Active Galaxies
First discovered in the 1940s, active galaxies release enormous quantities of energy into space. Learn about some active galaxies, including seyfert, quasar, and radio galaxies. Black holes--bodies so massive and dense that they exert an irresistible gravitational force on the objects around it--are probably the reason for the intense activities of active galaxies. Once black holes swallow up all nearby stars, active galaxies return to normal brightness.
