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Yahoo
26-06-2025
- Science
- Yahoo
A Gigantic Megacomet Is Erupting as It Zooms through the Solar System
There's a giant ball of ice barreling through the solar system right now, and it's bigger than any we've seen before. It poses no threat to Earth, but this comet, called C/2014 UN271 (Bernardinelli-Bernstein), has enraptured astronomers ever since its discovery in 2021. The hulking object, sometimes jovially called a 'megacomet,' is 100 times bigger than most comets we see in the solar system. And now we're learning more about it than ever before as it zooms toward its closest approach to our sun in 2031. In a study published in the Astrophysical Journal Letters on June 12, Nathan Roth of American University and his colleagues report the first conclusive detection of carbon monoxide on the megacomet. That's a crucial finding because it might tell us more about the object's origins, history and likely upcoming behavior as it dives deeper into the solar system. 'We wanted to test what drives activity in this comet,' Roth says. 'It's so far from the sun and so cold that trying to explain what makes a comet 'work' at these distances is difficult.' C/2014 UN271 was first imaged by chance in observations from 2014. Seven years later, when astronomers actually spotted it in their archives, the comet was at more than 20 times the Earth-sun distance, inside the orbit of Neptune. But they also found that it is on a path that will bring it nearly to Saturn's orbit in 2031 before it heads out again. The comet's orbit is huge, extending out to about 55,000 times the Earth-sun distance—87 percent of a light-year and well out into the Oort Cloud of icy objects that surrounds our sun. [Sign up for Today in Science, a free daily newsletter] Following the comet's discovery astronomers used various telescopes, including the James Webb Space Telescope and the Hubble Space Telescope, to scrutinize it from afar. The object was initially thought to be as big as 370 kilometers (230 miles) across. Revised observations showed it to be about 140 kilometers (87 miles) wide. But that's still the biggest anyone has ever seen—most comets in the solar system are only one or two kilometers across. 'It's huge,' says Quanzhi Ye, an astronomer at the University of Maryland, who was not involved in Roth's study. 'It represents a part of the cometary spectrum that we don't understand.' Some of those observations revealed bursts of activity from the comet, which sprouted an enormous, enveloping 'coma' of expelled gas that stretches some 250,000 kilometers (155,000 miles) across (more than half the distance from the Earth to the moon). To find out the cause of this activity, Roth and his team used the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile to observe the comet in radio waves for about eight hours in March 2024. They found a clear trace of carbon monoxide spewing from the comet, suggesting that its sprawling coma is fueled, at least in part, by carbon monoxide ice sublimating—turning from solid to gas—as the comet approaches the sun. The carbon monoxide appears to be vented in jets from spots on the object's surface, possibly the result of the overhead sun heating a localized region and causing the ice to sublimate. 'If you were standing on the comet, and the sun was right overhead, this is the area where the sun is heating the surface the most and the jet originates from,' Roth says. What's not clear so far, however, is how fast the comet is spinning and whether the location of the jets is changing over time. 'Are there different jets being activated at different times? We don't know yet,' Roth says. As C/2014 UN271 gets closer, other ices that are often found on comets, such as methane and hydrogen sulfide ice, might start to sublimate, too, and add their own contributions to the object's activity. 'As we continue to monitor it, we'll be able to get a better idea of the chemical fingerprint that's preserved inside the comet,' Roth says. Rosita Kokotanekova, an astronomer at the Rozhen National Astronomical Observatory in Bulgaria, who was not part of Roth's research team, says the detection of carbon monoxide is useful because it is 'important to identify what prompts activity at these large distances.' Researchers have witnessed gas venting from other, much smaller comets at a similar distance, 'which was very puzzling,' she adds. 'People were trying to figure out what exactly is causing this activity [so far from the sun].' C/2014 UN271's size makes it an especially alluring target for study. The presence of carbon monoxide ice is doubly interesting: Analysis of available data about the comet revealed that it first exhibited signs of activity at more than 25 times the Earth-sun distance. But according to theoretical models, its carbon monoxide ice should have been sublimated by the sun's rays when the object was even farther out in the solar system. This discrepancy may mean the comet made a pass of the sun before, with sublimation first eating away at layers of ice on its surface and its current activity only being kickstarted at closer distances, when heat from sunlight reached ice deeper within the object. Finding a behemoth like C/2014 UN271, Kokotanekova says, could hint at the existence of a whole class of gigantic progenitor comets. Such comets might have been the first large, icy objects to coalesce in the solar system, after which they could have eventually broken apart to form smaller comets. 