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CNN
3 days ago
- General
- CNN
Once inevitable collision between Milky Way and Andromeda galaxies now seems less likely, astronomers say
A collision between our Milky Way galaxy and its largest neighbor, the Andromeda galaxy, predicted to occur in about 4.5 billion years, has been anticipated by astronomers since 1912. But new research suggests that the likelihood of this galactic clash, dubbed 'Milkomeda,' is smaller than it seems. At first glance, it appears likely that the galactic duo — separated by about 2.5 million light-years — is on an inevitable collision course. The Milky Way and Andromeda are barreling toward each other at about 223,694 miles per hour (100 kilometers per second). However, the Local Group, or our corner of the universe, includes 100 known smaller galaxies. A team of astronomers factored in some of the largest among them, including the Large Magellanic Cloud, or LMC, and M33, or the Triangulum galaxy, to see how much of a role they might play on the chessboard of our galaxy's future over the next 10 billion years. After factoring in the gravitational pull of Local Group galaxies and running 100,000 simulations using new data from the Hubble and Gaia space telescopes, the team found there is about a 50% chance of a collision between the Milky Way and Andromeda in the next 10 billion years. There is only about a 2% chance the galaxies will collide in 4 to 5 billion years as previously thought, according to the study published Monday in the journal Nature Astronomy. A merger of the Milky Way and Andromeda galaxies would destroy them both, eventually turning both spiral structures into one elongated galaxy, the study authors said. Collisions between other galaxies have been known to create 'cosmic fireworks, when gas, driven to the center of the merger remnant, feeds a central black hole emitting an enormous amount of radiation, before irrevocably falling into the hole,' said study coauthor Carlos Frenk, professor at Durham University in England. 'Until now we thought this was the fate that awaited our Milky Way galaxy,' Frenk said. 'We now know that there is a very good chance that we may avoid that scary destiny.' However, there are many unknown factors that make it difficult to predict the ultimate fate of our galaxy, according to the study authors. And, Frenk warns, the Milky Way has a greater chance of colliding with the LMC within 2 billion years, which could fundamentally alter our galaxy. The LMC orbits the Milky Way, while M33 is a satellite of Andromeda. The LMC's mass is only about 15% of the Milky Way's. But the team found that the satellite galaxy has a gravitational pull, perpendicular to Andromeda, that changes the Milky Way's motion enough to reduce the chance of a merger between the two giant galaxies. It's a similar case for M33. 'The extra mass of Andromeda's satellite galaxy M33 pulls the Milky Way a little bit more towards it,' said lead study author Dr. Till Sawala, astronomer at the University of Helsinki in Finland. 'However, we also show that the LMC pulls the Milky Way off the orbital plane and away from Andromeda. It doesn't mean that the LMC will save us from that merger, but it makes it a bit less likely.' Previous research also has assumed most likely values for unknown data, such as the uncertainties in the present positions, motions and masses of the Local Group galaxies. In the new study, the team accounted for 22 different variables, including those unknowns, that could contribute to a collision. 'We ran many thousands of simulations, which allowed us to account for all the observational uncertainties,' Sawala said. 'Because there are so many variables that each have their errors, that accumulates to rather large uncertainty about the outcome, leading to the conclusion that the chance of a direct collision is only 50% within the next 10 billion years.' In just over half of the simulations predicting what could occur in 8 to 10 billion years, the Milky Way and Andromeda galaxies initially sailed somewhat closely past each other before circling back and then losing enough orbital energy to collide and merge as one galaxy. These initial close encounters between each galaxy's halo — a large envelope of gas — would eventually lead to a collision. 'In general, the merger would most likely involve a strong starburst, during which many new stars would form, followed by a period of intense radiation caused by exploding young stars and the newly active supermassive black hole, eventually shutting down star formation completely,' Sawala said. 'A few billion years later, any traces of the former Milky Way and Andromeda would disappear, and the remnant would be a largely featureless elliptical galaxy.' In the other simulations, both galaxies crossed paths without disturbing each other. Geraint Lewis, a professor of astrophysics at the University of Sydney's Institute for Astronomy, finds the results showing the gravitational influence of M33 and the LMC interesting. He has previously authored research on a potential collision between Andromeda and the Milky Way. 'We won't know if the collision is definitely off in the future, but this clearly shows that the story that people tell — that there will be a collision that will destroy the Milky Way and Andromeda — is not as clear or certain that people think,' Lewis said. 