Transcript: Seen from afar, our galaxy the Milky Way would be a beautiful but unremarkable spiral galaxy. However, we have a ringside seat at a distance of only thirty thousand lightyears from the nucleus. The central regions of our galaxy have a very compact radio source, a region of intense star formation, a lot of ionized gas, and stellar dynamics that strongly indicate the presence of a supermassive black hole a few million times the mass of the Sun. Thus the definition of an active galaxy is mostly a matter of degree. It may be that most or many galaxies have modest nuclear activity and a black hole about the size of the black hole in the galactic center whereas only the occasional galaxy has extreme nuclear activity and a black hole that may be thousands of times larger up to a billion times the mass of the Sun.