Your Local Airport Might Be Attracting Alien Attention
The SETI Institute's goal is to lead a science-based mission to find evidence of intelligent life beyond our own planet.
A new study shows what aliens within 200 light-years might see if they trained their own powerful radio telescopes on our planet.
It turns out the aviation radar—both civilian and military—would create a repeatable Effective Isotropic Radiated Power (EIRP) pattern due to the distribution of radar equipment across the Earth's surface.
Professional outfits like the Search for Extraterrestrial Intelligence (SETI) Institute scan the skies with radio telescopes for any sign of extraterrestrial life. They're especially tuned in to potential presence of technosignatures—electromagnetic radiation emitted by an advanced society's technology. While that effort has produced some exciting close calls, humanity most likely has yet to find any sign of alien life.
Of course, there's another way to look at this problem. If an alien civilization in our galactic neighbor also had their own SETI-esque programs—similarly probing the skies in search for an answer to that ever-elusive 'Are we alone?' question—could they hear us?
Well, as it turns out, the answer is an emphatic 'yes'—not, however, because we're purposefully shooting some kind of high-powered radio beam into the cosmos that's acting like a galactic flare gun. No, aliens could hear us just from our everyday airport and military radar systems.
In a new study—the preliminary results of which were revealed at the Royal Astronomical Society's National Astronomy Meeting 2025 in Durham, U.K.—lead researcher Ramiro Caisse Saide from the University of Manchester concluded that an alien civilization within 200 light-years of Earth could likely spot our planet's radar signals using an advanced radio telescope similar to the Green Bank Telescope in West Virginia. The study concluded that worldwide airport radar alone outputs a radio signal of roughly 2×10¹⁵ watts, while military radar outputs distinctive directional radio beams up to 1×10¹⁴ watts.
At first, 200 light-years may not seem like a lot—after all, the Milky Way stretches some 100,000 light-years across. But even a distance this short (at cosmic scales, at least) includes some 120,000 stars, which very likely host plenty of candidates capable of sustaining life.
'This would look clearly artificial to anyone watching from interstellar distances with powerful radio telescopes,' Caisse Saide said in a press statement. 'In fact, these military signals can appear up to a hundred times stronger from certain points in space, depending on where an observer is located.'
The authors looked at this 'hidden electromagnetic leakage' from the perspective of six stellar systems: Barnard star (6 light-years away), HD 48948 (55 light-years away), HD 40307 (42 light-years away), HD 216520 (64 light-years away), LHS 475 (40 light-years away), and AU Microscopii (32 light-years away).
To help others understand what the 'leakage' might look like, the researchers published a video showing the mean distribution of Earth's Effective Isotropic Radiated Power (EIRP) over a 24-hour period as it would appear on AU Microscopii. A distinct pattern emerges based on the distribution of radio equipment across the planet. So, if some alien civilization took a keen interest in a particular rocky planet located in the Origin-Cygnus arm of the galaxy, this clearly artificial EIRP signature might just raise an eyebrow (or whatever aliens would do to show confusion).
'Our findings suggest that radar signals—produced unintentionally by any planet with advanced technology and complex aviation system—could act as a universal sign of intelligent life,' Caisse Saide said in a press statement. 'In this way, our work supports both the scientific quest to answer the question 'Are we alone?' and practical efforts to manage the influence of technology on our world and beyond.'
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CNN
3 hours ago
- CNN
The asteroid that will spare Earth might hit the moon instead. What happens if it does?
