Gaia BH3: 'Sleeping Giant' Black Hole Found in Milky Way
September 21, 2025
Astronomers using the Gaia space telescope have discovered Gaia BH3, the most massive stellar black hole yet found in our Milky Way galaxy.
In a stunning discovery that has reshaped our understanding of the cosmic neighborhood, astronomers using the European Space Agency’s (ESA) Gaia mission have identified a colossal 'sleeping giant' black hole right here in our Milky Way galaxy. Named Gaia BH3, this stellar-mass black hole weighs in at an astonishing 33 times the mass of our Sun, making it the most massive of its kind ever found in our galaxy. Lurking just 2,000 light-years away in the constellation Aquila, it's also remarkably close to Earth.
An Unexpected Discovery in the Wobble
Unlike many black holes, Gaia BH3 is dormant, meaning it is not actively feeding on nearby material and therefore doesn't emit the tell-tale X-rays that usually give away their position. Its existence was revealed through a subtle, yet undeniable, clue: the peculiar 'wobble' of its companion star. As Gaia meticulously mapped the positions and motions of billions of stars, scientists noticed an old giant star being pulled into an eccentric orbit. The only explanation for such a gravitational dance was the presence of a massive, unseen companion—the black hole Gaia BH3.
What Makes Gaia BH3 a Landmark Find?
- Record-Breaking Mass: At 33 solar masses, Gaia BH3 shatters the previous record for a stellar black hole in the Milky Way, which typically average around 10 solar masses.
- Unique Origin: The black hole's companion is a very old, 'metal-poor' star. This suggests Gaia BH3 formed from a similarly metal-poor star, confirming long-held theories that such stars can collapse into exceptionally massive black holes.
- Proximity to Earth: Being the second-closest known black hole to our solar system, Gaia BH3 offers an unprecedented opportunity for close-up study and to test our theories of gravity and black hole evolution.
No one was expecting to find a high-mass black hole lurking nearby, undetected so far. This is the kind of discovery you make once in your research life.
The discovery of Gaia BH3 is a testament to the incredible precision of the Gaia mission. It not only provides a new target for astronomers to probe the mysteries of black holes but also confirms a key pathway for their formation. As Gaia continues its survey, we may find that our galaxy is hiding many more of these sleeping giants, quietly shaping the cosmos around them.
Gaia BH3: 'Sleeping Giant' Black Hole Found in Milky Way - FAQs
Gaia BH3 is a stellar-mass black hole in the Milky Way, located 2,000 light-years away in the Aquila constellation. It's exceptionally massive, weighing 33 times more than our Sun.
Its discovery is significant because it's the most massive stellar black hole found in our galaxy to date and provides the first concrete evidence that such massive black holes form from metal-poor stars.
It was discovered indirectly through data from ESA's Gaia mission, which detected an unusual 'wobble' in the motion of its companion star, revealing the gravitational pull of the unseen black hole.
A dormant or 'sleeping' black hole is one that is not actively consuming matter from a companion star or its surroundings. This means it doesn't emit bright X-rays, making it much harder to detect.