This dramatic cosmic collision occurred at a safe distance of approximately 570 million light-years from Earth. Peering out from the corner is the elliptical galaxy NGC 6041, which is the central member of the galaxy cluster to which Arp 122 belongs but was not involved in the merger.
Galactic collisions and mergers are hugely energetic and dramatic events, but they happen very slowly. For example, the Milky Way is about to collide with its nearest neighbor, the Andromeda Galaxy (M31), but it will take another 4 billion years for the two galaxies to actually meet. The process of collision and merger won't happen overnight either: it could take hundreds of millions of years. The reason these collisions take so long is because the distances involved are truly vast.
Galaxies are made up of stars and their solar systems, dust and gas. Therefore, in galactic collisions, these components may experience large changes in the gravitational force acting on them. Over time, this can radically change the structure of two (or more) colliding galaxies, sometimes ultimately forming a merged galaxy. This is likely the result of the collision in this image.
Merged galaxies are thought to have regular or elliptical structures, as the merger process destroys more complex structures (such as those observed in spiral galaxies). It would be very interesting to know what Arp122 will look like after the collision is complete, but it will take a long, long time.
Compiled source: ScitechDaily