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Supermoons are boring – here are 5 things in the sky worth your time

<a href="https://theconversation.com/profiles/michael-j-i-brown-113">Michael J. I. Brown</a>, <a href="https://theconversation.com/institutions/monash-university-1065">Monash University</a> A <a href="https://science.nasa.gov/solar-system/moon/what-is-a-supermoon/">supermoon</a> may sound exciting, but it’s a modest coincidence. As the Moon orbits Earth, its distance from us varies from 357,000 to 407,000 kilometres. When the Moon and the Sun are in almost opposite directions from Earth, we get a full moon. A “supermoon” is a full moon where its position along its orbit is within 10% of its closest approach to Earth. That’s it. This means a supermoon has an apparent diameter that’s 14% larger than the smallest possible full moon. That’s not a lot. You can’t really notice the difference by eye. As an astronomer, I have a problem with supermoons. There are genuine wonders to see in the night sky, so don’t be disappointed by a dull, overhyped supermoon. <h2>When is the best time to view the Moon?</h2> Articles hyping supermoons are easy. ChatGPT can do it. Say it’s the first supermoon since whenever, add some superlatives, and throw in a telephoto lens photo of a full moon with a landmark. Perhaps the supermoon coincides with another otherwise normal full moon, so it can be a “<a href="https://moon.nasa.gov/news/197/super-blue-moons-your-questions-answered/">blue supermoon</a>” or a “<a href="https://www.accuweather.com/en/space-news/super-worm-moon-how-to-see-the-final-full-moon-of-winter/695656">worm supermoon</a>” or whatever. It’s still just a full moon. If you do want to look at the Moon and it happens to be a supermoon, go for it. But there are better times to admire our only natural satellite, particularly with binoculars or a telescope. The best time to look at the Moon is when its shadows, as seen from Earth, are longest. These long shadows help the craters and mountains stand out from the surrounding plains, so you can appreciate the dramatic landscape of our neighbouring world. The shadows are longest when the Moon appears as a half moon in the night sky. During a full moon or a supermoon the shadows are at their shortest – not nearly as impressive. <h2>Supermoons are a distraction</h2> Have you seen the craters of the Moon, <a href="https://skyandtelescope.org/observing/viewing-saturn-the-planet-rings-and-moons/#:%7E:text=Viewing%20Saturn's%20Rings,the%20ball%20of%20the%20planet.">the rings of Saturn</a>, the clouds of Jupiter or <a href="https://skyandtelescope.org/observing/celestial-objects-to-watch/observing-the-great-orion-nebula/#:%7E:text=First%20locate%20Orion's%20Belt%2C%20which,ll%20find%20the%20Orion%20Nebula.">the Orion nebula</a> with a telescope? They truly are awe-inspiring. Even the most dedicated astronomers return to view them time and time again. <figure class="align-right zoomable"></figure> In fact, astronomers prefer to avoid nights with supermoons and catch up on lost sleep. Full moons flood the night sky with light and make it harder to view more subtle and interesting sights. Want to look at the grand expanse of the Milky Way with the unaided eye? Want to see a meteor shower, comet or aurora? Best done without a damn supermoon. It can be fun to see something truly rare or unusual in the sky. But supermoons don’t qualify for that either. Using the definition I mentioned earlier, there are typically three or four supermoons each year. More restrictive definitions give us one or two supermoons per year. Not only is that not rare, it still just looks like a full moon. There are rarer celestial events that really can inspire. Millions of people across the globe saw <a href="https://science.nasa.gov/science-research/heliophysics/how-nasa-tracked-the-most-intense-solar-storm-in-decades/">bright auroras in May 2024</a>, including places where truly spectacular auroras are few and far between. Comets can also be wonderful. Every decade or so, a comet swings into the inner Solar System and produces a bright tail, millions of kilometres long and visible from Earth. Back when I was a student, I saw <a href="https://en.wikipedia.org/wiki/Comet_Hyakutake">Comet Hyakutake’s bright blue tail</a> stretch across a huge expanse of sky. Sometimes comets fizzle, but when they’re great they are amazing. <h2>Want something impressive? Try an eclipse</h2> Auroras and comets can be fickle, but eclipses are predictable and put on a reliable show. Take total solar eclipses, when the Moon covers the Sun and day turns briefly into night. Thousands travel across the globe to see them. I will be travelling to New South Wales for the <a href="https://eclipse.asa.astronomy.org.au/eclipse-australia-2028/">2028 eclipse</a>. <figure class="align-left zoomable"><a href="https://images.theconversation.com/files/613126/original/file-20240813-17-ewfavl.jpeg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"> </a></figure> <a href="https://www.space.com/15689-lunar-eclipses.html">Lunar eclipses</a>, when the Moon falls within Earth’s shadow, can be a more accessible eclipse experience, which is visible from your own home <a href="https://en.wikipedia.org/wiki/List_of_lunar_eclipses_in_the_21st_century">every few years</a>. During the best lunar eclipses, the Moon turns a dark red as the only light that reaches it comes through Earth’s atmosphere. As an astronomer, I encourage people to look at celestial sights. Go out and see the Moon when it can really impress – during an eclipse or viewed through a telescope. Or enjoy the planets, auroras, comets and meteor showers when there is no Moon at all. But please don’t waste time on supermoons.<img style="border: none !important; box-shadow: none !important; margin: 0 !important; max-height: 1px !important; max-width: 1px !important; min-height: 1px !important; min-width: 1px !important; opacity: 0 !important; outline: none !important; padding: 0 !important;" src="https://counter.theconversation.com/content/236416/count.gif?distributor=republish-lightbox-basic" alt="The Conversation" width="1" height="1" /> <a href="https://theconversation.com/profiles/michael-j-i-brown-113">Michael J. I. Brown</a>, Associate Professor in Astronomy, <a href="https://theconversation.com/institutions/monash-university-1065">Monash University</a> Image credits: Shutterstock This article is republished from <a href="https://theconversation.com">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/supermoons-are-boring-here-are-5-things-in-the-sky-worth-your-time-236416">original article</a>.

