FIVE THINGS ABOUT BLACK HOLES

1 WHAT’S NEW?

The centre of our galaxy is teeming with black holes, sort of like a Times Square for strange super gravity objects, astronomers discovered. For decades, scientists theorized that circling in the centre of galaxies, including ours, were lots of stellar black holes, collapsed giant stars where the gravity is so strong even light doesn’t get out. But they hadn’t seen evidence of them in the Milky Way core until now.

2 HOW HAVE THEY DETERMINED THIS?

Astronomers pouring over old X-ray observations have found signs of a dozen black holes in the inner circle of the Milky Way. And since most black holes can’t even be spotted that way, they calculate that there are likely thousands of them there, according to a study in Nature. The stellar black holes are in addition to the already known supermassive black hole, called Sagittarius A, at the centre of the Milky Way.

3 EXACTLY WHERE ARE THEY?

The newly discovered black holes are within about 30.9 trillion kilometres of the supermassive black hole at the centre. So there’s still a lot of empty space and gas amid all those black holes. But if you took the equivalent space around Earth there would be zero black holes, not thousands, lead author Chuck Hailey said. Earth is in a spiral arm around 3,000 light-years away from the centre of the galaxy.

4 HOW BIG ARE THEY?

The newly confirmed black holes are about 10 times the mass of our sun, as opposed to the central supermassive black hole, which has the mass of 4 million suns.

5 WHAT IS THE REACTION?

Harvard astronomer Avi Loeb praised the finding as exciting but confirming what scientists had long expected. “There’s lots of action going on there,” said Hailey, a Columbia University astrophysicist.