'But even if there is a pretty close encounter rather than smashing head-on, the gravitational tearing that each will assert on each other is likely to leave the two large galaxies in a sorry state.' While including the LMC's gravitational effects on the Milky Way is important, accounting for uncertainties is the most important aspect of the new study, said Scott Lucchini, a postdoctoral fellow in the Institute for Theory and Computation at the Center for Astrophysics, Harvard & Smithsonian. 'Here, they've sampled from the uncertainties in the positions, velocities, and masses of the galaxies to obtain the relative probabilities of different outcomes,' Lucchini wrote in an email. 'This really gives us the whole picture of what could happen in the future.' Galaxies are full of intricacies. Their shapes can become distorted, interactions can change their orbits and they can lose mass in different ways. Such complexities make predictions difficult, Lucchini said. That essentially leaves the fate of the Milky Way 'completely open,' the study authors wrote in the new paper. However, more data coming from the Gaia space telescope in the summer of 2026 will provide measurements that refine some of the uncertainties about the speed and direction at which Andromeda is moving across the sky, Sawala said. The fate of the sun may have a bigger impact on Earth's future than the motions of galaxies, according to the researchers. Our sun is 4.5 billion years old. When it starts to die in another 5 billion years, it will swell into a red giant that engulfs Mercury, Venus and potentially Earth, according to NASA. 'The short answer is that the end of the sun is far worse for our planet than the collision with Andromeda,' Sawala said. 'While that merger would mean the end of our galaxy, it would not necessarily be the end of the sun or the Earth. Although our work also shows that earlier studies, that purported to predict precisely what the fate of the solar system would be after the merger, were clearly premature, in general, collisions between stars or planets are extremely rare during galaxy mergers. And while the end of the sun is certain, our study shows that the end of the galaxy is anything but.' While the team didn't model a merger between the LMC and the Milky Way in detail, they found a 'virtual certainty' that a merger between the two galaxies will occur within the next 2 billion years, which aligns with previous research, Sawala said. But the effects will likely be more minor than a merger between the Milky Way and Andromeda. 'The merger (between the Milky Way and the LMC) will not destroy our galaxy but it will change it profoundly, particularly impacting our central supermassive black hole and the galactic halo,' Frenck wrote in an email. He also served as a coauthor on a 2019 paper on the potential merger.
ABC News
4 days ago
- General
- ABC News
Milky Way may not collide with the Andromeda galaxy in 5 billion years after all: study
It's a fun fact pulled out at parties by every space nerd on the block — our Milky Way galaxy is going to crash into our nearest neighbour (the Andromeda galaxy) in 5 billion years. But forecasts of the impending "Milkomeda" mega-galaxy may be exaggerated. According to a new study, published in Nature Astronomy, there's a close to 50 per cent chance they won't collide at all. Even if they did collide, it would probably take much longer — more like 10 billion years. This means it will happen long after the death of our Sun, expected in roughly 5 billion years. It's a finding that surprised the team, said study co-author Ruby Wright, an astrophysicist at the University of Western Australia. "We expected [the study] to confirm the classic picture that the Milky Way and Andromeda merger is a done deal," Dr Wright said. The Andromeda and Milky Way galaxies are the two biggest galaxies in our section of the universe, referred to as the Local Group. Despite being 2.5 million light-years away, Andromeda's huge size, at about 200,000 light-years wide, makes it visible with the naked eye. From Australia, it can be seen just above the northern horizon in spring and summer. In 1913, US astronomer Vesto Slipher discovered Andromeda was getting closer to the Milky Way — even before we knew it was a separate galaxy, or how far away it was. We now know Andromeda is closing the distance to the Milky Way at about 100 kilometres per second. Astronomers have generally agreed that the two spiral galaxies would crash into each other within 5 billion years, leaving behind an elliptical pile of stars. To predict the fate of the galaxies, the researchers used datasets from the Gaia and Hubble space telescopes to model how they would move over the next 10 billion years. While it's fairly straightforward to learn whether something is getting closer or further in space, it's harder to tell if it's moving in any other directions. "At the moment, the galaxies are being drawn together by the influence of their own gravity, but obviously these galaxies don't exist in isolation," Dr Wright said. While Andromeda and the Milky Way are the biggest players, there are about 100 other smaller galaxies in the Local Group. The largest of these are the Triangulum Galaxy and the Large Magellanic Cloud (LMC), a major satellite galaxy of the Milky Way in the southern sky that is visible to