NASA researchers say they successfully tested a new way to measure the mass of black holes. As a black holes sucks up its surrounding disk of gas, the gas heats up. The new method assumes that the distance from the hottest region of gas to the black hole depends on the latter's mass and can be detected by variations in x-ray intensity. The team found that the masses of three black holes estimated with this technique match measurements made using older methods, as will be described in an upcoming issue of The Astrophysical Journal. According to their measure, nearby galaxy NGC 5408 harbors a black hole with a mass of about 2,000 suns.