Astronomers from the Institute of Astronomy (IoA) in Cambridge, England have watched a bundle of matter at the heart of a galaxy 100 million light-years away as it orbited a supermassive black hole four times on its way to being destroyed. The material was approximately the same distance as our Earth is from the Sun, but instead of taking a year, it only took a quarter of a day, because of the massive gravity of the black hole. By tracking the matter's doomed orbit, astronomers were then able to calculate the mass of the black hole: between 10 and 50 million solar masses.
Astronomers Watch a Black Hole Eat a Meal