logo (79K)

Man must rise above the Earth, to the top of the atmosphere and beyond, for only then will he fully understand the world in which he lives.
Socrates, 469 - 399 BC

HOME SOLAR SYSTEM





titlebarconstellations (2K)

ANDROMEDA   AQUARIUS   AQUILA   ARIES   AURIGA   BOOTES   CAMELOPARDALIS   CANCER   CANES VENATICI   CANIS MAJOR   CANIS MINOR   CAPRICORNUS   CARINA   CASSIOPEIA   CENTAURUS   CEPHEUS   CETUS   COLUMBA   COMA BERENICES   CORONA AUSTRALIS   CORONA BOREALIS   CORVUS   CRATER   CRUX   CYGNUS   DELPHINUS   DORADO   DRACO   EQUULEUS   ERIDANUS   FORNAX   GEMINI   HERCULES   HYDRA   LACERTA   LEO   LEO MINOR   LEPUS   LIBRA   LUPUS   LYNX   LYRA   MONOCEROS   OPHIUCHUS   ORION   PEGASUS   PERSEUS   PISCES   PISCIS AUSTRALIS   PUPPIS   SAGITTA   SAGITTARIUS   SCORPIUS   SCULPTOR   SCUTUM   SERPENS   SEXTANS   TAURUS   TRIANGULUM   TUCANA   URSA MAJOR   URSA MINOR   VELA   VIRGO   VULPECULA  

CRUX

The Southern Cross

Australia New Zealand
crux-flag-australia (17K) crux-flag-new-zealand (16K)
Papua New Guinea Samoa
crux-flag-papua-new-guinea (14K) crux-flag-western-samoa (7K)
Brasil
crux-flag-brazil (15K)

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.

crux-May15-1030pm-15north (44K)
Crux - May 15, 10:30 PM - Latitude 15° North, Longitude 95° West





Stars of Crux

Acrux (RA: 12h26m35.814s DE:-6305'56.96")

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.

crux (41K)

Becrux (RA: 12h47m43.167s DE:-5941'19.75")

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.

Gacrux (RA: 12h31m10.012s DE:-5706'51.60")

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.

Planets of Crux

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.



Deep Skies of Crux

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.

crux-eso-cr (308K)
Crux and the Coal Sack - European Southern Observatory - December, 2009

NGC 4755 - The Jewel Box (RA: 12h53m 36.0s DE:-6021'00")

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.

ngc4755-eso-sm (250K)
NGC 4755 - The Jewel Box - European Southern Observatory, Chile - October, 2009

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.


ngc4755-eso closeup-sm (114K)
NGC 4755 - Close-up - European Southern Observatory, Chile - October, 2009






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  

cometarrowbcentaurus (3K) contact (3K) SOLAR SYSTEM copyright (2K) cometarrowflupus (3K)