Galaxy cluster Abell 370

This is a composite colour image of the Abell 370 cluster of galaxies. The light of a very distant object is deformed by the foreground cluster. Abell 370, at the center of the photo, contains a large number of galaxies — most of them are ellipticals. The two brightest red galaxies slightly above the gravitational arc are the most massive in the cluster and give an important contribution to the lensing event.