Antennae Galaxies

At a glance

Key points

• Two galaxies in mid-merger
• Forming billions of new stars
• Named for its two tidal tails

A preview

Two discs are colliding; their cores are still separate, and the gas between them is collapsing into massive young clusters. Similar mergers shaped many large galaxies.

How it was found

William Herschel discovered the pair in February 1785 with his 18.7-inch reflector, and they entered the New General Catalogue in 1888 as NGC 4038 and NGC 4039. The faint streamers that give the 'Antennae' name, like an insect's feelers, are tidal tails of stars and gas flung out during the first close encounter some 200 to 300 million years ago.

A cluster factory with few survivors

Hubble's images show the collision packing new stars into clusters, many of them holding tens of thousands of stars; the brightest and most compact are called super star clusters. Most will not last. Only about one in ten of the new super star clusters is expected to reach an age of 10 million years, and roughly a hundred of the most massive may survive long enough to become globular clusters like those orbiting the Milky Way.

Seeded with heavy elements

Chandra's X-ray view, released in 2004, found hot gas rich in neon, magnesium and silicon, thrown out by supernovae occurring about 30 times as often as in the Milky Way. In one cloud magnesium and silicon are 16 and 24 times more abundant than in the Sun. The Chandra team suggested that stars forming as this gas cools may be unusually likely to have planets.

How far away?

In 2008 a Hubble study using the brightest red giant stars as standard candles put the Antennae at about 45 million light-years, rather than the long-used 65 million. At the smaller distance the pair is less luminous and its clusters look ordinary for a merger instead of 1.5 times too large. Other methods still give higher values, so the distance is quoted as a range.

Observing it

The Antennae lie in Corvus, south of the celestial equator, and are best placed in evening skies around April and May. At roughly 10th to 11th magnitude the pair needs a moderate telescope and dark skies; the tidal tails are much fainter and usually show only in long-exposure photographs.

Missions

1. 1990–

   Hubble Space Telescope

   NASA / ESAActive

   Ultraviolet to near-infrared imaging from low Earth orbit.

   Mission page (opens in a new tab)

2. 2021–

   James Webb Space Telescope

   NASA / ESA / CSAActive

   Infrared observatory at Sun–Earth L2, about 1.5 million km from Earth.

   Mission page (opens in a new tab)

Related entries

• Cartwheel GalaxyA ring galaxy made by a collision
• Stephan's QuintetFour interacting galaxies and an interloper

Sources

1. Deep Sky Corner: NGC 4038/4039 discovery history (opens in a new tab)
2. NASA Chandra (7 Jan 2004): heavy elements in the Antennae (opens in a new tab)
3. SIMBAD (CDS): NGC 4038 (opens in a new tab)
4. ESA: ESA/Hubble heic0812 (opens in a new tab)
5. ESA: ESA/Hubble heic0615 (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.