>
1300.  
1301. <p>The current <a href="https://www.science.org/content/article/mysterious-radio-pulses-traced-dance-stellar-dwarfs">landscape</a> of long period transients is sparse. We need to find more of them to get a full understanding of these mysterious objects and how they work.</p>
1302.  
1303. <p>However, we now know that white dwarfs, with a little help from a stellar friend, can produce radio pulses just as bright as neutron stars.</p><img src="https://counter.theconversation.com/content/250251/count.gif" alt="The Conversation" width="1" height="1" />
1304. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Iris de Ruiter acknowledges support through the Australian Research Council Centre of Excellence for Gravitational Wave Discovery (OzGrav) and the CORTEX project of the research programme NWA-ORC which is (partly) financed by the Dutch Research Council (NWO).&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
1305.    <summary>Recently, astronomers have been puzzled by an unknown type of cosmic radio signal. A new breakthrough has finally traced one of them.</summary>
1306.    <author>
1307.      <name>Iris de Ruiter, Postdoctoral Researcher in OzGrav, University of Sydney</name>
1308.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/iris-de-ruiter-2269977"/>
1309.    </author>
1310.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
1311.  </entry>
1312.  <entry>
1313.    <id>tag:theconversation.com,2011:article/249141</id>
1314.    <published>2025-03-03T19:11:44Z</published>
1315.    <updated>2025-03-03T19:11:44Z</updated>
1316.    <link rel="alternate" type="text/html" href="https://theconversation.com/ghosts-of-the-radio-universe-astronomers-have-discovered-a-slew-of-faint-circular-objects-249141"/>
1317.    <title>‘Ghosts of the radio universe’: astronomers have discovered a slew of faint circular objects</title>
1318.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/648791/original/file-20250213-17-3jg5ar.png?ixlib=rb-4.1.0&amp;amp;rect=9%2C417%2C1260%2C785&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;Some of the objects captured by ASKAP.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;span class="source"&gt;Author provided&lt;/span&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;Radio astronomers see what the naked eye can’t. As we study the sky with telescopes that record radio signals rather than light, we end up seeing a lot of circles. &lt;/p&gt;
1319.  
1320. <p>The newest generation of radio telescopes – including the <a href="https://www.csiro.au/en/about/facilities-collections/atnf/askap-radio-telescope">Australian Square Kilometre Array Pathfinder</a> (ASKAP) and <a href="https://www.sarao.ac.za/science/meerkat/about-meerkat/">MeerKAT</a>, a telescope in South Africa – is revealing incredibly faint cosmic objects, never before seen.</p>
1321.  
1322. <p>In astronomy, surface brightness is a measure that tells us how easily visible an object is. The extraordinary sensitivity of MeerKAT and ASKAP is now revealing a new “low surface brightness universe” to radio astronomers. It’s comprised of radio sources so faint they have never been seen before, each with their own unique physical properties.</p>
1323.  
1324. <p>Many of the ASKAP results presented here were obtained with one of its major observing programs called EMU (<a href="https://emu-survey.org/">Evolutionary Map of the Universe</a>). EMU is mapping the entire southern sky with an unprecedented sensitivity and will deliver the most detailed map of the southern hemisphere sky to date – a spectacular new radio atlas that will be used for decades to come.</p>
1325.  
1326. <p>EMU’s all-hemisphere coverage paired with ASKAP’s exceptional sensitivity, especially within the Milky Way, is what’s yielded so many recent discoveries.</p>
1327.  
1328. <p>Here’s what they’re teaching us.</p>
1329.  
1330. <h2>Unstable stars</h2>
1331.  
1332. <figure class="align-center zoomable">
1333.            <a href="https://images.theconversation.com/files/648513/original/file-20250212-15-7vrpw3.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/648513/original/file-20250212-15-7vrpw3.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/648513/original/file-20250212-15-7vrpw3.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=285&fit=crop&dpr=1 600w, https://images.theconversation.com/files/648513/original/file-20250212-15-7vrpw3.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=285&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/648513/original/file-20250212-15-7vrpw3.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=285&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/648513/original/file-20250212-15-7vrpw3.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=358&fit=crop&dpr=1 754w, https://images.theconversation.com/files/648513/original/file-20250212-15-7vrpw3.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=358&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/648513/original/file-20250212-15-7vrpw3.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=358&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1334.            <figcaption>
1335.              <span class="caption">Kyklos (left) and WR16 (r).</span>
1336.              <span class="attribution"><span class="source">Author provided</span></span>
1337.            </figcaption>
1338.          </figure>
1339.  
1340. <p>The ghostly ring <a href="https://ui.adsabs.harvard.edu/link_gateway/2024A&A...690A..53B/doi:10.1051/0004-6361/202450766">Kýklos</a> (from the Greek κύκλος, circle or ring) and the object WR16 both show the environment of rare and unusual celestial objects known as Wolf-Rayet stars. </p>
1341.  
1342. <p>When big stars are close to running out of fuel, they become unstable as they enter one of the last stages of the stellar life cycle, becoming a Wolf-Rayet star. They begin surging and pulsing, shedding their outer layers which can form bright nebulous structures around the star.</p>
1343.  
1344. <p>In these objects, a previous outflow of material has cleared the space around the star, allowing the current outburst to expand symmetrically in all directions. This sphere of stellar detritus shows itself as a circle.</p>
1345.  
1346. <h2>Exploded stars</h2>
1347.  
1348. <figure class="align-center zoomable">
1349.            <a href="https://images.theconversation.com/files/648516/original/file-20250212-17-zqavq3.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/648516/original/file-20250212-17-zqavq3.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/648516/original/file-20250212-17-zqavq3.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=568&fit=crop&dpr=1 600w, https://images.theconversation.com/files/648516/original/file-20250212-17-zqavq3.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=568&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/648516/original/file-20250212-17-zqavq3.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=568&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/648516/original/file-20250212-17-zqavq3.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=713&fit=crop&dpr=1 754w, https://images.theconversation.com/files/648516/original/file-20250212-17-zqavq3.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=713&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/648516/original/file-20250212-17-zqavq3.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=713&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1350.            <figcaption>
1351.              <span class="caption">Left to right clocwise: the supernova remnants Stingray 1, Perun, Ancora and Unicycle.</span>
1352.              <span class="attribution"><span class="source">Author provided</span></span>
1353.            </figcaption>
1354.          </figure>
1355.  
1356. <p>Stingray 1, <a href="https://ui.adsabs.harvard.edu/abs/2024MNRAS.534.2918S/abstract">Perun</a>, <a href="https://ui.adsabs.harvard.edu/abs/2024A&A...684A.150B/abstract">Ancora</a> and <a href="https://ui.adsabs.harvard.edu/abs/2024RNAAS...8..158S/abstract">Unicycle</a> are supernova remnants. When a big star finally runs out of fuel, it can no longer hold back the crush of gravity. The matter falling inwards causes one final explosion, and the remains of these violent star deaths are known as supernovas.</p>
1357.  
1358. <p>Their expanding shockwaves sweep up material into an expanding sphere, forming beautiful circular features.</p>
1359.  
1360. <p>The supernova remnant will be deformed by its environment over time. If one side of the explosion slams into an interstellar cloud, we’ll see a squashed shape. So, a near-perfect circle in a messy universe is a special find.</p>
1361.  
1362. <p>Teleios – named from the Greek Τελεɩοσ (“perfect”) for its near-perfectly circular shape – is shown below. This unique object has never been seen in any wavelength, including visible light, demonstrating ASKAP’s incredible ability to discover new objects.</p>
1363.  
1364. <p>The shape indicates Teleios has remained relatively untouched by its environment. This presents us with an opportunity to make inferences about the initial supernova explosion, providing rare insight into one of the most energetic events in the universe.</p>
1365.  
1366. <figure class="align-center zoomable">
1367.            <a href="https://images.theconversation.com/files/648789/original/file-20250213-17-ofqbic.png?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/648789/original/file-20250213-17-ofqbic.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/648789/original/file-20250213-17-ofqbic.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=439&fit=crop&dpr=1 600w, https://images.theconversation.com/files/648789/original/file-20250213-17-ofqbic.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=439&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/648789/original/file-20250213-17-ofqbic.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=439&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/648789/original/file-20250213-17-ofqbic.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=552&fit=crop&dpr=1 754w, https://images.theconversation.com/files/648789/original/file-20250213-17-ofqbic.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=552&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/648789/original/file-20250213-17-ofqbic.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=552&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1368.            <figcaption>
1369.              <span class="caption">ASKAP EMU radio image of the Teleios supernova remnant.</span>
1370.              <span class="attribution"><span class="source">Author provided</span></span>
1371.            </figcaption>
1372.          </figure>
1373.  
1374. <p>At the other extreme, we can take an object and discover something entirely new about it. The Diprotodon supernova remnant is shown below. </p>
1375.  
1376. <p>This remnant is one of the largest objects in the sky, appearing approximately six times larger than the Moon. Hence the name: the animal Diprotodon, <a href="https://australian.museum/learn/australia-over-time/extinct-animals/diprotodon-optatum/">one of Australia’s most famous megafauna</a>, a giant wombat that lived about 25,000 years ago.</p>
1377.  
1378. <p>ASKAP’s sensitivity has uncovered the object’s full extent. This discovery led to further analysis, uncovering more of the history and the physics behind this object. The messy internal structure can be seen as different parts of the expanding shell slam into a busy interstellar environment.</p>
1379.  
1380. <figure class="align-center zoomable">
1381.            <a href="https://images.theconversation.com/files/648790/original/file-20250213-15-sgnfa7.png?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/648790/original/file-20250213-15-sgnfa7.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/648790/original/file-20250213-15-sgnfa7.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=608&fit=crop&dpr=1 600w, https://images.theconversation.com/files/648790/original/file-20250213-15-sgnfa7.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=608&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/648790/original/file-20250213-15-sgnfa7.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=608&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/648790/original/file-20250213-15-sgnfa7.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=764&fit=crop&dpr=1 754w, https://images.theconversation.com/files/648790/original/file-20250213-15-sgnfa7.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=764&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/648790/original/file-20250213-15-sgnfa7.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=764&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1382.            <figcaption>
1383.              <span class="caption">ASKAP radio image of Diprotodon, a supernova remnant. Green circle shows the previous measured size, and the yellow circle shows the new ASKAP measured size. Earth’s Moon size is shown in the top right for scale, and Diprotodon’s namesake is shown in the top left.</span>
1384.              <span class="attribution"><span class="source">Author provided</span></span>
1385.            </figcaption>
1386.          </figure>
1387.  
1388. <h2>A cosmic mirror</h2>
1389.  
1390. <p>Lagotis is another object that can show how new telescope data can reclassify previously discovered objects. The reflection nebula VdB-80 has been seen before, within the plane of our Milky Way galaxy. The light we see was emitted by nearby stars, and then reflected off a nearby cloud of gas and dust.</p>
1391.  
1392. <figure class="align-right zoomable">
1393.            <a href="https://images.theconversation.com/files/648519/original/file-20250212-15-y6z2ok.png?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/648519/original/file-20250212-15-y6z2ok.png?ixlib=rb-4.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/648519/original/file-20250212-15-y6z2ok.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=541&fit=crop&dpr=1 600w, https://images.theconversation.com/files/648519/original/file-20250212-15-y6z2ok.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=541&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/648519/original/file-20250212-15-y6z2ok.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=541&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/648519/original/file-20250212-15-y6z2ok.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=680&fit=crop&dpr=1 754w, https://images.theconversation.com/files/648519/original/file-20250212-15-y6z2ok.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=680&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/648519/original/file-20250212-15-y6z2ok.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=680&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1394.            <figcaption>
1395.              <span class="caption">Lagotis, with its cloud of ionised hydrogen or HII region seen on the right.</span>
1396.              <span class="attribution"><span class="source">Author provided</span></span>
1397.            </figcaption>
1398.          </figure>
1399.  
1400. <p>However, with newly available ASKAP EMU data, we were able <a href="https://arxiv.org/abs/2502.05299">to discover an associated cloud of ionised hydrogen</a> (known as an HII region, pronounced “aitch two”), where stellar energy has caused the gaseous matter to lose its electrons.</p>
1401.  
1402. <p>This HII region is seen to coexist with the reflection nebula, sharing the same stellar centre, and is created from the star pushing into a molecular cloud. This movement is akin to burrowing, so the object earned the name Lagotis after <a href="https://australian.museum/learn/animals/mammals/greater-bilby/"><em>Macrotis lagotis</em>, the Australian greater bilby</a>.</p>
1403.  
1404. <h2>Outside the galaxy</h2>
1405.  
1406. <p>ASKAP and MeerKAT are also illuminating objects from outside our Milky Way galaxy – for example, “radio ring” galaxies. When we use visible light to look at the stars in this galaxy, we see a rather plain disk.</p>
1407.  
1408. <p>But in radio light, we see a ring. Why is there a hole in the middle? Perhaps the combined force of many exploding supernovas has pushed all the radio-emitting clouds out of the centre. We’re not sure – we’re looking for more examples to test our ideas.</p>
1409.  
1410. <p>Finally, LMC-ORC is an Odd Radio Circle (ORC), a prominent <a href="https://theconversation.com/odd-radio-circles-that-baffled-astronomers-are-likely-explosions-from-distant-galaxies-178290">new class of objects with unfamiliar origins</a>. Only being visible in radio light, they are perhaps the most mysterious of all.</p>
1411.  
1412. <figure class="align-center zoomable">
1413.            <a href="https://images.theconversation.com/files/648522/original/file-20250212-15-o142h6.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/648522/original/file-20250212-15-o142h6.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/648522/original/file-20250212-15-o142h6.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=279&fit=crop&dpr=1 600w, https://images.theconversation.com/files/648522/original/file-20250212-15-o142h6.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=279&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/648522/original/file-20250212-15-o142h6.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=279&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/648522/original/file-20250212-15-o142h6.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=351&fit=crop&dpr=1 754w, https://images.theconversation.com/files/648522/original/file-20250212-15-o142h6.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=351&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/648522/original/file-20250212-15-o142h6.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=351&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1414.            <figcaption>
1415.              <span class="caption">A radio ring galaxy (left) and LMC-ORC (r).</span>
1416.              <span class="attribution"><span class="source">Author provided</span></span>
1417.            </figcaption>
1418.          </figure>
1419.  
1420. <h2>The next generation</h2>
1421.  
1422. <p>MeerKAT and ASKAP are revealing incredible insights into the low surface brightness universe. However, they are precursors for <a href="https://theconversation.com/in-australia-and-south-africa-construction-has-started-on-the-biggest-radio-observatory-in-earths-history-195818">the Square Kilometre Array</a>, an international collaborative endeavour that will increase the abilities of radio astronomers and reveal even more unique features of the universe.</p>
1423.  
