The flag of Australia comprises a blue field with a Union Jack in the canton, augmented with the Commonwealth Star (a white seven pointed star) and the Southern Cross constellation (made up of five white stars - one five pointed and four seven pointed). The flag of Australia is based on the British maritime Blue Ensign, which is identical to the Australia flag minus the Commonwealth star and the Southern Cross constellation. The Australian flag's ratio is 1:2.
The design of the Australian flag was chosen in 1901, the year of Federation, from a pool of approximately 32,000 entries in a competition to choose the new nation's official flag. The Australian flag was first flown on 3 September 1901 in Melbourne, Victoria, although the flag was not officially adopted until 11 February 1903. The date of 3 September is the official Australian National Flag Day. A small modification was made to the original Australian flag on 8 December 1908, with the six pointed Commonwealth Star becoming the seven pointed Commonwealth Star that remains to this day. In 1954, the Australian flag became recognised by, as well as legally defined in, the Flags Act 1953.
The Australian flag is rich with symbolism. The Union Jack is a clear reference to Australia's history and founding as six British colonies. The Commonwealth Star, which is also known as the Federation Star, originally had six points representing the six colonies coming together at Federation (the seventh point was added to represent the Territory of Papua, as well as any future territories). The inclusion of the Southern Cross is a nod to the most distinctive constellation visible in the Southern Hemisphere and has been considered a symbol of Australia since the early days of British settlement.
A large Australian flag sits atop Parliament House in Canberra, Australia