Sagittarius A*
black_hole
Sagittarius A* — the supermassive black hole at the centre of the Milky Way, about 4.15 million times the Sun's mass, ~26,700 light-years away. In 2022 the Event Horizon Telescope imaged the glowing ring of hot gas around its shadow — a real photograph of the region just outside a black hole.
Open in 3D viewSee Sagittarius A* in the live, interactive 3D map
Science
Classification
- Type
- Supermassive black hole
- Location
- The Galactic Centre, in Sagittarius
- Distance
- ~26,700 light-years
Physical
- Mass
- ~4.15 million solar masses
- Event-horizon width
- ~2.5×10⁷ km · ~17 Suns wide — computed from the mass (Schwarzschild radius)
- Shown here
- an enlarged marker · the real hole is far too small to see at galaxy scale
How we know
- Note
- The 2022 Event Horizon Telescope image is a REAL photograph — of the ring of hot gas bent around the black hole's shadow, not the hole itself (a black hole emits no light). Its mass comes from decades of tracking stars orbiting an invisible point (2020 Nobel Prize). Its size here is an enlarged marker for the galactic centre; the true event horizon is only ~2.5×10⁷ km across.
Discovery & history
- Name
- 'Sagittarius A*' — the compact radio source in the constellation Sagittarius; the asterisk (star) marks it as the exciting, point-like core.
A bright, compact radio source at the galactic centre was found by Balick & Brown in 1974. Decades of tracking stars whipping around an invisible ~4-million-solar-mass point (Genzel and Ghez, 2020 Nobel Prize) proved it a black hole; the EHT imaged its shadow in 2022.
Images
Images from open archives · credit shown per image