|Meaning in English||Southern cross|
|Right ascension||12 h|
|Visible to latitude||Between 20° and -90°|
68 sq. deg.
|Number of stars with|
apparent magnitude < 3
- Apparent magnitude
|Mimosa (β Cru)|
|Table of contents|
2 Notable deep sky objects
With the the lack of a significant pole star in the southern sky (σ Octantis is closest to the pole, but is so faint as to be useless for the purpose), two of the stars of Crux (Alpha and Gamma, Acrux and Gacrux respectively) are commonly used to mark south. Following the line defined by the two stars for approximately four times the distance between them leads to a point close to the Southern Celestial Pole.
Alternatively, if a line is constructed perpendicularly between α Centauri (Toliman) and β Centauri, where the above line and this line intersect marks the Southern Celestial Pole.
Crux was formerly part of Centaurus, and was first introduced as a separate constellation by A. Royer in 1679.
Due to precession of the equinox, Crux and Centaurus were visible from the Mediterranean area in antiquity, so their stars had to be known by Greek astronomers.