Centaurus A
What is Centaurus A?
Galaxies· Distance ~12 million ly. An oddly beautiful elliptical galaxy sliced through by a warped dust lane — the nearest active galaxy to Earth. Jets from its central black hole spread across twenty full-moon widths in radio light, making it one of the brightest radio sources in the southern sky.
📍 Visible from where you are right now — computed in your browser
bearing · altitude · rise time · best time tonight
Where Centaurus A is in your sky right now: https://nowsky.org/solar/sky?sel=centaurus a — location and time set automatically, no login.
Its place in the sky
A galaxy, in the direction of Centaurus, spanning about 25.7 arcminutes of sky — 0.8 times the width of the full Moon.
Distance and scale
| Distance | ~12 million ly |
|---|---|
| Diameter | ~60,000 ly |
| Central black hole | ~55 million Suns, firing jets |
| Constellation | Centaurus |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
Discovery and name
Found by Dunlop in 1826. Its dust lane is the wreck of a swallowed spiral — the nearest active galaxy.
Frequently asked
- How far is Centaurus A from Earth?
- ~12 million ly.
- How big is Centaurus A?
- ~60,000 ly.
- Where in the sky is Centaurus A?
- In the direction of Centaurus.
- Where is Centaurus A in the sky right now?
- Open the sky view for your location and time and it shows the position in the sky right now.
Imaging the root of the jet — the Event Horizon Telescope, 2021
In 2021 the Event Horizon Telescope aimed at the centre of Centaurus A and imaged, at the highest resolution ever, the root of the jet just as it leaves the black hole. It was the same array that photographed M87*'s shadow, but Centaurus A's black hole is two hundred times lighter, so no shadow appeared; instead the image revealed for the first time that the jet's edges shine brighter than its middle — a jet lit like a hollow tube.
As the nearest active galactic nucleus, the galaxy is the standard target for jet studies. The jet streams out at nearly half the speed of light, covers twenty full Moons of sky in radio images, and in X-rays shows knots that shift position within a few years. The twisted dust lane is the wreckage of a spiral galaxy swallowed hundreds of millions of years ago, and that merger is thought to have pushed into the centre the fuel that powers the jet today.
The galaxy in depth
Centaurus A (NGC 5128) is a giant elliptical galaxy about 12 million light-years away and the fifth-brightest galaxy in the sky. A thick, twisted dust lane cuts across what should be a smooth elliptical — the remains of a small spiral it swallowed a few hundred million years ago. Roughly 60,000 light-years across, it hides a black hole of about 55 million solar masses at its core.
James Dunlop discovered it in 1826, and in 1949 early radio surveys tagged it 'A' as the strongest radio source in Centaurus. Jets from the central black hole stretch a million light-years beyond the galaxy in radio and X-rays, and as the nearest active galactic nucleus it serves as a laboratory for black-hole jets. In 2021 the Event Horizon Telescope resolved the root of the jet almost down to the black hole itself.
It is a southern object, barely grazing the horizon from southern Korea. Select Centaurus A in the Sky view to mark it near Hadar and Omega Centauri; switch to a southern location and even a small telescope shows the dust lane.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.