Closest Black Hole To Earth Found 'Hiding in Plain Sight'

The massive cosmic object lurks in a star system you can see with the naked eye. From a report: During winter in the Southern Hemisphere, a blue point of light in the constellation Telescopium gleams overhead. The brilliant pinprick on the sky, which looks like a bright star, is actually two stars in close orbit -- accompanied by the closest known black hole to Earth. The newly discovered black hole is about 1,011 light-years from our solar system in the star system HR 6819. Unveiled today in Astronomy & Astrophysics, the invisible object is locked in an orbit with two visible stars. It's estimated to be about four times the mass of the sun and roughly 2,500 light-years closer than the next black hole.

"It seems like it's been hiding in plain sight," says astronomer Kareem El-Badry, a Ph.D. student at the University of California, Berkeley, who specializes in binary star systems but wasn't involved with the study. "It's a bright enough star [system] that people have been studying it since the 80s, but it seems like it's had some surprises." On a human scale, a thousand light-years is an immense distance. If a model of the Milky Way were scaled so that Earth and the sun were only a hair's width apart, HR 6819 would be about four miles away. But in the grand scheme of the galaxy, which is more than 100,000 light-years across, HR 6819 is quite close, and it suggests the Milky Way is littered with black holes. "If you find one that is very close to you, and you assume you're not special, then they must be out there everywhere," says lead study author Thomas Rivinius, an astronomer at the European Southern Observatory (ESO) in Chile.

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