Travel Tips

Humans are still hunting for aliens. Here’s how astronomers are looking for life beyond Earth

We have long been fascinated with the idea of alien life. The earliest written record presenting the idea of “aliens” is seen in the satiric work of Assyrian writer <a href="https://blogs.scientificamerican.com/life-unbounded/the-first-alien/">Lucian of Samosata</a> dated to 200 AD. In one novel, Lucian <a href="https://www.yorku.ca/inpar/lucian_true_tale.pdf">writes of a journey to the Moon</a> and the bizarre life he imagines living there – everything from three-headed vultures to fleas the size of elephants. Now, 2,000 years later, we still write stories of epic adventures beyond Earth to meet otherworldly beings (<a href="https://www.britannica.com/topic/The-Hitchhikers-Guide-to-the-Galaxy-novel-by-Adams">Hitchhiker’s Guide</a>, anyone?). Stories like these entertain and inspire, and we are forever trying to find out if science fiction will become science fact. <h2>Not all alien life is the same</h2> When looking for life beyond Earth, we are faced with two possibilities. We might find basic microbial life hiding somewhere in our Solar System; or we will identify signals from intelligent life somewhere far away. <div data-id="17"> </div> Unlike in <a href="https://www.britannica.com/topic/Star-Wars-film-series">Star Wars</a>, we’re not talking far, far away in another galaxy, but rather around other nearby stars. It is this second possibility which really excites me, and should excite you too. A detection of intelligent life would fundamentally change how we see ourselves in the Universe. In the last 80 years, programs dedicated to the search for extraterrestrial intelligence (SETI) have worked tirelessly searching for cosmic “hellos” in the form of radio signals. The reason we think any intelligent life would communicate via radio waves is due to the waves’ ability to travel vast distances through space, rarely interacting with the dust and gas in between stars. If anything out there is trying to communicate, it’s a pretty fair bet they would do it through radio waves. <h2>Listening to the stars</h2> One of the most exciting searches to date is <a href="https://breakthroughinitiatives.org/initiative/1">Breakthrough Listen</a>, the largest scientific research program dedicated to looking for evidence of intelligent life beyond Earth. This is one of many projects funded by US-based Israeli entrepreneurs Julia and Yuri Milner, with some serious dollars attached. Over a ten-year period a total amount of <a href="https://breakthroughinitiatives.org/initiative/1">US$100 million</a> will be invested in this effort, and they have a mighty big task at hand. Breakthrough Listen is currently targeting the closest one million stars in the hope of identifying any unnatural, alien-made radio signals. Using telescopes around the globe, from the 64-metre Murriyang Dish (Parkes) here in Australia, to the 64-antenna MeerKAT array in South Africa, the search is one of epic proportions. But it isn’t the only one. Hiding away in the Cascade Mountains north of San Francisco sits the <a href="https://www.seti.org/ata">Allen Telescope Array</a>, the first radio telescope built from the ground up specifically for SETI use. This unique facility is another exciting project, able to search for signals every day of the year. This project is currently upgrading the hardware and software on the original dish, including the ability to target several stars at once. This is a part of the non-profit research organisation, the SETI Institute. <h2>Space lasers!