10 - Seeking the Cross - June 2013

Seek the Southern Cross

Visitors from overseas often ask to be shown our famous Southern Cross. Easy, you think? But could you step outside your house tonight and point it out?    

Australians best know the Southern Cross as the stars on our national flag. The largest star on our flag, the Federation star, is not part of the Southern Cross.    

Unlike the constellations in the Northern Hemisphere, the Southern Cross does not represent some part of Greek mythology. Seamen named it Crux in the 16th century because of its resemblance to…yes, a cross. However, the Australian Aboriginals have a number of stories describing what the stars of the Southern Cross represent. These are just as fascinating as any Greek mythology.    

One story describes the brightest stars of the cross as the four daughters of Mulula, the leader of the Kanda tribe, and the brightest Pointer star as their father Mulula himself. Another describes how Bunya, a member of the spirit world, was frightened by hunters and hid up a tree. For his cowardice, he was turned into a tree-lurking possum, represented by the stars of the Cross. Silly possum.    

To find the Southern Cross step outside this month about 7 pm and face south. Look up high and you’ll see two bright stars pointing slightly upwards. They are the Pointers Alpha and Beta Centauri. Follow their line west and you will find the Southern Cross, which at this time and month is standing vertical.    

On a dark night, you should see the Cross’s four bright stars and a fainter fifth star, Epsilon Crucis, between the right and bottom stars.     Other times of the year the Cross is much lower in the sky. In December, it is so low, its reddish top star (the Cross is upside down then) almost touches the horizon.

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In the image above, at the left of the frame you see the two Pointers, with Alpha Centauri on the left and Beta on the right.  Alpha Centauri is the closest star to our Sun, a mere 4.37 light years away. Beta is a 'bit' further away at 525 light years.

To their right (west) you see the five main stars of the Southern Cross, Crux. Notice their difference in colouring, especially the orange colour of the top star, Gamma Crucis.

Very prominent in the image, nestled below the left side of the cross is the dark nebula, known as the Coal Sack.

And immediately below the Coal Sack and Alpha Crucis, is the irregular shaped trapezium of the constellation Musca, the Fly.  

All this imbedded within the glorious star field of the Milky Way.
 

   

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