The X-ray Universe.

The history of cosmic X-ray astronomy is presented. The satellite observations of Uhuru and Ariel are outlined with attention to current X-ray maps and the monitoring of X-ray variability. The models of X-ray binary stars are examined, and consideration is given to the experimental evidence for the existence of black holes. The dwarf nova SS Cygni and X-ray transients are discussed along with X-ray sources from supernova remnants, galaxy clusters, and active galaxies. It is noted that the Einstein Observatory will provide the first images of cosmic X-ray sources with a resolution of a few arcseconds.