What it looks like
Crux is a compact southern constellation of five main stars forming the famous Southern Cross. It appears on the flags of Australia, New Zealand, Brazil, Samoa and Papua New Guinea, and has guided southern-hemisphere navigators for centuries. Its long axis points toward the south celestial pole.
Brightest stars
All four main stars of the cross are bright — Acrux, Mimosa, Gacrux and Imai — with Acrux the brightest at magnitude 0.77.
| Star | Magnitude | Distance | Meaning |
|---|---|---|---|
| Acrux (α Crucis) | +0.77 | 321 ly | — |
| Mimosa (β Crucis) | +1.25 | 280 ly | — |
| Gacrux (γ Crucis) | +1.63 | 89 ly | — |
| Imai (δ Crucis) | +2.79 | 345 ly | — |
Mythology and history
Crux was known to the ancient Greeks as part of Centaurus, but its stars were so far south they were forgotten in Europe until Portuguese sailors charted them in the 15th century.
Lost and rediscovered
Crux was visible from the Mediterranean in classical antiquity, but precession slowly pushed it below the horizon for European observers by around 400 AD. The ancient Greeks regarded its stars as part of Centaurus, the Centaur. Portuguese navigators rediscovered it on voyages around the Cape of Good Hope in the 15th century, and it was formally separated into its own constellation by Augustin Royer in 1679. Because of its unmistakable cross shape, it became a navigational landmark and a symbol of the southern hemisphere.
How to find it
Look for a compact cross of four bright stars in the southern sky on autumn and winter evenings from the southern hemisphere.
- Extend the long axis of the cross about 4.5 times to reach the south celestial pole.
- Nearby are the two bright Pointers, Alpha and Beta Centauri.
- Only visible from tropical and southern latitudes.
Key facts
- Abbreviation
- Cru
- Genitive
- Crucis
- Meaning
- The Southern Cross
- Brightest star
- Acrux
- Main stars
- 4
- Area rank
- 88th
- Best visible
- May
- Declination
- -60°
- Meteor showers
- Crucids
- Neighbours
- Centaurus, Musca
Deep-sky objects
The Coalsack Nebula is one of the most prominent dark nebulae in the sky, a dense cloud of dust blocking the Milky Way behind it. The constellation also contains the Jewel Box (NGC 4755), a striking open cluster of colourful stars.
Frequently asked questions
What does the constellation Crux look like?
Crux is the smallest of the 88 constellations, known as the Southern Cross, and one of the most recognisable patterns in the southern sky.
What is the brightest star in Crux?
The brightest star in Crux is Acrux, shining at around magnitude 0.77.
When is Crux best visible?
Crux is best seen from southern hemisphere during May.
What is the story behind Crux?
Crux was known to the ancient Greeks as part of Centaurus, but its stars were so far south they were forgotten in Europe until Portuguese sailors charted them in the 15th century.
Which constellations are near Crux?
Crux borders Centaurus and Musca.
Centaurus
Musca