Fortune Telling Collection - Zodiac Analysis - How did humans discover black holes? How far is the black hole from the earth?

How did humans discover black holes? How far is the black hole from the earth?

It was originally a solution and theory calculated by Schwarzschild according to general relativity. Later observation confirmed it.

How far is it? . . Sorry, there are many black holes in the universe. The nearest black hole is located in Sagittarius, which forms a binary system with an ordinary star numbered V464 1SGR, about 1600 light-years away from the Earth.