Latest news with #LarryDenneau
Yomiuri Shimbun
5 hours ago
- Science
- Yomiuri Shimbun
Newly Spotted Comet Is 3rd Interstellar Object Seen in Solar System
WASHINGTON (Reuters) — Astronomers are tracking a newly spotted comet hailing from parts unknown, only the third time such an interstellar object has been observed visiting our solar system. According to U.S. space agency NASA, the interloper — named 3I/ATLAS — was first spotted on July 1 by an Asteroid Terrestrial-impact Last Alert System, or ATLAS, telescope located in Rio Hurtado, Chile. Astronomers said its unusual trajectory indicated it had ventured from beyond our solar system. Journeying at a speed of around 60 kilometers per second from the direction of the center of the Milky Way galaxy, 3I/ATLAS is presently located about 670 million kilometers from Earth. 'Beyond that we do not know very much, and there are many efforts underway to observe this object with larger telescopes to determine composition,' University of Hawaii astronomer Larry Denneau, coprincipal investigator for ATLAS, said on July 3. The only other such interstellar visitors previously observed by astronomers were objects called 1I/'Oumuamua (pronounced oh-MOO-uh-MOO-uh), detected in 2017, and 2I/Borisov, discovered in 2019. 'The comet has some similarities to 2I/Borisov in that it appears to be an icy comet, but it is much larger, possibly 10 kilometers in diameter,' Denneau said. 'It currently has a faint coma,' Denneau added, referring to the cloud of gas and dust surrounding a comet's nucleus, 'but the coma and tail may increase dramatically as the object comes closer to the sun. Its closest approach to the sun will be later this year, when it will come inside the orbit of Mars. We don't know what will happen, so that's exciting.' Astronomers said the comet poses no threat to Earth and will never come closer than 240 million kilometers away, equivalent to more than 1½ times the distance between Earth and the sun. It is currently located about 670 million kilometers from the sun and will reach its closest approach to the sun around Oct. 30, when it will be about 210 million kilometers away from our star. The ATLAS network is a NASA-funded telescope survey built and operated by the University of Hawaii, with five telescopes around the world that scan the night sky continuously to look for objects that could threaten Earth.
Scientific American
3 days ago
- Science
- Scientific American
7 Big Mysteries about Interstellar Object 3I/ATLAS
Earlier this month astronomers were thrilled to discover only the third known interstellar object ever seen in our solar system. Now dubbed 3I/ATLAS, the suspected comet has just zoomed past the orbit of Jupiter, traveling so fast that it's bound to slip through our sun's gravitational grip. The high speed and hyperbolic trajectory of 3I/ATLAS means it must have come from another star and was cast adrift in the Milky Way by some unknown process before it eventually, by chance, briefly swooped by our sun. It will reach about the orbit of Mars before it boomerangs back toward interstellar space, never to be seen again, at the end of this year. That's why astronomers have been racing to study 3I/ATLAS since July 1, when Larry Denneau of the University of Hawaii first spied it using a telescope in Chile that's part of the globe-spanning Asteroid Terrestrial-Impact Last Alert System (ATLAS). Soon more powerful observatories, including the James Webb Space Telescope (JWST) and Hubble Space Telescope, will scrutinize the object—which, thanks to its alien, interstellar provenance may be the oldest comet anyone has ever seen. 'I didn't get any sleep for like 35 hours,' says Bryce Bolin of Eureka Scientific in California, who rushed to release a preprint paper and arrange additional observations following 3I/ATLAS's discovery. 'It ruined my weekend.' 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. Stefanie Milam of NASA's Goddard Space Flight Center is part of a group that had reserved time on JWST to observe an interstellar object—if the researchers were fortunate enough for one to be discovered. But the group's luck was tested when it couldn't reach the lead of its program—Martin Cordiner, also at Goddard—to kick the observations into action. 'He was hiking in Maine when the object was discovered, and we could not reach him—he was completely off the grid,' Milam says. 'When he finally got back, his phone just blew up. I said, 'You're never allowed to go on vacation again!'' So why exactly are astronomers so eager to observe this object, and what do they hope to learn? Where did 3I/ATLAS come from? The first major question to answer about 3I/ATLAS is its origin. Tracing it back to an individual star is likely impossible, given the mixing of myriad stars in their orbits around our galaxy across billions of years. But we might be able to work out roughly the region it came from. One team of astronomers has already begun doing just that, using the high velocity of the object with respect to our sun—60 kilometers (37 miles) a second—to argue that it might have come from the vicinity of our galaxy's thick disk. This is a puffy torus of older stars moving at high velocities above and below the main flat plane of the Milky Way—which is where our sun serenely orbits. A thick-disk origin might mean that 3I/ATLAS is extremely ancient, more than eight billion years old. 