</h2> The SETI Institute is also looking for signals that would be best explained as “space lasers”. Some astronomers hypothesise that intelligent beings might use massive lasers to communicate or even to propel spacecraft. This is because even here on Earth we’re investigating <a href="https://www.nasa.gov/feature/goddard/2022/the-future-of-laser-communications/">laser communication</a> and laser-propelled <a href="https://www.insidescience.org/news/new-light-sail-design-would-use-laser-beam-ride-space">light sails</a>. To search for these mysterious flashes in the night sky, we need speciality instruments in locations around the globe, which are currently being developed and deployed. This is a research area I’m excited to watch progress and eagerly await results. As of writing this article, sadly no alien laser signals have been found yet. <h2>Out there, somewhere</h2> It’s always interesting to ponder who or what might be living out in the Universe, but there is one problem we must overcome to meet or communicate with aliens. It’s the speed of light. Everything we rely on to communicate via space requires light, and it can only travel so fast. This is where my optimism for finding intelligent life begins to fade. The Universe is big – really big. To put it in perspective, humans started using radio waves to communicate across large distances in 1901. That <a href="https://ethw.org/Milestones:Reception_of_Transatlantic_Radio_Signals,_1901">first transatlantic signal</a> has only travelled 122 light years, reaching just 0.0000015% of the stars in our Milky Way. Did your optimism just fade too? That is okay, because here is the wonderful thing… we don’t have to find life to know it is out there, somewhere. When we consider the <a href="https://theconversation.com/how-many-stars-are-there-in-space-165370">trillions of galaxies</a>, septillion of stars, and likely many more planets just in the observable Universe, it feels near impossible that we are alone. We can’t fully constrain the parameters we need to estimate how many other lifeforms might be out there, as famously proposed by Frank Drake, but using our best estimates and <a href="https://www.cambridge.org/core/journals/international-journal-of-astrobiology/article/numerical-testbed-for-hypotheses-of-extraterrestrial-life-and-intelligence/0C97E7803EEB69323C3728F02BA31AFA">simulations</a> the current best answer to this is tens of thousands of possible civilisations out there. The Universe <a href="https://theconversation.com/is-space-infinite-we-asked-5-experts-165742">might even be infinite</a>, but that is too much for my brain to comprehend on a weekday. <h2>Don’t forget the tiny aliens</h2> So, despite keenly listening for signals, we might not find intelligent life in our lifetimes. But there is hope for aliens yet. The ones hiding in plain sight, on the planetary bodies of our Solar System. In the coming decades we’ll explore the moons of Jupiter and Saturn like never before, with missions hunting to find traces of basic life. Mars will continue to be explored – eventually by humans – which could allow us to uncover and retrieve samples from new and unexplored regions. Even if our future aliens are only tiny microbes, it would still be nice to know we have company in this Universe. Images: Getty <em style="box-sizing: border-box; color: #212529; font-family: -apple-system, 'system-ui', 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol', 'Noto Color Emoji'; font-size: 16px; background-color: #ffffff;">This article originally appeared on <a href="https://theconversation.com/humans-are-still-hunting-for-aliens-heres-how-astronomers-are-looking-for-life-beyond-earth-197621" target="_blank" rel="noopener">The Conversation</a>.

