Sagittarius A is a bright and very compact astronomical radio source at the Galactic Center of the Milky Way. It is located near the border of the constellations Sagittarius and  Scorpius. Sagittarius A is the location of a supermassive black hole similar to those at the centers of most, if not all, spiral and elliptical galaxies.

Based on mass and increasingly precise radius limits, astronomers have concluded that Sagittarius A is the Milky Way's central supermassive black hole.

Reinhard Genzel and Andrea Ghez were awarded the 2020 Nobel Prize in Physics for their discovery that Sagittarius A is a supermassive compact object, for which a black hole is the only currently known explanation.