Centaurus A

At a glance

Key points

• Nearest active galaxy to us
• A dust lane left by a galactic merger
• Jets glow in X-rays and radio

A merger's aftermath

The twisted dark band is gas and dust from a spiral galaxy that Centaurus A swallowed. Jets from the central black hole run perpendicular to it, glowing in X-rays and radio.

From nebula to radio galaxy

James Dunlop recorded NGC 5128 in 1826 from Parramatta, near Sydney, during his survey of southern nebulae and clusters. In 1949 John Bolton, Gordon Stanley and Bruce Slee, working at Dover Heights in Sydney, matched one of the strong radio sources they had found to this galaxy, making it one of the first radio sources identified with an object beyond the Milky Way. Distance estimates range from about 11 to 13 million light-years, close enough that it is often called the nearest active galaxy.

Jets and lobes

Chandra's deep X-ray image shows a jet about 13,000 light-years long on one side of the core and a shorter counterjet on the other, with bright knots probably produced by shocks. On much larger scales, radio lobes each nearly a million light-years long spread far beyond the visible galaxy; in radio waves Centaurus A appears almost 20 times wider than the full Moon. In 2010 Fermi showed that the lobes also shine in gamma rays, with more than ten times their radio output.

Close to the black hole

In 2021 the Event Horizon Telescope imaged the base of the jet with about 16 times sharper resolution than any earlier image. Only the outer edges of the jet glow brightly, a pattern that challenges theoretical models, and its structure closely resembles M87's jet on comparable scales relative to the black hole.

Observing it

At magnitude 6.8 Centaurus A is one of the brightest galaxies in the sky, a round glow in binoculars from dark sites; a small telescope begins to show the dust lane across it. It lies far south in Centaurus, so it is a southern-hemisphere object, best in evening skies in the southern autumn, and stays below the horizon north of about 47°N.

Missions

1. 1990–

   Hubble Space Telescope

   NASA / ESAActive

   Ultraviolet to near-infrared imaging from low Earth orbit.

   Mission page (opens in a new tab)

Related entries

• QuasarsFeeding supermassive black holes
• Messier 87Giant elliptical with the first imaged black hole

Sources

1. Robertson et al. 2010, PASA 27:402, early Australian observations of Centaurus A (arXiv) (opens in a new tab)
2. NASA Chandra (2008): Centaurus A's 13,000-light-year jet (opens in a new tab)
3. NASA (1 Apr 2010): Fermi maps an active galaxy's smokestack plumes (opens in a new tab)
4. Janssen et al. 2021, Nature Astronomy 5:1017, EHT images Centaurus A's jet (opens in a new tab)
5. SIMBAD (CDS): NGC 5128 (opens in a new tab)
6. ESO: eso0903: Centaurus A composite (opens in a new tab)

Last reviewed 10 Oct 2026 against these sources. Built from public NASA, ESA and JPL data; not affiliated with or endorsed by any agency.