The asteroid known as 2024 YR4 is out of sight yet still very much on scientists' minds. The building-sized object, which initially appeared to be on a potential collision course with Earth, is currently zooming beyond the reach of telescopes on its orbit around the sun. But as scientists wait for it to reappear, its revised trajectory is now drawing attention to another possible target: the moon. Discovered at the end of 2024, the space rock looked at first as if it might hit our planet by December 22, 2032. The chance of that impact changed with every new observation, peaking at 3.1% in February — odds that made it the riskiest asteroid ever observed. Ground- and space-based telescope observations were crucial in helping astronomers narrow in on 2024 YR4's size and orbit. With more precise measurements, researchers were ultimately able to rule out an Earth impact. The latest observations of the asteroid in early June, before YR4 disappeared from view, have improved astronomers' knowledge of where it will be in seven years by almost 20%, according to NASA. That data shows that even with Earth avoiding direct impact, YR4 could still pose a threat in late 2032 by slamming into the moon. The impact would be a once-in-a-lifetime event for humanity to witness — but it could also send fine-grained lunar material hurtling toward our planet. While Earth wouldn't face any significant physical danger should the asteroid strike the moon, there is a chance that any astronauts or infrastructure on the lunar surface at that time could be at risk — as could satellites orbiting our planet that we depend on to keep vital aspects of life, including navigation and communications, running smoothly. Any missions in low-Earth orbit could also be in the pathway of the debris, though the International Space Station is scheduled to be deorbited before any potential impact. Initially, YR4 was seen as a case study in why scientists do the crucial work of planetary defense, discovering and tracking asteroids to determine which ones have a chance of colliding with Earth. Now, astronomers say this one asteroid could redefine the range of risks the field addresses, expanding the purview of the work to include monitoring asteroids that might be headed for the moon as well. 'We're starting to realize that maybe we need to extend that shield a little bit further,' said Dr. Paul Wiegert, a professor of astronomy and physics at the Western University in London, Ontario. 'We now have things worth protecting that are a bit further away from Earth, so our vision is hopefully expanding a little bit to encompass that.' In the meantime, researchers are assessing just how much chaos a potential YR4 lunar impact could create — and whether anything can be done to mitigate it. 'City killer' on the moon The threatening hunk of rock appears as just a speck of light through even the strongest astronomical tools. In reality, YR4 is likely about 60 meters (about 200 feet) in diameter, according to observations in March by the James Webb Space Telescope, the most powerful space-based observatory in operation. 'Size equals energy,' said Julien de Wit, associate professor of planetary sciences at the Massachusetts Institute of Technology, who observed YR4 with Webb. 'Knowing YR4's size helped us understand how big of an explosion it could be.' Astronomers believe they have found most of the near-Earth asteroids the field would classify as ' planet killers ' — space rocks that are 1 kilometer (0.6 mile) across or larger and could be civilization-ending, said Dr. Andy Rivkin, planetary astronomer from the Johns Hopkins University's Applied Physics Laboratory in Maryland. The planet killer that slammed into Earth 66 million years ago and led to the extinction of dinosaurs was estimated to be roughly 6 miles (about 10 kilometers) in diameter. Smaller asteroids such as YR4, which was colloquially dubbed a 'city killer' after its discovery, could cause regional devastation if they collide with our planet. About 40% of near-Earth space rocks larger than 140 meters (460 feet) but smaller than a kilometer — capable of more widespread destruction — have been identified, according to NASA. But astronomers have never really had a chance to watch a collision of that size occur on the moon in real time, Wiegert said. The latest glimpses of YR4 on June 3 before it passed out of view revealed a 4.3% chance of a YR4 lunar impact — small but decent enough odds for scientists to consider how such a scenario might play out. A striking meteor shower — and a risk Initial calculations suggest the impact has the largest chance of occurring on the near side of the moon — the side we can see from Earth. 'YR4 is so faint and small we were able to measure its position with JWST longer than we were able to do it from the ground,' said Rivkin, who has been leading the Webb study of YR4. 'And that lets us calculate a much more precise orbit for it, so we now have a much better idea of where it will be and won't be.' The collision could create a bright flash that would be visible with the naked eye for several seconds, according to Wiegert, lead author of a recent paper submitted to the American Astronomical Society journals analyzing the potential lunar impact. The collision could create an impact crater on the moon estimated at 1 kilometer wide (0.6 miles wide), Wiegert said — about the size of Meteor Crater in Arizona, Rivkin added. It would be the largest impact on the moon in 5,000 years and could release up to 100 million kilograms (220 million pounds) of lunar rocks and dust, according to the modeling in Wiegert's study. Even pieces of debris that are just tens of centimeters in size could present a hazard for any astronauts who may be present on the moon, or any structures they have built for research and habitation, Wiegert said. The moon has no atmosphere, so the debris from the event could be widespread on the lunar surface, he added. On average, the moon is 238,855 miles (384,400 kilometers) away from Earth, according to NASA. Particles the size of large sand grains, ranging from 0.1 to 10 millimeters in size, of lunar material could reach Earth between a few days and a few months after the asteroid strike because they'll be traveling incredibly fast, creating an intense, eye-catching meteor shower, Wiegert said. 