简体中文
The closest black hole to Earth has been discovered about 1,000 light-years away, scientists have said.
It is so near that two companion stars swirling around the invisible object can be seen with the naked eye by people in the southern hemisphere on a dark, clear night.
The previous nearest black hole - A0620-00 - is probably about three times further, around 3,200 light-years, according to European Southern Observatory astronomer Thomas Rivinius, who led the study.
Each light year is 5.9 trillion miles.
Dr Rivinius said of the latest discovery: "This system contains the nearest black hole to Earth that we know of."
He told The Atlantic: "On the scale of the Milky Way, it's in our backyard. Almost on our doorstep."
In comparison, the black hole at the centre of the Milky Way galaxy is more than 25,000 light-years away.
Usually, scientists can only spot holes like the latest one when they are absorbing parts of a partner star or another object falls into them.
And most go undiscovered as they do not have anything close enough to swallow.
But with this latest black hole, experts were helped in their discovery by an inner star's orbit being warped.
The hole, thought to be about 25 miles in diameter, is part of what used to be a three-star dance in a system called HR 6819.
And the two other stars were not close enough to be sucked in.
European scientists, using a telescope in Chile, found something about four or five times the mass of the sun was pulling on the inner star and concluded it could only be a black hole.
The discovery in the constellation Telescopium hints that there are more out there.
Astronomers believe there are between 100 million to one billion of these small but dense objects in the Milky Way.