'It's possible that the small objects are mostly fragments, while the large ones, like UN271, have never collided with anything,' she says. That might mean there are more primordial megacomets awaiting discovery. If so, the recently completed Vera C. Rubin Observatory in Chile, which will begin a 10-year panoramic survey of the heavens later this year, could find more of them. 'It's so sensitive that it will certainly pick up comets of this size, quite probably even further away from us,' Ye says. Rubin's wide eye on the sky should also give us more information on C/2014 UN271 itself, says Meg Schwamb, an astronomer at Queen's University Belfast uninvolved with this latest finding. 'Rubin's going to watch it come in,' she says. That could help us get a better handle on its activity, in partnership with telescopes like ALMA. 'You need both of those pieces of information—if it got brighter, and whether the amount of carbon monoxide changed—to tell you what's going on,' Schwamb says. For now Comet UN271 remains a fascinating target of study, a giant comet like no other that is giving us a unique window into the dark frontiers of the outer solar system. 'This is just an incredibly exciting object,' Roth says. And, for astronomers eager to learn more about this and other mega comets, the best is yet to come.
Scientific American
26-06-2025
- Science
- Scientific American
Astronomers Spy Jets Spewing from Megacomet Zooming through the Solar System
There's a giant ball of ice barreling through the solar system right now, and it's bigger than any we've seen before. It poses no threat to Earth, but this comet, called C/2014 UN271 (Bernardinelli-Bernstein), has enraptured astronomers ever since its discovery in 2021. The hulking object, sometimes jovially called a 'megacomet,' is 100 times bigger than most comets we see in the solar system. And now we're learning more about it than ever before as it zooms toward its closest approach to our sun in 2031. In a study published in the Astrophysical Journal Letters on June 12, Nathan Roth of American University and his colleagues report the first conclusive detection of carbon monoxide on the megacomet. That's a crucial finding because it might tell us more about the object's origins, history and likely upcoming behavior as it dives deeper into the solar system. 'We wanted to test what drives activity in this comet,' Roth says. 'It's so far from the sun and so cold that trying to explain what makes a comet 'work' at these distances is difficult.' C/2014 UN271 was first imaged by chance in observations from 2014. Seven years later, when astronomers actually spotted it in their archives, the comet was at more than 20 times the Earth-sun distance, inside the orbit of Neptune. But they also found that it is on a path that will bring it nearly to Saturn's orbit in 2031 before it heads out again. The comet's orbit is huge, extending out to about 55,000 times the Earth-sun distance—87 percent of a light-year and well out into the Oort Cloud of icy objects that surrounds our sun. On supporting science journalism If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today. Following the comet's discovery astronomers used various telescopes, including the James Webb Space Telescope and the Hubble Space Telescope, to scrutinize it from afar. The object was initially thought to be as big as 370 kilometers (230 miles) across. Revised observations showed it to be about 140 kilometers (87 miles) wide. But that's still the biggest anyone has ever seen—most comets in the solar system are only one or two kilometers across. 'It's huge,' says Quanzhi Ye, an astronomer at the University of Maryland, who was not involved in Roth's study. 'It represents a part of the cometary spectrum that we don't understand.' Some of those observations revealed bursts of activity from the comet, which sprouted an enormous, enveloping 'coma' of expelled gas that stretches some 250,000 kilometers (155,000 miles) across (more than half the distance from the Earth to the moon). To find out the cause of this activity, Roth and his team used the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile to observe the comet in radio waves for about eight hours in March 2024. They found a clear trace of carbon monoxide spewing from the comet, suggesting that its sprawling coma is fueled, at least in part, by carbon monoxide ice sublimating—turning from solid to gas—as the comet approaches the sun. The carbon monoxide appears to be vented in jets from spots on the object's surface, possibly the result of the overhead sun heating a localized region and causing the ice to sublimate. 