Galaxy Collisions Preview Milky Way's Fate

In approximately five billion years, as the sun expands into a red giant star roughly the diameter of Earth's orbit around it, our galaxy will collide with its nearest large neighbor, Andromeda. As gravity draws the pair toward each other for a close encounter, stars will be ripped from their orbits to make spectacular tails, and gas and dust will be squeezed toward the approaching nuclei, destroying the stately, grand spirals that have existed for almost three quarters of the age of the universe.