The following image is a composite of two pictures: the one on the left is a picture from a ground-based telescope, the one on the right is a close-up of the centers of the two colliding galaxies (marked with a green box on the left picture) taken by the Hubble Space Telescope. When two galaxies collide, sometimes long "tails" of stars are thrown off (like these two) - these "tails" are called Tidal Tails.
A glancing blow by two spiral galaxies - note how the shape of the smaller one is becoming distorted...
Galaxy Cannibalism: one spiral "eating" another...
A small elliptical "hit" the edge of this large spiral and is drawing off a "tail" of stars.
The following is a group of several interacting galaxies. Note that there are two spirals on the right edge of the image which have almost combined. Also the long tidal tail heading off to the left side of the image from the galaxy in the upper middle part of the images. The bottom galaxy (which is only partly visible) is a foreground galaxy and is not associated with the others.
The next picture is of a VERY unusual group of disrupted galaxies: the wheel-shaped galaxy (formerly a spiral galaxy), had the small, blue, irregularly shaped galaxy "crash" straight through its center and come out the other side. The small yellow spiral to the upper right is a background galaxy, and had nothing to do with the collision.
