#celectialnavigation

Celestial navigation, the skill of figuring out where you are by looking at the stars, works the same way in the Southern hemisphere as it does in the Northern - except for the lack of a ‘South Pole’ star.Knowing where North and South are is very very important. It’s where it all starts. In the Northern hemisphere, we have a Pole Star that seems to sit right above the North Pole of the Earth. It’s pretty easy to find.

Sometimes, the ‘Verse just decides to screw you over. Sorry, Australia. :-( You guys need to do a little work to find your South Pole. Those slackers in the Northern hemisphere got it so easy.However, that same ‘Verse has given the Southern hemisphere something almost as cool - the Southern Cross. Yep, the same one on the flag of Australia. It also appears on four other country’s flags, so it’s gotta be cool.

There it is - over towards the right of the image. The upper star of the cross is reddish-orange, the other three blue. Keep this in mind, as there are several ‘false crosses’ in the Southern sky that can confuse someone. Only accept genuine Southern Crosses for navigational accuracy.

The easiest method of determining where south lies involves drawing an imaginary line vertically from the reddish-orange star (Gamma Crucis - the closest red giant to Earth at 27 parsecs) through Alpha Crucis (the large blue double-star at the ‘bottom’ of the cross) and extending it down. The line should be 4 ½ times the distance from Gamma Crucis to Alpha Crucis.Be sure your line is drawn through the reddish star. 

It would be easy for someone who had heard about using the Cross for navigation getting it wrong either by using one of the ‘fake crosses’ or by drawing the line through the wrong two stars. You can use the two bright stars to the left of the Cross (know as the Pointers - Alpha and Beta Centauri, two of the closest stars to Earth at 1.35 parsecs) to help ensure you’re doing it correctly. 

Here’s a short video by an Australian that explains it.