'There's absolutely no danger to anyone on the surface,' Wiegert said. 'We're not expecting large boulders or anything larger than maybe a sugar cube, and our atmosphere will protect us very nicely from that. But they're traveling faster than a speeding bullet, so if they were to hit a satellite, that could cause some damage.' Not all lunar debris that reaches the Earth is so small, and it depends on the angle and type of impact to the moon, according to Washington University in St. Louis. Space rocks slamming into the lunar surface over millions of years have resulted in various sizes of lunar meteorites found on Earth. Preparing for impact Hundreds to thousands of impacts from millimeter-size debris could affect Earth's satellite fleet, meaning satellites could experience up to 10 years' equivalent of meteor debris exposure in a few days, Wiegert said. Humankind depends on vital space infrastructure, said Dan Oltrogge, chief scientist at COMSPOC, a space situational awareness software company that develops solutions for handling hazards such as space debris. 'Space touches almost every aspect of our lives today, ranging from commerce, communications, travel, industry, education, and social media, so a loss of access to and effective use of space presents a serious risk to humanity,' Oltrogge said. The event is unlikely to trigger a Kessler Syndrome scenario in which debris from broken satellites would collide with others to create a domino effect or fall to Earth. Instead, it might be more akin to when a piece of gravel strikes a car windshield at high speed, meaning solar panels or other delicate satellite parts might be damaged, but the satellite will remain in one piece, Wiegert said. While a temporary loss of communication and navigation from satellites would create widespread difficulties on Earth, Wiegert said he believes the potential impact is something for satellite operators, rather than the public, to worry about. Protecting Earth and the moon Scientists and astronomers around the world are thinking about the possible scenarios since they could not rule out a lunar impact before YR4 disappeared from view, Wiegert said. 'We realize that an impact to the moon could be consequential, so what would we do?' de Wit said. A potential planetary defense plan might be clearer if the asteroid were headed straight for Earth. Rivkin helped test one approach in September 2022 as the principal investigator of NASA's Double Asteroid Redirection Test, or DART, which intentionally slammed a spacecraft into the asteroid Dimorphos in September 2022. Dimorphos is a moonlet asteroid that orbits a larger parent asteroid known as Didymos. Neither poses a threat to Earth, but the double-asteroid system was a perfect target to test deflection technology because Dimorphos' size is comparable to asteroids that could harm our planet in the event of an impact. The DART mission crashed a spacecraft into the asteroid at 13,645 miles per hour (6 kilometers per second) to find out whether such a kinetic impact would be enough to change the motion of a celestial object in space. It worked. Since the day of the collision, data from ground-based telescopes has revealed that the DART spacecraft did alter Dimorphos' orbital period — or how long it takes to make a single revolution around Didymos — by about 32 or 33 minutes. And scientists have continued to observe additional changes to the pair, including how the direct hit likely deformed Dimorphos due to the asteroid's composition. Similarly, if YR4 strikes the moon and doesn't result in damaging effects for satellites, it could create a tremendous opportunity for researchers to learn how the lunar surface responds to impacts, Wiegert said. But whether it would make sense to send a DART-like mission to knock YR4 off a collision course with the moon remains to be seen. It will depend on future risk assessments by planetary defense groups when the asteroid comes back into view around 2028, de Wit said. Though defense plans for a potential moon impact still aren't clear, YR4's journey underscores the importance — and the challenges — of tracking objects that are often impossible to see. Hidden threats YR4 was detected by the Asteroid Terrestrial-impact Last Alert System, or ATLAS telescope, in Río Hurtado, Chile, two days after the asteroid had already made its closest pass by Earth, hidden by the bright glare of the sun as it approached our planet. The same thing occurred when an asteroid measuring roughly 20 meters (about 65 feet) across hit the atmosphere and exploded above Chelyabinsk, Russia, on February 15, 2013, damaging thousands of buildings, according to the European Space Agency. While no one died, about 1,500 people were injured when the windows in homes and businesses blew out due to the shock wave. Trying to observe asteroids is challenging for many reasons, Rivkin said. Asteroids are incredibly faint and hard to see because rather than emitting their own light, they only reflect sunlight. And because of their relatively tiny size, interpreting observations is not a clear-cut process like looking through a telescope at a planet such as Mars or Jupiter. 