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4 days ago
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Venus's hidden asteroids could be Earth's next major impact risk
It may look like Earth's twin, but Venus is keeping secrets. New research suggests that dozens—possibly hundreds—of asteroids are quietly orbiting the Sun in sync with Venus. Known as Venus co-orbitals, these stealthy rocks follow a similar path around the Sun, making them difficult to spot from Earth. For a long time, experts have only known about 20 of them, and most have been easier to spot. However, new research suggests a significant yet undetected population of these asteroids. "Twenty co-orbital asteroids of Venus are currently known. Co-orbital status protects these asteroids from close approaches to Venus, but it does not protect them from encountering Earth," a team led by Valerio Carruba, an assistant professor at São Paolo University in Brazil, wrote in the study paper. Venusian co-orbital asteroids are classified as Potentially Hazardous Asteroids (PHAs) if they are at least 140 meters (460 feet) in diameter. In terms of distance, these asteroids are calculated to approach Earth's orbit within 0.05 astronomical units (4.6 million miles). An important question researchers are investigating is whether these objects pose a genuine collision threat to Earth or not. 'We aim to assess the possible threat that the yet undetected population of Venus co-orbitals may pose to Earth and investigate their detectability from Earth and space observatories,' the study noted. The team suspects the known 20 Venus co-orbitals are just the tip of the iceberg. It could be even more challenging to spot Venus's hidden co-orbital asteroids. Current ground-based telescopes face limitations in detecting Venus co-orbital asteroids due to fleeting observation windows and the Sun's bright glare. A particularly unsettling aspect is that these asteroids have a "Lyapunov time" of roughly 150 years. Universe Today explained that the Lyapunov time measures the point at which an object's orbit enters a chaotic, unpredictable state. In a nutshell, experts might be able to monitor the path of asteroids for a while, but the future orbital behavior will remain unpredictable. This makes it challenging to assess whether they will have a close encounter with Earth or even a collision. Researchers digitally replicated these hidden asteroids and conducted 36,000-year orbital simulations to understand the potential threat. The findings are alarming: "There is a sizable population of potential co-orbitals at lower eccentricity capable of numerous close encounters—and perhaps collisions—with Earth." "There is a range of orbits with e < 0.38, larger at lower inclinations, for which Venus' co-orbitals can pose a collisional hazard to Earth," the study added. The results indicate that the asteroids with eccentricities below 0.38 could strike Earth. Eccentricity measures how stretched out an orbit is. An eccentricity of 0 means a perfectly circular path, while larger numbers indicate a more elongated ellipse. In terms of studying the hidden asteroids, the upcoming Vera Rubin Observatory offers hope. Its incredibly powerful camera may help us catch some elusive objects under favorable conditions. But even Rubin's capabilities might not be enough to find the entire population. The researchers suggest that a space-based observatory, perhaps a constellation of spacecraft near Venus, could be our best bet. NASA has already taken a step towards planetary defense by successfully executing the DART asteroid mission. In the worst-case scenario, it could prevent a catastrophe similar to the one that led to the extinction of the dinosaurs. However, accurately predicting the precise path of these Venus co-orbitals is critical for any successful deflection effort. The study is posted on the pre-print server it has also been submitted for publication in Astronomy and Astrophysics.
