Latest news with #solarsystem
Yahoo
17 hours ago
- Science
- Yahoo
Earth may have at least 6 'minimoons' at any given time. Where do they come from?
When you buy through links on our articles, Future and its syndication partners may earn a commission. Half a dozen fragments of the moon may briefly orbit Earth at any given time, before moving on to circle the sun, new research suggests — but the minimoons' small size and quick pace make them challenging to spot. When objects collide with the moon, they send up a shower of material, some of which manages to escape into space. Although there may be an occasional large chunk, most are fast-moving and smaller than 6.5 feet (2 meters) in diameter. The bulk of the lunar material falls into orbit around the more gravitationally attractive sun. But some of the debris may occasionally be pulled into an orbit around Earth before returning to circle the sun, researchers explained in a study published in the journal Icarus. It's "kind of like a square dance, where partners change regularly and sometimes leave the dance floor for a while," Robert Jedicke, a researcher at the University of Hawaii and lead author of the study, told by email. Although the International Astronomical Union doesn't have an official definition, previous research suggested that a minimoon could be an object that is at least temporarily bound to Earth, makes at least one revolution of the planet, and is closer than about four times the Earth-moon distance at some point in its orbit. Minimoons can come from anywhere in the solar system, but a 2018 study suggested most come from the region of the asteroid belt, between the orbits of Mars and Jupiter. The recent appearance of minimoons from the moon, however, is calling that finding into question. In 2016, the Pan-STARRS1 asteroid survey telescope in Hawaii spotted a 131- to 328-foot-wide (40 to 100 meters) near-Earth object identified as Kamo'oalewa, or "469219 Kamo'oalewa," orbiting the sun in sync with Earth. Later studies revealed that Kamo'oalewa was a slice of the moon excavated between 1 million and 10 million years ago in the crash that formed the Giordano Bruno crater. Earlier this year, astronomers announced that a second temporary terrestrial satellite appeared to have a lunar origin. Discovered last year, the object — called 2024 PT5 — looks more like the moon than an asteroid. Together, these two objects suggest that the moon could be birthing its own tiny moons. So Jedicke and his colleagues decided to calculate just how many lunar minimoons might exist. Relying on simulations of how particles blown from the moon might behave, they found that many of the particles blasted into space could be captured at least temporarily by Earth, and about a fifth of them were likely to become minimoons. The new findings nominally predict that 6.5 lunar-born satellites may be circling Earth at a time. The individual objects are changeable; if they could be counted today, and then again in a year, some would be new objects. A typical minimoon dances around Earth for an average of about nine months, Jedicke said, and these minimoons are constantly replenished from the material traveling in an Earth-like orbit. But when it comes to nailing down the predicted number of minimoons, Jedicke cautioned that the uncertainty is "ginormous — many orders of magnitude." That's due to many unknowns, including the size of a crater formed by an impact and the size and speed distribution of the ejected material. "If there were that many [temporarily bound objects], the telescopic surveys would probably detect more of them," Jedicke said. "So the nominal prediction is almost certainly wrong. That's science." Because science builds on new information, identifications of more lunar minimoons and a better understanding of their size distribution will help to refine that prediction and provide new insight into the crater formation process. Due to their size, the tiny, temporary moons are challenging to spot. The problem relates to both their size and their speed. With most of the fragments ranging from 3 to 7 feet (1 to 2 m) in diameter, even the most seasoned instruments can struggle to detect them. Jedicke compares them to a car or an SUV. "Detecting objects in that size range means they have to be close so they are bright, but if they are close, it means they also appear to be moving quickly across the sky," Jedicke said. "It is incredible that modern telescopic surveys have the ability to detect such small objects up to millions of kilometers away." In massive sky surveys, computers usually work to pull out motion. When minimoons are close enough to be seen, their rapid motion may leave trails, rather than spots, on images of the sky. "Trails are more difficult for computer algorithms to identify," Jedicke said. RELATED STORIES —Newborn moon may have had many mini-siblings in Earth orbit long ago —Earth's mini-moon has finally departed. Will it ever return as a 'second moon?' —NASA raises the odds that an asteroid could hit the moon in 2032 But all is not lost. The new research suggests that 2020 CD3 was visible to the Catalina Sky Survey on only two of the roughly 1,000 nights the object was in range. The successful detection bodes well for future observations. Once the objects have been identified, tracking becomes easier because astronomers know where and when to look for the minimoons. These brief visitors could also have intriguing commercial applications, since they would require the least amount of fuel to visit, Jedicke said. Instead of flying to the asteroid belt to extract water, minerals and other commercially desirable elements, companies could find ways to snag the transients as they briefly orbit Earth. From a scientific perspective, minimoons and their kin "may help reveal how the solar system formed and continues to evolve," Jedicke said. Understanding how lunar debris was flung off of the moon during an impact can help researchers better understand and estimate damage due to asteroid impacts on Earth.