'For asteroids, we only see them as a point of light, and so by measuring how bright they are and measuring their temperature, basically we can get a size based on how big do they have to be in order to be this bright,' Rivkin said. For decades, astronomers have had to search for faint asteroids by night, which means missing any that may be on a path coming from the direction of the sun — creating the world's biggest blind spot for ground-based telescopes that can't block out our star's luminosity. But upcoming telescopes — including NASA's NEO Surveyor expected to launch by the end of 2027 and the European Space Agency's Near-Earth Object Mission in the InfraRed, or NEOMIR satellite, set for liftoff in the early 2030s — could shrink that blind spot, helping researchers detect asteroids much closer to the sun. 'NEOMIR would have detected asteroid 2024 YR4 about a month earlier than ground-based telescopes did,' said Richard Moissl, head of ESA's Planetary Defence Office, in a statement. 'This would have given astronomers more time to study the asteroid's trajectory and allowed them to much sooner rule out any chance of Earth impact in 2032.' NASA and other space agencies are constantly on the lookout for potentially hazardous asteroids, defined as such based on their distance from Earth and ability to cause significant damage should an impact occur. Asteroids that can't get any closer to our planet than one-twentieth of Earth's distance from the sun are not considered to be potentially hazardous asteroids, according to NASA. When the new Vera C. Rubin Observatory, located in the Andes in Chile, released its first stunning images of the cosmos in June, researchers revealed the discovery of more than 2,100 previously unknown asteroids after seven nights of observations. Of those newly detected space rocks, seven were near-Earth objects. A near-Earth object is an asteroid or comet on an orbit that brings it within 120 million miles (about 190 million kilometers) of the sun, which means it has the potential to pass near Earth, according to NASA. None of the new ones detected by Rubin were determined to pose a threat to our planet. Rubin will act as a great asteroid hunter, de Wit said, while telescopes such as Webb could be a tracker that follow up on Rubin's discoveries. A proposal by Rivkin and de Wit to use Webb to observe YR4 in the spring of 2026 has just been approved. Webb is the only telescope with a chance of glimpsing the asteroid before 2028. 'This newly approved program will buy decision makers two extra years to prepare — though most likely to relax, as there is an 80% chance of ruling out impact — while providing key experience-based lessons for handling future potential impactors to be discovered by Vera Rubin,' de Wit said. And because of the twists and turns of YR4's tale thus far, asteroids that have potential to affect the moon could become objects of even more intense study in the future. 'If this really is a thing that we only have to worry about every 5,000 years or something, then maybe that's less pressing,' Rivkin said. 'But even just asking what would we do if we did see something that was going to hit the moon is at least something that we can now start thinking about.'
Washington Post
5 hours ago
- Washington Post
Astronauts need clean water. That's an engineering challenge.
When you're on a camping trip, you might have to pack your own food, and maybe something to filter or treat water that you find. But imagine your campsite is in space, where there's no water, and packing jugs of water would take up room when every inch of cargo space counts. That's a key challenge engineers faced when designing the International Space Station.
Yahoo
14 hours ago
- Yahoo
Interstellar Meteors Hit Earth All the Time but Still Elude Astronomers
Astronomers think small space rocks from beyond our solar system routinely strike Earth—but proving it isn't easy Aliens are visiting our solar system. Not little green men, sadly, but natural alien objects—cosmic bodies such as comets and asteroids born elsewhere in the galaxy that zip by the sun as they drift through the Milky Way. They're not so much visiting as just passing through. Though these objects were speculated to exist for a long time, we didn't know they were out there for sure until October 2017, when astronomers noticed a small body moving through space at exceptionally high speed. Observations over just a few nights showed it was moving far too quickly to be orbiting the sun and thus must have come from some other star. It was our first known interstellar visitor. [Sign up for Today in Science, a free daily newsletter] Eventually designated 1I/'Oumuamua, it was 30 million kilometers from Earth and already outward bound from the solar system when it was discovered, offering scant time for follow-up studies. But then, less than two years later, a second such object was found, also moving far faster than usual. 