'It's from a star that's potentially not even there anymore,' says Michele Bannister of the University of Canterbury in New Zealand, a co-author on the work. Aster Taylor of the University of Michigan performed a different age analysis based on the trajectory of 3I/ATLAS and suggests the object is 11 billion to three billion years old. 'We get similar answers,' Taylor says. Such estimates might soon be revised if subsequent observations can show just how much space weathering the object has endured during its interstellar sojourn. How big is it? Currently, 3I/ATLAS is inside the orbit of Jupiter and approaching the orbit of Mars, which it will cross in October, passing about 0.2 astronomical unit (one fifth the Earth-sun distance) from the Red Planet. Although early observations have led astronomers to categorize 3I/ATLAS as a comet, at the moment, it's not behaving exactly like one. The object doesn't display a large tail or enveloping coma of cast-off gas, only a hint of dust—but that is expected to change soon. As it traverses the asteroid belt between Mars and Jupiter and basks in the sun's radiance, its surface should warm enough to sublimate ice, venting sufficient material to form a large coma and perhaps a prominent tail. A substantial coma would be like a curtain drawn over astronomers' eyes, obscuring their view of the object and complicating efforts to gauge its dimensions. Before that happens, a team led by David Jewitt at the University of California, Los Angeles, is hoping to pin down its size with Hubble in August. (Other telescopes might be able to determine the size of 3I/ATLAS, too.) Initial estimates suggested 3I/ATLAS might be up 20 kilometers (12 miles) across—very big for a comet—but most astronomers now think it is much smaller. 'It's probably somewhere in the range of one or two kilometers,' says John Noonan at Auburn University in Alabama. That would be somewhat comparable in size to our first two interstellar visitors: 1I/ʻOumuamua, which was discovered in 2017 and was up to about 400 meters (0.25 mile) long, and 2I/Borisov, which was found in 2019 and was about one kilometer (0.6 mile) wide. If 3I/ATLAS turns out to be much bigger, 10 kilometers (six miles) or more, this would pose problems for preexisting estimates of many big interstellar objects reside in the galaxy. 'It's statistically extremely unlikely we should ever see something that size,' Noonan says. 'Theorists don't like that. But as an observer, I would love to see a really weird, big object.' How fast is it spinning? As well as its size, one of the key properties astronomers want to know about 3I/ATLAS is its rotation rate—something they might discern by watching the object's changing brightness as it spins. The spin of 3I/ATLAS could carry clues as to how the object was ejected from its home star in the first place. 'Certain ways of kicking these objects out tend to make them spin up,' Taylor says. A close pass of a gas giant planet, for instance, could easily set the object twirling while hurling it away from its home star. Conversely, a slow rotation period would suggest the object experienced a more gentle ejection. 'You could do this when stars die,' Taylor says. 'They lose a lot of mass, and so the gravitational force on objects at the outer edge of their system goes away. Those objects become unbound and just flow out into the galaxy.' The rotation period can also tell us more about the shape of 3I/ATLAS—a steady rotation suggests a fairly spherical form, whereas a fluctuating rotation speed might suggest a 'wonky shape,' Taylor says, like that of 'Oumuamua, which was estimated to be cigar- or pancake-shaped. What is 3I/ATLAS made of? If 3I/ATLAS really is an ancient cometary castaway that has been drifting through the galaxy for eons, it might be full of ice that has never been heated by a star. If so, then as it gets closer, the object might suddenly erupt into activity. While that could be bad news for measuring its size, it would aid efforts to determine 3I/ATLAS's chemical composition. JWST and Hubble would be best suited for the task of picking apart the different species of molecules that might erupt from 3I/ATLAS. Unfortunately, however, in October, when the object will be at its warmest, closest point to our star (called perihelion), Earth will be on the other side of the sun. This will make observations from our planet almost impossible. In November, post-perihelion, Noonan will use Hubble to study 3I/ATLAS and its emissions, looking for signs of substances such as hydroxide and hydrogen that can help clarify its composition. If the object is several billion years old, as predicted, then it might be rich in water because of the suspected formation environment around older stars. 'You would expect a lot of hydrogen coming from these water-rich irradiated objects, if this is really as old as [thought],' Noonan says. Milam and her colleagues, meanwhile, will use JWST in August and December to observe 3I/ATLAS before and after perihelion. Thanks to its keen infrared vision, JWST is better suited for teasing out the presence of molecules such as water, carbon monoxide, carbon dioxide and ammonia. 'We can really home in and see what this thing looks like,' she says. 