The history of the Universe has seen the formation of some enormous cosmic structures, including galaxy groups, clusters, and superclusters — the largest known ones in the cosmos!
November 05 | 2017
This particular cluster is seen by the Hubble Space Telescope (@NASAHubble) and is rich since it contains at least 300 individual galaxies. Although we are still unsure how such gigantic things come to be, the current leading theory is that small clumps of matter collide and merge to grow ever larger. Image credit: ESA/Hubble & NASA