The first black hole ever discovered was Cygnus X-1, located within the Milky Way in the constellation of Cygnus, the Swan. Astronomers saw the first signs of the black hole in 1964 via gas it sucked away from a closely orbiting blue supergiant star. As this gas spiraled into the black hole, it became so hot it emitted high-energy X-rays and gamma-rays that satellites could detect. However, the 2011 research did not collect data from the black hole throughout a full orbit around its companion star. \"Cygnus X-1 is unlikely the most massive stellar-mass black hole that can be produced,\" Miller-Jones said.