Technology

Astronomers have detected another ‘planet killer’ asteroid. Could we miss one coming our way?

If you surfed the web this morning, you may have seen news of the latest existential threat to humanity: a “planet killer” asteroid named 2022 AP7. Luckily for us 2022 AP7 “has no chance to hit the Earth currently”, <a href="https://www.theguardian.com/science/2022/nov/01/huge-planet-killer-asteroid-discovered-and-its-heading-our-way">according</a> to Scott Sheppard at the Carnegie Institution for Science. He and his international team of colleagues <a href="https://iopscience.iop.org/article/10.3847/1538-3881/ac8cff/pdf">observed 2022 AP7</a> in a trio of “rather large” asteroids obscured by the Sun’s glare (the other two don’t pose a risk). 2022 AP7 orbits the Sun every five years, and currently crosses Earth’s orbit when Earth is on the other side of the Sun to it. Eventually its movement will sync with Earth’s and it will cross much closer by, but this will be centuries into the future. We simply don’t know enough about 2022 AP7 to precisely predict the danger it may pose centuries from now. At the same time, we suspect there could be other “planet killers” out there yet to be discovered. But how many? And what’s being done to find them? What makes a planet killer? Asteroid 2022 AP7 is the largest potentially hazardous asteroid (PHA) found in eight years, with a diameter between 1.1km and 2.3km. For context, an asteroid with a diameter more than 1km is enough to trigger a <a href="https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_extinction_event">mass extinction event</a> on Earth. As well as having a diameter greater than 1km, an asteroid also needs to have an orbit that crosses Earth’s to be considered potentially dangerous. In the case of 2022 AP7, any threat is centuries down the track. The important point is it has been detected and can now be tracked. This is the best possible outcome. It is estimated we’ve already <a href="https://theconversation.com/in-a-world-first-nasas-dart-mission-is-about-to-smash-into-an-asteroid-what-will-we-learn-189391">discovered</a> about 95% of potentially hazardous asteroids, and that there are fewer than 1,000 of these. The work of Sheppard and colleagues highlights that hunting down the remaining 5% – some 50 asteroids – will be a massive effort. <figure class="align-center "><img src="https://images.theconversation.com/files/492923/original/file-20221102-25180-74aqvo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px" srcset="https://images.theconversation.com/files/492923/original/file-20221102-25180-74aqvo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=304&fit=crop&dpr=1 600w, https://images.theconversation.com/files/492923/original/file-20221102-25180-74aqvo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=304&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/492923/original/file-20221102-25180-74aqvo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=304&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/492923/original/file-20221102-25180-74aqvo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=382&fit=crop&dpr=1 754w, https://images.theconversation.com/files/492923/original/file-20221102-25180-74aqvo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=382&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/492923/original/file-20221102-25180-74aqvo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=382&fit=crop&dpr=3 2262w" alt="" /><figcaption>Statistically, there’s less of a chance of a larger asteroid colliding with Earth compared to a smaller one. NASA</figcaption></figure> What constitutes a near miss? NASA <a href="https://www.jpl.nasa.gov/asteroid-watch">closely tracks</a> all known objects in the Solar System. But every now and again an object will catch us off guard. In 2021, we had a close call with an asteroid called <a href="https://en.wikipedia.org/wiki/2021_UA1">2021 UA1</a>. It came only a few thousand kilometres from Earth, over the Antarctic. In cosmic terms, this is uncomfortably close. However, 2021 UA1 was only two metres across, and therefore posed no substantial risk. There are likely hundreds of millions of objects of this size in our Solar System, and it’s not uncommon for them to impact Earth. In these cases, most of the object burns up in the atmosphere and creates a spectacular light show, with little risk to life. In 2019 another <a href="https://theconversation.com/an-asteroid-just-buzzed-past-earth-and-we-barely-noticed-in-time-120972">asteroid</a> with a 100m diameter passed Earth some 70,000km away. It was publicly announced mere hours before it flew past. While it wasn’t as close, it was of a much more concerning size. These near misses reiterate how important it is for us to speed up the search for near-Earth objects. Blind spots The reason we haven’t already found every object that could one day pass nearby Earth is largely because of observational blind spots, and the fact we can’t observe all parts of the sky all the time. To find 2022 AP7, Sheppard and colleagues used a telescope at twilight soon after the Sun had set. They had to do this because they were looking for asteroids in the vicinity of Venus and Earth. Venus is currently on the <a href="https://theskylive.com/where-is-venus">other side of