Yahoo
19 hours ago
- Science
- Yahoo
Scientists find Uranus is surprisingly warm, heating up the case for a new planetary mission
When you buy through links on our articles, Future and its syndication partners may earn a commission. Scientists have found that Uranus is emitting its own internal heat — even more than it receives from sunlight — and this discovery contradicts observations of the distant gas giant made by NASA's Voyager 2 probe nearly four decades ago. Scientists led by Xinyue Yang of the University of Houston analyzed decades of readings from spacecraft and computer models to find that Uranus emits 12.5% more internal heat than the amount of heat it receives from the sun. However, that amount is still far less than the internal heat of other outer solar system planets like Jupiter, Saturn and Neptune, which emit 100% more heat than they get from the sun. The researchers behind this new study say Uranus' internal heat could help reveal the origins of the curious, tilted world. "This means it's still slowly losing leftover heat from its early history, a key piece of the puzzle that helps us understand its origins and how it has changed over time," Wang said in a statement. In 1986, the iconic Voyager 2 probe flew by Uranus while headed out of the solar system and into interstellar space. A good deal of what scientists understand about the seventh planet from the sun comes from that flyby, that found that Uranus does not reveal significant internal heat. But it turns out that we may have caught Uranus at a weird time, and some of the readings Voyager 2 collected could have been skewed by a surge in solar weather that occurred during its flyby of the planet. By reviewing a large set of archival data and combining that with computer models, researchers now believe the internal heat emitted by Uranus could imply a completely different internal structure or evolutionary history for the planet we thought we knew. Its believed that Uranus formed around 4.5 billion years ago along with the rest of the solar system, and NASA believes it formed closer to the sun before moving to the outer solar system around 0.5 billion years later. That story, however, is now called into question by these new findings. "From a scientific perspective, this study helps us better understand Uranus and other giant planets," Wang said in the statement. The researchers also believe this new understanding of Uranus' internal processes could help NASA and other agencies plan for missions to the distant planet. In 2022, the National Academy of Sciences flagged a mission concept known notionally as Uranus Orbiter and Probe (UOP) as one of the highest-priority planetary science missions for the next decade. But even then, before massive budget uncertainty hit NASA and the science community in the wake of President Donald Trump's overhaul of U.S. government spending, scientists knew such an ambitious and expensive mission would be difficult to put into motion. "There are many hurdles to come — political, financial, technical — so we're under no illusion," Leigh Fletcher, a planetary scientist at the University of Leicester in the U.K. who participated in the decadal survey process, told in 2022 when the report was published. "We have about a decade to go from a paper mission to hardware in a launch fairing. There's no time to lose." Whether or not new research into Uranus helps boost support for such a mission, scientists are already hailing these new results as groundbreaking on their own. Study co-author Liming Li said the study of Uranus' internal heat not only helps us understand the distant, icy world better, but could also help inform studies of similar processes here on Earth, including our own changing climate. "By uncovering how Uranus stores and loses heat, we gain valuable insights into the fundamental processes that shape planetary atmospheres, weather systems and climate systems," Li said in the statement. "These findings help broaden our perspective on Earth's atmospheric system and the challenges of climate change." A study on Uranus' internal heat was published in the journal Geophysical Research Letters.