'If you were standing on the comet, and the sun was right overhead, this is the area where the sun is heating the surface the most and the jet originates from,' Roth says. What's not clear so far, however, is how fast the comet is spinning and whether the location of the jets is changing over time. 'Are there different jets being activated at different times? We don't know yet,' Roth says. As C/2014 UN271 gets closer, other ices that are often found on comets, such as methane and hydrogen sulfide ice, might start to sublimate, too, and add their own contributions to the object's activity. 'As we continue to monitor it, we'll be able to get a better idea of the chemical fingerprint that's preserved inside the comet,' Roth says. Rosita Kokotanekova, an astronomer at the Rozhen National Astronomical Observatory in Bulgaria, who was not part of Roth's research team, says the detection of carbon monoxide is useful because it is 'important to identify what prompts activity at these large distances.' Researchers have witnessed gas venting from other, much smaller comets at a similar distance, 'which was very puzzling,' she adds. 'People were trying to figure out what exactly is causing this activity [so far from the sun].' C/2014 UN271's size makes it an especially alluring target for study. The presence of carbon monoxide ice is doubly interesting: Analysis of available data about the comet revealed that it exhibited signs of activity when it was more than 25 times as far out as the Earth-sun distance. But according to theoretical models, its carbon monoxide ice should have been sublimated by the sun's rays when the object was even farther out in the solar system. This discrepancy may mean the comet made a pass of the sun before, with sublimation first eating away at layers of ice on its surface and its current activity only being kickstarted at closer distances, when heat from sunlight reached ice deeper within the object. Finding a behemoth like C/2014 UN271, Kokotanekova says, could hint at the existence of a whole class of gigantic progenitor comets. Such comets might have been the first large, icy objects to coalesce in the solar system, after which they may could have eventually broken apart to form smaller comets. 'It's possible that the small objects are mostly fragments, while the large ones, like UN271, have never collided with anything,' she says. That might mean there are more primordial megacomets awaiting discovery. If so, the recently completed Vera C. Rubin Observatory in Chile, which will begin a 10-year panoramic survey of the heavens later this year, could find more of them. 'It's so sensitive that it will certainly pick up comets of this size, quite probably even further away from us,' Ye says. Rubin's wide eye on the sky should also give us more information on C/2014 UN271 itself, says Meg Schwamb, an astronomer at Queen's University Belfast uninvolved with this latest finding. 'Rubin's going to watch it come in,' she says. That could help us get a better handle on its activity, in partnership with telescopes like ALMA. 'You need both of those pieces of information—if it got brighter, and whether the amount of carbon monoxide changed—to tell you what's going on,' Schwamb says. For now Comet UN271 remains a fascinating target of study, a giant comet like no other that is giving us a unique window into the dark frontiers of the outer solar system. 'This is just an incredibly exciting object,' Roth says. And, for astronomers eager to learn more about this and other mega comets, the best is yet to come.
Yahoo
25-04-2025
- Science
- Yahoo
Scientists discover super-Earth exoplanets are more common in the universe than we thought
When you buy through links on our articles, Future and its syndication partners may earn a commission. Astronomers have discovered that "super-Earth" planets may exist on wider orbits than previously thought — and this implies these rocky, or "terrestrial," worlds are far more common than was suspected. Super-Earths, in short, are planets with masses up to 10 times that of our planet, but still less than the masses of gas giant planets. The discovery came after a small extrasolar planet, or "exoplanet," in a wide orbit around its star was discovered, courtesy of a gravitational "microlensing" event designated OGLE-2016-BLG-0007. This event indicated the exoplanet had a planet-to-star mass ratio that roughly doubles the Earth-sun mass ratio. "We found a small planet in an orbit similar to Saturn's. This planet is part of a larger sample that shows super-Earth planets between the orbits of Earth and Saturn are abundant," team member Jennifer Yee of the Center for Astrophysics | Harvard & Smithsonian told "The abundance of super-Earths was a surprise." Yee explained that scientists previously knew from data delivered by the Kepler space telescope mission that super-Earths are common around other stars, but only within a distance from their respective stars equivalent to the distance between Earth and the sun. That