What Was the First Black Hole?

The first black hole to be discovered was Cygnus X-1, a bright X-ray source in the constellation Cygnus. It was identified as a black hole in 1971 by Charles Thomas Bolton, Louise Webster, and Paul Murdin, who observed that it was emitting X-rays at a much higher rate than any known star. Cygnus X-1 is located about 6,000 light-years from Earth and is part of a binary system, meaning it orbits around another star. The black hole is estimated to be about 15 times more massive than the Sun and is surrounded by a disk of gas and dust that is being pulled in by the black hole's gravity.