1424. <p>The low-surface brightness universe presents many mysteries. These discoveries push our understanding further. Currently, the EMU survey using ASKAP is only 25% complete. </p>
1425.  
1426. <p>As more of this survey becomes available, we will discover many more unique and exciting objects, both new to astrophysics and extensions on previously known objects. </p>
1427.  
1428. <hr>
1429.  
1430. <p><em>Acknowledgements: Aaron Bradley and Zachary Smeaton, Masters Research Students at Western Sydney University, made valuable contributions to this article.</em></p><img src="https://counter.theconversation.com/content/249141/count.gif" alt="The Conversation" width="1" height="1" />
1431. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Nicholas Tothill receives funding from the Australian Research Council. &lt;/span&gt;&lt;/em&gt;&lt;/p&gt;&lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Andrew Hopkins, Luke Barnes, and Miroslav Filipovic do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
1432.    <summary>The newest generation of radio telescopes can detect objects so faint, we’ve never seen them before.</summary>
1433.    <author>
1434.      <name>Miroslav Filipovic, Professor, Western Sydney University</name>
1435.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/miroslav-filipovic-123940"/>
1436.    </author>
1437.    <author>
1438.      <name>Andrew Hopkins, Professor of Astronomy, Macquarie University</name>
1439.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/andrew-hopkins-784566"/>
1440.    </author>
1441.    <author>
1442.      <name>Luke Barnes, Senior Lecturer in Physics, Western Sydney University</name>
1443.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/luke-barnes-123126"/>
1444.    </author>
1445.    <author>
1446.      <name>Nicholas Tothill, Associate professor, Western Sydney University</name>
1447.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/nicholas-tothill-2323063"/>
1448.    </author>
1449.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
1450.  </entry>
1451.  <entry>
1452.    <id>tag:theconversation.com,2011:article/250187</id>
1453.    <published>2025-02-27T14:53:51Z</published>
1454.    <updated>2025-02-27T14:53:51Z</updated>
1455.    <link rel="alternate" type="text/html" href="https://theconversation.com/a-new-study-reveals-the-structure-of-violent-winds-1-300-light-years-away-250187"/>
1456.    <title>A new study reveals the structure of violent winds 1,300 light years away</title>
1457.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/649756/original/file-20250218-32-a7mbe.jpg?ixlib=rb-4.1.0&amp;amp;rect=17%2C23%2C3976%2C2574&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;The largest telescopes in the world are used to look at the atmospheres of planets orbiting other stars and located at astronomical distances.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://cdn.eso.org/images/large/potw1401a.jpg"&gt;Y. Beletsky(LCO)/ESO&lt;/a&gt;, &lt;a class="license" href="http://creativecommons.org/licenses/by/4.0/"&gt;CC BY&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;The planet WASP-121b is extreme. It’s a gas giant almost twice as big as Jupiter orbiting extremely close to its star–50 times closer than the Earth does around the Sun. WASP-121b is so close to its star that tidal forces have locked its rotation in a “resonance”: the planet always shows the same face to its star, like the Moon to the Earth. Therefore, one side of WASP-121b constantly bakes in light whereas the other is in perpetual night. This difference causes huge variations in temperature across the planet. It can be more than 3,000°C on one side and drop 1,500°C on the other.&lt;/p&gt;
1458.  
1459. <p>This huge temperature contrast is the source of violent winds, blowing several kilometres per second, which try to redistribute the energy from day to night. Until now, we had to guess the strength and direction of the winds with indirect measurements, such as measurements of the planet’s temperature. In recent years, with the arrival of new instruments on giant telescopes, we’ve been able to directly measure the wind speed of certain exoplanets, including WASP-121b.</p>
1460.  
1461. <p>In <a href="https://www.nature.com/articles/s41586-025-08664-1">our study published in the journal Nature</a> that was conducted by my colleague, Julia Seidel, we not only looked at wind speed on an exoplanet, but also at how these winds vary with altitude. We were able to measure for the first time that winds in the deepest layers of the atmosphere are very different from those at higher altitudes. Put it this way: on Earth, winds blowing a few dozen kilometres per hour already make it hard to ride a bike; on WASP-121b, pedalling would be impossible, because the winds are a hundred times faster.</p>
1462.  
1463. <p>Our measurements reveal the behaviour of a pivotal zone of the atmosphere that forms the link between the deep atmosphere–usually surveyed by telescopes such as the James Webb Space Telescope–and the outer zones where the atmosphere escapes into space, blown by the wind coming from its star.</p>
1464.  
1465. <h2>How did we measure the atmosphere of a planet millions of billions of kilometres away?</h2>
1466.  
1467. <p>To make our measurements, we used one of the most precise spectrographs on Earth, mounted on the largest telescope available to us: ESPRESSO at the <a href="https://www.eso.org/public/france/teles-instr/paranal-observatory/vlt/">European Southern Observatory (ESO) Very Large Telescope</a> (VLT), located in the Atacama desert in Chile. To collect as much light as possible, we combined the light from the VLT’s four 8-metre diameter telescopes. Thanks to this combination, which is still being tested, we collected as much light as would a 16-metre diameter telescope–which would be larger than any optical telescope on Earth.</p>
1468.  
1469. <p>The ultra-precise ESPRESSO spectrograph then enabled us to separate the light from the planet into 1.3 million wavelengths. This allows us to observe as many colours in the visible spectrum. This precision is necessary to detect different types of atoms in the planet’s atmosphere. This time, we studied how three different types of atoms–absorb light from the star: hydrogen, sodium and iron (all in a gaseous state, given the very high temperatures).</p>
1470.  
1471. <p>By measuring the position of these spectral lines very precisely, we were able to directly measure the speed of these atoms. The Doppler effect tells us that an atom coming toward us will absorb more blue light, while an atom moving away from us will absorb more red light. By measuring the absorption wavelength of each of these atoms, we have as many different measurements of the wind speed on this planet.</p>
1472.  
1473. <p>We found that the lines of the different atoms tell different stories. Iron moves at 5 kilometres per second from the substellar point (the region of the planet closest to its host star) to the anti-stellar point (the most distant) in a very symmetrical way. Sodium, on the other hand, splits in two: some of the atoms move like iron, while the others move at the equator directly from east to west four times faster, at the staggering speed of 20 kilometres per second. Finally, hydrogen seems to move with the east-west current of sodium but, also, vertically, no doubt allowing it to escape from the planet.</p>
1474.  
1475. <p>To reconcile all this, we calculated that these three different atoms are, in fact, in different parts of the atmosphere. While iron atoms lie at the deeper layers, where symmetrical circulation is expected, sodium and hydrogen let us probe much higher layers, where the planet’s atmosphere is blown by the wind coming from its host star. This stellar wind, combined with the rotation of the planet, probably carries the material asymmetrically, with a preferential direction given by the rotation of the planet.</p>
1476.  
1477. <figure class="align-center zoomable">
1478.            <a href="https://images.theconversation.com/files/649690/original/file-20250218-44-c2iq27.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="diagram of the composition and winds of the atmosphere of WASP-121b" src="https://images.theconversation.com/files/649690/original/file-20250218-44-c2iq27.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/649690/original/file-20250218-44-c2iq27.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=408&fit=crop&dpr=1 600w, https://images.theconversation.com/files/649690/original/file-20250218-44-c2iq27.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=408&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/649690/original/file-20250218-44-c2iq27.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=408&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/649690/original/file-20250218-44-c2iq27.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=513&fit=crop&dpr=1 754w, https://images.theconversation.com/files/649690/original/file-20250218-44-c2iq27.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=513&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/649690/original/file-20250218-44-c2iq27.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=513&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1479.            <figcaption>
1480.              <span class="caption">There are violent winds in the atmosphere of WASP-121b. The three types of atoms travel at different speeds, helping to reconstruct the structure of the atmosphere, even though the planet is millions of billions of kilometres away from Earth.</span>
1481.              <span class="attribution"><a class="source" href="https://cdn.eso.org/images/large/eso2504c.jpg">ESO/M. Kornmesser</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
1482.            </figcaption>
1483.          </figure>
1484.  
1485. <h2>Why study the atmospheres of exoplanets?</h2>
1486.  
1487. <p>WASP-121b is one of those giant gaseous planets with temperatures of over 1,000°C that are known as “hot Jupiters”. The first observation of these planets <a href="https://web.pa.msu.edu/courses/2011summer/ast208/mayorQueloz.pdf">by Michel Mayor and Didier Queloz</a> (which later earned them a Nobel Prize in Physics) came as a surprise in 1995, particularly because planetary formation models predicted that these giant planets could not form so close to their star. Mayor and Queloz’s observation made us realise that planets do not necessarily form where they are currently located. Instead, they can migrate, i.e., move around in their youth.</p>
1488.  
1489. <p>How far from their star do “hot Jupiters” form? Over what distances do these objects migrate in their infancy? Why did the Jupiter in our solar system not migrate toward the Sun? (We’re lucky it didn’t, because it would have sent Earth into our star at the same time.)</p>
1490.  
1491. <p>Some answers to these questions may lie in the atmosphere of exoplanets, which exhibit traces of the conditions of their formation. However, variations in temperature or chemical composition within each atmosphere can radically skew the abundance measurements that we are trying to take with large telescopes such as the James Webb. In order to exploit our measurements, we first need to grasp how complex these atmospheres are.</p>
1492.  
1493. <p>To do this, we need to understand the fundamental mechanisms that govern the atmosphere of these planets. In the solar system, winds can be measured directly by, for example, looking at how fast clouds move. On exoplanets, we cannot see any details directly.</p>
1494.  
1495. <p>In particular, “hot Jupiters” orbit so close to their stars that we cannot separate them spatially and take photos of the exoplanets. Instead, from among the thousands of known exoplanets, we select <a href="https://arxiv.org/abs/1806.04617">those that have the good taste to periodically pass between their star and us</a>. During this “transit”, light from the star is filtered by the planet’s atmosphere, which allows us to measure the signs of absorption by different atoms or molecules. In general, the data we obtain are not good enough to separate the light that passes on one side of the planet from the other, and we end up with an average of what the atmosphere has absorbed. As conditions along the atmospheric limb (i.e., the slice of atmosphere surrounding a planet as observed from space) can vary drastically, interpreting the final average is often a headache.</p>
1496.  
1497. <p>This time, by using a telescope that, in effect, is larger than any other optical telescope on Earth, and combining it with an extremely precise spectrograph, we were able to separate the signal absorbed by the eastern side of the planet’s limb from the signal absorbed by the western side. This allowed us to measure the spatial variation of the winds in the planet.</p>
1498.  
1499. <h2>The future of atmospheric study of exoplanets</h2>
1500.  
1501. <p>Europe is currently building the next generation of telescopes, led by the ESO’s Extremely Large Telescope, which is scheduled for 2030. The ELT will have a mirror 30 metres in diameter, twice the size of the telescope we obtained by combining the light from the four 8-metre telescopes of the VLT.</p>
1502.  
1503. <p>This giant telescope will gather even more precise details about the atmospheres of exoplanets. In particular, it will measure the winds in exoplanets both smaller and colder than “hot Jupiters”.</p>
1504.  
1505. <p>But what we are all really waiting for is the ELT’s ability to measure the presence of molecules in the atmosphere of rocky planets orbiting in the habitable zone of their star, where water may be present in a liquid state.</p>
1506.  
1507. <hr>
1508.  
1509.  
1510.  
1511. <p><em>The <a href="https://anr.fr/Projet-ANR-23-CE31-0001">EXOWINDS</a> project is supported by the French National Research Agency (ANR), which funds project-based research in France. Its mission is to support and promote the development of fundamental and applied research in all disciplines, and to strengthen the dialogue between science and society. For more information, visit the <a href="https://anr.fr/">ANR website</a>.</em></p><img src="https://counter.theconversation.com/content/250187/count.gif" alt="The Conversation" width="1" height="1" />
1512. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Vivien Parmentier received funding from the French National Research Agency (exowinds, ANR-23-CE31-0001-01). &lt;/span&gt;&lt;/em&gt;&lt;/p&gt;&lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Julia Victoria Seidel is an ESO (European Southern Observatory) Research Fellow. &lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
1513.    <summary>Scientists already knew how to study the chemical composition of the atmosphere of exoplanets. Now, they can also study details about their powerful winds.</summary>
1514.    <author>
1515.      <name>Vivien Parmentier, Professeur junior spécialiste des atmosphères d'exoplanètes au laboratoire LAGRANGE, Observatoire de la Côte d’Azur, CNRS, Université Côte d’Azur</name>
1516.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/vivien-parmentier-2327239"/>
1517.    </author>
1518.    <author>
1519.      <name>Julia Victoria Seidel, ESO Research Fellow - visiteuse long durée Lab Lagrange, Observatoire de la Côte d'Azur, Observatoire Européen Austral</name>
1520.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/julia-victoria-seidel-2327299"/>
1521.    </author>
1522.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
1523.  </entry>
1524.  <entry>
1525.    <id>tag:theconversation.com,2011:article/250496</id>
1526.    <published>2025-02-24T22:22:19Z</published>
1527.    <updated>2025-02-24T22:22:19Z</updated>
1528.    <link rel="alternate" type="text/html" href="https://theconversation.com/scientists-have-discovered-a-3-billion-year-old-beach-buried-on-mars-250496"/>
1529.    <title>Scientists have discovered a 3 billion-year-old beach buried on Mars</title>
1530.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/650873/original/file-20250224-32-mj6x7x.jpg?ixlib=rb-4.1.0&amp;amp;rect=0%2C8%2C1920%2C1063&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;A view of the Utopia Planitia region on Mars which is believed to be the site of an ancient ocean. &lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://commons.wikimedia.org/w/index.php?curid=116520946"&gt;ESA/DLR/FU Berlin&lt;/a&gt;, &lt;a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/"&gt;CC BY-SA&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;In the 1970s, images from the NASA Mariner 9 orbiter revealed water-sculpted surfaces on Mars. This settled the once-controversial question of whether water ever rippled over the red planet.&lt;/p&gt;
1531.  
1532. <p>Since then, more and more evidence has emerged that water once played a large role on our planetary neighbour.</p>
1533.  
1534. <p>For example, <a href="https://theconversation.com/a-4-45-billion-year-old-crystal-from-mars-reveals-the-planet-had-water-from-the-beginning-243172">Martian meteorites</a> record evidence for water back to 4.5 billion years ago. On the young side of the timescale, impact craters formed over the past few years show the presence of <a href="https://theconversation.com/mars-how-we-discovered-two-huge-unusual-impact-craters-and-the-secrets-they-unveil-194297">ice under the surface today</a>.</p>
1535.  
1536. <p>Today the hot topics focus on when water appeared, how much was there, and how long it lasted. Perhaps the most burning of all Mars water-related topics nowadays is: were there ever oceans?</p>
1537.  