the Sun</a> to Earth. Making observations close to the Sun is difficult. The Sun’s glare overwhelms the weak light reflected off small asteroids – presenting a blind spot. But just before and after sunset, there’s a small window in which the Sun’s glare no longer blocks the view. Right now there are only about 25 asteroids known to have well-determined orbits that lie entirely within Earth’s orbit. More are likely to be discovered, and these may contribute significantly to the missing 5% of potentially hazardous asteroids. The Near-Earth Object Surveyor A recent NASA mission spectacularly demonstrated that humans can purposefully change the trajectory of an asteroid. NASA’s DART (<a href="https://www.nasa.gov/planetarydefense/dart/dart-news">Double Asteroid Redirection Test</a>) mission collided a vending-machine-sized spacecraft into a 160m diameter minor-planet moon called Dimorphos. <figure class="align-center "><img src="https://images.theconversation.com/files/492925/original/file-20221102-28436-f16d5x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px" srcset="https://images.theconversation.com/files/492925/original/file-20221102-28436-f16d5x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/492925/original/file-20221102-28436-f16d5x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/492925/original/file-20221102-28436-f16d5x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/492925/original/file-20221102-28436-f16d5x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/492925/original/file-20221102-28436-f16d5x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/492925/original/file-20221102-28436-f16d5x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" alt="" /><figcaption>The DART spacecraft successfully collided with Dimorphos, which itself was orbiting a larger asteroid named Didymos. NASA/Johns Hopkins APL/Steve Gribben</figcaption></figure> The collision altered Dimorphos’s 12-hour orbital period by more than 30 minutes, and was declared a resounding success. So it’s plausible for humans to redirect a hazardous asteroid if we find one. That said, we’d have to find it well in advance. Potentially hazardous asteroids are much larger than Dimorphos, so a bigger collision would be required with plenty of lead time. To do this, NASA has plans to survey for potentially hazardous objects using a telescope in space. Its <a href="https://www.jpl.nasa.gov/missions/near-earth-object-surveyor">Near-Earth Object (NEO) Surveyor</a>, scheduled to launch in 2026, will be able to survey the Solar System very efficiently – including within blind spots caused by the Sun. That’s because the glare we see while observing from Earth is caused by Earth’s atmosphere. But in space there’s no atmosphere to look through. <figure class="align-center "><img src="https://images.theconversation.com/files/492932/original/file-20221102-26-zoxo13.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px" srcset="https://images.theconversation.com/files/492932/original/file-20221102-26-zoxo13.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=363&fit=crop&dpr=1 600w, https://images.theconversation.com/files/492932/original/file-20221102-26-zoxo13.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=363&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/492932/original/file-20221102-26-zoxo13.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=363&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/492932/original/file-20221102-26-zoxo13.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=457&fit=crop&dpr=1 754w, https://images.theconversation.com/files/492932/original/file-20221102-26-zoxo13.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=457&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/492932/original/file-20221102-26-zoxo13.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=457&fit=crop&dpr=3 2262w" alt="" /><figcaption>The NEO Surveyor spacecraft won’t have the issue of observational blind spots when hunting for asteroids. NASA/JPL/University of Arizona</figcaption></figure> It’s very likely the Near-Earth Object Surveyor will reveal new objects, and help us characterise a large number of objects to greatly improve our understanding of threats. The key is to find as many objects as possible, categorise them, track the risks, and plan a redirection mission as much in advance as possible. The fact that all of these elements of planetary defence are now a reality is an amazing feat of science and engineering. It is the first time in human history we have these capabilities.<img style="border: none !important; box-shadow: none !important; margin: 0 !important; max-height: 1px !important; max-width: 1px !important; min-height: 1px !important; min-width: 1px !important; opacity: 0 !important; outline: none !important; padding: 0 !important;" src="https://counter.theconversation.com/content/193709/count.gif?distributor=republish-lightbox-basic" alt="The Conversation" width="1" height="1" /> Writen by Steven Tingay. Republished with permission from <a href="https://theconversation.com/astronomers-have-detected-another-planet-killer-asteroid-could-we-miss-one-coming-our-way-193709" target="_blank" rel="noopener">The Conversation</a>. Image: DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA/J. da Silva/Spaceengine

