South Star

From Wikipedia, the free encyclopedia

The South Star is the star which is circumpolar to the celestial South Pole (as Polaris, the North Star, is for the celestial North Pole), and can thus be reliably used for navigation. The present South Star is Sigma Octantis, which is very faint. As such, it is not as useful as Polaris Borealis for navigation.

The constellation Crux, the Southern Cross, points towards the celestial South Pole. If the constellation is viewed as though it were a standing Christian cross, the Southern celestial pole is currently 4.5 times the height of the cross below its base. Very few stars of any great note lie between Crux and the pole, although the constellation Musca is fairly easily recognised immediately beneath Crux.

Although the South Celestial Pole currently lacks a bright star like Polaris to mark its position, that will change in the future due to precession. During the next 7500 years, the South Celestial Pole will pass close to the stars Gamma Chamaeleontis (4200 CE), HD 90589, Omega Carinae (5800 CE), Upsilon Carinae, Iota Carinae (Aspidiske, 8100 CE) and Delta Velorum (9200 CE).

Kappa Velorum is only a couple of degrees from the south celestial pole of Mars, so it could therefore be considered the current south star of Mars.

[edit] See also

• Pole star
• North star