Gaia BH3
What is Gaia BH3?
Black holes & quasars· Distance 1,930 ly. The most massive stellar black hole found in the Milky Way. An ancient giant star circles it every 11.6 years, 1,930 light-years away in Aquila. The companion is almost free of heavy elements, hinting that the black hole was born from a first-generation-style star.
📍 Visible from where you are right now — computed in your browser
bearing · altitude · rise time · best time tonight
Where Gaia BH3 is in your sky right now: https://nowsky.org/solar/sky?sel=gaia bh3 — location and time set automatically, no login.
Its place in the sky
A black hole, in the direction of Sagitta.
Mass, distance, nature
| Mass | ~33 Suns |
|---|---|
| Distance | ~1,930 ly |
| Companion | ancient metal-poor giant, 11.6-yr orbit |
| Discovered | 2024, Gaia astrometry |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
Discovery and name
A 33-solar-mass black hole found by Gaia in 2024 — the heaviest stellar black hole in our galaxy, 2,000 ly away.
Frequently asked
- What is the mass of Gaia BH3?
- ~33 Suns.
- How far is Gaia BH3 from Earth?
- ~1,930 ly.
- When was Gaia BH3 discovered?
- 2024, Gaia astrometry.
- Where in the sky is Gaia BH3?
- In the direction of Sagitta.
- Where is Gaia BH3 in the sky right now?
- Open the sky view for your location and time and it shows the position in the sky right now.
A star from the halo — what the orbit says about its origin
The companion star of Gaia BH3 moves on an orbit nearly opposite to the stars of the Milky Way's disk. Its motion matches a stellar stream called ED-2, the remains of a small galaxy or globular cluster the Milky Way swallowed long ago, stretched out through the halo. The black hole and its partner, then, were not born in the Milky Way but descend from stars that came in from outside, and the companion's near-total lack of metals supports that origin.
That origin explains the mass of 33 Suns. Metal-poor stars have weak winds and lose less mass before they die, so they leave heavier black holes. The same logic explains why black holes above 30 solar masses are common in the mergers detected by gravitational waves in the distant universe, and Gaia BH3 is the first case confirming it in the flesh, 1,900 light-years away inside our own galaxy.
The black hole in depth
Gaia BH3, announced in April 2024, is a 33-solar-mass black hole and the heaviest stellar black hole yet confirmed in the Milky Way. It lies about 1,930 light-years away toward Aquila, orbited every 11.6 years by an old giant star slightly lighter than the Sun. It is the third dormant black hole the Gaia satellite has uncovered purely from a companion's wobble, after Gaia BH1 and BH2.
The remarkable part is the companion's chemistry. It holds less than a hundredth of the Sun's share of iron and other heavy elements, the signature of a star born early in cosmic history. Metal-poor stars shed less mass in winds over their lives and so can leave heavier black holes, which makes BH3 a nearby example of why the massive black holes seen in gravitational-wave mergers are so large.
The companion shines at magnitude 11.2, within reach of small telescopes, though the black hole stays invisible. Find its position near Altair in the Sky view, compare its roughly 200-kilometre event horizon with a city or a mountain on the size ladder, and see its distance among the Sun's neighbours in the nearby-stars 3D view.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.