The most massive known black hole in the universe has been discovered, weighing in with the mass of 18 billion Suns. Observing the orbit of a smaller black hole around this monster has allowed astronomers to test Einstein’s theory of general relativity with stronger gravitational fields than ever before. The black hole is about six times as massive as the previous record holder and in fact weighs as much as a small galaxy. It lurks 3.5 billion light years away, and forms the heart of a quasar called OJ287. A quasar is an extremely bright object in which matter spiralling into a giant black hole emits copious amounts of radiation. But rather than hosting just a single colossal black hole, the quasar appears to harbour two – a setup that has allowed astronomers to accurately ‘weigh’ the larger one.
Biggest black hole in the cosmos discovered