Galactic collision. Image 1 of 2. Supercomputer model of a collision between two spiral galaxies. Each frame, from left to right along the top then the bottom, is separated by 100 million years. As the galaxies approach each other (top right) there is a burst of star formation (blue) due to compression of their gas. As they carry on through each other, tails of stars are flung out. These tails form a bridge between the galaxies, and long arcing tails of stars are formed pointing away from the other galaxy. Over time, the galaxies will attract each other more, and eventually coalesce. See image R826/091 for this process.