A Mystery of Space: S T A R S- [Where are Black Holes?]

Black holes are located throughout space, but only a couple of black holes have been actually located. The first evidence that a black hole existed was in 1994, when the Hubble Space Telescope discovered something around galaxy M 87. The discovery was made by looking at the acceleration of gases around a certain point. The gases showed that an object that was about 2.5 billion to 3.5 billion solar masses was present in galaxy M 87.

Black hole in galaxy M87

In 1995, the second discovery was made by an array of radio telescopes called VLBA (Very Long Baseline Array). They found a black hole that existed in galaxy NGC 4258.