Over next couple of billion years, these two spiral galaxies will end up in a complete galactic merger—the two galaxies will become a single, larger one. They’re about 150 million light-years away in the constellation of Canis Major (the Great Dog), so what we can see now is what was happening 150 million years ago.
The gravitational attraction of NGC 2207, the larger of the pair, is already stirring things up throughout its smaller partner, distorting IC 2163’s shape and throwing stars and gas into long streamers that extend over 100,000 light-years. However, most of the space between stars in a galaxy is empty. When these galaxies collide, almost none of the stars in them will crash into another star.
This 150 million old image is a vision of the Milky Way’s future. About the time NGC 2207 and IC 2163 have finished their merger, the Milky Way will begin colliding with the Andromeda Galaxy.
Image Credit: ESO