When Galaxies Collide: A Gallery of Stellar Chaos
In about 4 billion years, the Milky Way will collide with the neighboring Andromeda galaxy. Colliding galaxies are surprisingly common, and the merging of smaller star systems likely led to the evolution of larger star systems that we see today. The stars within colliding galaxies probably don’t collide, but the gravitational chaos can alter planetary positions and star locations.
Wired has a great gallery of colliding galaxies for your chaotic beauty needs. And because looking at them isn’t enough, Galaxy Zoo has a Java app that lets you create, and then collide your own galaxies.