The center of a galaxy, usually small, very bright, and containing a high density of stars and other objects. ◇ An active galactic nucleus is a nucleus that emits more radiation than can be explained in terms of stars alone. Blazars and quasars are thought to be active galactic nuclei; the nuclei of Seyfert galaxies are also active, and are thought to contain an extremely massive black hole.
/ɡəˈlæktɪˌkəʊ/ noun 1. (informal) a famous and highly paid footballer
noun, Astronomy. 1. the plane of the galactic equator. noun 1. the plane passing through the spiral arms of the Galaxy
noun, Astronomy. 1. either of the two opposite points on the celestial sphere that are farthest north and south of the Milky Way.
noun, Astronomy. 1. the duration of a complete rotation of the Milky Way, approximately 200 million years.