Crux, being Latin for cross, commonly known as the Southern Cross (in contrast to the Northern Cross), is the smallest of the 88 modern constellations, but nevertheless one of the most famous. It is surrounded on three sides by the constellation Centaurus while to the south lies the Fly (Musca). It is the brightest constellation in the sky, with an overall brightness of 29.218.
Crux - Notable features.
With the lack of a significant pole star in the southern sky (Sigma Octantis is close ...
The Coalsack Nebula.
The Coalsack Dark Nebula (or simply the Coalsack) is the most prominent dark nebula in the skies, easily visible to the naked eye as a dark patch silhouetted against the southern Milky Way. It was known pre-historically on the Southern Hemisphere and was observed by Vincente Yanez Pinzon in 1499. The Coalsack is located at a distance of approximately 600 l ...
With the lack of a significant pole star in the southern sky (Sigma 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 4.5 times the distance between them leads to a point close to the Southern Celestial Pole.
Alternatively, if a line is constructed perpendicularly between Alpha Centauri and Beta Centauri, the point where the above line ...
With the lack of a significant pole star in the southern sky (Sigma 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 4.5 times the distance between them leads to a point close to the Southern Celestial Pole.
Alternatively, if a line is constructed perpendicularly between Alpha Centauri and Beta Centauri, the point where the above line and this line int ...
The Coalsack Nebula is the most prominent dark nebula in the skies, well visible to the naked eye as big dark patch in the southern Milky Way.
Another deep sky object within Crux is the Open Cluster NGC 4755, better known as the Jewel Box or Kappa Crucis Cluster, that was discovered by Nicolas Louis de Lacaille in 1751-1752. It lies at a distance of about 7,500 light years and consists of approximatel ...
Due to precession of the equinox the stars comprising Crux were visible from the Mediterranean area in antiquity, so their stars had to be known by Greek astronomers. However, it was not regarded as a constellation of its own, but rather as part of Centaurus.
The invention of Crux as a separate constellation is generally attributed to the French astronomer Augustin Royer in 1679. It was known in that ...