expected distance is represented by one astronomical unit (au). This new work, however, shows that super-Earths are also common at larger distances from their host stars, in this case around 10 au (or 10 times the distance between our planet and the sun). "Previously, there were only upper limits on the numbers of super-Earths [in wide orbits], and there was a suggestion that they might not exist at all," Yee continued. When factoring in this super-Earth data, the team calculated that there should be around 0.35 super-Earth planets per star on wide Jupiter-like orbits. Yee explained that the overall distribution of planetary mass ratios could reflect the specifics of planet formation processes. "Specifically, the distribution suggests that the planets can be separated into two populations, one of super-Earths and Neptunes and one of more massive gas giant planets," Yee added. The team suspects this division in populations reflects the differences in formation processes between terrestrial planets and massive gas giant a larger population of super-Earths in Jupiter-like and Saturn-like orbits could also have implications for our understanding of so-called "habitable zones" around other stars. Habitable zones are defined as regions around stars that are temperate enough to allow liquid water to exist at the surfaces of terrestrial planets within the area. Any closer to a star than its habitable zone band, and a planet's liquid water evaporates. Further away, it freezes. This is why habitable zones are also called "Goldilocks zones" (like the perfect bear's porridge, liquid water is neither too hot nor too cold in these zones). Though Jupiter and Saturn are outside the solar system's habitable zone, super-Earths in similar orbits around hotter stars could fit within such regions — if they are extended. "The habitable zone region where we expect to find life in other planetary systems is extremely narrow. Our expectations regarding this zone have been driven by our own planet because that is the only place where we have definitively detected life, so far," Yee said. "Nature continuously surprises us."Yee added that the best way to understand the habitable zone region around stars in general is to measure the properties of the larger planet population. "This gives more room for the unexpected," Yee said. "This measurement of the super-Earth population provides a new piece of the habitable zone picture, which will ultimately contribute to our characterization of the population of Earth-like planets." Yee and colleagues made this discovery using the Korea Microlensing Telescope Network (KMTNet), consisting of three sites in Chile, South Africa and Australia. The three telescopes in three different time zones mean KMTNet can allow astronomers to monitor the night sky uninterrupted over the southern hemisphere. "This discovery of this planet wasn't a surprise because KMTNet was designed to do this, but it is extremely exciting because it proves KMTNet is capable of routinely finding smaller planets, which is a requirement for understanding planet populations," Yee hunts exoplanets using a phenomenon first predicted by Albert Einstein in his 1915 theory of gravity, general relativity. General relativity suggests objects with mass cause the fabric of space and time to "warp," with gravity arising from this curvature. When light passes by this curvature, its light gets curved, too. That means when a body of mass comes between Earth and a background light source, the image of that source is warped, magnified, or even multiplied upon reaching our instruments. A planetary system acting as a gravitational lens and coming between Earth and a background source can cause a tiny distortion in that source, a situation called "microlensing." "It is a funny coincidence of physics," Yee said. "Microlensing is good at finding planets near the Einstein radius [the characteristic angle for gravitational lensing]."This radius is set by the mass of the lensing planetary system, including its star, the distance from Earth to that lens system, and the distance from Earth to the background source whose light is distorted. "In fact, it was the realization of this coincidence in the early 1990s that led to the first microlensing planet searches," Yee added. Related Stories: — Scientists discover bizarre double-star system with exoplanet on a sideways orbit (video) — Does exoplanet K2-18b host alien life or not? Here's why the debate continues — Earth-size planet discovered around cool red dwarf star shares its name with a biscuit The team will now continue to use KMTNet and gravitational lensing to hunt for lensing planetary systems in an attempt to discover more super-Earths in wide orbits. "We are working on increasing the size of the planet sample by including more seasons of KMTNet data in the analysis," Yee concluded. "We are also working on improving the quality of the data reductions to allow us to find weaker planetary signals."The team's research was published on Thursday (April 24) in the journal Science.
