The Coma Cluster (Abell 1656) is a large cluster of galaxies containing over 1,000 identified galaxies. Together with the Leo cluster (Abell 1367), it is one of the two main clusters of the Coma Super Cluster. It is located in the constellation Coma Berenices, to which it also owes its name. Due to its location close to the galactic north pole, this direction of view (almost perpendicular to the plane of the Milky Way) is not affected by the gas and dust clouds of the plane. Therefore, some foreground galaxies are well observable at distances of 20 to 40 million light years.

The mean distance of the cluster from Earth is 99 Mpc (321 million light years). Its ten brightest spiral galaxies have apparent sizes of mag. 12 to 14, which can be observed with amateur telescopes larger than 20 cm. The central region is dominated by two large elliptical galaxies: NGC 4874 and NGC 4889, located within a few degrees of the galactic north pole in the sky. Most galaxies that inhabit the central part of the coma cluster are ellipses. Both dwarf and giant ellipses can be found in abundance in the Coma cluster.

The galaxies are not distributed homogeneously in space, but are grouped in superordinate clusters. Cosmologists assume that these structures were already formed in the early universe from a large-scale foam-like mass distribution under the influence of gravity. Large clusters contain several thousand single galaxies, which circulate on different orbits with 500 to 1000 km/s the center of gravity of the system.