The Coma Galaxy Cluster, listed as Abell 1656, is a regular cluster more than 350
million light years away from Earth in the constellation of Coma Berenices, near
the north galactic pole. It is estimated that over 1000 galaxies are part of the
Coma Cluster, making it very rich. Coma is nearly spherical and has a
one-megaparsec diameter consisting mainly of elliptical and highly-flattened
eliptical galaxies. These galaxies have been estimated to be approximately 15
billion years old.
Like other galaxy clusters,
Coma's center consists of a diffuse cloud of hot gas which emits X-rays and is
held by the cluster's gravity. The gas, which is invisible to the naked eye, was
discovered in 1971 through X-ray observation.