Hercules Cluster

These are galaxies of the Hercules Cluster, an archipelago ofisland universes a mere 500 million light-years away. Also known asAbell 2151, this cluster is loaded with gas and dust rich, star-forming spiral galaxies but has relatively few elliptical galaxies, which lack gas and dust and the associated newborn stars. The colors inthis remarkably deep composite image clearly show the star forming galaxies with a blue tint and galaxies with older stellar populations with a yellowish cast. The sharp picture spans about 3/4 degree across the cluster center, corresponding to over 6 million light-years at the cluster's estimated distance. Diffraction spikes around brighter foreground stars in our own Milky Way galaxy are produced by the imaging telescope's mirror support vanes. In the cosmic vista many galaxies seem to becolliding ormergingwhile others seemdistorted - clear evidence thatcluster galaxiescommonly interact.In fact, the Hercules Cluster itself may be seen as the result of ongoing mergers of smaller galaxy clusters and is thought to be similar toyoung galaxy clusters in the much more distant, early Universe.