Technology

This object in space flashed brilliantly for 3 months, then disappeared. Astronomers are intrigued

<blockquote> “Holy sharks, Batman, it’s periodic!” </blockquote> I exclaimed on Slack. It was the first lockdown of 2021 in Perth, and we were all working from home. And when astronomers look for something to distract themselves from looming existential dread, there’s nothing better than a new cosmic mystery. In 2020 I gave an undergraduate student, Tyrone O'Doherty, a fun project: look for radio sources that are changing in a <a href="https://www.ted.com/talks/natasha_hurley_walker_how_radio_telescopes_show_us_unseen_galaxies">large radio survey</a> I’m leading. By the end of the year he’d found a particularly unusual source that was visible in data from early 2018, but had disappeared within a few months. The source was named GLEAM-X J162759.5-523504, after the survey it was found in and its position. Sources that appear and disappear are called “radio transients” and are usually a sign of extreme physics at play. <h2>The mystery begins</h2> Earlier this year I started investigating the source, expecting it to be something we knew about – something that would change slowly over months and perhaps point to an exploded star, or a big collision in space. To understand the physics, I wanted to measure how the source’s brightness relates to its frequency (in the electromagnetic spectrum). So I looked at observations of the same location, taken at different frequencies, before and after the detection, and it wasn’t there. I was disappointed, as spurious signals do crop up occasionally due to telescope calibration errors, Earth’s ionosphere reflecting TV signals, or aircraft and satellites streaking overhead. So I looked at more data. And in an observation taken 18 minutes later, there the source was again, in exactly the same place and at exactly the same frequency – like nothing astronomers had ever seen before. At this point I broke out in a cold sweat. There is a worldwide research effort searching for repeating cosmic radio signals transmitted at a single frequency. It’s called the <a href="https://theconversation.com/curious-kids-what-has-the-search-for-extraterrestrial-life-actually-yielded-and-how-does-it-work-122454">Search for Extra-Terrestrial Intelligence</a>. Was this the moment we finally found that the truth is … out there? <iframe src="https://player.vimeo.com/video/657269342" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe> One of the brightest pulses from the new radio transient detected with the Murchison Widefield Array. <h2>The plot thickens</h2> I rapidly downloaded more data and posted updates on Slack. This source was incredibly bright. It was outshining everything else in the observation, which is nothing to sniff at. The brightest radio sources are supermassive black holes flaring huge jets of matter into space at nearly the speed of light. What had we found that could possibly be brighter than that? Colleagues were beginning to take notice, posting: <blockquote> It’s repeating too slowly to be a pulsar. But it’s too bright for a flare star. What is this? (alien emoji icon)??? </blockquote> Within a few hours, I breathed a sigh of relief: I had detected the source across a wide range of frequencies, so the power it would take to generate it could only come from a natural source; not artificial (and not aliens)! Just like <a href="https://www.space.com/32661-pulsars.html">pulsars</a> – highly magnetised rotating neutron stars that beam out radio waves from their poles – the radio waves repeated like clockwork about three times per hour. In fact, I could predict when they would appear to an accuracy of one ten-thousandth of a second. So I turned to our enormous data archive: 40 petabytes of radio astronomy data recorded by the Murchison Widefield Array in Western Australia, during its eight years of operation. Using <a href="https://pawsey.org.au/">powerful supercomputers</a>, I searched hundreds of observations and picked up 70 more detections spanning three months in 2018, but none before or after. The amazing thing about radio transients is that if you have enough frequency coverage, you can work out how far away they are. This is because lower radio frequencies arrive slightly later than higher ones depending on how much space they’ve traveled through. Our new discovery lies about 4,000 light years away – very distant, but still in our galactic backyard. <img src="https://images.theconversation.com/files/442445/original/file-20220125-13-54xe4a.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" alt="" /> Interstellar space slows down long wavelength radio waves more than short. ICRAR We also found the radio pulses were almost completely <a href="https://www.sciencefocus.com/science/what-is-polarised-light/">polarised</a>. In astrophysics this usually means their source is a strong magnetic field. The pulses were also changing shape in just half a second, so the source has to be less than half a light second across, much smaller than our Sun. Sharing the result with colleagues across the world, everyone was excited, but no one knew for sure what it was. <h2>The jury is still out</h2> There were two leading explanations for this compact, rotating, and highly magnetic astrophysical object: a white dwarf, or a neutron star. These remain after stars run out of fuel and collapse, generating magnetic fields billions to quintillions times stronger than our Sun’s. And while we’ve never found a neutron star that behaves quite this way, theorists have predicted such objects, called an “ultra-long period magnetars”, could exist. Even so, no one expected one could be so bright. <iframe src="https://player.vimeo.com/video/657248792" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe> We think the source could be either a magnetar or a white dwarf, or something completely unknown. This is the first time we’ve ever seen a radio source that repeats every 20 minutes. But maybe the reason we never saw one before is that we weren’t looking. When I first started trying to understand this source, I was biased by my expectations: transient radio sources either change quickly like pulsars, or slowly like the fading remnants of a supernova. I wasn’t looking for sources repeating at 18-minute intervals – an unusual period for any known class of object. Nor was I searching for something that would appear for a few months and then disappear forever. No one was. As astronomers build <a href="https://www.skatelescope.org/">new</a> <a href="https://www.lsst.org/">telescopes</a> that will collect vast quantities of data, it’s vital we keep our minds, and our search techniques, open to unexpected possibilities. The universe is full of wonders, should we only choose to look.<img style="border: none !important; box-shadow: none !important; margin: 0 !important; max-height: 1px !important; max-width: 1px !important; min-height: 1px !important; min-width: 1px !important; opacity: 0 !important; outline: none !important; padding: 0 !important; text-shadow: none !important;" src="https://counter.theconversation.com/content/175240/count.gif?distributor=republish-lightbox-basic" alt="The Conversation" width="1" height="1" /> <a href="https://theconversation.com/profiles/natasha-hurley-walker-197768">Natasha Hurley-Walker</a>, Radio Astronomer, <a href="https://theconversation.com/institutions/curtin-university-873">Curtin University</a> This article is republished from <a href="https://theconversation.com">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/this-object-in-space-flashed-brilliantly-for-3-months-then-disappeared-astronomers-are-intrigued-175240">original article</a>. Image: Artist visualisation