CNN
a day ago
- Science
- CNN
Researchers may have solved mystery of Mercury's missing meteorites, but doubts remain
Researchers suspect that two meteorites found in the Sahara Desert in 2023 may originally have come from Mercury, which would make them the first identified fragments of the solar system's innermost planet. The least studied and most mysterious of the solar system's rocky planets, Mercury is so close to the sun that exploring it is difficult even for probes. Only two uncrewed spacecraft have visited it to date — Mariner 10, launched in 1973, and MESSENGER, launched in 2004. A third, BepiColombo, is en route and due to enter orbit around the planet in late 2026. Scientists know little about Mercury's geology and composition, and they have never been able to study a fragment of the planet that landed on Earth as a meteorite. In contrast, there are more than 1,100 known samples from the moon and Mars in the database of the Meteoritical Society, an organization that catalogs all known meteorites. These 1,100 meteorites originated as fragments flung from the surfaces of the moon and Mars during asteroid impacts before making their way to Earth after a journey through space. Not every planet is likely to eject fragments of itself Earth-ward during collisions. Though Venus is closer to us than Mars is, its greater gravitational pull and thick atmosphere may prevent the launch of impact debris. But some astronomers believe that Mercury should be capable of generating meteors. 'Based on the amount of lunar and Martian meteorites, we should have around 10 Mercury meteorites, according to dynamical modeling,' said Ben Rider-Stokes, a postdoctoral researcher in achondrite meteorites at the UK's Open University and lead author of a study on the Sahara meteorites, published in June in the journal Icarus. 'However, Mercury is a lot closer to the sun, so anything that's ejected off Mercury also has to escape the sun's gravity to get to us. It is dynamically possible, just a lot harder. No one has confidently identified a meteorite from Mercury as of yet,' he said, adding that no mission thus far has been capable of bringing back physical samples from the planet either. If the two meteorites found in 2023 — named Northwest Africa 15915 (NWA 15915) and Ksar Ghilane 022 (KG 022) — were confirmed to be from Mercury, they would greatly advance scientists' understanding of the planet, according to Rider-Stokes. But he and his coauthors are the first to warn of some inconsistencies in matching those space rocks to what scientists know about Mercury. The biggest is that the fragments appear to have formed about 500 million years earlier than the surface of Mercury itself. However, according to Rider-Stokes, this finding could be based on inaccurate estimates, making a conclusive assessment unlikely. 'Until we return material from Mercury or visit the surface,' he said, 'it will be very difficult to confidently prove, and disprove, a Mercurian origin for these samples.' But there are some compositional clues that suggest the meteorites might have a link to the planet closest to the sun. It's not the first time that known meteorites have been associated with Mercury. The previous best candidate, based on the level of interest it piqued in astronomers, was a fragment called Northwest Africa (NWA) 7325, which was reportedly found in southern Morocco in early 2012. Rider-Stokes said that was the first meteorite to be potentially associated with Mercury: 'It got a lot of attention. A lot of people got very excited about it.' Further analysis, however, showed a richness in chrome at odds with Mercury's predicted surface composition. More recently, astronomers have suggested that a class of meteorites called aubrites — from a small meteorite that landed in 1836 in Aubres, France — might come from Mercury's mantle, the layer below the surface. However, these meteorites lack a chemical compatibility with what astronomers know about the planet's surface, Rider-Stokes said. 'That's what's so exciting about the samples that we studied — they have sort of the perfect chemistry to be representative of Mercury,' he said. Most of what is known about Mercury's surface and composition comes from NASA's MESSENGER probe, which assessed the makeup of the planet's crust from orbit. Both meteorites from the study, which Rider-Stokes analyzed with several instruments including an electron microscope, contain olivine and pyroxene, two iron-poor minerals confirmed by MESSENGER to be present on Mercury. The new analysis also revealed a complete lack of iron in the space rock samples, which is consistent with scientists' assumptions about the planet's surface. However, the meteorites contained only trace amounts of plagioclase, a mineral believed to dominate Mercury's surface. The biggest point of uncertainty, though, is still the meteorites' age. 'They are about 4.5 billion years old,' Rider-Stokes said, 'and most of Mercury's surface is only about 4 billion years old, so there's a 500 million-year difference.' However, he said he thinks this discrepancy is not sufficient to rule out a Mercurian origin, due to the limited reliability of MESSENGER's data, which has been also used to estimate the age of Mercury's surface layer. 