I've added some explanations to the Interacting Galaxies Map. The Interacting Galaxies map highlights the European Space Agency's recent release of Hubble images of interacting galaxies.
Don't forget to view the videos on the Star Viewer Map as well.
Galaxy mergers, which were more common in the early Universe than they are today, are thought to be one of the main driving forces for cosmic evolution, turning on quasars, sparking frenetic star births and explosive stellar deaths. Even apparently isolated galaxies will show signs in their internal structure that they have experienced one or more mergers in their past. Each of the various merging galaxies in the map is a snapshot of a different instant in the long interaction process.