The idea of black holes dates back to 1783, when the Cambridge scholar John Michell realized that a sufficiently massive object in a sufficiently small space can attract even light, preventing him from escaping. Over a century later, Karl Schwarzschild found an exact solution for the General theory of relativity, which predicted the same result: a black hole. As Michelle and Schwarzschild predicted a clear link between the event horizon, or the radius of the area from which light can not escape, and the mass of the black hole.
For 103 years after Schwarzschild’s predictions could not be verified. And only 10 April 2019, scientists revealed the first ever photo of the event horizon. Einstein’s theory worked again, as always.
Although we already knew about black holes quite a lot, even before the first image of the event horizon, he was much changed and clarified. We had a lot of questions that now have answers.
By the way, here’s 10 facts about black holes that everyone should know.
10 April 2019 Event Horizon Telescope collaboration presented the first successful the event horizon of a black hole. The black hole is located in the galaxy Messier 87: the largest and most massive galaxy in our local supercluster of galaxies. The angular diameter of the event horizon was 42 micro-arc-seconds. This means that in order to cover the whole sky, have 23 quadrillion black holes of the same size.