1538. <p>A new study <a href="https://dx.doi.org/10.1073/pnas.2422213122">published</a> in PNAS today has made quite a splash. The study involved a team of Chinese and American scientists led by Jianhui Li from Guangzhou University in China, and was based on work done by the China National Space Administration’s Mars rover Zhurong. </p>
1539.  
1540. <p>Data from Zhurong provide an unprecedented look into rocks buried near a proposed shoreline billions of years old. The researchers claim to have found beach deposits from an ancient Martian ocean.</p>
1541.  
1542. <figure class="align-center zoomable">
1543.            <a href="https://images.theconversation.com/files/650832/original/file-20250223-32-mwpxdh.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A large body of water covering most of the northern portion of an orange planet." src="https://images.theconversation.com/files/650832/original/file-20250223-32-mwpxdh.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/650832/original/file-20250223-32-mwpxdh.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=343&fit=crop&dpr=1 600w, https://images.theconversation.com/files/650832/original/file-20250223-32-mwpxdh.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=343&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/650832/original/file-20250223-32-mwpxdh.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=343&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/650832/original/file-20250223-32-mwpxdh.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=431&fit=crop&dpr=1 754w, https://images.theconversation.com/files/650832/original/file-20250223-32-mwpxdh.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=431&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/650832/original/file-20250223-32-mwpxdh.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=431&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1544.            <figcaption>
1545.              <span class="caption">An illustration of Mars 3.6 billion years ago, when an ocean may have covered nearly half the planet. The orange star (right) is the landing site of the Chinese rover Zhurong. The yellow star is the landing site of NASA’s Perseverance rover.</span>
1546.              <span class="attribution"><a class="source" href="https://www.eurekalert.org/multimedia/1061024">Robert Citron/Southwest Research Institute/NASA</a></span>
1547.            </figcaption>
1548.          </figure>
1549.  
1550. <h2>Blue water on a red planet</h2>
1551.  
1552. <p>Rovers exploring Mars study many aspects of the planet, including the geology, soil and atmosphere. They’re often looking for any evidence of water. That’s in part because water is a vital factor for determining if Mars ever supported life.</p>
1553.  
1554. <p>Sedimentary rocks are often a particular focus of investigations, because they can contain evidence of water – and therefore life – on Mars. </p>
1555.  
1556. <p>For example, the <a href="https://science.nasa.gov/mission/mars-2020-perseverance/location-map/">NASA Perseverance rover</a> is currently searching for life in a delta deposit. Deltas are triangular regions often found where rivers flow into larger bodies of water, depositing large amounts of sediment. Examples on Earth include the Mississippi delta in the United States and the Nile delta in Egypt.</p>
1557.  
1558. <p>The delta the Perseverance rover is exploring is located within the roughly 45km wide Jezero impact crater, believed to be the site of an ancient lake.</p>
1559.  
1560. <p>Zhurong had its sights set on a very different body of water – the vestiges of an ancient ocean located in the northern hemisphere of Mars.</p>
1561.  
1562. <figure class="align-center zoomable">
1563.            <a href="https://images.theconversation.com/files/650843/original/file-20250224-32-u8lj4z.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Aerial, multicoloured map with large areas of red on the left hand side and a patch of dark blue near the right hand side." src="https://images.theconversation.com/files/650843/original/file-20250224-32-u8lj4z.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/650843/original/file-20250224-32-u8lj4z.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=274&fit=crop&dpr=1 600w, https://images.theconversation.com/files/650843/original/file-20250224-32-u8lj4z.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=274&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/650843/original/file-20250224-32-u8lj4z.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=274&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/650843/original/file-20250224-32-u8lj4z.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=344&fit=crop&dpr=1 754w, https://images.theconversation.com/files/650843/original/file-20250224-32-u8lj4z.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=344&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/650843/original/file-20250224-32-u8lj4z.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=344&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1564.            <figcaption>
1565.              <span class="caption">Topography of Utopia Planitia. Lower parts of the surface are shown in blues and purples, while higher altitude regions show up in whites and reds, as indicated on the scale to the top right.</span>
1566.              <span class="attribution"><a class="source" href="https://commons.wikimedia.org/w/index.php?curid=132702736">ESA/DLR/FU Berlin</a></span>
1567.            </figcaption>
1568.          </figure>
1569.  
1570. <h2>The god of fire</h2>
1571.  
1572. <p>The Zhurong rover is named after a mythical god of fire. </p>
1573.  
1574. <p>It was <a href="https://theconversation.com/on-its-first-try-chinas-zhurong-rover-hit-a-mars-milestone-that-took-nasa-decades-161078">launched by the Chinese National Space Administration in 2020</a> and was active on Mars from 2021 to 2022. Zhurong landed within Utopia Planitia, a vast expanse and the largest impact basin on Mars which stretches some 3,300km in diameter.</p>
1575.  
1576. <p>Zhurong is investigating an area near a series of ridges – described as paleoshorelines – that extend for thousands of kilometres across Mars. The paleoshorelines have previously been interpreted as the <a href="https://www.nature.com/articles/nature05873">remnants of a global ocean</a> that encircled the northern third of Mars. </p>
1577.  
1578. <p>However, there are differing views among scientists about this, and more observations are needed. </p>
1579.  
1580. <p>On Earth, the geologic record of oceans is distinctive. Modern oceans are only a few hundreds of millions of years old. Yet the global rock record is riddled with deposits made by many older oceans, some several billions of years old.</p>
1581.  
1582. <figure class="align-center zoomable">
1583.            <a href="https://images.theconversation.com/files/650839/original/file-20250224-32-c30pu7.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram depicting an ocean lapping at the foreshore, forming several beach ridges." src="https://images.theconversation.com/files/650839/original/file-20250224-32-c30pu7.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/650839/original/file-20250224-32-c30pu7.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=207&fit=crop&dpr=1 600w, https://images.theconversation.com/files/650839/original/file-20250224-32-c30pu7.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=207&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/650839/original/file-20250224-32-c30pu7.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=207&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/650839/original/file-20250224-32-c30pu7.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=260&fit=crop&dpr=1 754w, https://images.theconversation.com/files/650839/original/file-20250224-32-c30pu7.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=260&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/650839/original/file-20250224-32-c30pu7.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=260&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1584.            <figcaption>
1585.              <span class="caption">This diagram shows how a series of beach deposits would have formed at the Zhurong landing site in the distant past on Mars.</span>
1586.              <span class="attribution"><a class="source" href="https://www.eurekalert.org/multimedia/1061026">Hai Liu/Guangzhou University</a></span>
1587.            </figcaption>
1588.          </figure>
1589.  
1590. <h2>What lies beneath</h2>
1591.  
1592. <p>To determine if rocks in Utopia Planitia are consistent with having been deposited by an ocean, the rover collected data along a 1.3km measured line known as a transect at the margin of the basin. The transect was oriented perpendicular to the paleoshoreline. The goal was to work out what rock types are there, and what story they tell. </p>
1593.  
1594. <p>The Zhurong rover used a technique called ground penetrating radar, which probed down to 100 metres below the surface. The data revealed many characteristics of the buried rocks, including their orientation. </p>
1595.  
1596. <p>Rocks imaged along the transect contained many reflective layers that are visible by ground penetrating radar down to at least 30 metres. All the layers also dip shallowly into the basin, away from the paleoshoreline. This geometry exactly reflects how sediments are deposited into oceans on Earth. </p>
1597.  
1598. <p>The ground penetrating radar also measured how much the rocks are affected by an electrical field. The results showed the rocks are more likely to be sedimentary and are not volcanic flows, which can also form layers.</p>
1599.  
1600. <p>The study compared Zhurong data gathered from Utopia Planitia with ground penetrating radar data for different sedimentary environments on Earth. </p>
1601.  
1602. <p>The result of the comparison is clear – the rocks Zhurong imaged are a match for coastal sediments deposited along the margin of an ocean.</p>
1603.  
1604. <p>Zhurong found a beach.</p>
1605.  
1606. <figure class="align-center zoomable">
1607.            <a href="https://images.theconversation.com/files/650846/original/file-20250224-44-ai8wzd.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A icy, rocky terrain beneath an orange sky." src="https://images.theconversation.com/files/650846/original/file-20250224-44-ai8wzd.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/650846/original/file-20250224-44-ai8wzd.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=643&fit=crop&dpr=1 600w, https://images.theconversation.com/files/650846/original/file-20250224-44-ai8wzd.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=643&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/650846/original/file-20250224-44-ai8wzd.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=643&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/650846/original/file-20250224-44-ai8wzd.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=808&fit=crop&dpr=1 754w, https://images.theconversation.com/files/650846/original/file-20250224-44-ai8wzd.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=808&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/650846/original/file-20250224-44-ai8wzd.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=808&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1608.            <figcaption>
1609.              <span class="caption">Photograph of frosted terrain on Utopia Planitia, taken by the Viking 2 lander in 1979.</span>
1610.              <span class="attribution"><a class="source" href="https://images.nasa.gov/details/PIA00571">NASA/JPL</a></span>
1611.            </figcaption>
1612.          </figure>
1613.  
1614. <h2>A wet Mars</h2>
1615.  
1616. <p>The Noachian period of Martian history, from 4.1 to 3.7 billion years ago, is the poster child for a wet Mars. There is abundant evidence from orbital images of valley networks and mineral maps that the surface of Noachian Mars had surface water. </p>
1617.  
1618. <p>However, there is less evidence for surface water during the Hesperian period, from 3.7 to 3 billion years ago. Stunning orbital images of large outflow channels in Hesperian land forms, including an area of canyons known as Kasei Valles, are believed to have formed from catastrophic releases of ground water, rather than standing water. </p>
1619.  
1620.  
1621.  
1622. <p>From this view, Mars appears to have cooled down and dried up by Hesperian time.</p>
1623.  
1624. <p>However, the Zhurong rover findings of coastal deposits formed in an ocean may indicate that surface water was stable on Mars longer than previously recognised. It may have lasted into the Late Hesperian period. </p>
1625.  
1626. <p>This may mean that habitable environments, around an ocean, extended to more recent times.</p><img src="https://counter.theconversation.com/content/250496/count.gif" alt="The Conversation" width="1" height="1" />
1627. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Aaron J. Cavosie has received funding from Australian Research Council and the Space Science and Technology Centre at Curtin University.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
1628.    <summary>The discovery indicates water may have remained stable on Mars for much longer than scientists thought.</summary>
1629.    <author>
1630.      <name>Aaron J. Cavosie, Senior lecturer, School of Earth and Planetary Sciences, Curtin University</name>
1631.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/aaron-j-cavosie-739177"/>
1632.    </author>
1633.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
1634.  </entry>
1635.  <entry>
1636.    <id>tag:theconversation.com,2011:article/247104</id>
1637.    <published>2025-02-23T19:06:16Z</published>
1638.    <updated>2025-02-23T19:06:16Z</updated>
1639.    <link rel="alternate" type="text/html" href="https://theconversation.com/nasas-new-telescope-will-create-the-most-colourful-map-of-the-cosmos-ever-made-247104"/>
1640.    <title>NASA’s new telescope will create the ‘most colourful’ map of the cosmos ever made</title>
1641.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/649066/original/file-20250214-17-eeze8e.jpg?ixlib=rb-4.1.0&amp;amp;rect=11%2C8%2C1902%2C1264&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;NASA&amp;#39;s SPHEREx observatory undergoes integration and testing at BAE Systems in Boulder, Colorado, in April 2024.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://images.nasa.gov/details/PIA26538"&gt;NASA/JPL-Caltech/BAE Systems&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;NASA will soon launch a new telescope &lt;a href="https://www.jpl.nasa.gov/news/why-nasas-spherex-mission-will-make-most-colorful-cosmic-map-ever/"&gt;which it says&lt;/a&gt; will create the “most colourful” map of the cosmos ever made. &lt;/p&gt;
1642.  
1643. <p>The SPHEREx telescope is relatively small but will provide a humongous amount of knowledge in its short two-year mission. </p>
1644.  
1645. <p>It is an infrared telescope designed to take spectroscopic images – ones that measure individual wavelengths of light from a source. By doing this it will be able to tell us about the formation of the universe, the growth of all galaxies across cosmic history, and the location of water and life-forming molecules in our own galaxy. </p>
1646.  
1647. <p>In short, the mission – which is scheduled for launch on February 27, all things going well – will help us understand how the universe came to be, and why life exists inside it.</p>
1648.  
1649. <figure>
1650.            <iframe width="440" height="260" src="https://www.youtube.com/embed/Jqw6QeUIDoU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
1651.            
1652.          </figure>
1653.  
1654. <h2>A massive leap forward</h2>
1655.  
1656. <p>Everything in the universe, including you and the objects around you, <a href="https://www.youtube.com/watch?v=_1mpHBAXh1c">emits light in many different colours</a>. Our eyes split all that light into three bands – the brilliant greens of trees, blues of the sky and reds of a sunset – to synthesise a specific image. </p>
1657.  
1658. <p>But SPHEREx – short for Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer – will divide light from everything in the sky into 96 bands. This is a massive leap forward. It will cover the entire sky and offer new insights into the chemistry and physics of objects in the universe. </p>
1659.  
1660. <p>The mission will complement the work being done by other infrared telescopes in space, such as the <a href="https://webbtelescope.org/contents/articles/spectroscopy-101--invisible-spectroscopy">James Webb Space Telescope</a> and Hubble Space Telescope. </p>
1661.  
1662. <p>Both of these telescopes are designed to make high-resolution measurements of the faintest objects in the universe, which means they only study a tiny part of the sky at any given time. For example, the sky is more than 15 million times larger than what the James Webb Space Telescope can observe at once.</p>
1663.  
1664. <p>In its entire mission the James Webb Space Telescope could not map out the whole sky the way SPHEREx will do in only a few months. </p>
1665.  
1666. <p>SPHEREx will take will take spectroscopic images of 1 billion galaxies, 100 million stars, and 10,000 asteroids. It will answer questions that require a view of the entire sky, which are missed out by the biggest telescopes that chase the highest resolution. </p>
1667.  
1668. <figure class="align-center zoomable">
1669.            <a href="https://images.theconversation.com/files/649072/original/file-20250214-15-bhdt1n.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Small metal casing containing three rainbow-coloured plates." src="https://images.theconversation.com/files/649072/original/file-20250214-15-bhdt1n.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/649072/original/file-20250214-15-bhdt1n.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/649072/original/file-20250214-15-bhdt1n.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/649072/original/file-20250214-15-bhdt1n.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/649072/original/file-20250214-15-bhdt1n.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/649072/original/file-20250214-15-bhdt1n.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/649072/original/file-20250214-15-bhdt1n.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1670.            <figcaption>
1671.              <span class="caption">NASA’s SPHEREx mission will use these filters to capture spectroscopic images of the cosmos.</span>
1672.              <span class="attribution"><a class="source" href="https://images.nasa.gov/details/PIA25788">NASA/JPL-Caltech</a></span>
1673.            </figcaption>
1674.          </figure>
1675.  
