Sagittarius A

Sagittarius A, abbreviated as Sgr A, is a complex radio source at the center of the Milky Way. Viewed from Earth, it is located near the border of the constellations Sagittarius and Scorpius, though it is hidden from view at optical wavelengths by large clouds of cosmic dust in the spiral arms of the Milky Way. The dust lane that obscures the Galactic Center from a vantage point around the Sun causes the Great Rift through the bright bulge of the galaxy.

The radio source consists of three components: the supernova remnantSagittarius A East; the spiral structure Sagittarius A West; and the supermassive black holeSagittarius A*, the source of the strongest radio emissions. Sagittarius A* is located at the center of Sagittarius A West, while Sagittarius A West appears off-center within Sagittarius A East. Sagittarius A East is by far the largest of the three.