Constellation, Southern Cross
Crux
The Southern Cross, one of the best known figures in the southern sky. Ptolemy counted its stars as the centaur’s hind legs, and sailors rediscovered it as a separate cross.
From New York the constellation Crux never rises above the horizon: it belongs to the other hemisphere’s sky.
From New York the constellation Crux never rises above the horizon: it belongs to the other hemisphere’s sky.
In the 3D sky
The sky over New York turned towards Crux. Drag to look around.
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Evening visibility over the year
Height of the constellation’s centre above the horizon at 10 pm local time on the 15th of each month, from New York. Above about 30° it is well placed.
Name and history
Ptolemy knew these stars as part of the centaur, Centaurus, marking its hind legs. Over the centuries, the slow wobble of Earth’s axis carried them below the horizon of Europe. European sailors exploring the southern seas found them again. The Portuguese astronomer João Faras sketched them in a letter from Brazil in 1500, and in 1516 the Italian Andrea Corsali described a marvellous cross of stars. Plancius and Hondius showed it in its modern form on their globes of 1598 and 1600, and Frederick de Houtman listed its stars apart from the centaur in 1603.
Its brightest stars are Acrux, Mimosa and Gacrux. The name Acrux is modern, formed from its catalogue label Alpha Crucis. Beside the cross lies the Coalsack, a dark cloud of dust that Amerigo Vespucci described in 1502 as a black canopus of immense size. Near Mimosa is the Jewel Box cluster, which John Herschel compared to a superb piece of fancy jewellery. Navigators used the cross to find the south celestial pole.
Sources: Ian Ridpath, Star Tales: Crux
Brightest stars
| Star | Designation | Magnitude | Distance |
|---|---|---|---|
| Acrux | α1 Cru | 0.77 | 322 light-years |
| Mimosa | β Cru | 1.25 | 279 light-years |
| Gacrux | γ Cru | 1.59 | 89 light-years |
| Imai | δ Cru | 2.79 | 345 light-years |
| Ginan | ε Cru | 3.59 | 230 light-years |
| μ1 Cru | μ1 Cru | 4.03 | 414 light-years |
| ζ Cru | ζ Cru | 4.06 | 358 light-years |
| η Cru | η Cru | 4.14 | 64 light-years |
| θ1 Cru | θ1 Cru | 4.32 | 235 light-years |
| HIP 62327 | HIP 62327 | 4.62 | 385 light-years |
Facts
| Area | about 69 square degrees (88 of 88) |
|---|---|
| IAU abbreviation | Cru |
| Sky | Southern sky |
| Origin | Counted by Ptolemy as part of Centaurus, first shown correctly as a separate figure on a globe by Plancius and Jodocus Hondius |
| Stars brighter than magnitude 5 | 14 |
| Centre (J2000) | 12.5 h, -61° |
Deep-sky objects
Galaxies, clusters and nebulae brighter than magnitude 9, from the OpenNGC catalogue. Most need binoculars or a telescope and a dark sky.
| Object | Type | Magnitude |
|---|---|---|
| NGC4609 · Coalsack Cluster | Open cluster | 6.9 |
| NGC4103 | Open cluster | 7.4 |
| NGC4349 | Open cluster | 7.4 |
| NGC4439 | Open cluster | 8.4 |
| NGC4052 | Open cluster | 8.8 |
| NGC4337 | Open cluster | 8.9 |
Boundaries: International Astronomical Union, via Astronomy Engine. Areas are computed from the boundaries by sampling (within about one percent). Names and lines: Stellarium. Stars: HYG Database. Deep-sky objects: OpenNGC. Calculated with Astronomy Engine, an open-source library verified against the US Naval Observatory and NASA JPL. Data sources
How to use this page
Choose your place and a night at the top. The answer and the 3D view show where the constellation is, when it is highest and whether it rises at all from where you are. The chart shows its stars and lines, and the tables list its brightest stars and the deep-sky objects inside it.
Frequently asked questions
When is a constellation best seen?
When it is highest in a dark sky, which the page gives for the night you pick. Each constellation is best placed in a particular season, because the stars rise about four minutes earlier every night.
Why can I not see a constellation from my place?
Constellations far south of the celestial equator never rise from northern places, and those far north never rise from southern ones. The page says when this is the case.
What are the constellation boundaries?
The International Astronomical Union divides the sky into 88 areas with official boundaries. The stick figures are only a drawing aid, the boundaries say which constellation a point in the sky belongs to.
Related guides
- How to learn the constellationsStart with one bright pattern you cannot miss, use it as a signpost to its neighbours, and come back a month later: the sky will have turned, and you will know a little more of it.
- Altitude and azimuth: finding things in the skyTwo angles tell you exactly where to look: which direction, and how high.
- Light pollution and dark skies: the Bortle scaleFrom a city centre you can count a few dozen stars. From a truly dark site you can count a few thousand, with the Milky Way bright enough to cast a shadow. The Bortle scale puts a number on the difference.
- Binoculars for stargazing: what to buy and what to look atA pair of 7x50 or 10x50 binoculars shows the craters of the Moon, the moons of Jupiter, dozens of star clusters and the Andromeda Galaxy, for a fraction of the cost of a telescope.