The Southern Cross - a star guide
The Southern Cross in the night sky has guided travellers, intrigued astronomers and inspired poets and musicians. Its five stars have been used as a sign of rebellion and as a sometimes controversial symbol of national pride.
Professor Matthew Colless, the Director of the Research School of Astronomy and Astrophysics at the Australian National University, is a big fan of the Southern Cross.
"I find it just a lovely constellation," he says, in his office at the Mt Stromlo observatory high above Canberra.
"For me, as for many Australians, it's the most famous, the most visible, most memorable and most personally relevant constellation."
The Southern Cross is officially an asterism, a collection of stars that belongs to the constellation of Crux.
With the two pointers (which belong to the constellation of Centaurus) it can be used as a navigational tool to find the South Pole.
The five stars that make up the Southern Cross - Alpha, Beta (also known as Mimosa), Delta, Gamma and Epsilon Crucis - are 10 to 20 million years old. The closest is 88 light-years from Earth, the furthest 364 light-years away.
Professor Colless says the stars were known to the Ancient Greeks and Egyptians but by Roman times the Southern Cross had sunk below the horizon, disappearing from sight in the Northern Hemisphere.
"It was lost for many years," explains Professor Colless, "until it was rediscovered by the Portuguese when they began to circumnavigate the globe."
Fair and Beautiful
The Italian explorer Andrea Corsali, who worked for the powerful Giuliano de Medici of Florence, observed the Southern Cross during a Portuguese voyage to India.
In a letter to his patron he drew a rough diagram of it and wrote "this cross is so fair and beautiful". The original letter hasn't survived but a 1516 copy inscribed on vellum is held in the collection of the State Library of New South Wales and has been on display in the Mapping our World exhibition at the National Library of Australia.
Exhibition co-curator Dr Susannah Helman says there are earlier depictions of the Southern Cross but Corsali was the first to draw and describe it as a separate constellation.
"You can sort of see many more stars than we know in the Southern Cross but what you have is some stars that seem to be in a cross like the Southern Cross we know," says Dr Helman.
Law and customs
Inhabitants of the Southern Hemisphere, including the Incas of South America and indigenous Australians, have always been familiar with the Southern Cross.
Dr Duane Hamacher, a research scientist and ethno-astronomer at the University of New South Wales, says that because there are hundreds of different Aboriginal language groups there are many different stories about the Southern Cross.
"It tells people about when seasons are changing, when food sources are coming in and also gives them a social aspect," Dr Hamacher says. "A lot of the law and the customs are recorded in the stars and the Southern Cross is very important for that."
In areas of South Australia and Queensland the Southern Cross represents a sting ray.
"Sometimes the two pointer stars represent fisherman pursuing the sting ray or it might represent two sharks chasing the sting ray."
From western Victoria there's a story about a man who was chased up a tree by a large emu and in punishment for his cowardice he was turned into a possum.
"So if you look at the Southern Cross it actually represents a possum at the top of a tree," explains Dr Hamacher. "The very top star ... is red. That represents the possum."
Symbol of resistance
In the mid 19th century the Southern Cross was used by some groups of early white settlers, including the Anti-Transportation League, as a symbol of resistance to imperial powers.
In 1854 it was famously flown at the Eureka Stockade.
"The Southern Cross became a symbol for the miners on the goldfield of their independence," says Michael Evans, the Manager of Visitor Experience at the Museum of Australian Democracy. "They put the five stars on their flag that symbolised their rebellion and which they swore an oath of allegiance to."
The Southern Cross has also been used as a sign of resistance in modern protest movements such as the anti-coal seam gas campaign.
For a few years it was also a popular tattoo.
Tattoo artist Peter "Bones" Bone says its popularity has waned, with many people now wanting it removed, perhaps because of its "bogan" association, but it's still favoured by newly nationalised Australians and members of the Australian Defence Force.
"I suppose [it's] their interpretation of wearing their Australian pride," he says. "A lot of military people definitely wear it as a badge of honour and you do find a lot of people particularly when they go on longer deployments ... are drawn towards that type of tattoo."
The Australian flag
The Southern Cross appears on the national flags of New Zealand, Papua New Guinea, Samoa and Brazil as well as on the Australian flag.
The Australian flag featuring the Union Jack, the Commonwealth star and the five stars of the Southern Cross was first flown in 1901.
Mr Evans says many Australians would be surprised to learn it didn't become the official flag until the Queen signed it into law during her first visit to Australia.
"It is only since 1954 that we have officially had a national flag," he says. "And that is the one we know now that proudly shows the Southern Cross."