the naked eye. The team ran 100,000 different simulations to test how the movements of the different galaxies affected each other. Although it is only about 15 per cent of the mass of the Milky Way, the study found the LMC could potentially tug our home galaxy out of Andromeda's path. In just under half of the simulations, the galaxies passed each other uneventfully: Andromeda got closer and then further away from the Milky Way, like watching a plane fly across the sky. In only 2 per cent of the simulations, the galaxies got close enough that they'd be pulled together within 5 billion years. "But if they miss by a certain amount, they end up in this almost galactic dance," Dr Wright said. "The gravity between them is still quite strong, so they'll pass by each other, reach another point where they are very far apart, and then they'll start coming back together again." These scenarios, which were roughly half of those modelled, saw the galaxies colliding within 10 billion years. Most simulations, though, predicted the Milky Way and the smaller LMC would merge within 2 billion years. But Dr Wright said there were huge uncertainties in each simulation. Lisa Harvey-Smith, an astrophysicist at the University of New South Wales who wasn't involved with the study, said predicting the future of Local Group movements was a very difficult thing to do. "It's almost like you're playing snooker, you've got 100 balls on the table, and you smash them and see where they're going to go in 10 billion years," she said. "The problem is the snooker balls are then soft and squishy, and they change shape, and there's all these invisible balls on the table as well — which is dark matter." Professor Harvey-Smith, who wrote a book centred on the collision of the Andromeda galaxy with our own, said the new study was "a really good paper to get people thinking". "You constantly have to update science knowledge," she said. "It's great to see a fresh perspective on things that sometimes become embedded." But she suspected that, because of the huge uncertainties involved, future research might come to different conclusions about the Local Group's movements again. "We in astronomy are always grasping at data beyond our reach," Professor Harvey-Smith said. Dr Wright believed data from newer telescopes would "absolutely" challenge the team's findings. "We're definitely not claiming to have predicted the future with certainty, but rather we're showing it's more uncertain than previously appreciated."
Yahoo
4 days ago
- General
- Yahoo
The Milky Way Might Not Crash Into The Andromeda Galaxy After All
"As it stands, proclamations of the impending demise of our Galaxy seem greatly exaggerated." That's the conclusion scientists have reached after revisiting the possibility of what we thought was a foregone conclusion: the eventual clash of giants, a collision between the Milky Way and the Andromeda galaxies. Led by astrophysicist Till Sawala of the University of Helsinki, a team of scientists has calculated that, in the next 10 billion years, the chance of a collision between the two galaxies is very close to 50 percent. In other words, there is just as much of a chance of collision as there is of the galaxies sailing right past each other, like ships in the eternal cosmic night. "We don't find that previous calculations were wrong – quite the contrary, when we start from the same assumptions, we reproduce the earlier results," Sawala told ScienceAlert. "However, we now find that the earlier prediction of a Milky Way-Andromeda collision is only one of several possibilities. Of course, the fate of the Local Group is not chaotic – with even better data, there will be a definite answer to the question of whether the Milky Way and Andromeda will merge or not, so our study certainly won't be the final word on this issue." The Milky Way-Andromeda collision has been predicted by scientists for years, occurring in an estimated timeframe of about 4.5 billion years. The predicted fusion of the two galaxies has been dubbed "Milkomeda", and has been considered to be all-but-inevitable. The Milky Way and Andromeda are not, however, alone in this little corner of the cosmos. They belong to a small group of galaxies within a radius of about 5 million light-years from the Milky Way known as the Local Group. The Milky Way and Andromeda are the largest members, but there are quite a few other objects hanging out that need to be taken into consideration when modeling the future. Sawala and his colleagues took the latest data from the Hubble and Gaia space telescopes, and the most recent mass estimates for the four most massive objects in the Local Group – the Milky Way, Andromeda, the Triangulum galaxy (M33), and the Large Magellanic Cloud (LMC). Then, they set about running simulations of the next 10 billion years, adding and removing galaxies to see how that changed the results. "Almost all of astrophysics, and actually all of my own previous work, is focused on trying to understand the past – how we got here, and why. There are good reasons for that, but I think it's also fascinating to think about the future," Sawala explained. "Initially, I was motivated to understand the potential impact of the wider cosmic environment on the Milky Way-Andromeda encounter, but as we show, there is actually a lot of complexity and uncertainty even in the relatively