Measured the radius of the black hole

As you know, a black hole - a region in space where the gravitational pull is so strong that nothing, not even light, can escape from it. Black holes can be billions of times more massive than our Sun, and can be at the center of most galaxies.
These supermassive black holes are so powerful that the activity on their borders can create "ripples" throughout the galaxy.
The international team led by researchers at the Haystack Observatory at the Massachusetts Institute of Technology for the first time to measure the radius of the black hole at the center of a distant galaxy - the minimum distance that the matter can approach before it is irrevocably drawn into the black hole.
For their study, the researchers chose the supermassive black hole at the center of the galaxy M87 and is about 50 million light-years away from our galaxy. The mass of the black hole is 6 solar masses.
Despite the fact that the event horizon of a black hole is an imaginary line that can not be observed, the scientists were able to roughly determine the location and calculate the closest stable orbit, where the substance crosses the boundary (event horizon) and is lost forever in a black hole.
Using a new telescope Event Horizon Telescope, scientists were able to determine that the event horizon of the black hole is at a distance of about 750 distance from the Earth to the Sun. And the distance from Earth to the Sun is 150 million kilometers