1676. <h2>Measuring inflation</h2>
1677.  
1678. <p>The first aim of SPHEREx is to measure what astronomers call cosmic inflation. This <a href="https://theconversation.com/cosmic-inflation-did-the-early-cosmos-balloon-in-size-a-mirror-universe-going-backwards-in-time-may-be-a-simpler-explanation-238343">refers to the rapid expansion</a> of the universe immediately after the Big Bang.</p>
1679.  
1680. <p>The physical processes that drove cosmic inflation remain poorly understood. Revealing more information about inflation is possibly the most important research area of cosmology. </p>
1681.  
1682. <p>Inflation happened everywhere in the universe. To study it astronomers need to map the entire sky. SPHEREx is ideal for studying this huge mystery that is fundamental to our cosmos. </p>
1683.  
1684. <p>SPHEREx will use the spectroscopic images to measure the 3D positions of about a billion galaxies across cosmic history. Astronomers will then create a picture of the cosmos not just in position but in time. </p>
1685.  
1686. <p>This, plus a lot of statistics and mathematics, will let the SPHEREx team test different theories of inflation. </p>
1687.  
1688. <figure class="align-center zoomable">
1689.            <a href="https://images.theconversation.com/files/649073/original/file-20250214-15-b1o4wa.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Thick clouds of gas and dust surrounded by stars and orange light." src="https://images.theconversation.com/files/649073/original/file-20250214-15-b1o4wa.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/649073/original/file-20250214-15-b1o4wa.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=562&fit=crop&dpr=1 600w, https://images.theconversation.com/files/649073/original/file-20250214-15-b1o4wa.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=562&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/649073/original/file-20250214-15-b1o4wa.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=562&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/649073/original/file-20250214-15-b1o4wa.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=706&fit=crop&dpr=1 754w, https://images.theconversation.com/files/649073/original/file-20250214-15-b1o4wa.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=706&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/649073/original/file-20250214-15-b1o4wa.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=706&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1690.            <figcaption>
1691.              <span class="caption">The SHEREx mission will complement the work of the James Webb Space Telescope, which captured this composite image of stars, gas and dust in a small region within the vast Eagle Nebula, 6,500 light-years away from Earth.</span>
1692.              <span class="attribution"><a class="source" href="https://www.flickr.com/photos/nasawebbtelescope/52534406448/in/album-72177720301006030">NASA/ESA/CSA/STScI</a></span>
1693.            </figcaption>
1694.          </figure>
1695.  
1696. <h2>Pinpointing the location of life-bearing molecules</h2>
1697.  
1698. <p>Moving much closer to home, SPHEREx aims to <a href="https://spherex.caltech.edu/page/the-origin-of-water-in-planetary-systems">identify water- and life-bearing molecules</a> (known as biogenic molecules) in the clouds of gas in our galaxy, the Milky Way. </p>
1699.  
1700. <p>In the coldest parts of our galaxy, the molecules that create life (such as water, carbon dioxide and methanol) are trapped in icy particles. Those icy biogenic molecules have to travel from the cold gas in the galaxy onto planets so life can come to be. </p>
1701.  
1702. <p>Despite years of study, this process remains a huge mystery. </p>
1703.  
1704. <p>To answer this fundamental question about human existence, we need to know where all those molecules are. </p>
1705.  
1706. <p>What SPHEREx will provide is a complete census of the icy biogenic molecules in our surrounding galaxy. Icy biogenic molecules have distinct features in the infrared spectrum, where SPHEREx operates. </p>
1707.  
1708. <p>By mapping the entire sky, SPHEREx will pinpoint where these molecules are, not only in our galaxy but also in nearby systems.</p>
1709.  
1710. <figure class="align-center zoomable">
1711.            <a href="https://images.theconversation.com/files/649077/original/file-20250214-15-xjncnh.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Cloud of pink and green dust surrounded by stars." src="https://images.theconversation.com/files/649077/original/file-20250214-15-xjncnh.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/649077/original/file-20250214-15-xjncnh.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/649077/original/file-20250214-15-xjncnh.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/649077/original/file-20250214-15-xjncnh.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/649077/original/file-20250214-15-xjncnh.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/649077/original/file-20250214-15-xjncnh.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/649077/original/file-20250214-15-xjncnh.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1712.            <figcaption>
1713.              <span class="caption">Located some 13,700 light-years away from Earth in the southern constellation Centaurus of the Milky Way, RCW 49 is a dark and dusty stellar nursery that houses more than 2,200 stars.</span>
1714.              <span class="attribution"><a class="source" href="https://images.nasa.gov/details/PIA05989">NASA/JPL-Caltech/University of Wisconsin</a></span>
1715.            </figcaption>
1716.          </figure>
1717.  
1718. <p>Once we know where they all are, we can determine the necessary conditions to form biogenic molecules in space. In turn, this can tell us about a crucial step in how life came to be.</p>
1719.  
1720. <p>Currently 200 spectra have been taken on biogenic molecules in space. We expect the James Webb Space Telescope will obtain a few thousand such measurements. </p>
1721.  
1722. <p>SPHEREx will generate 8 million new spectroscopic images of life-bearing molecules. This will revolutionise our understanding. </p>
1723.  
1724. <p>Mapping the whole sky enables astronomers to identify promising regions for life and gather large-scale data to separate meaningful patterns from anomalies, making this mission a transformative step in the search for life beyond Earth.</p><img src="https://counter.theconversation.com/content/247104/count.gif" alt="The Conversation" width="1" height="1" />
1725. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Deanne Fisher receives funding from the Australian Research Council.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
1726.    <summary>The SPHEREx mission will image 1 billion galaxies, 100 million stars, and 10,000 asteroids – and help to answer some of the biggest scientific mysteries.</summary>
1727.    <author>
1728.      <name>Deanne Fisher, Associate Professor of Astronomy, Swinburne University of Technology</name>
1729.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/deanne-fisher-2204921"/>
1730.    </author>
1731.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
1732.  </entry>
1733.  <entry>
1734.    <id>tag:theconversation.com,2011:article/249590</id>
1735.    <published>2025-02-12T19:00:26Z</published>
1736.    <updated>2025-02-12T19:00:26Z</updated>
1737.    <link rel="alternate" type="text/html" href="https://theconversation.com/3-5-kilometres-underwater-scientists-found-a-staggeringly-energetic-particle-from-outer-space-249590"/>
1738.    <title>3.5 kilometres underwater, scientists found a staggeringly energetic particle from outer space</title>
1739.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/648240/original/file-20250211-15-ktac8r.jpg?ixlib=rb-4.1.0&amp;amp;rect=470%2C0%2C1861%2C1343&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;An artist&amp;#39;s impression of a high-energy particle travelling through the KM3NeT neutrino telescope.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;span class="source"&gt;KM3NeT&lt;/span&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;Three and a half kilometres beneath the Mediterranean Sea, around 80km off the coast of Sicily, lies half of a very unusual telescope called &lt;a href="https://www.km3net.org"&gt;KM3NeT&lt;/a&gt;.&lt;/p&gt;
1740.  
1741. <p>The enormous device is still under construction, but today the telescope’s scientific team announced they have already detected a particle from outer space with a staggering amount of energy. </p>
1742.  
1743. <p>In fact, as the team <a href="https://doi.org/10.1038/s41586-024-08543-1">report in Nature</a>, they found the most energetic neutrino anyone has ever seen – and it represents a tremendous leap forward in exploring the uncharted waters of the extreme universe.</p>
1744.  
1745. <p>To explain why it’s such a remarkable discovery, we need to understand what KM3NeT is, what it’s looking for, and what it saw.</p>
1746.  
1747. <h2>What is KM3NeT?</h2>
1748.  
1749. <p>KM3NeT is a gigantic deep sea telescope being built by an international collaboration of more than 300 scientists and engineers from 21 countries. </p>
1750.  
1751. <p>At the site off Sicily, and another off the coast of Provence in France, KM3NeT will be made up of more than 6,000 light detectors hanging in the pitch-black depths. When the telescope is complete, it will cover about a cubic kilometre of sea.</p>
1752.  
1753. <figure class="align-center zoomable">
1754.            <a href="https://images.theconversation.com/files/648469/original/file-20250212-17-8i6qy8.jpeg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Photo of a person in a lab coat handling a large spherical object covered in lenses." src="https://images.theconversation.com/files/648469/original/file-20250212-17-8i6qy8.jpeg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/648469/original/file-20250212-17-8i6qy8.jpeg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/648469/original/file-20250212-17-8i6qy8.jpeg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/648469/original/file-20250212-17-8i6qy8.jpeg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/648469/original/file-20250212-17-8i6qy8.jpeg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/648469/original/file-20250212-17-8i6qy8.jpeg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/648469/original/file-20250212-17-8i6qy8.jpeg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1755.            <figcaption>
1756.              <span class="caption">The KM3NeT telescope will eventually have more than 6,000 detectors like this one floating in the depths of the Mediterranean watching for tell-tale flashed of blue light.</span>
1757.              <span class="attribution"><span class="source">N Busser / CNRS</span></span>
1758.            </figcaption>
1759.          </figure>
1760.  
1761. <p>Down deep, KM3NeT is shielded from ordinary sources of light, such as the Sun. It is also shielded from other particles like electrons and protons, which are absorbed by the water long before they reach the detectors. So what does it see?</p>
1762.  
1763. <h2>What is KM3NeT looking for?</h2>
1764.  
1765. <p>Of all the particles that physicists have discovered, only the elusive neutrino can reach all the way down to KM3NeT. </p>
1766.  
1767. <p>The neutrino is an elementary particle with no electric charge and only a very tiny mass. It interacts with matter so weakly that it can pass through kilometres of ocean – and even thousands of kilometres of Earth itself – to reach the detector. That’s why KM3NeT is at the bottom of the sea: to see neutrinos, and only neutrinos.</p>
1768.  
1769. <p>But won’t the neutrinos pass through the detector, too? Yes, <em>almost</em> all of them.</p>
1770.  
1771. <figure class="align-center zoomable">
1772.            <a href="https://images.theconversation.com/files/648470/original/file-20250212-15-kf0ozd.gif?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Animation showing side and top views of a particle passing through a grid of detectors and triggering them to light up." src="https://images.theconversation.com/files/648470/original/file-20250212-15-kf0ozd.gif?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/648470/original/file-20250212-15-kf0ozd.gif?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/648470/original/file-20250212-15-kf0ozd.gif?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/648470/original/file-20250212-15-kf0ozd.gif?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/648470/original/file-20250212-15-kf0ozd.gif?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/648470/original/file-20250212-15-kf0ozd.gif?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/648470/original/file-20250212-15-kf0ozd.gif?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1773.            <figcaption>
1774.              <span class="caption">When a high-energy particle passes through KM3NeT, the detectors register the tell-tale blue flashes and allow scientists to figure out how fast the particle was going and where it came from.</span>
1775.              <span class="attribution"><span class="source">KM3NeT</span></span>
1776.            </figcaption>
1777.          </figure>
1778.  
1779. <p>But very rarely, a neutrino will crash right into a water molecule. When it does, it can pack an enormous punch. </p>
1780.  
1781. <p>The energy of the neutrino can create many more particles. As these particles blast through the water, they create a bluish glow. That’s what KM3NeT detectors see.</p>
1782.  
1783. <p>By analysing this bluish light, and by timing each flash, scientists can reconstruct the original energy of the neutrino, and the direction from which it came. (Either that, or they’ve just clocked one of those deep-sea glowing fish travelling at nearly the speed of light.)</p>
1784.  
1785. <h2>The most energetic neutrino ever detected</h2>
1786.  
1787. <p>On February 13 2023, KM3NeT detected a neutrino travelling so fast it had 30 times more energy than any previously detected.</p>
1788.  
1789. <p>The amount of energy is 220 petaelectronvolts, but that doesn’t mean much to a non-particle physicist. It’s hard to imagine, but let’s try. </p>
1790.  
1791. <p>The neutrino had 100 trillion times more energy than a typical particle at the centre of the Sun. It’s a trillion times more energy than medical X-rays, and ten billion times more than the most dangerous radioactive particles. Earth’s biggest particle accelerators can’t produce a particle with even one ten thousandth of this energy.</p>
1792.  
1793. <p>Short story: it’s a lot of energy for one particle.</p>
1794.  
1795. <h2>Making neutrinos in space</h2>
1796.  
1797. <p>Neutrinos interact with matter very weakly, so how could a single neutrino have been given so much energy? What sort of cosmic event could create such a particle?</p>
1798.  
1799. <p>That’s the exciting part: we don’t know. </p>
1800.  
1801. <p>We know there are colossal explosions in the universe, such as supernovas: when a star exhausts its fuel and collapses. And there are gamma ray bursts, which are even more energetic explosions of supermassive stars, or collisions of neutron stars. These create extremely energetic neutrinos.</p>
1802.  
1803. <p>But there are other candidates. Supermassive black holes at the centre of galaxies have millions to billions of times as much mass as the Sun. </p>
1804.  
1805. <p>As matter is swallowed by these black holes, it is accelerated to extreme speeds, and becomes wrapped around intense magnetic fields. The particles that aren’t swallowed can be shot out at extreme speeds. These “active galactic nuclei” are another way that the universe could create extreme neutrinos.</p>
1806.  
1807. <p>Third, the neutrinos could be created more locally (cosmically speaking). Explosions and active galactic nuclei also create cosmic rays: extremely energetic protons and electrons. </p>
1808.  
1809. <p>These could stream across the universe towards us, before colliding with a particle of light along the way. That collision can create an energetic neutrino.</p>
1810.  
1811. <h2>How can we find the source?</h2>
1812.  
1813. <p>Here’s where the Australian connection comes in. KM3NeT tells us this neutrino came from a particular spot in the southern sky. </p>
1814.  
1815. <p>If it came from an extreme explosion or an active galactic nucleus, we might hope to spot the source with other telescopes. In particular, both supernova remnants and active galactic nuclei can be spotted using radio waves.</p>
1816.  
1817. <p>Australia has the biggest radio telescopes in the southern hemisphere. The Australian Square Kilometre Array Pathfinder (ASKAP) has mapped a lot of the southern sky, and found many supernova remnants and active galactic nuclei.</p>
1818.  
1819. <p>My colleagues and I at Western Sydney University are using ASKAP to follow up on KM3NeT detections like this one. For this particular neutrino, there are no obvious candidates in the radio sky that it came from. </p>
1820.  
1821. <p>However, KM3NeT doesn’t provide a very accurate position, so we can’t be completely sure. We’ll keep looking.</p>
1822.  