'These estimates are based on impact cratering models and not absolute age dating, and therefore may not be entirely accurate,' Rider-Stokes said. 'It doesn't mean that these samples aren't good analogs for regional areas on the surface of Mercury, or the early Mercurian crust that is not visible on the modern surface of Mercury.' With more modern instruments now available, BepiColombo, the European Space Agency probe that will start studying Mercury in early 2027, may be able to answer long-standing questions about the planet, such as where it formed and whether it has any water. Having material confirmed to have come from other planetary bodies helps astronomers understand the nature of early solar system's building blocks, Rider-Stokes said, and identifying fragments of Mercury would be especially crucial since a mission to gather samples from the planet closest to the sun and bring them back would be extremely challenging and expensive. Sean Solomon, principal investigator for NASA's MESSENGER mission to Mercury, said in an email that he believes the two meteorites described in the recent paper likely did not originate from Mercury. Solomon, an adjunct senior research scientist at Columbia University in New York City, was not involved with the study. The primary reason Solomon cited for his doubts is that the meteorites formed much earlier than the best estimates for the ages of rocks now on Mercury's surface. But he said he thinks the samples still hold research value. 'Nonetheless, the two meteorites share many geochemical characteristics with Mercury surface materials, including little to no iron … and the presence of sulfur-rich minerals,' he added. 'These chemical traits have been interpreted to indicate that Mercury formed from precursor materials much more chemically reduced than those that formed Earth and the other inner planets. It may be that remnants of Mercury precursor materials still remain among meteorite parent bodies somewhere in the inner solar system, so the possibility that these two meteorites sample such materials warrants additional study.' Solomon also noted that it was difficult to persuade the planetary science community that there were samples from Mars in meteorite collections, and that it took precise matching of their chemistry with data about the surface of Mars taken by the Viking probes to convince researchers to take a closer look. Lunar meteorites were also not broadly acknowledged to be in meteorite collections until after the existence of Martian meteorites had been demonstrated in the 1980s, he added, even though the Apollo and Luna missions had returned abundant samples of lunar materials more than a decade earlier. Once samples are confirmed to be from a planetary body, Solomon said, they can provide crucial information not available from remote sensing by an orbiting spacecraft on the timing of key geological processes, the history of internal melting of the body, and clues to planet formation and early solar system processes. Rider-Stokes plans to continue the discussion around these meteorites at the annual meeting of the Meteoritical Society, which takes place in Perth this week. 'I'm going to discuss my findings with other academics across the world,' he said. 'At the moment, we can't definitively prove that these aren't from Mercury, so until that can be done, I think these samples will remain a major topic of debate across the planetary science community.'
Daily Mail
a day ago
- Science
- Daily Mail
Comet or alien? Key piece of evidence shows interstellar object is a UFO
Earlier this month, astronomers spotted a bizarre interstellar object hurtling through the solar system. Dubbed 3I/ATLAS, this 12-mile long visitor has travelled to our sun from another star on a journey that could have taken billions of years. However, physicist Professor Avi Loeb says he has spotted the key piece of evidence that shows 3I/ATLAS could be an alien spacecraft as it's too big to be natural. Experts suggest that it must either be an exceptionally large solid mass or a smaller comet with a bright envelope of gas and dust. If it is not a comet, Professor Loeb says 3I/ATLAS is so impossibly large that the chances of it naturally reaching our sun are incredibly low. Professor Loeb says: 'It is difficult to imagine a natural process that would favor a plunge towards the inner solar system at 60km per second. 'An alternative is that the object targets the inner solar system by some technological design.' 