'Borisov had a pretty boring chemistry, but it wasn't like any object in our solar system—there was hardly any water at all but a lot of carbon monoxide and hydrogen cyanide. With JWST, we're hoping to see a lot of carbon dioxide [on 3I/ATLAS], maybe even water, if it's as pristine as people are projecting.' Although the overall view from Earth degrades as the object approaches perihelion, some telescopes will be less visually impaired. Those operated by the Lowell Observatory in Arizona, for instance, are primed to observe 3I/ATLAS at dawn and dusk, when the sun is below the horizon. This will allow for studies even when the object will be close to our star from our planet-bound perspective. 'The Lowell Discovery Telescope is really well suited to observations close to the horizon,' says Nick Moskowitz, an astronomer at Lowell Observatory. 'We will be able to track it closer in to perihelion than other facilities.' An unlikely additional capability will be at Mars, where spacecraft such as NASA's Mars Atmosphere and Volatile Evolution (MAVEN) orbiter may be able to see 3I/ATLAS as it passes about 30 million kilometers (19 million miles) from the planet. 'It'll be pretty large and apparent in the sky,' Noonan says, providing the object kicks into activity as hoped. 'They'll be able to see the coma,' giving us an insight into 3I/ATLAS's activity near the sun that would otherwise be impossible to see from Earth. Will it survive? A big unknown about 3I/ATLAS is whether it will actually survive its close encounter with our sun. While 'Oumuamua did so, Comet Borisov was not so fortunate, with the object appearing to split and break apart on its way out of our solar system. The same fate could befall 3I/ATLAS. 'Borisov fragmented, which is pretty usual for comets,' Bannister says. All eyes will be on our latest visitor to see if the same thing happens again. An additional quirk of 3I/ATLAS's survivability is the impact of solar wind, which may snip away any cometary tail as it is ejected. By chance, the object is entering our solar system at quite a shallow angle, much flatter than that of most comets, which means it will experience stronger solar headwinds. Sarah Watson of the University of Reading in England and her colleagues are using this quirk to study how the solar wind traverses into the outer solar system. 'We can potentially calculate the speed of the solar wind,' she says, by noticing the impact of the solar wind on the purported comet's tail, if one materializes. Could we reach it? No spacecraft will be able to reach 3I/ATLAS. It is moving too fast and is too far from Earth for us to consider launching something in time. Yet an upcoming European Space Agency (ESA) mission called Comet Interceptor, set to launch in 2029, might attempt to visit another interstellar object, if we find one within its reach. The spacecraft will be positioned past the moon's orbit away from the sun and, if a suitable target is found, will be commanded to fire its engines and try and intercept the incoming alien object. If no suitable interstellar object is found, Comet Interceptor will instead be sent to one of several intriguing comets of our solar system. 'It is possible we could get an interstellar object, but we have to be really lucky,' says Colin Snodgrass, an astronomer at the University of Edinburgh, who is deputy lead on the mission. How many are there? One of our biggest outstanding questions about interstellar objects concerns their unknown abundance. The object 3I/ATLAS is our third interstellar visitor in eight years—a real but weak hint of how many are out there, waiting to be found. Predictions estimate there are trillions upon trillions of interstellar objects drifting around our galaxy, and perhaps one in our solar system at any given time—but they're typically just so faint that they're unlikely to be found by most telescopes. This is expected to change when a new telescope called the Vera C. Rubin Observatory begins a 10-year survey of the sky later this year. Rubin is expected to see somewhere between six and 51 interstellar objects in its 10-year survey. Seeing such a population will tell us 'how unique, or varied, planetesimal formation is across different parts of the galaxy,' Bannister says, referring to kilometer-scale objects thought to coalesce around newborn stars that become the feedstock for planets—and, when kicked to a system's hinterlands, become a reservoir of comets. One puzzling question is why we haven't seen much smaller interstellar objects, Moskowitz says. If smaller objects are more plentiful than larger objects, as scientists expect, then we should have seen some small interstellar objects entering our atmosphere, appearing as meteors streaking across Earth's skies at speeds and trajectories that clearly convey their interstellar origins. Detections of such objects have been claimed, but the evidence behind them has failed to convince most experts. The apparent absence of small interstellar interlopers 'is telling us something, but we don't know what that is yet,' Moskowitz says. 'I think that's going to be one of the major questions: Why are we seeing these big cometlike things coming through the solar system, but we're not seeing things that are smaller? It may have to do with the survivability of stuff out there in the galaxy, but we need more data.'
