Cygnus X-1, the first black hole ever detected, is more massive than we thought

The discovery of black holes began as a theoretical curiosity following Einstein’s general relativity, but was confirmed in 1971 with Cygnus X-1, an invisible object pulling matter from a star.Black holes are regions where gravity is so intense that nothing, not even light, escapes the "event horizon." At their core lies a singularity of infinite density where known physics breaks down. They are often ringed by a glowing accretion disk of superheated gas, which allows astronomers to detect them.

Cygnus Constellation: Stars, Myth, and Location (2025) | Planet Guide