Yahoo
08-04-2025
- Science
- Yahoo
1 year since the Great North American Eclipse — Here's how the 2026 total eclipse will compare
When you buy through links on our articles, Future and its syndication partners may earn a commission. One year ago today, a total solar eclipse graced the skies of North America, as the moon fully blocked out the sun a narrow slice of Earth, bringing sudden darkness and a breathtaking view of the solar corona, the sun's outer atmosphere. The April 8 2024 total solar eclipse was our last total solar eclipse until the next one on Aug. 12, 2026. With a little over 16 months until this next event, how will the 2026 total eclipse compare to the one a year ago? Related: The 7 best total solar eclipses of the next 10 years The April 8 2024 total solar eclipse began in the southern Pacific Ocean, before crossing northern Mexico, the USA, and east of Canada. Altogether, the eclipse path passed over the residences of 44 million people, 32 million of which live in the U.S. The August 12 2026 eclipse, on the other hand, which passes primarily through Greenland, Iceland and Spain, will eclipse the homes of around 15 million people — about a third of that in the previous event. Most of Europe will also get to enjoy a partial solar eclipse. Image 1 of 4 Image 2 of 4 Image 3 of 4 Image 4 of 4 But it's not just the location that differs vastly between the two eclipses, but the direction. Almost all eclipse paths travel from west to east, due to the relative motion of the moon and Earth. This includes the 2024 eclipse path, which traveled from southwest to northeast. The 2026 eclipse, however, begins by traveling east to west, before moving from the north-west to south-east — opposite to the 2024 event. What's happening here? Two things, actually. The first effect is that the eclipse path is traveling over the top of Earth, missing the North Pole by 60 miles (100 kilometers). This can happen because of the northern hemisphere summer, where the north of our planet points towards the sun. At the start of the eclipse, in rural northern Siberia, the eclipse begins in the middle of the night, this is possible at high latitudes where the sun doesn't set during the peak summer months. Because of the projection of the eclipse path over the pole, we'll experience the rare event of an eclipse path moving from east to west. Whether an eclipse moves towards the north-east or south-east depends on another factor — whether the moon's orbit is passing through the Earth-sun plane from above (called the ascending node), or below (the descending node). The 2024 eclipse occurred during the ascending node, whilst the 2026 eclipse will be during the descending node. For all of North America, the totality phase of the 2024 eclipse was seen high in the sky. In Mexico and Texas, the event was seen close the noon, whilst even the easternmost coast of Newfoundland and Labrador in Canada still saw totality 2.5 hours before sunset. The same cannot be said for the 2026 eclipse. In Spain, the most populated region of the eclipse path, also with the highest likelihood of clear skies in mid-August, the eclipse will happen close to sunset. On the east coast of mainland Spain, totality will occur at 8:30 p.m. local time, just thirty minutes before sunset. As a result of this, the sun will be low in the sky, and finding a vantage point clear of buildings, hills or clouds may be tricky. Further east still, on the island of Mallorca, the total solar eclipse begins just 15 minutes before sunset. In both of these locations, the sun will set on the horizon during the partial eclipse phase. Related stories: — Eclipse at sea: Best cruises for the total solar eclipse 2026 — 10 tips for planning your 2026 solar eclipse trip — Where can I see the total solar eclipse on Aug. 12, 2026? The 2024 total solar eclipse was a relatively long one, with the longest eclipse duration of 4 minutes and 28 seconds in Mexico. But, not all eclipses have the same duration; for a couple of reasons. If the moon is marginally closer to the Earth, it will cast a bigger shadow during totality, which takes longer to pass over a given area. The speed of the moon's shadow varies significantly between eclipses too, traveling nearly five times faster at the poles, or near regions of sunrise and sunset, than at the equator during midday. Although the 2026 eclipse will have an eclipse path 60% wider than in 2024 (183 miles versus 115, at the widest point), the eclipse will be far shorter, due to occurring at higher latitudes and/or late in the day. The longest duration of the 2026 eclipse will be 2 minutes and 18 seconds, far in the high Arctic. Down in the more populated Spain, the eclipse will only last around 1 minute 44 seconds. Total solar eclipses are rare. Or are they? Although, indeed, a total solar eclipse happens somewhere in the world every approximately 1 and a half years, the chances of one happening in your country are slim. Take the U.K., for example, which last experienced a total solar eclipse in 1999. The next one? 2090. The U.S. experienced total solar eclipses in 2017 and 2024. The relatively close-together pair of eclipses has brought recency bias to the country's perception of how rare these events are! Before 2017, the contiguous USA did not see a total eclipse since 1979. The next one? 2044. Except for a lucky minority, if you want to see a total solar eclipse in your lifetime — you'll need to travel for it.
