|Papua New Guinea||Samoa|
The Southern Cross is the smallest of all the 88 constellation, yet it enjoys more renown than anything else in the southern sky, evidenced by its presence on no less than five national flags. Here in the 21st century, you have to be south of 25 degrees north latitude to see it, but in ancient times, due to precession, it was visible further north. Ancient Greeks knew it well, and considered it part of Centaurus. The four stars that form the cross are all quite bright and impossible to miss. A common misconception is that the Southern Cross contains the southern sky equivalent of the North Star, Polaris. The truth is there are no stars close enough to the south celestial pole to be called the "South Star", and the Southern Cross is not even close. It does point the way, however, and if you follow an imaginary line along the vertical axis of the cross four and a half lengths to the south, you will be very close to the south celestial pole.
The brightest star in Crux is at the base of the cross, its designation as the alpha star giving it the rather unimaginative name of Acrux. At the brilliant magnitude of 0.8, it is the 13th brightest star in the sky. Turn a telescope on it and you discover it is actually two very big, bright stars in orbit around each other. Alpha1 is a B0IV blue/white subgiant with a surface temperature of 30,000 degrees. Alpha2 is only slightly smaller and cooler, classified as a B1V blue/white main sequence star, with a surface temperature of 27,000 degrees. To complicate matters further, Alpha1 is thought to have another, smaller companion, making Acrux a triple star system, all located about 300 light years away.
Beta Crucis has the official name of Becrux, for obvious reasons, but it is also sometimes known by the much nicer name of Mimosa, a flowering shrub native to the southern tropics, traditionally known for its medicinal and psychotropic properties. The star is similar to Acrux in many ways. It is the same distance away (300 light years), only slightly less luminous (magnitude 1.25), and it is a binary system with the primary a very hot B1IV blue/white subgiant with a surface temperature of 27,000 degrees. The companion star orbits very close making it difficult to assess, and there may be one or two other companions as well.
The last of the named stars, Gamma Crucis, couldn't be more different from the other two. Quite predictably named Gacrux, it is not a young, hot blue star like Acrux and Becrux. It is an old, cool red star, classified as an M3III red giant, with a surface temperature of only 3,400 degrees. It is also much closer, only 88 light years away, making it the closest red giant to Earth, and allowing it to shine quite brightly at magnitude 1.59. The star's rich ruby red colour makes it a most pleasing sight to the naked eye, and through a telescope it becomes truly splendorous.
Three stars in Crux have been found to host planets, but they are all very far away and too dim for the naked eye, and the planets are all enormous gas giants. For more information on these and other extrasolar planets, visit NASA's New Worlds Atlas, and The Open Exoplanets Catalogue.
The Southern Cross sits right in the middle of the Milky Way, and is surrounded by rich star fields and dark nebulae. Just below the cross is a large dark nebula known as the Coal Sack. It is an area of thick interstellar dust 600 light years away that measures 35 light years across, and blocks all the light from the stars behind it. It is so large and prominent, it is visible with the naked eye.
The Southern Cross also contains one of the finest star clusters in the sky, NGC 4755, also known as the Jewel Box. It is a grouping of over 100 stars, about 6,500 light years away, with a combined magnitude of 4.2.
Most of the stars in the Jewel Box are very young, and sparkle with varying shades of blue. One notable exception is the prominent, bright orange supergiant Kappa Crucis. This star is so distinctive, the entire group is sometimes called the Kappa Crucis Cluster.
|Winter: Orion Canis Major Canis Minor Monoceros Lepus Eridanus Taurus Auriga Camelopardalis Lynx Gemini Cancer|
|Spring: Hydra Sextans Crater Corvus Leo Leo Minor Ursa Major Ursa Minor Canes Venatici Coma Berenices Virgo Bootes|
|Summer: Draco Corona Borealis Hercules Ophiuchus Serpens Libra Scorpius Sagittarius Scutum Aquila Sagitta Vulpecula Lyra Cygnus|
|Autumn: Andromeda Perseus Pegasus Cassiopeia Cepheus Cetus Lacerta Delphinus Equuleus Capricornus Aquarius Pisces Aries Triangulum|
|Southern Skies: Centaurus Crux Lupus Corona Australis Piscis Australis Sculptor Tucana Fornax Dorado Columba Puppis Carina Vela|