We live in the Milky Way Galaxy, a collection of gas, dust and hundreds of billions of stars. Two million light years (20 billion billion kilometers) away lies the Andromeda Galaxy, about the same size and shape as the Milky Way. Current measurements suggest that, in about five billion years, the Milky Way and Andromeda may collide! What will happen? The stars in the galaxies, our Sun included, will probably not hit each other, but the galaxies' mutual gravity will probably pull, twist and distort them until, about a billion years later, a new elliptical-shaped galaxy is born.

Gravity and tides at work

This movie shows a supercomputer simulation of one possible collision scenario between the Milky Way and Andromeda. Each spiral galaxy is represented by a disk of stars surrounded by a spherical "dark matter" halo. The simulation contains a total of more than 100,000,000 virtual particles. of "dark matter" halo for a total of more than 100M particles for the galaxy pair. The Milky Way is shown face-on and moves from the bottom up to the left of Andromeda and the to the upper right. Andromeda is tilted from this perspective. The movie's field of view is about one million light years (10 billion billion kilometers) across, and the total elapsed time of the movie is about 1,000,000,000 years! The complex patterns and structures created during the collisions are caused by tides - the same process that works on Earth's oceans. The gravitational pull of the two galaxies' stars and dark matter twist, tear and distort their original disk-like structures, leaving a single elliptical galaxy and lots of tidal debris after all is said and done.

File Format: MPEG
File Size: 1.0M

Additional Information:

Dr. John Dubinski web site of galaxy simulations   Dr. John Dubinski's web site provides more detailed information about galaxy collisions, as well as additional supercomputer-produced scientific visualizations.

Key Words: galaxies, collision, andromeda, milky way