Colliding Galaxies

by Dave Patton, former UVic Astronomy PhD Student (now at Trent University)

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Large galaxies like our own Milky Way often collide with neighbouring galaxies. Most of the time the collision is with a smaller "dwarf" galaxy, resulting in the smaller galaxy being eaten or cannibalized by the larger galaxy. However, once in awhile, a large galaxy may encounter another large galaxy. The result may be the merger of these galaxies, forming a single elliptical galaxy.

Galaxy collisions take much longer than collisions we are used to. A merger of two large galaxies may take as long as 1 billion years to occur! As a result, we are unable to sit back and watch a collision happen. The best we can do is to take a snapshot of a collision-in-progress. A number of these snapshots have been compiled below. Some involve galaxies which are relatively nearby. Here at UVic, some of us are involved in a detailed study of distant galaxies. We have identified some galaxy collisions taking place in distant parts of the universe. One way to see what collisions might look like is to generate a computer simulation. To see some neat movies of these collisions, click on the icon below.

Click here to see images of some nearby colliding galaxies

Click here to see images of some distant colliding galaxies

Click here to see some movies of simulated galaxy collisions