Astronomers say they discovered the black hole because of the star that orbits around it and they found it lurking right around the corner from Earth. So how big and how close is it?
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00:00 Black holes are notoriously hard to detect, as anything which crosses one of their event
00:07 horizons, even light, can never escape again.
00:10 And that's likely why astronomers have just discovered one of these cosmic mysteries essentially
00:15 right around the corner from our solar system.
00:17 This black hole was named Gaia BH3, and while it's the second closest one we've ever
00:21 detected and only 1,924 light years away, it's interesting for another reason, as BH3
00:28 is the largest stellar mass black hole ever detected in the Milky Way.
00:32 BH3 is some 33 times the mass of our sun, or more than 3 times the size of the closest
00:37 stellar mass black hole.
00:39 So how was it discovered?
00:40 Well, it's in a binary orbit with a star, whose movement couldn't be explained other
00:44 than by an unseen companion.
00:46 This is an artist's impression of what that star's elliptical orbit might look like, with
00:50 the black hole sitting stationary and the star moving in a wide arc around it.
00:54 Astronomers say one orbit around the black hole takes the star roughly 11.6 years.
00:59 And while this is the largest one ever discovered, experts estimate stellar mass black holes
01:03 in our galaxy have an upper range of 100 million solar masses.
01:07 However, many are detected only if and when they gobble up a companion star, an event
01:12 which actually generates a ton of heat, something we can actually detect.
01:16 [music]