The Coma Galaxy Cluster

About This Photograph

Unlike stars, which are exceedingly far apart relative to their size, galaxies are often found clustered together in large groups. The Coma Cluster is one of the most well-known and largest of these, containing over 1,000 individual galaxies. Galaxies in clusters are often close enough to one another to interact due to their mutual gravitational attraction. They orbit one another, and because of their essentially flimsy nature, they eventually distort one another and merge into larger and larger elliptical galaxies.

Most of the galaxies in this photograph are indeed already ellipticals, as can be deduced by the lack of any spiral structure in most of them. If you look closely (dim the lights), you may notice a common glow surrounding the two brightest cluster members. This is a clear indication of their interaction. These two galaxies are known as NGC 4889 (left) and NGC 4874 (right).