In one sense, black holes are just ridiculously exotic. Their surface gravity is so powerful that even something as fast as light can’t escape (that’s why they’re black). And what’s actually inside a black hole isn’t just strange: it’s literally indescribable by any known law of physics. But while they’re among the strangest things in the universe, they aren’t especially uncommon.
Astronomers now know that black holes with the mass of millions or even billions of stars lurk at the cores of most galaxies, including the Milky Way, while much smaller black holes, containing just a few tens of stars’ worth of matter, are scattered all over the known universe. In theory, there’s no reason intermediate-size black holes shouldn’t exist as well, with masses of a few hundred or a few thousand stars. But so far, despite some tantalizing hints, nobody has definitively found one. That may just have changed, however: a new report in Nature has flagged just such an object in the nearby galaxy Messier 82, which lies about 12 million light-years from Earth in the direction of the Big Dipper.