The measure of a black hole is what it does with its stars.
That’s one lesson astronomers are taking from the first-ever picture of a black hole, released on April 10 by an international telescope team (SN Online: 4/10/19). That image confirmed that the mass of the supermassive black hole in the center of galaxy M87 is close to what astronomers expected from how nearby stars orbit — solving a long-standing debate over how best to measure a black hole’s mass.