- Galaxy collisions and mergers are monumentally energetic and dramatic events
The Hubble Space Telescope has captured two galaxies that are in the middle of a collision at a very safe distance of approximately 570 million light years from Earth. This is Arp 122, a peculiar cosmic object that actually comprises two galaxies: NGC 6040, the tilted and warped spiral galaxy, and LEDA 59642, the round and front spiral galaxy.
Looming in the lower left corner is the elliptical galaxy NGC 6041, a central member of the galaxy cluster in which Arp 122 resides, but which is otherwise not involved in this monstrous merger.
Galactic collisions and mergers are monumentally energetic and dramatic events, but they take place on a very slow time scale. For example, the Milky Way is on a collision course with its closest galactic neighbor, the Andromeda galaxy (M31), but these two galaxies are about four billion years away before they actually meet.
Collision would take millions of years
The collision and merger process will not be quick either: it could take hundreds of millions of years to develop. These collisions take so long because of the truly enormous distances they involve, NASA explains in a statement.
Galaxies are made up of stars and their solar systems, dust, gas, and invisible dark matter. Therefore, in galactic collisions, these constituent components can experience enormous changes in the gravitational forces acting on them. Over time, this completely changes the structure of the two (or more) colliding galaxies and sometimes ultimately results in a single merging galaxy. This could well be the result of the collision shown in the image.