2I/Borisov turned out to be a comet very similar to those we're familiar with, except for its trajectory, which clearly showed it came from interstellar space. And now a third such alien body is barreling through the solar system: 3I/ATLAS, moving so rapidly its path is barely bent at all by the sun's gravity as it zooms past. In science, one is an anomaly and two might be coincidence, but three is a trend. Clearly, objects like this are passing by on the regular. Roughly speaking, there could be ones 100 meters in size or larger passing through the inner solar system at any time. Given their speed and intrinsic faintness, though, they're difficult to detect. We also know that when it comes to things such as asteroids and comets, nature tends to make many more smaller ones than bigger ones. In our own solar system, for example, only a couple of dozen main-belt asteroids are bigger than 200 km wide, but more than a million are 1 km across or larger. This generalization should hold for interstellar interlopers as well. For every kilometer-scale one that we see, there should be far more that are smaller. In fact, there could be millions of sand-grain-sized alien objects whizzing past us right now. And we already know that they're out there: in 2014 astronomers announced they had found seven grains of cosmic dust brought down to Earth from the Stardust space probe, which was designed to catch material ejected from a comet. Also, embedded in some meteorites that have hit Earth are tiny bits of material, called presolar grains, that are so old they actually formed around other stars. They got here after being blown across the void of space into the collapsing cloud of gas and dust that formed the sun and planets 4.6 billion years ago. Larger material could be ejected from an alien planetary system if it's given a gravitational assist when passing by a planet there, or it could be torn away from its parent star by another star passing closely to that system. So it seems certain interstellar jetsam would occasionally hit our planet. Earth is a small target, but with so many galactic bullets, you'd think some would actually find their way to our planetary bull's-eye. The problem is detecting them. Every day Earth is hit by very roughly 100 tons of locally grown interplanetary debris—material ejected from asteroids and comets native to our solar system—which translates into billions of tiny specks zipping across our sky daily. Detecting the tiny fraction that have an interstellar origin is tough. And the difficulty is not just in the sheer numbers. It's in tracing the trajectories of that small handful across the sky back up into space to calculate their orbits. When an object such as a planet or an asteroid orbits the sun, we say it's gravitationally bound to our star. That orbit in general is an ellipse, an oval shape. These can be defined mathematically, with the key factor being the eccentricity: how much the ellipse deviates form a circle. A perfect circle has an eccentricity of 0, and the higher the eccentricity, the more elliptical the orbit, up to a value of just under 1. An orbit with an eccentricity of 0.99, say, is extremely elongated; you might find that an object dropping down very close to the sun from the outer solar system has an eccentricity that high. It's possible to have an eccentricity higher than 1 as well. That kind of trajectory is called hyperbolic—named after the mathematical curve, not because it's exaggeratedly over-the-top—and an object on this path is not bound to the sun gravitationally. Once it's heading out, it's gone forever. It ain't coming back. This is how we know 'Oumuamua, Borisov and ATLAS are from interstellar space; each has an eccentricity greater than 1—'Oumuamua's is about 1.2 and Borisov's 3.4, which is quite high, but ATLAS has them both beat with an astonishing eccentricity of 6.2. That's extraordinarily high and also indicates it's hauling asteroid (or, more accurately, it's not comet back). Do we see any meteors with eccentricities like these? If the exact path of a meteoroid (the term for the solid bit that burns up in the air and becomes a meteor) through Earth's atmosphere can be determined, that can be backtracked up into space, allowing the object's trajectory, including its eccentricity, to be calculated. This can be done with multiple sky cameras set up in various locations; if a meteor streaks across their field of view, the multiple vantages can allow astronomers to triangulate on the rock and measure its path. There are quite a few such camera networks. It's actually difficult getting good enough data to determine solid orbits for meteoroids, though. Many do have eccentricities very close to 1; these likely come from long-period comets that originate out past Neptune. NASA's Jet Propulsion Laboratory maintains a database of bright fireballs—exceptionally luminous meteors—at the Center for Near-Earth Object Studies (CNEOS). The earliest recorded meteors in the database date back to 1988, so there is a rich hunting ground in the data. Are any of the meteors listed hyperbolic? Unfortunately, no. At least, not unambiguously—there have been false positives but nothing clear-cut. Additionally, a study from 2020 looked at 160,000 measurements by the Canadian Meteor Orbit Radar covering 7.5 years. The researchers found just five potential interstellar meteors. The results aren't quite statistically strong enough to claim detections for sure, but they're very compelling. What we need are more eyes on the sky, more meteor camera networks that can catch as many of these pieces of cosmic ejecta burning up in our atmosphere as possible. It's a numbers game: the more we see, the more likely we'll see some that are not from around here. The science would be, well, stellar: these meteors can tell us a lot about the environments around other stars, the ways they formed and perhaps even the stars they come from. We're getting physical samples from the greater galaxy for free. We should really try to catch them. Hat tip to planetary scientist Michele Bannister for the link to the CNEOS article. Solve the daily Crossword
