Astronomy Picture of the Day . Dwarf Galaxies in the Coma Cluster . ... JPL-Caltech , SDSS , NASA Explanation: In visible light images, over a thousand galaxies are seen to lie within a volume about 20 million light-years across in the rich Coma Galaxy Cluster . But infrared images of the Coma Cluster have now been used to add thousands more to the Coma's galaxy count in the form of previously undiscovered dwarf galaxies. ... Publications with keywords: galaxy cluster - dwarf galaxy . ...