What Is The Southern Cross?

The Southern Cross in the Milky Way.
The Southern Cross in the Milky Way.

The Southern Cross is the smallest and one of the eighty eight known constellations in the galaxy. Also known as The Crux, it is comprised of four or five major stars arranged in a cross like pattern and visible in the southern sky at night. These stars are labeled alpha, beta, gamma, delta and epsilon. They are arranged in a clockwise manner in order of increasing magnitude. The Southern Cross is visible in the southern hemisphere, but in winter and spring at night for a few hours it is visible from the northern hemisphere at the tropical latitudes. This constellation is highly symbolic to some nations in that hemisphere, having been used as a navigation aid. This high symbolism is depicted in the inclusion of the crux in the flags of nations like New Zealand, Australia, Brazil, Papua New Guinea and Samoa.

Components Of The Southern Cross

Stars form the major constituents of this asterism. There however are other deep sky objects which are within the borders of the crux. Alpha (Acrux), beta (Mimosa), gamma and delta (Gacrux) form the major constituent stars of the crux. Acrux, which has a blue tinge is 321 light years from the earth and is a triple star whose first, second and third component have a magnitude of 1.3, 1.8 and 5 respectively. The closely related blue hued beta star is 353 light years from the earth and possesses a magnitude of 1.3. The gamma star is red hued with a primary and a secondary component, whose magnitudes are 1.6 and 6.5 respectively. The primary is 88 light years from Earth whereas the secondary is 264 light years from Earth. The last major star , Gacrux, is the dimmest of the four with the distance from Earth being 364 light years. Its magnitude is 2.8. Other stars attributed to this constellation are epsilon crucis, lota crucis and mu crucis. They are 228, 125 and 370 light years from Earth. Deep sky objects associated with the Southern Cross are the Coalsack nebula and the fuzzy star-like open cluster NGC4755.

Significance Of The Southern Cross

Other than its wide application as a navigation aid, the Southern Cross has an outstanding cultural significance to nations localized to the southern hemisphere especially in New Zealand and Australia. It is included in the flag designs of 5 countries; Brazil, Australia, New Zealand, Samoa and Papua New Guinea. When included in flags, the crux is a national symbol. In the Brazil flag, the five-pointed star pattern that is white in color was introduced as a replacement for arms of the Empire of Brazil. The Southern Cross, in form of 4 large and 1 small star, is situated in the fly half of the Australian flag. This is in variation with the New Zealand flag which, on its outer part, contains 4 red stars which are consistent with the Southern Cross. The flag of Samoa has the Southern Cross placed on the upper outer quadrant of the flag. For Papua New Guinea, its flag is divided diagonally into two and the Southern Cross is held in the lower triangle.

Other than the flags of these five nations, there are other flags onto which the Southern Cross is embedded. These include those belonging to the Australian Capital Territory, Australian State of Victoria, several Argentine provinces and Magallanes Region of Chile.


More in World Facts