Octans

Octans /ˈɒktænz/ is a faint constellation located in the deep southern sky. Its name is Latin for the eighth part of a circle, but it is named after the octant, a navigational instrument. The constellation was devised by French astronomer Nicolas Louis de Lacaille in 1752, and it remains one of the 88 modern constellations.

History and mythology

Octans was one of 14 constellations created by Nicolas Louis de Lacaille during his expedition to the Cape of Good Hope, and was originally named "l’Octans de Reflexion", French for “the reflecting octant”. It was part of his catalogue of the southern sky, the Coelum Australe Stelliferum, which was published posthumously in 1763. In Europe, it became more widely known as "Octans Hadleianus", in honor of English mathematician John Hadley, who invented the octant in 1730. There is no real mythology related to Octans, partially due to its faintness and relative recentness, but mostly because of its extreme southerly latitude.

Characteristics

Octans is bordered by seven different constellations, most of which are far more prominent than itself: Apus (the bird-of-paradise), Mensa (the table), Chamaeleon (the chamaeleon), Pavo (the peacock), Indus (the Indian), Tucana (the toucan), and Hydrus (the male water snake). The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Oct. The official constellation boundaries are defined by an eight-sided polygon. Covering 291 square degrees, Octans ranks 50th in area out of the 88 modern constellations.

Octans (Chinese astronomy)

The modern constellation Octans is not included in the Three Enclosures and Twenty-Eight Mansions system of traditional Chinese uranography because its stars are too far south for observers in China to know about them prior to the introduction of Western star charts. Based on the work of Xu Guangqi and the German Jesuit missionary Johann Adam Schall von Bell in the late Ming Dynasty, this constellation has been classified under the 23 Southern Asterisms (近南極星區, Jìnnánjíxīngōu) with the names Snake's Tail (蛇尾, Shéwěi) and Exotic Bird (異雀, Yìquè).

The name of the western constellation in modern Chinese is 南極座 (nán jí zuò), meaning "the south pole constellation".

Stars

The map of Chinese constellation in constellation Octans area consists of:

See also

References