1823. <p>KM3NeT is still under construction, and ASKAP continues to survey the sky. Our window on the extreme universe is just opening up.</p><img src="https://counter.theconversation.com/content/249590/count.gif" alt="The Conversation" width="1" height="1" />
1824. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Luke Barnes does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
1825.    <summary>In the search for elusive particles called neutrinos, researchers are stringing thousands of detectors in the depths of the Mediterranean.</summary>
1826.    <author>
1827.      <name>Luke Barnes, Lecturer in Physics, Western Sydney University</name>
1828.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/luke-barnes-123126"/>
1829.    </author>
1830.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
1831.  </entry>
1832.  <entry>
1833.    <id>tag:theconversation.com,2011:article/248753</id>
1834.    <published>2025-01-31T06:13:18Z</published>
1835.    <updated>2025-01-31T06:13:18Z</updated>
1836.    <link rel="alternate" type="text/html" href="https://theconversation.com/astronomers-have-spied-an-asteroid-that-may-be-heading-for-earth-heres-what-we-know-so-far-248753"/>
1837.    <title>Astronomers have spied an asteroid that may be heading for Earth. Here’s what we know so far</title>
1838.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/646029/original/file-20250131-17-j4t54q.jpg?ixlib=rb-4.1.0&amp;amp;rect=0%2C0%2C4256%2C2828&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;Artist&amp;#39;s impression of an asteroid with Earth in the background.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://www.shutterstock.com/image-photo/planet-earth-big-asteroid-space-outer-2234515385"&gt;Buradaki / Shutterstock&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;On 27 December last year, astronomers using the ATLAS survey telescope in Chile &lt;a href="https://minorplanetcenter.net/mpec/K24/K24YE0.html"&gt;discovered&lt;/a&gt; a small asteroid moving away from Earth. Follow up observations have revealed that the asteroid, 2024 YR4, is on a path that &lt;a href="https://cneos.jpl.nasa.gov/sentry/details.html#?des=2024%20YR4"&gt;might lead to a collision&lt;/a&gt; with our planet on December 22 2032.&lt;/p&gt;
1839.  
1840. <p>In other words, the newly-discovered space rock poses a significant impact threat to our planet.</p>
1841.  
1842. <p>It sounds like something from a <a href="https://www.imdb.com/title/tt0120591/">bad Hollywood movie</a>. But in reality, there’s no need to panic – this is just another day living on a target in a celestial shooting gallery.</p>
1843.  
1844. <p>So what’s the story? What do we know about 2024 YR4? And what would happen if it did collide with Earth?</p>
1845.  
1846. <h2>A target in the celestial shooting gallery</h2>
1847.  
1848. <p>As Earth moves around the Sun, it is continually encountering dust and debris that dates back to the birth of the Solar system. The system is littered with such debris, and the <a href="https://theconversation.com/explainer-why-meteors-light-up-the-night-sky-35754">meteors and fireballs seen every night</a> are evidence of just how polluted our local neighbourhood is.</p>
1849.  
1850. <p>But most of the debris is far too small to cause problems to life on Earth. There is far more tiny debris out there than larger chunks – so impacts from objects that could imperil life on Earth’s surface are much less frequent.</p>
1851.  
1852. <p>The <a href="https://eps.harvard.edu/files/eps/files/renne.kt_.science.2013.pdf">most famous impact</a> came some 66 million years ago. A giant rock from space, <a href="https://www.newscientist.com/definition/chicxulub/#:%7E:text=At%20the%20end%20of%20the,and%2015%20kilometres%20in%20diameter.">at least 10 kilometres in diameter</a>, crashed into Earth – causing a mass extinction that wiped out something like 75% of all species on Earth.</p>
1853.  
1854. <p>Impacts that large are, fortunately, very rare events. Current estimates suggest that objects like the one which killed the dinosaurs only hit Earth every 50 million years or so. Smaller impacts, though, are more common.</p>
1855.  
1856. <p>On June 30 1908, there was <a href="https://doi.org/10.1016%2Fj.icarus.2019.01.001">a vast explosion</a> in a sparsely populated part of Siberia. When explorers later reached the location of the explosion, they found an astonishing site: a forest levelled, with all the trees fallen in the same direction. As they moved around, the direction of the fallen trees changed – all pointing inwards towards the epicentre of the explosion.</p>
1857.  
1858. <figure class="align-center zoomable">
1859.            <a href="https://images.theconversation.com/files/646024/original/file-20250131-15-su3v72.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Old photo of flattened trees in a forest." src="https://images.theconversation.com/files/646024/original/file-20250131-15-su3v72.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/646024/original/file-20250131-15-su3v72.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/646024/original/file-20250131-15-su3v72.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/646024/original/file-20250131-15-su3v72.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/646024/original/file-20250131-15-su3v72.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/646024/original/file-20250131-15-su3v72.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/646024/original/file-20250131-15-su3v72.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1860.            <figcaption>
1861.              <span class="caption">The Tunguska event flattened trees over an area of around 2,200 square kilometres.</span>
1862.              <span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Tunguska_event#/media/File:Tunguska_Ereignis.jpg">Leonid Kulik / Wikimedia</a></span>
1863.            </figcaption>
1864.          </figure>
1865.  
1866. <p>In total, the Tunguska event levelled an area of almost 2,200 square kilometres – roughly equivalent to the area of greater Sydney. Fortunately, that forest was extremely remote. While plants and animals were killed in the blast zone, it is thought that, at most, only three people perished.</p>
1867.  
1868. <p>Estimates <a href="https://ntrs.nasa.gov/api/citations/20190002302/downloads/20190002302.pdf">vary</a> of how frequent such large collisions should be. Some argue that Earth should experience a similar impact, on average, once per century. Others suggest such collisions might only happen every 10,000 years or so. The truth is we don’t know – but that’s part of the fun of science.</p>
1869.  
1870. <p>More recently, a smaller impact created global excitement. On 15 February 2013, a small asteroid (likely about 18 metres in diameter) <a href="https://en.wikipedia.org/wiki/Chelyabinsk_meteor">detonated near the Russian city of Chelyabinsk</a>. </p>
1871.  
1872.  
1873.  
1874. <p>The explosion, about 30 kilometres above the Earth’s surface, generated a powerful shock-wave and extremely bright flash of light. Buildings were damaged, windows smashed, and almost 1,500 people were injured – although there were no fatalities. </p>
1875.  
1876. <p>It served as a reminder, however, that Earth will be hit again. It’s only a question of when. </p>
1877.  
1878. <p>Which brings us to our latest contender – asteroid 2024 YR4.</p>
1879.  
1880. <h2>The 1-in-77 chance of collision to watch</h2>
1881.  
1882. <p>2024 YR4 has been under close observation by astronomers for a little over a month. It was discovered just a few days after making a relatively close approach to our planet, and it is now receding into the dark depths of the Solar System. By April, it will be lost to even the world’s largest telescopes.</p>
1883.  
1884. <p>The observations carried out over the past month have allowed astronomers to extrapolate the asteroid’s motion forward over time, working out its orbit around the Sun. As a result, it has become clear that, on December 22 2032, it will pass very close to our planet – and may even collide with us.</p>
1885.  
1886. <figure class="align-center zoomable">
1887.            <a href="https://images.theconversation.com/files/646026/original/file-20250131-15-1iqqr6.png?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A map of Earth showing a red streak stretching from Central America to Southeast Asia." src="https://images.theconversation.com/files/646026/original/file-20250131-15-1iqqr6.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/646026/original/file-20250131-15-1iqqr6.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/646026/original/file-20250131-15-1iqqr6.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/646026/original/file-20250131-15-1iqqr6.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/646026/original/file-20250131-15-1iqqr6.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/646026/original/file-20250131-15-1iqqr6.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/646026/original/file-20250131-15-1iqqr6.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1888.            <figcaption>
1889.              <span class="caption">The area at risk of a strike, based on current (highly uncertain) data.</span>
1890.              <span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/File:2024_YR4_risk_corridor.png">Daniel Bamberger / Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
1891.            </figcaption>
1892.          </figure>
1893.  
1894. <p>At present, <a href="https://cneos.jpl.nasa.gov/sentry/details.html#?des=2024%20YR4">our best models</a> of the asteroid’s motion have an uncertainty of around 100,000 kilometres in its position at the time it would be closest to Earth. At around 12,000 kilometres in diameter, our planet falls inside that region of uncertainty. </p>
1895.  
1896. <p>Calculations suggest there is currently around a 1-in-77 chance that the asteroid will crash into our planet at that time. Of course, that means there is still a 76-in-77 chance it will miss us.</p>
1897.  
1898. <h2>When will we know for sure?</h2>
1899.  
1900. <p>With every new observation of 2024 YR4, astronomers’ knowledge of its orbit improves slightly – which is why the collision likelihoods you might see quoted online keep changing. We’ll be able to follow the asteroid as it recedes from Earth for another couple of months, by which time we’ll have a better idea of exactly where it will be on that fateful day in December 2032. </p>
1901.  
1902. <p>But it is unlikely we’ll be able to say for sure whether we’re in the clear at that point.</p>
1903.  
1904. <figure class="align-center zoomable">
1905.            <a href="https://images.theconversation.com/files/646027/original/file-20250131-25-ttfjk9.gif?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Video showing a faint dot in the middle of a background of moving stars" src="https://images.theconversation.com/files/646027/original/file-20250131-25-ttfjk9.gif?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/646027/original/file-20250131-25-ttfjk9.gif?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=434&fit=crop&dpr=1 600w, https://images.theconversation.com/files/646027/original/file-20250131-25-ttfjk9.gif?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=434&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/646027/original/file-20250131-25-ttfjk9.gif?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=434&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/646027/original/file-20250131-25-ttfjk9.gif?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=546&fit=crop&dpr=1 754w, https://images.theconversation.com/files/646027/original/file-20250131-25-ttfjk9.gif?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=546&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/646027/original/file-20250131-25-ttfjk9.gif?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=546&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1906.            <figcaption>
1907.              <span class="caption">Recent observations of 2024 YR4 – the faint unmoving dot in the centre of the image.</span>
1908.              <span class="attribution"><a class="source" href="https://www.eso.org/public/videos/YR4-2/">ESO</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
1909.            </figcaption>
1910.          </figure>
1911.  
1912. <p>Fortunately, the asteroid will make another close approach to the Earth in December 2028 – passing around 8 million kilometres from our planet. Astronomers will be ready to perform a wide raft of observations that will help us to understand the size and shape of the asteroid, as well as giving an incredibly accurate overview of where it will be in 2032. </p>
1913.  
1914. <p>At the end of that encounter, we will know for sure whether there will be a collision in 2032. And if there is to be a collision that year, we’ll be able to predict where on Earth that collision will be – likely to a precision of a few tens of kilometres.</p>
1915.  
1916. <h2>How big would the impact be?</h2>
1917.  
1918. <p>At the moment, we don’t know the exact size of 2024 YR4. Even through Earth’s largest telescopes, it is just a single tiny speck in the sky. So we have to estimate its size based on its brightness. Depending on how reflective the asteroid is, current estimates place it as being somewhere between 40 and 100 metres across.</p>
1919.  
1920. <p>What does that mean for a potential impact? Well, it would depend on exactly what the asteroid is made of. </p>
1921.  
1922. <p>The most likely scenario is that the asteroid is a rocky pile of rubble. If that turns out to be the case, then the impact would be very similar to the Tunguska event in 1908. </p>
1923.  
1924. <p>The asteroid would detonate in the atmosphere, with a shockwave blasting Earth’s surface as a result. The Tunguska impact was a “city killer” type event, levelling forest across a city-sized patch of land. </p>
1925.  
1926. <figure class="align-center zoomable">
1927.            <a href="https://images.theconversation.com/files/646028/original/file-20250131-15-etjl7u.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Satellite photo of a large rocky crater." src="https://images.theconversation.com/files/646028/original/file-20250131-15-etjl7u.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/646028/original/file-20250131-15-etjl7u.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/646028/original/file-20250131-15-etjl7u.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/646028/original/file-20250131-15-etjl7u.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/646028/original/file-20250131-15-etjl7u.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/646028/original/file-20250131-15-etjl7u.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/646028/original/file-20250131-15-etjl7u.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1928.            <figcaption>
1929.              <span class="caption">Meteor Crater in Arizona is believed to have been created by a 50m metallic meteorite impact around 50,000 years ago.</span>
1930.              <span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Meteor_Crater#/media/File:Meteor_Crater_-_Arizona.jpg">NASA Earth Observatory / Wikimedia</a></span>
1931.            </figcaption>
1932.          </figure>
1933.  
1934. <p>A less likely possibility is that the asteroid is made of metal. Based on its orbit around the Sun, this seems unlikely – but we can’t rule it out. </p>
1935.  
1936. <p>In that case, the asteroid would make it through the atmosphere intact, and crash into Earth’s surface. If it hit on the land, it would carve out a new impact crater, probably more than a kilometre across and a couple of hundred metres deep – something similar to Meteor Crater in Arizona. </p>
1937.  
1938. <p>Again, this would be quite spectacular for the region around the impact – but that would be about it.</p>
1939.  
1940. <h2>Living in a remarkable time</h2>
1941.  
1942. <p>This all sounds like doom and gloom. After all, we know that the Earth will be hit again – either by 2024 YR4 or something else. But there’s a real positive to take out of all this.</p>
1943.  
1944. <p>There has been life on Earth for more than 3 billion years. In all that time, impacts have come along and caused destruction and devastation many times.</p>
1945.  
1946. <p>But there has never been a species, to our knowledge, that understood the risk, could detect potential threats in advance, and even do something about the threat. Until now.</p>
1947.  
1948. <p>In just the past few years, we have discovered 11 asteroids before they hit our planet. In each case, we have predicted where they would hit, and watched the results. </p>
1949.  
1950. <p>We have also, in recent years, demonstrated a growing capacity to deflect potentially threatening asteroids. NASA’s <a href="https://www.nasa.gov/press-release/nasa-s-dart-mission-hits-asteroid-in-first-ever-planetary-defense-test">DART mission</a> (the Double Asteroid Redirection Test) was an astounding success.</p>
1951.  
