Astronomers spot a massive ‘sleeping giant’ black hole less than 2,000 light-years from Earth mega Astronomers have spotted the most massive known stellar black hole in the Milky Way galaxy after detecting an unusual wobble in space. The so-called “sleeping giant,” named Gaia BH3, has a mass that is nearly 33 times that of our sun, and it’s located 1,926 light-years away in the Aquila constellation, making it the second-closest known black hole to Earth. The closest black hole is Gaia BH1, which is located about 1,500 light-years away and has a mass that is nearly 10 times that of our sun. Astronomers discovered the black hole while combing through observations taken by European Space Agency’s Gaia space telescope for an upcoming data release to the scientific community. The researchers weren’t expecting to find anything, but a peculiar motion — caused by Gaia BH3’s gravitational influence on a nearby companion — caught their eye. Many “dormant” black holes don’t have a companion close enough to munch on, so they are much more difficult to spot and don’t generate any light. But other stellar black holes siphon material from companion stars, and this exchange of matter releases bright X-rays that can be spotted through telescopes. The wobbling movement of an old giant star in the Aquila constellation revealed that it was in an orbital dance with a dormant black hole, and it’s the third such dormant black hole spotted by Gaia. The researchers used the European Southern Observatory’s Very Large Telescope in Chile’s Atacama Desert and other ground-based observatories to confirm the mass of Gaia BH3, and their study has also offered new clues to how such huge black holes came to be. The findings appeared Tuesday in the journal Astronomy & Astrophysics. “No one was expecting to find a high-mass black hole lurking nearby, undetected so far,” said lead study author Pasquale Panuzzo, an astronomer at the Observatoire de Paris, part of France’s National Centre for Scientific Research, and a Gaia collaboration member, in a statement. “This is the kind of discovery you make once in your research life.”