How many galaxies are the result of collisions and mergers?
Probably all of them! In space, we see evidence that galaxies collide and in many instances absorb their neighbors. The Hubble Space Telescope has shown that at very great distances, galaxies become significantly more irregular in shape and we see increasing traces of deformed, odd-shaped galaxies that resemble nearby galaxies undergoing merger. The Milky Way is in the process of absorbing the Magellanic Clouds, a process that will be complete in another few billion years. In 5 – 10 billion years, the Milky Way and the Andromeda Galaxy will collide. There are also small clusters of galaxies such as Stephan’s Quintet where we see 5 galaxies in a volume of space only a million light years across. This is not a stable situation, and eventually these galaxies will shred themselves into one large new galaxy. Based on statistical evidence and the images from Hubble, many astronomers now believe that mergers and collisions are the mechanisms by which galaxies grow from smaller collections of
