Measuring the Universe’s 'Exit Door': For the First Time, an International Team Has Measured the Radius of a Black Hole

The point of no return: In astronomy, it's known as a black hole -- a region in space where the pull of gravity is so strong that nothing, not even light, can escape. Black holes that can be billions of times more massive than our sun may reside at the heart of most galaxies. Such supermassive black holes are so powerful that activity at their boundaries can ripple throughout their host galaxies.

Now, an international team, led by researchers at MIT's Haystack Observatory, has for the first time measured the radius of a black hole at the center of a distant galaxy -- the closest distance at which matter can approach before being irretrievably pulled into the black hole.