Big Boy Black Hole

Astronomers have found the most massive black hole to date, a monster 18 billion times as massive as the Sun. It lies 3.5 billion light years away-- which is to say, we see it as it was 3.5 billion years ago, when Earth was very young-- in the constellation Cancer the Crab.

The mass of this object, which is six times more massive than the previous record holder, was able to be determined because another black hole is in orbit around it. Masses of objects in space are derived from their gravitational influence on other objects. The more powerful the gravity, the more massive the body-- that's the essential relationship. So, this is the most massive black hole for which we have been able to calculate a mass. There likely are bigger ones we haven't gotten around to yet, and unless the biggest ones happen to have bodies orbiting them, we'll be able to estimate their masses only through indirect means.