These pages diplay and discuss the many objects we see in our universe. The emphasis is on high energy astrophysics data. Galaxies are made up of billions of stars that are gravitationally bound to eachother.
Galaxies tend to clump together in the universe, forming clusters of galaxies .
This indicates the existence of diffuse hot gas and implies the existence of a halo of dark matter. On the right is an optical image obtained from the digitized sky survey of the Palomar plates using SkyView . Cosmic Journeys Part of the NASA OSS Structure and Evolution of the Universe theme.