Astronomers have a new candidate in their search for the nearest black hole to Earth. It’s about 1,000 light-years away, or roughly 9.5 thousand, million, million km, in the Constellation Telescopium. That might not sound very close, but on the scale of the Universe, it’s actually right next door.

Scientists discovered the black hole from the way it interacts with two stars – one that orbits the hole, and the other that orbits this inner pair. Normally, black holes are discovered from the way they interact violently with an accreting disc of gas and dust. As they shred this material, copious X-rays are emitted. It’s this high-energy signal that telescopes detect, not the black hole itself. So this is an unusual case, in that it’s the motions of the stars, together known as HR 6819, that have given the game away. “This is what you might call a ‘dark black hole’; it’s truly black in that sense,” said Dietrich Baade, emeritus astronomer at the European Southern Observatory (ESO) organisation in Garching, Germany.(BBC)…[+]