A prominent radio source 28 000 l.y. away in the constellation Sagittarius, coincident with or close to the centre of our Galaxy. This highly complex region consists of a central core about 50 l.y. in diameter connected to a band of arched, parallel filaments more than 300 l.y. long crossing at right angles to the galactic plane. Sagittarius A*, a compact component at the heart of the central core, is believed to mark the physical centre of the Galaxy. It resembles a small-scale version of the energetic nuclei of active galaxies, and may contain a massive black hole of several million solar masses.

http://chandra.harvard.edu/photo/2010/sgra/