Ammon
05-07-2025
- Science
- Ammon
Newly spotted comet is third interstellar object seen in our solar system
Ammon News - Astronomers are tracking a newly spotted comet hailing from parts unknown, only the third time such an interstellar object has been observed visiting our solar system. According to U.S. space agency NASA, the interloper - named 3I/ATLAS - was first spotted on Tuesday by an Asteroid Terrestrial-impact Last Alert System, or ATLAS, telescope located in Rio Hurtado, Chile. Astronomers said its unusual trajectory indicated it had ventured from beyond our solar system. Journeying at a speed of around 37 miles (60 km) per second from the direction of the center of the Milky Way galaxy, 3I/ATLAS is presently located about 420 million miles (670 million kilometers) from Earth. "Beyond that we do not know very much, and there are many efforts underway to observe this object with larger telescopes to determine composition," University of Hawaii astronomer Larry Denneau, co-principal investigator for ATLAS, said on Thursday. The only other such interstellar visitors previously observed by astronomers were objects called 1I/'Oumuamua (pronounced oh-MOO-uh-MOO-uh), detected in 2017, and 2I/Borisov, discovered in 2019. "The comet has some similarities to 2I/Borisov in that it appears to be an icy comet, but it is much larger, possibly 10 km (6.2 miles) in diameter," Denneau said. "It currently has a faint coma," Denneau added, referring to the cloud of gas and dust surrounding a comet's nucleus, "but the coma and tail may increase dramatically as the object comes closer to the sun. Its closest approach to the sun will be later this year, when it will come inside the orbit of Mars. We don't know what will happen, so that's exciting." Astronomers said the comet poses no threat to Earth and will never come closer than 150 million miles (240 million km) away, equivalent to more than 1-1/2 times the distance between Earth and the sun. It is currently located about 416 million miles (670 million km) from the sun and will reach its closest approach to the sun around October 30, when it will be about 130 million miles (210 million km) away from our star. The ATLAS network is a NASA-funded telescope survey built and operated by the University of Hawaii, with five telescopes around the world that scan the night sky continuously to look for objects that could threaten Earth. Reuters
The Herald
05-07-2025
- Science
- The Herald
Newly spotted comet is third interstellar object seen in our solar system
Astronomers are tracking a newly spotted comet hailing from parts unknown, only the third time such an interstellar object has been observed visiting our solar system. According to US space agency NASA, the interloper — named 3I/ATLAS — was first spotted on Tuesday by an Asteroid Terrestrial-impact Last Alert System, or ATLAS, telescope located in Rio Hurtado, Chile. Astronomers said its unusual trajectory indicated it had ventured from beyond our solar system. Journeying at a speed of about 60km per second from the direction of the centre of the Milky Way galaxy, 3I/ATLAS is now located about 670-million kilometres from Earth. 'Beyond that we do not know very much, and there are many efforts under way to observe this object with larger telescopes to determine composition,' University of Hawaii astronomer Larry Denneau, co-principal investigator for ATLAS, said on Thursday. The only other such interstellar visitors previously observed by astronomers were objects called 1I/'Oumuamua (pronounced oh-MOO-uh-MOO-uh), detected in 2017, and 2I/Borisov, discovered in 2019. 'The comet has some similarities to 2I/Borisov in that it appears to be an icy comet, but it is much larger, possibly 10km in diameter,' Denneau said. 'It has a faint coma,' Denneau added, referring to the cloud of gas and dust surrounding a comet's nucleus, 'but the coma and tail may increase dramatically as the object comes closer to the sun. Its closest approach to the sun will be later this year, when it will come inside the orbit of Mars. We don't know what will happen, so that's exciting.' Astronomers said the comet poses no threat to Earth and will never come closer than 240-million km away, equivalent to more than 1-1/2 times the distance between Earth and the sun. It is located about 670-million km from the sun and will reach its closest approach to the sun on about October 30, when it will be about 210-million km away from our star. The ATLAS network is a NASA-funded telescope survey built and operated by the University of Hawaii, with five telescopes around the world that scan the night sky continuously to look for objects that could threaten Earth. Reuters
