Science & history · Constellation guide
Crux, the Southern Cross
Crux, the Southern Cross, is the smallest of all 88 constellations, and one of the most famous. Its four bright stars make a compact cross, with two brilliant Pointers beside it.
About this picture
NASA/Goddard Space Flight Center Scientific Visualization Studio. Gaia DR2: ESA/Gaia/DPAC. Constellation figures based on those developed for the IAU by Alan MacRobert of Sky and Telescope magazine (Roger Sinnott and Rick Fienberg). NASA's page (opens in a new tab).
The map is a composite of 1.7 billion catalogued stars, not a photograph from one place: it shows stars far too faint for the eye, and no weather, Moon or city light. It is drawn here in this chart's projection, with each star where it was in 2000; the fastest-moving bright star has shifted about a minute of arc since, far less than a pixel here.
How to spot it: Four bright stars in a small cross, with the two Pointers beside it. Source (opens in a new tab)
What you are looking at
The smallest constellation, with the most southerly first-magnitude star and two borrowed Pointers.
Crux is the smallest of all 88 constellations (opens in a new tab). Its brightest star, Acrux, at declination −63°, is the most southerly first-magnitude star.
The two bright stars beside it, Alpha and Beta Centauri, are the Pointers (opens in a new tab), and belong to the neighbouring Centaurus; on modern maps the cross lies under the centaur's body.
Sources for this section Ian Ridpath, Star Tales: Crux (opens in a new tab); Ian Ridpath, Star Tales: Centaurus (opens in a new tab)
How to find it
A Southern Hemisphere sight: from the north you need to be near the equator.
NASA's Hubble team (opens in a new tab) says the Coalsack beside the cross is easiest to spot from the Southern Hemisphere in autumn, and that Northern Hemisphere observers need to be near the equator and look in spring. By this site's calculation (opens in a new tab), the whole cross is above the horizon only south of about 27°N, and from 35°S it stands about 65° up in the south at its highest, highest at about 9 p.m. local time in mid-May.
It has long been a navigator's sign: by the early 1500s (opens in a new tab), Ridpath writes, sailors were regularly using the cross to point to the south celestial pole, and NASA (opens in a new tab) names the Southern Cross as a way to find due south, where there is no bright pole star.
Keep in mind From mid-northern latitudes Crux never rises at all. Why the sky depends on latitude.
Sources for this section NASA Hubble, Caldwell 99 (the Coalsack Nebula) (opens in a new tab); Bright Star Catalogue, 5th Revised Ed. (Hoffleit & Warren 1991), as computed by this site's star engine (opens in a new tab); Ian Ridpath, Star Tales: Crux (opens in a new tab); Preston Dyches, What is the North Star and How Do You Find It?, NASA Science (2021, updated 2024) (opens in a new tab)
Lost and found
Ptolemy knew these stars as part of the centaur; Europe lost them, and found them again as a cross.
Ptolemy catalogued these stars, but as the hind legs of the centaur (opens in a new tab). The slow wobble of Earth's axis then carried them out of sight from the Mediterranean, and European seafarers rediscovered them in the 15th and 16th centuries. In 1516 Andrea Corsali sketched the cross and wrote that no other sign in the sky seemed comparable.
Crux first appears in its modern form on celestial globes by Petrus Plancius and Jodocus Hondius (opens in a new tab) in 1598 and 1600, and was listed as a separate constellation for the first time, as De Cruzero, in Frederick de Houtman's southern star catalogue of 1603.
Sources for this section Ian Ridpath, Star Tales: Crux (opens in a new tab)
Not the False Cross
A bigger, fainter cross nearby fools people; the real one is smaller and has the Pointers beside it.
A second, larger and fainter cross (opens in a new tab) nearby, made of stars from Carina and Vela, is known as the False Cross.
The real Southern Cross is smaller and brighter, and it has the two Pointers (opens in a new tab), Alpha and Beta Centauri, right beside it. If there are no brilliant Pointers, it is probably the False Cross.
