Loading video... VIDEO: An animation showing the Cygnus X-1 system, consisting of a black hole in orbit with a giant star. Recent observations by radio telescopes have found the system is 20 per... view more Credit: Credit: International Centre for Radio Astronomy Research. New observations of the first black hole ever detected have led astronomers to question what they know about the Universe's most mysterious objects. Published today in the journal Science, the research shows the system known as Cygnus X-1 contains the most massive stellar-mass black hole ever detected without the use of gravitational waves. Cygnus X-1 is one of the closest black holes to Earth. It was discovered in 1964 when a pair of Geiger counters were carried on board a sub-orbital rocket launched from New Mexico.