Yahoo
19-05-2025
- Science
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Alien Hunters Detect "Unexplained Pulses" Emanating From Two Distant Stars
When looking for extraterrestrial life, scientists found something odd — two bizarre electromagnetic pulses coming from a distant constellation that cannot be explained. In a new study published in the journal Acta Astronautica, researchers from NASA and CalTech's Jet Propulsion Laboratory admitted they could not rule out the chance that the twin star pulses they detected within Ursa Major, some 100 light-years away, were related to alien life. The star in question, HD 89389, is slightly larger and brighter than our Sun and was the focus of observation for veteran NASA scientist Richard Stanton. In 2023, Stanton detected an unexpected signal emanating from the star: two identical and fast pulses roughly 4.4 seconds apart that made it flash brightly, dim, and then flash again. "The star gets brighter-fainter-brighter and then returns to its ambient level," Stanton told Universe Today. "This variation is much too strong to be caused by random noise or atmospheric turbulence. How do you make a star, over a million kilometers across, partially disappear in a tenth of a second? The source of this variation can't be as far away as the star itself." This signal had never been detected before, but to make sure it wasn't something else, the researcher spent an estimated 1,500 hours, which is the equivalent of about two months straight, comparing it to everything from planes and lightning to meteors and system malfunctions. When none of those searches yielded anything similar, Stanton told Universe Today that he felt confident that what he was seeing had not been observed for that Ursa Major star before. However, it did resemble another surprise twin pulse observation from 2019 that emanated from a hot gas giant now named Dimidium located about 50 light-years from Earth. The electromagnetic pulses emitted from Dimidium were initially dismissed as having been caused by birds, as Universe Today notes. To avoid a similarly false conclusion, Stanton began positing all manner of explanations related to the strange signals, including atmospheric conditions on Earth or even an anomalous reading due to our planet's gravity — but none of them "are really satisfying at this point," he said. "We don't know what kind of object could produce these pulses or how far away it is," the scientist said. "We don't know if the two-pulse signal is produced by something passing between us and the star or if it is generated by something that modulates the star's light without moving across the field." It's way too soon to tell what's going on with those strange signals from Ursa Major — but it seems certain that something weird is going on there, and that whatever is causing it will be fascinating indeed. "Until we learn more," Stanton concluded, "we can't even say whether or not extraterrestrials are involved!" More on stars: NASA's James Webb Telescope Just Found Frozen Water Around Another Star
Yahoo
05-04-2025
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Scientists Say There May Be Life on the Moon
The dark nooks and crannies of the lunar surface just might harbor life, according to new research. In a preprint study presented at the 56th Lunar and Planetary Science Conference last month, scientists propose that permanently shadowed regions of the Moon, or PSRs, have the right conditions to shelter microbial life forms — which could have profound implications for our efforts to explore the Earth's craggy satellite. Some PSRs haven't seen sunlight in billions of years, due to the slight tilt the Moon has on its axis. That's not news, but what's surprising is that these lightless voids could also be sanctuaries from deadly UV radiation, too. "In space, microbes are typically killed by high heat and ultraviolet radiation," study lead author John Moores, a planetary scientist and associate professor at York University in the UK, told Universe Today. "However, the PSRs are very cold and very dark and, as a result, they are one of the most protective environments in the Solar System for the kinds of microbes that are typically present on spacecraft." In other words, the PSRs could act as a freezer, preserving the microbes for years — "preserving" being the key word. "To be clear, those microbes cannot metabolize, replicate or grow here, but they likely remain viable for decades until their spores are killed by the effects of vacuum," Moores added. "The organic molecules that make up their cells likely would persist far longer." The chance of contaminating the lunar surface with Earth germs has always been a top concern for scientists. Beyond ethical and philosophical considerations, there's a practical case for ensuring that we don't ruin the data we collect in our quest to deepen our understanding of the lunar environment. One item on that checklist? PSRs, which have seen a surge of scientific interest in recent years. In fact, NASA's Artemis program is targeting a landing near the lunar South Pole, where the enduring shadows cloak the landscape. One PSR, the Shackleton Crater, is even being considered as a potential landing site. If the PSRs could serve as microbial freezers, however, then any contamination that humans bring there could persist for decades and more — far longer than other regions on the Moon — setting back lunar ambitions there for generations. Grimly, it's possible that this may already be the case. "The chance that there is already terrestrial microbial contamination in the PSRs is low but not zero," Moores told Universe Today. "Several spacecraft have impacted within or near the PSRs. Though they all did so at high speed, past research by others has suggested that small numbers of spores can survive simulated impacts into regolith-like materials. If any microbes survived those impacts, they would have been widely dispersed." More on the Moon: Robot Survived Failed Lunar Landing But Was Trapped Inside and Died Afterward
Yahoo
25-03-2025
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Scientists Intrigued by "Star Grinder" Pulverizing Entire Star Systems in Our Galaxy