simple three- or four-body systems." Their results showed that the presence of M33 and LMC dramatically altered the probability of a collision between the Milky Way and Andromeda. When it is just the two large spiral galaxies, the merger occurred in slightly less than half the simulation runs. The addition of M33 increased the merger probability to two in three. Taking M33 back out and adding LMC had the opposite effect, decreasing the probability to one in three. When all four galaxies were present, the probability of a merger between the Milky Way and Andromeda within 10 billion years is slightly more than 50 percent. "We find that there are basically two types of outcomes," Sawala said. "The Milky Way and Andromeda will either come close enough on their first encounter (first 'pericenter') that dynamical friction between the two dark matter haloes will drag the orbit to an eventual merger, which very likely happens before 10 billion years, or they do not come close enough, in which case dynamical friction is not effective, and they can still orbit for a very long time thereafter." That 10 billion-year timeframe was chosen because it was well beyond the timeframe in which the merger was predicted to occur, but the further you try to peer into the future, the more difficult it becomes to predict. That's because other factors that can't be predicted may come into play; the further forward you go, the more likely those factors are to appear. This is far from the final word on the matter, however. Although we have access to some pretty great data now, ongoing observations and future instruments will be able to refine the measurements of motions and masses of objects in the Local Group to inform more detailed simulations in the future. "The main result of our work is that there is still significant uncertainty about the future evolution – and eventual fate – of our galaxy," Sawala said. "Of course, as a working astrophysicist, the best results are those that motivate future studies, and I think our paper provides motivation both for more comprehensive models and for more precise observations." The research has been published in Nature Astronomy. Tiny Pebbles Created One of The Most Extreme Worlds in The Galaxy Haunting Image Shows The Moon Deimos From The Surface of Mars Stunning Images Reveal The Sun's Surface in Unprecedented Detail
Gizmodo
4 days ago
- General
- Gizmodo
The Milky Way Might Not Smash Into the Andromeda Galaxy After All, New Simulation Indicates
For over a decade, researchers have suggested a high possibility of our Milky Way galaxy smashing into neighboring galaxy Andromeda around 5 billion years from now. The collision would merge the two galaxies into a single (very creatively named) 'Milkomeda'—but new research now indicates that this is less likely than previously assumed. Integrating new data from the Gaia and Hubble telescopes, an international team of researchers has simulated our galaxy's movement for the next 10 billion years. The computer model also makes use of new mass estimates for other galaxies within the Local Group—a galactic group that hosts the Milky Way and Andromeda, among others. Ultimately, the simulation indicates that there is only about a 50% probability that the two galaxies will collide in the next 10 billion years, bolstering similar results from previous studies. 'Here we consider the latest and most accurate observations by the Gaia and Hubble space telescopes, along with recent consensus mass estimates, to derive possible future scenarios and identify the main sources of uncertainty in the evolution of the Local Group over the next 10 billion years,' the researchers, including experts from the University of Helsinki and Durham University, wrote in the study. 'We found that uncertainties in the present positions, motions and masses of all galaxies leave room for drastically different outcomes and a probability of close to 50% that there will be no Milky Way–Andromeda merger during the next 10 billion years.' 'The fate of our Galaxy is still completely open.' Just as planets exert gravitational forces on each other, galaxies also impact their galactic neighbors. Specifically, Andromeda, the Triangulum galaxy, and the Large Magellanic Cloud (a galaxy orbiting the Milky Way) influence the Milky Way's path. According to the researchers, previous analyses that calculated higher chances likely didn't factor in the gravitational pull of the Large Magellanic Cloud. 'The orbit of the Large Magellanic Cloud runs perpendicular to the Milky Way–Andromeda orbit and makes their merger less probable,' they explained. Their simulation also accounted for uncertainties, another factor that could have lowered the probability. Still, the team highlights the fact that even with the newest information, there are still a number of unknowns that make it difficult to determine exactly how the Milky Way and Andromeda will move, although more data from the Gaia telescope could continue to refine their predictions. While 'Milkomeda' might never come to life, the researchers did find another highly likely collision almost certainly slated for sometime in the next two billion years: a Milky Way–Large Magellanic Cloud merger (I don't even want to know what they'd call the resulting galaxy). Nevertheless, 'the fate of our Galaxy is still completely open,' they concluded.