International Travel

Astronomers dedicate constellation of stars to David Bowie

As tributes to David Bowie continue, a group of astronomers in Belgium have come up with a canny way to pay homage to the late pop music icon registering a constellation in his honour. Consisting of seven stars in the vicinity of Mars, the constellation forms the shape of a lightning bolt similar to the one painted on Bowie’s face on the cover of the 1973 album Aladdin Sane. <img width="500" height="300" src="https://oversixtydev.blob.core.windows.net/media/14053/stardust-for-bowie_500x300.jpg" alt="Stardust For Bowie" style="display: block; margin-left: auto; margin-right: auto;"/> In a statement, Philippe Mollet from the MIRA Observatory said, “It was not easy to determine the appropriate stars. Studio Brussels asked us to give Bowie a unique place in the galaxy.” “Referring to his various albums, we chose seven stars — Sigma Librae, Spica, Alpha Virginis, Zeta Centauri, SAA 204 132, and the Beta Sigma Octantis Trianguli Australis — in the vicinity of Mars. The constellation is a copy of the iconic Bowie lightning and was recorded at the exact time of his death.” Bowie passed away on 10 January aged 69 after an 18 month battle with cancer. Related links: <a href="/news/news/2016/01/chihuahua-begs-for-freedom-photos/">Photographer captures moment dog begs for freedom</a> <a href="/news/news/2016/01/service-dog-steals-the-show-at-wedding/">Service dog steals the show at wedding</a> <a href="/news/news/2016/01/nsw-gold-opal-daily-cap-could-rise/">Gold Opal daily cap could rise and self-funded retirees could lose cards</a>

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