The Coma Cluster of Galaxies

Abell 1656 is a cluster of galaxies in Coma Berenices, a small constellation with no stars brighter than magnitude 4.

The cluster contains over 1000 galaxies and lies at a distance of about 320 million light years.

The most prominent members are two giant ellipticals (NGC4874 and NGC4889) and a face-on spiral, NGC4921.

In 1933  astronomer Fritz Zwicky was the first to publish evidence of what would later be named Dark Matter, by demonstrating that the galaxies in the Coma cluster were moving too fast for gravity to hold them together, based on the amount of stars and galaxies visible.It is now believed that dark matter accounts for about 90% of the mass of the cluster.

Technical details:

Planewave CDK-14 corrected Dall-Kirkham reflector, FLI Proline P9000 cooled CCD camera and filter wheel with Astrodon LRGB filters. Total exposure times were 20 hours Lum, 12 hours Red, 10 hours green and 10 hours Blue. All processing carried out in PixInsight.