Want to stay on top of all the space news? Follow @universetoday on TwitterThe Southern Cross is the smallest of the current 88 constellations. The latin name for the Southern Cross is Crux. In the celestial sphere it located opposite of the constellation Cassiopeia and rises and sets with it in the night sky. Other constellations near it are Centarus and Musca. centuarus acts as its main border surrounding it on three sides. The constellation is considered as the South Pole equivalent of Ursa Major acting as navigational aid pointing south.
The southern cross is well known as a constellation that is always visible in the southern hemisphere. The Southern Cross can also be in tropical regions and the northern hemisphere during winter and spring. The southern cross is significant for southern navigation because there is no usefully bright pole star in the South as there is in the north. The star that is closest to the South Pole is Stigma Ocantis but its apparent magnitude makes it too dim for reasonable navigation. The Southern Cross is important because it points towards where the South Pole should be.
The constellation is made of five stars with only three having proper names. In all they are also known by their greek letter designations, alpha, beta, gama, delta, and epsilon. The first named star is Acrux, the second is Mimosa, and the third is Gacrux. The first and second stars are named afer their Greek letter designations. Acrux was named by American Elijah Burritt in the 19th century.
The Southern Cross was known to the ancient Greeks around 1000 BC. The constellation was thought to be apart of Centaurus. However the precision of the equinoxes caused it to sink out sight from Athens and it was largely forgotten. The constellation was later rediscovered by the Portuguese during the Age of Exploration in the 1500s when they rounded the Cape of Good Hope. The first astronomer attributed from seperating the constellation from Centaurus was French astronomerAugustin Royer in 1679.
We’ve done many episodes of Astronomy Cast about stars. Listen here, Episode 12: Where Do Baby Stars Come From?