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The Southern Cross

why...

What has to do the Southern Cross with a tourist guide dedicated to Sydney?
Crux Constellation map
©2006 Gabriel Ditu
  • The Southern Cross is on the Australian flag and is also part of many Australian companies logo. Example, Commonwealth bank.
  • I am sure that sometimes you find reference to The Southern Cross in the novels you read or you've read when you were young.
  • The Southern Cross is constellation visible only from the southern hemisphere. If you are a tourist chances are that you are from the northern hemisphere, therefore you wouldn't have seen it before.
  • I haven't seen a tourist guide to encourage you to look at the stars.

brief history ...

Due to precession of the equinox the stars comprising Crux were visible from the Mediterranean area in antiquity, so their stars had to be known by Greek astronomers. However, it was not regarded as a constellation of its own, but rather as part of Centaurus.

The idea of Crux as a separate constellation is generally attributed to the French astronomer Augustin Royer in 1679. It was known in that shape well before that, however.

Trivia: the five brightest stars of Crux appear on the flags of Australia, Brazil, New Zealand, Papua New Guinea and Samoa, and the Australian States and Territories of Victoria, the Australian Capital Territory, the Northern Territory.

the stars...

  • Alpha Crucis (Acrux) is the principal star and a splendid binary. The combined visual magnitude of both stars results in a magnitude of 0.72. The stars are 320 light years away, and each is approximately one and a half to twice the size of our Sun.
  • Beta Crucis (Mimosa) is the brightest star of the group, a blue-white giant (nearly five times the Sun's size) with a visual magnitude of 1.25. The star is an estimated 580 light years away, and has a luminosity of nearly 8000. The star is a variable
  • Gamma Crucis (Gacrux) forms the top of the cross. The reported distance may be erroneous; it's been calculated from the visual and absolute magnitudes. The resulting parallax is so large that it should be measurable.
  • Delta Crucis is the western arm, very similar in size and distance to alpha Crucis, and part of the star cluster mentioned above. The star is a beta-CMa type variable.

finding the south pole...

Method 1 Two of the stars of Crux (Alpha and Gamma, Acrux and Gacrux respectively) are commonly used to mark south. Following the line defined by the two stars for approximately 4.5 times the distance between them leads to a point close to the Southern Celestial Pole.

Method 2 If a line is constructed perpendicularly between Alpha Centauri and Beta Centauri, the point where the above line and this line intersect marks the Southern Celestial Pole.

tourist information ...

How to get there
If you are in Sydney, or for that matter in the Southern Hemisphere and is a night with clear sky, just look at the sky and you are there...
22 Octomber
1929 - James Scullin becomes the ninth and first Australian-born Prime Minister of Australia.
Australian slang
  • in the shit in serious trouble
  • coldie a beer
  • Pommy's towel, as dry as a very dry
  • hoon hooligan
  • croc crocodile, load of rubbish, nonsense
  • matilda sleeping bag
  • shonky dubious
  • give it a burl give it a go
  • Gabba Wooloongabba - the Brisbane cricket stadium
Sydney coordinates:
Latitude: 33.9° South
Longitude: 151.2° East
 
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