Sources for this section Ian Ridpath, Star Tales: Crux (opens in a new tab); Ian Ridpath, Star Tales: Centaurus (opens in a new tab)
The Coalsack
Beside the cross, a dark cloud of dust blots out a patch of the Milky Way.
The Coalsack (opens in a new tab) is a dark nebula: a dense cloud of interstellar dust about 600 light-years away and about 100 light-years across, which completely blocks the visible light of the stars behind it. On a clear night it is easy to see with the naked eye as a dark patch next to the Southern Cross.
Southern stargazers have known it for millennia; NASA (opens in a new tab) credits the Spanish explorer Vicente Yáñez Pinzón, in 1499, with first reporting it to Europeans, and Ridpath (opens in a new tab) quotes Amerigo Vespucci, on a voyage of 1501–02, describing a huge black patch beside six bright stars.
The Night Sky Network (opens in a new tab) notes that many cultures tell stories about dark clouds like this one as well as about the stars: the Emu in the Sky begins here.
Sources for this section NASA Hubble, Caldwell 99 (the Coalsack Nebula) (opens in a new tab); Ian Ridpath, Star Tales: Crux (opens in a new tab); Kat Troche (Astronomical Society of the Pacific), The Great Rift, NASA Night Sky Network (2025) (opens in a new tab)
The Jewel Box
Next to Mimosa, a young star cluster that John Herschel named for its colours.
The Jewel Box (opens in a new tab), NGC 4755, is just bright enough to see with the unaided eye. John Herschel gave it its nickname in the 1830s because its pale blue and orange stars, seen through a telescope, reminded him of exotic jewellery. It is about 6,400 light-years away and about 16 million years old.
Ridpath (opens in a new tab) places it just below Beta Crucis, Mimosa, on the old charts.
How to see it It is just bright enough for the unaided eye (opens in a new tab); the colours that gave it its name need a telescope.
Sources for this section ESO, Opening up a Colourful Cosmic Jewel Box (eso0940, 2009) (opens in a new tab); Ian Ridpath, Star Tales: Crux (opens in a new tab)
Where on Earth, and when
The whole key pattern rises from anywhere south of about 27°N.
North of about 33°N, none of it rises.
South of about 33°S, the whole key pattern never sets.
Its middle climbs at least 20° high, the finder's threshold for a suggestion, from anywhere south of about 10°N.
It is highest in the evening sky, at about 9 p.m. local time, in mid-May, from either hemisphere, wherever it rises. With daylight saving time, that is nearer 10 p.m. on the clock.
Worked out by this site from the Bright Star Catalogue, for a flat, clear horizon. Hills, buildings, haze and city light all cut into this; the air also lifts objects near the horizon by about half a degree. For your own place and night, use the sky finder.
Sources
- History Ian Ridpath, Star Tales: Crux (opens in a new tab) for the figure, its history, the False Cross, Vespucci and the Jewel Box's place · checked 27 September 2026
- History Ian Ridpath, Star Tales: Centaurus (opens in a new tab) for the Pointers · checked 27 September 2026
- Astronomy NASA Hubble, Caldwell 99 (the Coalsack Nebula) (opens in a new tab) for the Coalsack and where to see it · checked 27 September 2026
- Astronomy Preston Dyches, What is the North Star and How Do You Find It?, NASA Science (2021, updated 2024) (opens in a new tab) for finding south · checked 27 September 2026
- Astronomy Kat Troche (Astronomical Society of the Pacific), The Great Rift, NASA Night Sky Network (2025) (opens in a new tab) for dark clouds in sky stories · checked 27 September 2026
- Astronomy ESO, Opening up a Colourful Cosmic Jewel Box (eso0940, 2009) (opens in a new tab) for the Jewel Box · checked 27 September 2026
- Astronomy Bright Star Catalogue, 5th Revised Ed. (Hoffleit & Warren 1991), as computed by this site's star engine (opens in a new tab) for where it rises, its height from 35°S and best month