1952. <p>For the first time in more than 3 billion years of life on Earth, we can do something about the risk posed by rocks from space. So don’t panic! But instead, sit back and watch the show.</p><img src="https://counter.theconversation.com/content/248753/count.gif" alt="The Conversation" width="1" height="1" />
1953. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Jonti Horner does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
1954.    <summary>Asteroid 2024 YR4 has around a 1-in-77 chance of hitting Earth in 2032 – but there’s no need to panic.</summary>
1955.    <author>
1956.      <name>Jonti Horner, Professor (Astrophysics), University of Southern Queensland</name>
1957.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/jonti-horner-3355"/>
1958.    </author>
1959.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
1960.  </entry>
1961.  <entry>
1962.    <id>tag:theconversation.com,2011:article/247097</id>
1963.    <published>2025-01-30T22:40:20Z</published>
1964.    <updated>2025-01-30T22:40:20Z</updated>
1965.    <link rel="alternate" type="text/html" href="https://theconversation.com/one-of-the-largest-searches-for-alien-life-started-30-years-ago-its-legacy-lives-on-today-247097"/>
1966.    <title>One of the largest searches for alien life started 30 years ago. Its legacy lives on today</title>
1967.    <content type="html">&lt;p&gt;In February 1995, a small research organisation known as the SETI Institute launched what was then the most comprehensive search for an answer to a &lt;a href="https://theconversation.com/the-beginnings-of-modern-science-shaped-how-philosophers-saw-alien-life-and-how-we-understand-it-today-213454"&gt;centuries-old question&lt;/a&gt;: are we alone in the universe? &lt;/p&gt;
1968.  
1969. <p>This Sunday marks the 30th anniversary of the first astronomical observations conducted for the search, named Project Phoenix. These observations were done at the Parkes Observatory on Wiradjuri country in the central west of New South Wales, Australia – home to one of the world’s largest radio telescopes.</p>
1970.  
1971. <p>But Project Phoenix was lucky to get off the ground. </p>
1972.  
1973. <p>Three years earlier, NASA had commenced an ambitious decade-long, US$100 million Search for Extra-Terrestrial Intelligence (SETI). However, in 1993, the United States Congress cut all funding for the program because of the growing US budget deficit. Plus, SETI sceptics in Congress <a href="https://ui.adsabs.harvard.edu/abs/1999JBIS...52....3G/abstract">derided the program</a> as a far-fetched search for “little green men”.  </p>
1974.  
1975. <p>Fortunately, the SETI Institute secured enough private donations to revive the project – and Project Phoenix rose from the ashes. </p>
1976.  
1977. <h2>Listening for radio signals</h2>
1978.  
1979. <p>If there is life elsewhere, it is natural to assume it evolved over many million years on a planet orbiting a long-lived star similar to our Sun. So SETI searches usually target the nearest Sun-like stars, listening for radio signals that are either being deliberately beamed our way, or are techno-signatures radiating from another planet. </p>
1980.  
1981. <p>Techno-signatures are confined to a narrow range of frequencies and produced by the technologies an advanced civilisation like ours might use. </p>
1982.  
1983. <p>Astronomers use radio waves as they can penetrate the clouds of gas and dust in our galaxy. They can also travel over large distances without excessive power requirements.</p>
1984.  
1985. <p><a href="https://www.csiro.au/en/news/all/articles/2020/november/parkes-telescope-indigenous-name">Murriyang</a>, CSIRO’s 64 metre radio telescope at the Parkes Observatory, <a href="https://theconversation.com/60-years-after-it-first-gazed-at-the-skies-the-parkes-dish-is-still-making-breakthroughs-170753">has been in operation since 1961</a>.
1986. It has made a wealth of astronomical discoveries and played a pivotal role in tracking space missions – <a href="https://theconversation.com/not-one-but-two-aussie-dishes-were-used-to-get-the-tv-signals-back-from-the-apollo-11-moonwalk-108177">especially the Apollo 11 moonwalk</a>.</p>
1987.  
1988. <p>As the largest single-dish radio telescope in the southern hemisphere, it is also the natural facility to use for SETI targets in the southern skies. </p>
1989.  
1990. <p>While Project Phoenix planned to use several large telescopes around the world, these facilities were undergoing major upgrades. So it was at Parkes that the observing program started. </p>
1991.  
1992. <p>On February 2 1995, Murriyang pointed towards a carefully chosen star 49 light-years from Earth in the constellation of, naturally, Phoenix. This was the first observation conducted as part of the project.</p>
1993.  
1994. <figure class="align-center zoomable">
1995.            <a href="https://images.theconversation.com/files/645678/original/file-20250129-19-nj09t0.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A metal cabin pointing to the sky, with a blue and yellow flag attached to it." src="https://images.theconversation.com/files/645678/original/file-20250129-19-nj09t0.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/645678/original/file-20250129-19-nj09t0.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=604&fit=crop&dpr=1 600w, https://images.theconversation.com/files/645678/original/file-20250129-19-nj09t0.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=604&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/645678/original/file-20250129-19-nj09t0.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=604&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/645678/original/file-20250129-19-nj09t0.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=759&fit=crop&dpr=1 754w, https://images.theconversation.com/files/645678/original/file-20250129-19-nj09t0.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=759&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/645678/original/file-20250129-19-nj09t0.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=759&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1996.            <figcaption>
1997.              <span class="caption">The focus cabin of Murriyang, the Parkes telescope, with the Flag of Earth, much favoured by SETI researchers.</span>
1998.              <span class="attribution"><span class="source">CSIRO Radio Astronomy Image Archive</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
1999.            </figcaption>
2000.          </figure>
2001.  
2002. <h2>A logistical and technological success</h2>
2003.  
2004. <p>Project Phoenix was led by Jill Tarter, a renowned SETI researcher who spent many long nights at Parkes overseeing observations during the 16 weeks dedicated to the search. (Jodie Foster’s character in the 1998 movie Contact was largely based on Jill.) </p>
2005.  
2006. <p>The Project Phoenix team brought a trailer full of computers with state-of-the-art touch screen technology to process the data. </p>
2007.  
2008. <p>Bogong moths caused some early interruptions to the processing. These large, nocturnal moths were attracted to light from computer screens, flying into them with enough force to change settings.</p>
2009.  
2010. <p>Over 16 weeks, the Project Phoenix team observed 209 stars using Murriyang at frequencies between 1,200 and 3,000 mega-hertz. They searched for both continuous and pulsing signals to maximise the chance of finding genuine signals of alien life.</p>
2011.  
2012. <figure class="align-center zoomable">
2013.            <a href="https://images.theconversation.com/files/645677/original/file-20250129-17-pk9cyr.png?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Woman with grey hair and wearing blue uniform sitting in a room crowded with computers." src="https://images.theconversation.com/files/645677/original/file-20250129-17-pk9cyr.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/645677/original/file-20250129-17-pk9cyr.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=457&fit=crop&dpr=1 600w, https://images.theconversation.com/files/645677/original/file-20250129-17-pk9cyr.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=457&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/645677/original/file-20250129-17-pk9cyr.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=457&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/645677/original/file-20250129-17-pk9cyr.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=574&fit=crop&dpr=1 754w, https://images.theconversation.com/files/645677/original/file-20250129-17-pk9cyr.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=574&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/645677/original/file-20250129-17-pk9cyr.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=574&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
2014.            <figcaption>
2015.              <span class="caption">Jill Tarter in the Parkes telescope control room.</span>
2016.              <span class="attribution"><span class="source">CSIRO Radio Astronomy Image Archive</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
2017.            </figcaption>
2018.          </figure>
2019.  
2020. <p>Radio telescopes are able to detect the faint radio emissions from distant celestial objects. But they are also sensitive to radio waves produced in modern society (our own techno-signatures) by mobile phones, Bluetooth connections, aircraft radar and GPS satellites. </p>
2021.  
2022. <p>These kinds of local interference can mimic the kinds of signal SETI searches are looking for. So distinguishing between the two is crucial.</p>
2023.  
2024. <p>To do this, Project Phoenix decided to use a second radio telescope some distance away for an independent check of any signals detected. CSIRO provided access to its 22 metre Mopra radio telescope, about 200 kilometres north of Parkes, to follow up signal candidates in real time.</p>
2025.  
2026. <p>Over the 16 weeks, the team detected a total of 148,949 signals at Parkes – roughly 80% of which could be easily dismissed as local signals. The team checked a little over 18,000 signals at both Parkes and Mopra. Only 39 passed all tests and looked like strong SETI candidates. But on closer inspection the team identified them as coming from satellites. </p>
2027.  
2028. <p>AS Jill Tarter summarised in an <a href="https://ui.adsabs.harvard.edu/abs/1997abos.conf..633T/abstract">article</a> in 1997:</p>
2029.  
2030. <blockquote>
2031. <p>Although no evidence for an [extraterrestrial intelligence] signal was found, no mysterious or unexplained signals were left behind and the Australian deployment was a logistical and technological success.</p>
2032. </blockquote>
2033.  
2034. <figure class="align-center zoomable">
2035.            <a href="https://images.theconversation.com/files/645681/original/file-20250130-15-bqm80p.png?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Three men and a woman standing under a tree in front of a large radio telescope." src="https://images.theconversation.com/files/645681/original/file-20250130-15-bqm80p.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/645681/original/file-20250130-15-bqm80p.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=423&fit=crop&dpr=1 600w, https://images.theconversation.com/files/645681/original/file-20250130-15-bqm80p.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=423&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/645681/original/file-20250130-15-bqm80p.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=423&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/645681/original/file-20250130-15-bqm80p.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=532&fit=crop&dpr=1 754w, https://images.theconversation.com/files/645681/original/file-20250130-15-bqm80p.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=532&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/645681/original/file-20250130-15-bqm80p.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=532&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
2036.            <figcaption>
2037.              <span class="caption">From left to right: journalist Robyn Williams, Jill Tarter, Australia Telescope National Facility Director, Ron Ekers, and Parkes Observatory Officer-in-Charge, Marcus Price, prior to the start of Project Phoenix.</span>
2038.              <span class="attribution"><span class="source">CSIRO Radio Astronomy Image Archive</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
2039.            </figcaption>
2040.          </figure>
2041.  
2042. <h2>The next generation of radio telescopes</h2>
2043.  
2044. <p>When Project Phoenix ended in 2004, project manager Peter Backus <a href="http://news.bbc.co.uk/2/hi/science/nature/3567729.stm">concluded</a> “we live in a quiet neighbourhood”.</p>
2045.  
2046. <p>But efforts are continuing to search for alien life with greater sensitivity, over a wider frequency range, and for more targets.  </p>
2047.  
2048. <p><a href="https://breakthroughinitiatives.org/initiative/1">Breakthough Listen</a>, another privately funded project, commenced in 2015, again <a href="https://theconversation.com/the-hunt-for-et-will-boost-australian-astronomy-44957">making use of the Parkes telescope</a> among others. </p>
2049.  
2050. <p>Breakthrough Listen aims to examine one million of the closest stars and 100 closest galaxies. </p>
2051.  
2052. <p>One <a href="https://theconversation.com/a-mysterious-signal-looked-like-a-sign-of-alien-technology-but-it-turned-out-to-be-radio-interference-170548">unexpected signal detected at Parkes</a> in 2019 as part of this project was examined in painstaking detail before it was concluded that it too was a locally generated signal.</p>
2053.  
2054. <p>The next generation of radio telescopes will provide a leap in sensitivity compared to facilities today – benefitting from greater collecting area, improved resolution and superior processing capabilities.</p>
2055.  
2056. <p>Examples of these next generation radio telescopes include the <a href="https://www.skao.int/en/explore/telescopes/ska-low">SKA-Low telescope</a>, under construction in Western Australia, and the <a href="https://www.skao.int/en/explore/telescopes/ska-mid">SKA-Mid telescope</a>, being built in South Africa. They will be used to answer a wide variety of astronomical questions – including whether there is life beyond Earth. </p>
2057.  
2058. <p>As SETI pioneer Frank Drake <a href="https://www.nature.com/articles/d41586-022-02962-8">once noted</a>:</p>
2059.  
2060. <blockquote>
2061. <p>the most fascinating, interesting thing you could find in the universe is not another kind of star or galaxy … but another kind of life.</p>
2062. </blockquote><img src="https://counter.theconversation.com/content/247097/count.gif" alt="The Conversation" width="1" height="1" />
2063. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Project Phoenix used Murriyang, the CSIRO Parkes radio-telescope, under contract for the work described in this article. I work for CSIRO, but joined in 2006 after this project had been completed.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
2064.    <summary>‘Project Phoenix’ was initiated by small research organisation known as the SETI Institute. But it was lucky to get off the ground.</summary>
2065.    <author>
2066.      <name>Phil Edwards, Senior Research Scientist, Australia Telescope National Facility Science, CSIRO</name>
2067.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/phil-edwards-1251869"/>
2068.    </author>
2069.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
2070.  </entry>
2071.  <entry>
2072.    <id>tag:theconversation.com,2011:article/248023</id>
2073.    <published>2025-01-26T10:10:48Z</published>
2074.    <updated>2025-01-26T10:10:48Z</updated>
2075.    <link rel="alternate" type="text/html" href="https://theconversation.com/south-african-telescope-discovers-a-giant-galaxy-thats-32-times-bigger-than-earths-248023"/>
2076.    <title>South African telescope discovers a giant galaxy that’s 32 times bigger than Earth’s</title>
2077.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/644650/original/file-20250124-15-5mfvev.jpg?ixlib=rb-4.1.0&amp;amp;rect=19%2C0%2C2539%2C2584&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;Inkathazo&amp;#39;s glowing plasma jets are shown in red and yellow. The starlight from other surrounding galaxies can be seen in the background.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;span class="source"&gt;K.K.L Charlton (UCT), MeerKAT, HSC, CARTA, IDIA&lt;/span&gt;, &lt;a class="license" href="http://creativecommons.org/licenses/by/4.0/"&gt;CC BY&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;You may not know it, but right now there’s a huge cosmic rave party happening far, far above our heads. The chief party goers are known as &lt;a href="https://theconversation.com/how-were-probing-the-secrets-of-a-giant-black-hole-at-our-galaxys-centre-108181"&gt;supermassive black holes&lt;/a&gt;. These mysterious objects can have masses several million or billion times that of the Sun and are so dense that they warp space time around them. &lt;/p&gt;
2078.  
2079. <p>As far as astronomers know, all galaxies harbour a <a href="https://theconversation.com/how-were-probing-the-secrets-of-a-giant-black-hole-at-our-galaxys-centre-108181">supermassive black hole</a> at their very centres. In some galaxies, large amounts of interstellar gas are spiralling around the supermassive black hole and getting pulled in beyond the event horizon and essentially on to the black hole. This process creates a huge amount of friction and energy, which can cause the “rave” I’m talking about – releasing huge amounts of light at many different colours and frequencies across the electromagnetic spectrum.</p>
2080.  
2081. <p>In some cases, the black hole will even spew jets of plasma, millions of light-years across intergalactic space. The plasma gas is so hot that it’s essentially a soup of electrons moving close to the speed of light. These plasma jets glow at radio frequencies, so they can be seen with a radio telescope and are, aptly, named radio galaxies. In a recent episode of the astronomy podcast <a href="https://thecosmicsavannah.com/episode-77-troublesome-inkathazo-and-the-age-of-giants/">The Cosmic Savannah</a>, I likened their appearance to two glow sticks (the plasma jets) poking out of a ball of sticky tack (the galaxy). Astronomers hypothesise that the plasma jets keep expanding outwards as time passes, eventually growing so large that they become giant radio galaxies.</p>
2082.  