The Irish Sun
26-05-2025
- Science
- The Irish Sun
Stunning photos of Milky Way dazzle in sensational space snap contest and wow judges
THERE'S some real stars quality in the nightscapes nominated for the annual Milky Way Photographer of the Year. Photos taken from space, Chile and the US are all in the running for the out-of-this-world picture prize. Advertisement 7 Taken from an ice hut on Austria's Dobratsch mountain with a Milky Way backdrop Credit: UroA� Fink/Milky Way Photographer of the Year/CMG 7 The Perseid Meteor Shower from the Eastern Sierra Nevada Credit: Mike Abramyan/Milky Way Photographer of the Year/CMG 7 A breath taking panorama of the Milky Way captured over Chile's remote Atacama Cactus Valley, famed for its dense cluster of towering cacti Credit: Pablo Ruiz/Milky Way Photographer of the Year/CMG Travel blog Capture The Atlas revealed the sensational photos that have wowed judges at this year's eighth annual competition. Photographer Uroš Fink, who took a snap from an Austrian ice hut, said: 'Undoubtedly my wildest location this winter – Austria's Dobratsch mountain! 'The sky was magnificent, with "In the foreground is the cabin, where I spent three freezing hours waiting for the perfect shot of the Milky Way's core. Advertisement READ MORE WORLD NEWS "It turned out exactly as I envisioned—a true winter fairytale.' 7 The heavens from Socotra, Yemen Credit: Benjamin Barakat/Milky Way Photographer of the Year/CMG 7 Guatemala's Volcan de Fuego against the Milky Way's backdrop Credit: Sergio Montúfar/Milky Way Photographer of the Year/CMG 7 Truly out of this world - the Milky Way from the International Space Station Credit: Don Pettit/Milky Way Photographer of the Year/CMG Advertisement 7 Capturing the Milky Way core from Otago, New Zealand Credit: Kavan Chay/Milky Way Photographer of the Year/CMG WHAT IS THE MILKY WAY The Milky Way is the galaxy that contains our Solar System. It is a barred spiral galaxy, meaning it has a central bar-shaped structure composed of stars, and spiral arms that extend outward. Here are some key features: Galactic Centre : A densely packed area of stars and other matter, believed to contain a supermassive black hole known as Sagittarius A*. Bulge : Surrounding the galactic centre, the bulge is a roughly spherical region filled with older stars. Disk : This flat, rotating disk contains most of the galaxy's stars, gas, and dust, and includes the spiral arms. Halo : An extended, roughly spherical region surrounding the disk, containing older stars and globular clusters. Spiral Arms : These are regions of higher density that contain a lot of young stars, gas, and dust. Our galaxy is about 100,000 light-years in diameter and contains between 100 billion and 400 billion stars. The Sun is located roughly 27,000 light-years from the galactic center, in one of the spiral arms known as the Orion Arm or Orion Spur. The Milky Way rotates, with stars in the disk orbiting the galactic centre. The speed of rotation varies with distance from the centre. The Milky Way is part of a group of galaxies known as the Local Group, which also includes the Andromeda Galaxy, the Triangulum Galaxy, and about 54 other smaller galaxies. From Earth, the Milky Way appears as a milky band of light stretching across the sky, which is the combined light of billions of distant stars that are too faint to be seen individually. Stunning clip of Milky Way captured in record-breaking detail - scientists say it 'changes view of our galaxy forever'
