The encounter will result in a major makeover for our galaxy, NASA astronomers said, that will see the sun flung into a new area of the Milky Way. However, Earth and the rest of the solar system will be in no danger of being destroyed, a NASA release said Thursday.
The prediction is the result of painstaking NASA Hubble Space Telescope measurements of the motion of Andromeda, also known as M31.
Currently 2.5 million light years away, Andromeda is inexorably falling toward the Milky Way under the mutual pull of gravity between the two galaxies and the invisible dark matter that surrounds them both, astronomers say.
"After nearly a century of speculation about the future destiny of Andromeda and our Milky Way, we at last have a clear picture of how events will unfold over the coming billions of years," Sangmo Tony Sohn of the Space Telescope Science Institute said.
Although the galaxies will collide with each other, stars inside each galaxy are so far apart that they will not collide with other stars during the encounter, astronomers said, but stars will be thrown into different orbits around the new galactic center.