2083. <p>Millions of normally sized radio galaxies are known to science. But by 2020 only about 800 giant radio galaxies had been found, nearly 50 years since they had been initially discovered. They were considered rare. However, a new generation of radio telescopes, including South Africa’s <a href="https://www.sarao.ac.za/science/meerkat/">MeerKAT</a>, have turned this idea on its head: in the past five years about 11,000 giants have been discovered.</p>
2084.  
2085. <p><a href="https://academic.oup.com/mnras/article-lookup/doi/10.1093/mnras/stae2543">MeerKAT’s newest giant radio galaxy find</a> is extraordinary. The plasma jets of this cosmic giant span 3.3 million light-years from end to end – over 32 times the size of the Milky Way. I’m one of the lead researchers who made the discovery. We’ve nicknamed it Inkathazo, meaning “trouble” in South Africa’s isiXhosa and isiZulu languages. That’s because it’s been a bit troublesome to understand the physics behind what’s going on with Inkathazo.</p>
2086.  
2087. <p>This discovery has given us a unique opportunity to study giant radio galaxies. The findings challenge existing models and suggest that we don’t yet understand much of the complicated plasma physics at play in these extreme galaxies.</p>
2088.  
2089. <h2>Here comes ‘trouble’</h2>
2090.  
2091. <p>The MeerKAT telescope is located in the Karoo region of South Africa, is made up of 64 radio dishes and is operated and managed by the <a href="https://www.sarao.ac.za/">South African Radio Astronomy Observatory</a>. It’s a precursor to the <a href="https://www.skao.int/en">Square Kilometre Array</a>, which will, when it commences science operations around 2028, be the world’s largest telescope. </p>
2092.  
2093. <p>MeerKAT has already been pivotal in uncovering some of the hidden treasures of the southern sky since it was first commissioned in 2018.</p>
2094.  
2095. <p>This is the third giant radio galaxy that my collaborators and I <a href="https://theconversation.com/discovery-of-two-new-giant-radio-galaxies-offers-fresh-insights-into-the-universe-153457">have discovered</a> with MeerKAT in a relatively small patch of sky near the equator, around the size of five full moons, that astronomers refer to as the “COSMOS field”. We pointed MeerKAT at COSMOS during the early stages of the most advanced surveys of distant galaxies ever conducted: the International Gigahertz Tiered Extragalactic Exploration (<a href="https://idia.ac.za/mightee/">MIGHTEE</a>).</p>
2096.  
2097. <hr>
2098. <p>
2099.  <em>
2100.    <strong>
2101.      Read more:
2102.      <a href="https://theconversation.com/discovery-of-two-new-giant-radio-galaxies-offers-fresh-insights-into-the-universe-153457">Discovery of two new giant radio galaxies offers fresh insights into the universe</a>
2103.    </strong>
2104.  </em>
2105. </p>
2106. <hr>
2107.  
2108.  
2109. <p>The MIGHTEE team, a collaboration of astronomers from around the world, and I first published the discovery of <a href="https://academic.oup.com/mnras/article/501/3/3833/6034001">the two other giant radio galaxies in COSMOS</a> in 2021. </p>
2110.  
2111. <p>We spotted Inkathazo more recently in my own MeerKAT follow-up observations of COSMOS, as well as in the full MIGHTEE survey.</p>
2112.  
2113. <p>However, Inkathazo differs from its cosmic companions in several ways. It doesn’t have the same characteristics as many other giant radio galaxies. For example, the plasma jets have an unusual shape. Rather than extending straight across from end-to-end, one of the jets is bent.</p>
2114.  
2115. <p>Additionally, Inkathazo lives at the very centre of a cluster of galaxies, rather than in relative isolation, which should make it difficult for the plasma jets to grow to such enormous sizes. Its location in a cluster raises questions about the role of environmental interactions in the formation and evolution of these giant galaxies.</p>
2116.  
2117. <figure class="align-center ">
2118.            <img alt="The same map as above but with the red and yellow jets marked in cyan, green and purple" src="https://images.theconversation.com/files/644653/original/file-20250124-15-5ep448.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/644653/original/file-20250124-15-5ep448.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=580&fit=crop&dpr=1 600w, https://images.theconversation.com/files/644653/original/file-20250124-15-5ep448.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=580&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/644653/original/file-20250124-15-5ep448.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=580&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/644653/original/file-20250124-15-5ep448.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=729&fit=crop&dpr=1 754w, https://images.theconversation.com/files/644653/original/file-20250124-15-5ep448.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=729&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/644653/original/file-20250124-15-5ep448.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=729&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
2119.            <figcaption>
2120.              <span class="caption">A spectral age map of ‘Inkathazo’. Cyan and green show younger plasma, while purple indicates older plasma.</span>
2121.              <span class="attribution"><span class="source">K.K.L Charlton (UCT), MeerKAT, HSC, CARTA, IDIA.</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
2122.            </figcaption>
2123.          </figure>
2124.  
2125. <p>MeerKAT’s exceptional capabilities are helping us to unravel this cosmic conundrum. We’ve created some of the highest-resolution spectral maps ever made for giant radio galaxies. These maps track the age of the plasma across different parts of the galaxy, providing clues about the physical processes at work.</p>
2126.  
2127. <p>The results revealed intriguing complexities in Inkathazo’s jets. Some electrons within the plasma jets receive unexpected boosts of energy. We think this may occur when the jets collide with hot gas in the voids between galaxies in a cluster. This gives us hints about what sort of plasma physics might be happening in these extreme parts of the Universe that we didn’t previously predict.</p>
2128.  
2129. <h2>A treasure trove</h2>
2130.  
2131. <p>The fact that we unveiled three giant radio galaxies by pointing MeerKAT at a single patch of sky suggests that there’s likely a huge treasure trove of these cosmic behemoths just waiting to be discovered in the southern sky. The telescope is incredibly powerful and it’s in a perfect location for this kind of research, so it’s ideally poised to uncover and learn more about giant radio galaxies in the years to come.</p>
2132.  
2133. <p><em>Kathleen Charlton, a Master’s student at the University of Cape Town, was the lead author of the research on which this article was based.</em></p><img src="https://counter.theconversation.com/content/248023/count.gif" alt="The Conversation" width="1" height="1" />
2134. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Jacinta Delhaize receives funding from the Africa-Oxford Initiative and the National Research Foundation. &lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
2135.    <summary>It’s been a bit troublesome to understand the physics behind what’s going on with Inkathazo.</summary>
2136.    <author>
2137.      <name>Jacinta Delhaize, Lecturer, University of Cape Town</name>
2138.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/jacinta-delhaize-1197764"/>
2139.    </author>
2140.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
2141.  </entry>
2142.  <entry>
2143.    <id>tag:theconversation.com,2011:article/246759</id>
2144.    <published>2025-01-24T13:41:11Z</published>
2145.    <updated>2025-01-24T13:41:11Z</updated>
2146.    <link rel="alternate" type="text/html" href="https://theconversation.com/one-large-milky-way-galaxy-or-many-galaxies-100-years-ago-a-young-edwin-hubble-settled-astronomys-great-debate-246759"/>
2147.    <title>One large Milky Way galaxy or many galaxies? 100 years ago, a young Edwin Hubble settled astronomy’s ‘Great Debate’</title>
2148.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/642735/original/file-20250115-19-jmd415.jpg?ixlib=rb-4.1.0&amp;amp;rect=7%2C7%2C5084%2C3351&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;The Andromeda galaxy helped Edwin Hubble settle a great debate in astronomy. &lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://www.gettyimages.com/detail/photo/the-andromeda-galaxy-also-known-as-messier-31-or-royalty-free-image/74039569"&gt;Stocktrek Images via Getty Images&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;A hundred years ago, astronomer &lt;a href="https://science.nasa.gov/people/edwin-hubble/"&gt;Edwin Hubble&lt;/a&gt; dramatically expanded the size of the known universe. At a meeting of the American Astronomical Society in January 1925, a paper read by one of his colleagues on his behalf reported that the Andromeda nebula, also called M31, was nearly a million light years away – too remote to be a part of the Milky Way. &lt;/p&gt;
2149.  
2150. <p>Hubble’s work opened the door to the study of the universe beyond our galaxy. In the century since Hubble’s pioneering work, <a href="https://chrisimpey-astronomy.com/">astronomers like me</a> have learned that the universe is vast and contains <a href="https://bigthink.com/starts-with-a-bang/galaxies-in-universe/">trillions of galaxies</a>.</p>
2151.  
2152. <h2>Nature of the nebulae</h2>
2153.  
2154. <p>In 1610, <a href="https://nmspacemuseum.org/inductee/galileo-galilei/">astronomer Galileo Galilei</a> used the newly invented telescope to show that the Milky Way was composed of a huge number of faint stars. For the next 300 years, astronomers assumed that the Milky Way was the entire universe.</p>
2155.  
2156. <p>As astronomers scanned the night sky with larger telescopes, they were intrigued by fuzzy patches of light called nebulae. Toward the end of the 18th century, astronomer <a href="https://www.space.com/17432-william-herschel.html">William Herschel</a> used star counts to <a href="https://doi.org/10.1098/rstl.1785.0012">map out the Milky Way</a>. He <a href="https://doi.org/10.1098/rstl.1786.0027">cataloged a thousand new nebulae and clusters of stars</a>. He believed that the nebulae were objects within the Milky Way.</p>
2157.  
2158. <p><a href="http://www.messier.seds.org/">Charles Messier</a> also produced a catalog of over 100 prominent nebulae in 1781. Messier was interested in comets, so his list was a set of fuzzy objects that might be mistaken for comets. He intended for comet hunters to avoid them since they did not move across the sky.</p>
2159.  
2160. <p>As more data piled up, 19th century astronomers started to see that the nebulae were a mixed bag. Some were gaseous, star-forming regions, such as the <a href="https://science.nasa.gov/mission/hubble/science/explore-the-night-sky/hubble-messier-catalog/messier-42/">Orion nebula, or M42</a> – the 42nd object in Messier’s catalog – while others were star clusters such as the <a href="https://science.nasa.gov/mission/hubble/science/explore-the-night-sky/hubble-messier-catalog/messier-45/">Pleiades, or M45</a>.</p>
2161.  
2162. <p>A third category – nebulae with spiral structure – particularly intrigued astronomers. The <a href="https://www.skyhound.com/observing/archives/oct/M_31.html">Andromeda nebula</a>, M31, was a prominent example. It’s visible to the naked eye from a dark site. </p>
2163.  
2164. <figure>
2165.            <iframe width="440" height="260" src="https://www.youtube.com/embed/aLlQxsGyhnw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
2166.            <figcaption><span class="caption">The Andromeda galaxy, then known as the Andromeda nebula, is a bright spot in the sky that intrigued early astronomers.</span></figcaption>
2167.          </figure>
2168.  
2169. <p>Astronomers as far back as the mid-18th century had speculated that some nebulae might be remote systems of stars or “island universes,” but there was <a href="https://www.northcoastjournal.com/life-outdoors/island-universes-part-1-24139005">no data to support this hypothesis</a>. Island universes referred to the idea that there could be enormous stellar systems outside the Milky Way – but astronomers now just call these systems galaxies.</p>
2170.  
2171. <p>In 1920, astronomers Harlow Shapley and Heber Curtis held a <a href="https://www.astronomy.com/science/the-great-debate-of-shapley-and-curtis-100-years-later/">Great Debate</a>. Shapley argued that the spiral nebulae were small and in the Milky Way, while Curtis took a more radical position that they were independent galaxies, extremely large and distant. </p>
2172.  
2173. <p>At the time, the debate was inconclusive. Astronomers now know that galaxies are isolated systems of stars, much smaller than the space between them.</p>
2174.  
2175. <h2>Hubble makes his mark</h2>
2176.  
2177. <p><a href="https://science.nasa.gov/people/edwin-hubble/">Edwin Hubble</a> was young and ambitious. At the of age 30, he arrived at Mount Wilson Observatory in Southern California just in time to use the new Hooker <a href="https://www.mtwilson.edu/building-the-100-inch-telescope/">100-inch telescope</a>, at the time the largest in the world. </p>
2178.  
2179. <figure class="align-right zoomable">
2180.            <a href="https://images.theconversation.com/files/642737/original/file-20250115-15-ogmz7k.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A black and white photo of a man looking through the lens of a large telescope." src="https://images.theconversation.com/files/642737/original/file-20250115-15-ogmz7k.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/642737/original/file-20250115-15-ogmz7k.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=960&fit=crop&dpr=1 600w, https://images.theconversation.com/files/642737/original/file-20250115-15-ogmz7k.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=960&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/642737/original/file-20250115-15-ogmz7k.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=960&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/642737/original/file-20250115-15-ogmz7k.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=1207&fit=crop&dpr=1 754w, https://images.theconversation.com/files/642737/original/file-20250115-15-ogmz7k.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=1207&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/642737/original/file-20250115-15-ogmz7k.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=1207&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
2181.            <figcaption>
2182.              <span class="caption">Edwin Hubble uses the telescope at the Mount Wilson Observatory.</span>
2183.              <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/edwin-powell-hubble-american-astronomer-in-the-obsevatory-news-photo/463908779?adppopup=true">Hulton Archives via Getty Images</a></span>
2184.            </figcaption>
2185.          </figure>
2186.  
2187. <p>He began taking <a href="https://www.mariamitchell.org/astronomical-plates-collection">photographic plates</a> of the spiral nebulae. These glass plates recorded images of the night sky using a light-sensitive emulsion covering their surface. The telescope’s size let it make images of very faint objects, and its high-quality mirror allowed it to distinguish individual stars in some of the nebulae.</p>
2188.  
2189. <p><a href="https://www.skyatnightmagazine.com/space-science/measuring-distance-space">Estimating distances</a> in astronomy is challenging. Think of how hard it is to estimate the distance of someone pointing a flashlight at you on a dark night. Galaxies come in a very wide range of sizes and masses. Measuring a galaxy’s brightness or apparent size is <a href="https://theconversation.com/astronomers-have-learned-lots-about-the-universe-but-how-do-they-study-astronomical-objects-too-distant-to-visit-214320">not a good guide</a> to its distance.</p>
2190.  
2191. <p>Hubble leveraged a discovery made by <a href="https://web.archive.org/web/20201111225447/https://cosmology.carnegiescience.edu/timeline/1912">Henrietta Swan Leavitt</a> 10 years earlier. She worked at the Harvard College Observatory as a “<a href="https://www.amnh.org/explore/news-blogs/harvard-computers-history">human computer</a>,” laboriously measuring the positions and brightness of thousands of stars on photographic plates. </p>
2192.  