Astronomers suggest there's a giant "star grinder" lurking at the center of the Milky Way, churning up potentially tens of thousands of star systems that are unfortunate enough to get too close. As detailed in a new paper to be published in the journal Astronomy & Astrophysics and first spotted by Universe Today, astronomers in the Czech Republic and Germany suggest that B-type stars, which are only a few times the mass of the Sun, as well as much heavier O-type stars, are being blended up with tens of thousands of smaller black holes near Sagittarius A*, the supermassive black hole at the center of our galaxy. According to the theory, only the smaller and older B-type stars can survive this ordeal, with the much more massive O-type stars succumbing to their early demise less than five million years into their lifespan — and turning into more small black holes in the maelstrom instead. The research could force us to reconsider what we know about the violent events happening at the center of our galaxy — a brutal cycle of life and death, right at the core of the Milky Way. The research could also explain an observation that has puzzled astronomers for years. Within less than a tenth of a light-year from Sagittarius*, O-type stars are nowhere to be found. B-type stars, however, are the predominant type so close to the giant black hole, many of which have been observed to be ejected from the center at extremely fast speeds. "The smaller B-stars can survive much longer, in fact for some 50 million years," said lead author and Charles University, Czechia, astronomy PhD Jaroslav Haas in a statement. "This explains why the heavy O-type stars are missing at distances smaller than about one-tenth of a light year from SgrA*, with only B-stars surviving there." "These results give us an entirely new understanding of the immediate surroundings of the central super-massive black hole," explained coauthor and Charles University astrophysicist Pavel Kroupa. Haas and his colleagues found that the density of black holes actually increases as you move away from the galactic center, before dropping again at a certain distance. Such a density profile is a "result of the complicated dynamical processes near the central super-massive black hole and our results will allow us to perform new computer simulations to better understand these," explained coauthor and head of the Charles University Astronomical Institute Ladislav Šubr. The researchers are now excited to better understand the "violent pack of thousands of black holes at the center of our Galaxy that is continuously destroying the stars down there," according to coauthor and Charles University astronomer Myank Singhal. More on Sagittarius A*: Scientists Capture Amazing Image of Black Hole at Center of Our Galaxy
Yahoo
16-02-2025
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Alpha Centauri Sending Stream of Objects Into Our Solar System, Scientists Propose
The detection of a large interstellar object in 2017 named 'Oumuamua was a landmark discovery. Figuring out where the wayward traveler came from, though, is another challenge entirely, especially since it subsequently cruised back out of our star system. Nevertheless, that hasn't stopped intrepid astronomers from trying. In a case study published in the Planetary Science Journal and spotlighted by Universe Today, the researchers from The University of Western Ontario hypothesize a scenario in which our nearest stellar neighbor, Alpha Centauri, may be sending a steady stream of "interstellar material" our way. And tantalizingly, what they found suggests that our solar system may already be flooded with visitors from the star system, which is about 4.25 light years away. These objects range from microscopic in size to well over 100 yards in diameter — a far more significant presence than the background level of gas and dust diffused throughout the cosmos. However, the odds of encountering one of these objects within the heart our solar system remain exceedingly low, with only a one-in-a-million chance that an interstellar visitor is located within ten astronomical units, or just short of one billion miles, of the Sun, according to the scientists. Though it appears as a single bright speck in the sky, Alpha Centauri is actually a triple star system, with several suspected exoplanets, including a super-Earth called Proxima Centauri b, with more thought to be lurking in the shadows. Two of the stars are Sun-like ones locked in a binary dance, while another star, a dim red dwarf, acts as the proverbial third wheel. And with all those big personalities involved and clashing gravitational egos, it's likely that Alpha Centauri boots out a significant amount of material, some of which may have reached the Oort Cloud, a shell of icy objects that surrounds the solar system, the researchers said. Alpha Centauri is also moving towards us, and in some 28,000 years from now, it'll reach its closest point at a distance of a little over three light years away, raising the odds of an interstellar influx in the future, too. "Though mature star systems likely eject less material than those in their planet-forming years, the presence of multiple stars and planets increases the likelihood of gravitational scattering of members from any remnant planetesimal reservoirs, much as asteroids or comets are currently being ejected from our solar system," the researchers wrote in the study. In fact, the astronomers estimated there could be over 1,000,000 objects larger than 328 feet in diameter from the nearby system lurking in the Oort Cloud. For reference, 'Oumuamua is believed to be anywhere between 328 to 3,280 feet long. That's a lot of refugees. It's unlikely we'll ever detect the vast majority of them, though. And when you consider the astronomers determined that particles as small as just ten microns, or about the size of a human blood cell, could survive the ten million-year journey over, it sounds like our corner of the universe may be awash with interstellar particles that even our most advanced instruments will have no chance of picking up on. A silver lining: the authors predict that around ten Alpha Centauri rejects could enter the Earth's atmosphere, where they'd be detectable as meteorites. With any luck, some of them could originate from one of the star system's exoplanets, providing a potential glimpse of worlds light years away. "A thorough understanding of the mechanisms by which material could be transferred from Alpha Centauri to the solar system not only deepens our knowledge of interstellar transport but also opens new pathways for exploring the interconnectedness of stellar systems and the potential for material exchange across the Galaxy," the paper reads. More on space: Don't Panic, But the Chances of That City Killer Asteroid Hitting Earth Just Almost Doubled
