Journey to the Galactic Center

The center of our Milky Way Galaxy, located about 27,000 light years from Earth in the direction of the constellation Sagittarius, is occupied by a supermassive black hole. This black hole contains over 4 million times the mass of our Sun in an area smaller than half the orbit of Mercury. Matter accreting into the black hole is heated up to millions of degrees, which makes the area shine bright in radio and infrared waves. This radio source is called Sagittarius A*; the black hole itself cannot be seen.