3I/ATLAS was first spotted by astronomers on July 1 by NASA's Asteroid Terrestrial-impact Last Alert System. After tracing its orbital path, scientists realized that its extremely elliptical orbit and high speed meant its origins lay outside the solar system. This makes it only the third interstellar object that humanity has detected, following 'Oumuamua in 2017 and Borisov in 2019. Arriving from the direction of the constellation Sagittarius, 3I/ATLAS is currently heading towards the inner solar system at 135,000 miles per hour. NASA predicts that it will reach its closest point to the sun on October 30, at a distance of 130 million miles - passing just within the orbit of Mars. Thankfully, the object poses no threat to Earth and will pass harmlessly at around 150 million miles away at its closest point. Since the object is currently around 300 million miles from Earth, astronomers can't directly measure how large it is. Instead, they try and work out how much light the object gives off and estimate its size based on how reflective it might be. If it is a solid object like an asteroid, which reflects around five per cent of the light that hits it, then 3I/ATLAS must be between 12 and 14 miles in diameter. That makes 3I/ATLAS up to 200 times larger than the 100-metre-long and extremely thin 'Oumuamua. Professor Loeb says this fact immediately made him suspicious since large objects are typically much rarer than smaller ones. Professor Loeb says: 'Now you ask, "how many objects on the scale of 'Oumuamua are there for each object that is 24km in size?" 'The answer is about a million. But we haven't seen a million 'Oumuamua-sized interstellar objects before seeing this one, it's very strange.' But Professor Loeb says that the strangeness of 3I/ATLAS' size doesn't stop there. In a paper, now accepted for publication by the Research Notes of the AAS, Professor Loeb asked what it would take for an object of 3I/ATLAS' size to reach Earth. Based on how often we see objects of this size, previous research calculated how many 12-mile-long objects could exist out in the Milky Way. When Professor Loeb took this number and multiplied it by the mass of 3I/ATLAS, the result 'makes zero sense'. He says: 'This ends up being a quarter of the mass of the stars in the Milky Way. 'But because only two per cent of the mass in stars is in heavy elements that make rocks, you don't have the mass to make enough rocks of this size.' The implication is that 3I/ATLAS is much, much rarer than its appearance in our Solar System suggests. In fact, Professor Loeb argues that objects this big are too rare for their appearance in the inner solar system to be random. Could it be anything else? The alternative explanation for 3I/ATLAS' apparent size is that it is much smaller and much more reflective than any asteroid. That would be possible if the interstellar object is a comet, a ball of ice and dust which moves very quickly through space. If it were a comet, the heat from the sun would evaporate a layer of ice and dust, which would reflect back a lot of light. This would explain why 3I/ATLAS appears to be so bright while maintaining that its core is small enough to be natural. This is the accepted answer among most astronomers and space agencies, with NASA and the European Space Agency labelling the object an 'interstellar comet'. 'Likely': The alternative explanation is that 3I/ATLAS is a comet with a bright, reflective envelope of gas and dust and a very small core While Professor Loeb says that this is the 'simplest and most likely' solution, he doesn't think that the evidence for the comet theory is conclusive. For example, he points to a recent observation by the European Southern Observatory (ESO) Very Large Telescope (VLT). The VLT did not find direct evidence of dust or gas being released by the object, but concluded that it was a comet based on surface 'reddening' caused by dust. Professor Loeb maintains that this could simply be caused by the fact that the surface is red. Likewise, observations showing the fuzzy streak of the comet's gas layer could be an artefact of the long exposure images and 3I/ATLAS' high speed. This doesn't mean that 3I/ATLAS isn't a comet, but Professor Loeb believes it's still too early to rule out the possibility that it is a solid object. The professor says: 'The good news is that it will come closer to the sun and it will get heated up by sunlight.
The Guardian
2 days ago
- Science
- The Guardian
Starwatch: use the moon to find Saturn before its pirouette in the sky
The moon will help us track down Saturn, the sixth planet in the solar system, this week. Currently residing in the constellation of Pisces, the fishes, Saturn is gradually building in brightness as the Earth's orbit is carrying the two planets closer together. This year, the closest approach between them will occur on 21 September. In the meantime, the moon can be useful as your guide to locate Saturn and then watch it over the coming months as the planet performs a lazy pirouette in the sky, known as retrograde motion. This is an optical illusion caused by our changing line of sight to the planet as Earth overtakes it on the inside. The chart shows the view looking east from London on 16 July at midnight BST, soon after the moon and Saturn have risen. The moon will be almost 20 days old and in its waning gibbous phase, rising later each night. Just over 72% of the moon's visible surface will be illuminated on this night, and it will be 373,842km away from Earth. Saturn, on the other hand, will be 1,368m km away. The conjunction will be easily visible from the southern hemisphere.