2193. <p>She was particularly interested in <a href="https://starchild.gsfc.nasa.gov/docs/StarChild/questions/cepheids.html">Cepheid variables</a>, which are stars whose brightness pulses regularly, so they get brighter and dimmer with a particular period. She found a relationship between their variation period, or pulse, and their <a href="https://homepages.uc.edu/%7Ehansonmm/ASTRO/LECTURENOTES/W03/Lec6/Page3.html">intrinsic brightness or luminosity</a>. </p>
2194.  
2195. <p>Once you measure a Cepheid’s period, you can calculate its distance from how bright it appears using the <a href="https://www.astronomynotes.com/starprop/s3.htm">inverse square law</a>. The more distant the star is, the fainter it appears.</p>
2196.  
2197. <p>Hubble worked hard, taking images of spiral nebulae every clear night and looking for the telltale variations of Cepheid variables. By the end of 1924, he had found 12 Cepheids in M31. He calculated M31’s distance as a prodigious 900,000 light years away, though he underestimated its true distance – about 2.5 million light years – by not realizing there were <a href="https://history.aip.org/exhibits/cosmology/ideas/hubble-distance-double.htm">two different types</a> of Cepheid variables. </p>
2198.  
2199. <p>His measurements marked the end of <a href="https://www.astronomy.com/science/how-edwin-hubble-won-the-great-debate/">the Great Debate</a> about the Milky Way’s size and the nature of the nebulae. Hubble wrote about his discovery to Harlow Shapley, who had argued that the Milky Way encompassed the entire universe. </p>
2200.  
2201. <p>“Here is the letter that destroyed my universe,” <a href="https://bigthink.com/13-8/great-debate-hubble/">Shapley remarked</a>.</p>
2202.  
2203. <p>Always eager for publicity, Hubble <a href="https://timesmachine.nytimes.com/timesmachine/1924/11/23/104162202.html?pageNumber=6">leaked his discovery</a> to The New York Times five weeks before a colleague presented his paper at the astronomers’ annual meeting in Washington, D.C.</p>
2204.  
2205. <h2>An expanding universe of galaxies</h2>
2206.  
2207. <p>But Hubble wasn’t done. His second major discovery also transformed astronomers’ understanding of the universe. As he dispersed the light from <a href="https://theconversation.com/explainer-seeing-the-universe-through-spectroscopic-eyes-37759">dozens of galaxies into a spectrum</a>, which recorded the amount of light at each wavelength, he noticed that the light was always shifted to longer or redder wavelengths. </p>
2208.  
2209. <p>Light from the galaxy passes through a prism or reflects off a <a href="http://spiff.rit.edu/classes/phys312/workshops/w10b/spectra/mystery_spectra.html">diffraction grating</a> in a telescope, which captures the intensity of light from blue to red.</p>
2210.  
2211. <p>Astronomers call <a href="https://earthsky.org/astronomy-essentials/what-is-a-redshift/">a shift to longer wavelengths a redshift</a>. </p>
2212.  
2213. <p>It seemed that these redshifted galaxies were all moving away from the Milky Way. </p>
2214.  
2215. <p>Hubble’s results suggested the farther away a galaxy was, the <a href="https://apod.nasa.gov/diamond_jubilee/1996/hub_1929.html">faster it was moving away from Earth</a>. Hubble got the lion’s share of the credit for this discovery, but Lowell Observatory astronomer <a href="https://www.roe.ac.uk/%7Ejap/slipher/">Vesto Slipher</a>, who noticed the same phenomenon but didn’t publish his data, also anticipated that result.</p>
2216.  
2217. <p>Hubble referred to galaxies having <a href="https://library.fiveable.me/key-terms/intro-astronomy/recession-velocity">recession velocities</a>, or speeds of moving away from the Earth, but he <a href="https://hubblesite.org/mission-and-telescope/hubble-30th-anniversary/hubbles-exciting-universe/measuring-the-universes-expansion-rate">never figured out</a> that they were moving away from Earth because the universe is getting bigger. </p>
2218.  
2219. <p>Belgian cosmologist and Catholic priest <a href="https://science.nasa.gov/mission/hubble/science/science-behind-the-discoveries/hubble-cosmological-redshift/">Georges Lemaitre</a> made that connection by realizing that the theory of <a href="https://www.scientificamerican.com/article/where-is-the-universe-exp/">general relativity</a> described an expanding universe. He recognized that space expanding in between the galaxies could cause the redshifts, making it seem like they were moving farther away from each other and from Earth. </p>
2220.  
2221. <p>Lemaitre was the first to argue that the expansion must have begun during <a href="https://www.amnh.org/learn-teach/curriculum-collections/cosmic-horizons-book/georges-lemaitre-big-bang">the big bang</a>. </p>
2222.  
2223. <figure class="align-center zoomable">
2224.            <a href="https://images.theconversation.com/files/641591/original/file-20250109-15-w52283.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="The Hubble telescope, which looks like a metal cylinder, floating in space." src="https://images.theconversation.com/files/641591/original/file-20250109-15-w52283.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/641591/original/file-20250109-15-w52283.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/641591/original/file-20250109-15-w52283.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/641591/original/file-20250109-15-w52283.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/641591/original/file-20250109-15-w52283.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/641591/original/file-20250109-15-w52283.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/641591/original/file-20250109-15-w52283.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
2225.            <figcaption>
2226.              <span class="caption">Edwin Hubble is the namesake for NASA’s Hubble Space Telescope, which has spent decades observing faraway galaxies.</span>
2227.              <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/HubbleSpaceTelescope/470a426147ee4d3a9eff52b78471f68c/photo?Query=hubble%20space%20telescope&mediaType=photo&sortBy=&dateRange=Anytime&totalCount=5&digitizationType=Digitized&currentItemNo=1&vs=true">NASA via AP</a></span>
2228.            </figcaption>
2229.          </figure>
2230.  
2231. <p>NASA named its flagship space observatory after Hubble, and it has been used to <a href="https://www.stsci.edu/hst/about/key-science-themes/galaxies">study galaxies for 35 years</a>. Astronomers routinely observe galaxies that are thousands of times fainter and more distant than galaxies observed in the 1920s. The <a href="https://webbtelescope.org/science/galaxies-over-time">James Webb Space Telescope</a> has pushed the envelope even farther. </p>
2232.  
2233. <p>The <a href="https://www.space.com/james-webb-space-telescope-earliest-galaxies-glimpse">current record holder</a> is a galaxy a staggering 34 billion light years away, seen just 200 million years after the big bang, when the universe was 20 times smaller than it is now. Edwin Hubble would be amazed to see such progress.</p><img src="https://counter.theconversation.com/content/246759/count.gif" alt="The Conversation" width="1" height="1" />
2234. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Chris Impey does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
2235.    <summary>Hubble’s work pushed the field of astronomy forward, starting with his paper demonstrating that some objects exist outside our galaxy.</summary>
2236.    <author>
2237.      <name>Chris Impey, University Distinguished Professor of Astronomy, University of Arizona</name>
2238.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/chris-impey-536311"/>
2239.    </author>
2240.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
2241.  </entry>
2242.  <entry>
2243.    <id>tag:theconversation.com,2011:article/246663</id>
2244.    <published>2025-01-15T10:46:08Z</published>
2245.    <updated>2025-01-15T10:46:08Z</updated>
2246.    <link rel="alternate" type="text/html" href="https://theconversation.com/blinking-radio-pulses-from-space-hint-at-a-cosmic-object-that-shouldnt-exist-246663"/>
2247.    <title>Blinking radio pulses from space hint at a cosmic object that ‘shouldn’t exist’</title>
2248.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/642215/original/file-20250114-17-skrm51.jpg?ixlib=rb-4.1.0&amp;amp;rect=24%2C9%2C3294%2C2468&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;Artist&amp;#39;s impression of ASKAP J1839-0756.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;span class="source"&gt;James Josephides&lt;/span&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;When some of the biggest stars reach the end of their lives, they explode in spectacular supernovas and leave behind incredibly dense cores called neutron stars. Some of these remnants emit powerful radio beams from their magnetic poles. &lt;/p&gt;
2249.  
2250. <p>As the star spins, these beams sweep past Earth and produce periodic pulses of radio waves, much like a cosmic lighthouse. This behaviour has earned them the name “pulsars”. </p>
2251.  
2252.  
2253.  
2254. <p>Pulsars typically spin incredibly fast, often completing a full rotation in just seconds – or even less. Over the last three years, some mysterious objects have emerged that emit periodic radio pulses at much slower intervals, which is hard to explain with our current understanding of neutron stars.</p>
2255.  
2256. <p>In new research, we have found the slowest cosmic lighthouse yet – one that spins once every 6.5 hours. This discovery, <a href="https://doi.org/10.1038/s41550-024-02452-z">published in Nature Astronomy</a>, pushes the boundaries of what we thought possible.</p>
2257.  
2258. <p>Our slow lighthouse also happens to be aligned with Earth in a way that lets us see radio pulses from both its magnetic poles. This rare phenomenon is a first for objects spinning this slowly and offers a new window into how these stars work.</p>
2259.  
2260. <h2>An object that shouldn’t exist?</h2>
2261.  
2262. <p>We discovered the object, named ASKAP J1839-0756, using CSIRO’s ASKAP radio telescope, located in Wajarri Yamaji country in Western Australia. </p>
2263.  
2264. <p>During a routine observation, ASKAP J1839-0756 stood out because no previously known object had been identified at its position. Its radio emission appeared as a fading burst, with its brightness plummeting by 95% in just 15 minutes.</p>
2265.  
2266. <p>At first, we had no idea the source was emitting periodic radio pulses. Only a single burst had been detected during the initial observation. </p>
2267.  
2268. <p>To uncover more, we conducted more observations with ASKAP as well as CSIRO’s Australia Telescope Compact Array on Kamilaroi country in Narrabri, NSW, and the highly sensitive MeerKAT radio telescope in South Africa. A long ASKAP observation eventually revealed two pulses separated by 6.5 hours, confirming the periodic nature of the source.</p>
2269.  
2270.  
2271.  
2272. <p>But here is the real surprise: according to what we know about neutron stars, ASKAP J1839-0756 shouldn’t even exist. </p>
2273.  
2274. <p>Neutron stars emit radio pulses by converting their rotational energy into radiation. Over time, they lose energy and slow down. </p>
2275.  
2276. <p>Standard theory says that once a neutron star’s spin slows beyond a certain point (about one rotation per minute), it should stop emitting radio pulses altogether. Yet here is ASKAP J1839-0756, lighting up the cosmos at a leisurely pace of one rotation every 6.5 hours.</p>
2277.  
2278. <h2>A tale of two poles</h2>
2279.  
2280. <p>Most pulsars, the faster-spinning cousins of ASKAP J1839-0756, are like one-sided flashlights. The axis they spin around is closely aligned to the axis of their magnetic field, which means we only see flashes from one magnetic pole.</p>
2281.  
2282. <p>But in about 3% of pulsars, the rotational and magnetic axes are almost at right angles to one another, which lets us see pulses from both poles. These rare double flashes, called interpulses, provide a unique window into the star’s geometry and magnetic field.</p>
2283.  
2284.  
2285.  
2286. <p>Whether a pulsar’s magnetic and rotational axes become more aligned or less aligned as it slows down is still an open question. </p>
2287.  
2288. <p>The interpulse from ASKAP J1839-0756 could provide clues to this question. About 3.2 hours after its main pulse, it emits a weaker pulse with different properties, strongly suggesting we’re seeing radio light from the opposite magnetic pole. </p>
2289.  
2290. <p>This discovery makes ASKAP J1839-0756 the first slowpoke in its class to emit interpulses, and it raises big questions about how such objects work.</p>
2291.  
2292. <h2>Magnetar or something new?</h2>
2293.  
2294. <p>So, what is powering this cosmic anomaly? One possibility is that it is a magnetar — a neutron star with a powerful magnetic field that makes Earth’s most powerful magnets look like featherweights. </p>
2295.  
2296. <p>Magnetars generate radio pulses through a different mechanism, which might allow them to keep shining even at slower spin rates. But even magnetars have limits, and their periods are usually measured in seconds, not hours. </p>
2297.  
2298. <p>The only exception is a magnetar named 1E 161348-5055, which has a period of 6.67 hours. However, it only emits X-ray and no radio pulses.</p>
2299.  
2300. <p>Could ASKAP J1839-0756 be something else entirely? Some astronomers wonder if <a href="https://theconversation.com/a-strange-intermittent-radio-signal-from-space-has-astronomers-puzzled-231385">similar objects</a> might be <a href="https://theconversation.com/astronomers-have-pinpointed-the-origin-of-mysterious-repeating-radio-bursts-from-space-244920">white dwarfs</a> – the leftover cores of less massive stars. </p>
2301.  
2302. <p>White dwarfs spin much more slowly than neutron stars, but no individual isolated white dwarfs have been observed to emit radio pulses. And so far, no observations in other wavelengths have found evidence of a white dwarf at this location in the sky.</p>
2303.  
2304. <h2>A cosmic puzzle</h2>
2305.  
2306. <p>Whatever ASKAP J1839-0756 turns out to be, it is clear that this object is rewriting the rulebook. Its strange combination of slow rotation, radio pulses and interpulses is forcing astronomers to rethink the limits of neutron star behaviour and explore new possibilities for what lies at the heart of this enigma.</p>
2307.  
2308. <p>The discovery of ASKAP J1839-0756 is a reminder that the universe loves to surprise us, especially when we think we have got it all figured out. As we continue to monitor this mysterious object, we’re bound to uncover more secrets.</p><img src="https://counter.theconversation.com/content/246663/count.gif" alt="The Conversation" width="1" height="1" />
2309. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Manisha Caleb acknowledges support of an Australian Research Council Discovery Early Career Research Award (project number DE220100819) funded by the Australian Government. Parts of this research were conducted by the Australian Research Council Centre of Excellence for Gravitational Wave Discovery (OzGrav), project number CE170100004.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;&lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Yu Wing Joshua Lee acknowledges funding from the Australian Research Council Discovery Project (project number DP 220102305) and the Australian Research Council Centre of Excellence for Gravitational Wave Discovery (OzGrav) (project number CE230100016).&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
2310.    <summary>The slowest ‘cosmic lighthouse’ ever found challenges our understanding of how neutron stars work.</summary>
2311.    <author>
2312.      <name>Manisha Caleb, Senior Lecturer in Astrophysics, University of Sydney</name>
2313.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/manisha-caleb-1349955"/>
2314.    </author>
2315.    <author>
2316.      <name>Yu Wing Joshua Lee, PhD Student in Radio Astronomy, University of Sydney</name>
2317.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/yu-wing-joshua-lee-2291843"/>
2318.    </author>
2319.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
2320.  </entry>
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