Sun, Earth to inhabit Milkomeda after violent galactic collision 5-bln-years later

Astronomers have figured out what will happen to the Sun and the Earth in five billion years time.

London, May 15 : Astronomers have figured out what will happen to the Sun and the Earth in five billion years time.

According to them, the Sun and Earth will inhabit "Milkomeda", the remains of a violent collision between the Milky Way and the giant Andromeda galaxy.

"We're living in the suburbs of the Milky Way right now, but we're likely to move much farther out after the coming cosmic smash-up," said TJ Cox from the Harvard-Smithsonian Center for Astrophysics (CfA), Cambridge, Massachusetts, US.

The Milky Way and the Andromeda, two of the largest known galaxies, are presently rushing towards each other at about 120 kilometres per second and will likely collide in future.

For their study, Cox and his CfA colleague Avi Loeb ran computer simulations of this collision using 2.6 million particles to model the matter in both galaxies, and in intergalactic space.

They found that the two galaxies would pass close to each other in less than two billion years, well within the Sun's lifetime.

"At this point, their mutual gravity would start to mess up their structures and tug out long tails of stars and gas. The two galaxies would then overshoot and come together again for a second close passage before finally merging about 5 billion years from now," the researchers wrote in their study to be published in the Monthly Notices of the Royal Astronomical Society.

"The merged galaxy will be a blobby elliptical galaxy, rather than a neat spiral like Andromeda or the Milky Way today. The Sun will almost certainly hang onto its clutch of planets throughout the mayhem, even if the Earth is no longer habitable," the researchers said.

Loeb and Cox further tagged all the stars in the simulation that currently share the Sun's orbit around the Milky Way, which lie some 26,000 light years from the galaxy's centre, and noted the future positions of these stars in the 'Milkomeda' galaxy.

They found that the Sun would then lie much deeper in the galactic suburbia than it does today, with a 67 percent chance of being more than 65,000 light years from Milkomeda's centre.

"However, there is also a remote three percent chance that the Sun will jump ship and defect to the Andromeda galaxy during the second close passage. In the night sky, we would then see the Milky Way from a distance," New Scientist quoted Loeb as saying.

Astrophysicist John Dubinski from the University of Toronto in Canada, while admitting that the new study would help legitimise this idea, cautioned that the outcome for the Sun was far from certain.

"There are various plausible models for the structure of matter in the two galaxies that might radically alter the Sun's final position. Another influential factor is the transverse, or sideways, speed of the Andromeda galaxy across the sky. Although its speed towards us is well known, its transverse velocity has never been measured directly," said Dubinski.

"Astronomers hope that will change after the European Space Agency launches a spacecraft called Gaia around 2011. This satellite will chart the positions of stars and galaxies with unprecedented accuracy, and possibly make the first direct measurement of the Andromeda galaxy creeping sideways across the sky," he said.

ANI