DW
04-07-2025
- Science
- DW
Should we panic about interstellar comet 3I/ATLAS? – DW – 07/04/2025
Sometimes "the universe comes to us," writes the European Space Agency. For the third time since 2017, an interstellar object will enter our solar system. What is it and are we prepared? Beyond the fact that this is the third known interstellar object to have entered our solar system, "we don't know very much," said Larry Denneau, co-principle investigator at ATLAS, a telescope in Chile that spotted 3I/ATLAS on July 1, 2025. It's not exactly reassuring when scientists say "we don't know," but at least it's honest. Astronomers do know that 3I/ATLAS is a comet that's about 670 million kilometers (416 million miles) away from the sun. Based on current projections, it poses no danger to planet Earth. "Scientists are still determining the velocity and trajectory to a degree that will allow accurate predictions for the future," wrote Richard Moissl, who heads the European Space Agency's Planetary Defense office, in an email to DW. The closest it will get to our planet is about 240 million kilometers away, when it will fly by in October. That is more than 1.5 times the distance between us and the sun, and about 624 times the distance between the Earth and our moon. It is also thought to be about 20 kilometers (12.4 miles) wide and traveling at about 60 kilometers per second (an impressive 134,000 miles per hour). But this is all relatively basic data — the very data that allowed astronomers at the Asteroid Terrestrial-impact Last Alert System in Chile to spot it. When they saw the object on an unusual trajectory, they immediately began to track and measure it. Then, other astronomers based at telescopes in Hawaii and Australia, began monitoring the object's flight progress and confirmed it as an interstellar comet. "We are seeing an onset of [normal] cometary activity," wrote Moissl. Comet 3I/ATLAS flew through the heliosphere to enter our solar system. The heliosphere is a barrier that protects us from interstellar winds and radiation. The heliosphere is, however, an imperfect barrier — some interstellar radiation gets through, and it clearly doesn't stop icy intergalactic wanderers like 3I/ATLAS. Interstellar objects in our solar system are thought to be quite rare though. The first known interstellar object was 1I/'Oumuamua, detected in 2017, and 2I/Borisov, detected in 2019. "This is only the third interstellar [object] ever to be detected, hence a precise forecast of the expected frequency is not possible at this point," wrote Moissl. But telescopes have got more technologically advanced and scientists do now scan the night sky continuously. So we may begin to see more of them. "The Legacy Survey in Space and Time at the Vera Rubins telescope in Chile goes online this year. It is more efficient than existing surveys and expected to detect several new Interstellar objects over the next 10 years," said Moissl's colleague at ESA, Michael Kueppers. Kueppers is a Comet Interceptor Project scientist. Comet Interceptor is a spacecraft that will rest in a "parking orbit" and intercept distant comets and asteroids if they come too close to Earth. It's scheduled to launch in 2029. The short (and obvious) answer is that comets, like 3I/ATLAS, 1I/'Oumuamua and 2I/Borisov, come from other planetary systems. To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video Much like comets and asteroids within our solar system, interstellar objects are considered to be untouched specimens from elsewhere in our galaxy, the Milky Way, if not fragments from the very beginnings of the universe. Moissl said this new object "came roughly from the direction of the Galactic Center region," which, as the name suggests, is towards the center of the Milky Way. But astronomers do not know its precise origin or "home star." Based on its brightness, 3I/ATLAS appears to be bigger than the other two stray comets — 1I/'Oumuamua and 2I/Borisov — which are thought to have entered our solar system from a different region of the Milky Way. Astronomers will want to continue monitoring 3I/ATLAS to assess its composition and behavior. ESA said that as an active comet, it may heat up as it gets closer to Earth, and "sublimate" — that's when frozen gases on a comet turn into vapor, creating a glowing coma and trail of dust and ice particles. You should be able to see it from Earth with a telescope by September — but "you'll need a big telescope to see it," wrote Jonathan McDowell of the Harvard-Smithsonian Center for Astrophysics in an email to DW. When it's closest to Earth it will be hidden by the sun but then reappear by early December.
