Thousands of galaxies make up the Coma Cluster, one of the largest and most massive clusters in the universe. This view shows hundreds of those galaxies, including the two most massive–a pair of giant elliptical galaxies just left and right of center. These galaxies contain a trillion or more stars, which spread across a million light-years. [Adam Block/Mount Lemmon SkyCenter/Univ. Arizona]
Find out more in our radio program entitled Coma Cluster.