The flag of Australia is based on the British maritime Blue Ensign – a blue field with the Union Jack in the canton or upper hoist quarter – augmented or defaced with a large white seven-pointed star (the Commonwealth Star) and a representation of the Southern Cross constellation, made up of five white stars – one small five-pointed star and four, larger, seven-pointed stars. There are other official flags representing Australia, its people and core functions of government.
The flag's original design (with a six-pointed Commonwealth Star) was chosen in 1901 from entries in a competition held following Federation, and was first flown in Melbourne on 3 September 1901, the date proclaimed as Australian National Flag Day. A slightly different design was approved by King Edward VII in 1903. The seven-pointed commonwealth star version was introduced by a proclamation dated 8 December 1908. The dimensions were formally gazetted in 1934, and in 1954 the flag became recognised by, and legally defined in, the Flags Act 1953, as the "Australian National Flag".
The Australian flag uses three prominent symbols: the Union Flag, the Commonwealth Star (also the Federation Star) and the Southern Cross (or Crux).
In its original usage as the flag of United Kingdom of Great Britain and Ireland, the Union Flag combined three heraldic crosses which represent the constituent countries of the United Kingdom (as constituted in 1801):
The Union Flag is thought to symbolise Australia's history as six British colonies and the principles upon which the Australian Federation is based, although a more historic view sees its inclusion in the design as demonstrating loyalty to the British Empire.
The Commonwealth Star, also known as the Federation Star, originally had six points, representing the six federating colonies. In 1908, a seventh point was added to symbolise the Papua and any future territories. Another rationale for the change was to match the star used on the Coat of Arms, which was created in the same year. The Commonwealth Star does not have any official relation to Beta Centauri, despite the latter's brightness and location in the sky; however, the 1870 version of the flag of South Australia featured the "pointer" stars, Alpha and Beta Centauri.
The Southern Cross is one of the most distinctive constellations visible in the Southern Hemisphere, and has been used to represent Australia since the early days of British settlement. Ivor Evans, one of the flag's designers, intended the Southern Cross to also refer to the four moral virtues ascribed to the four main stars by Dante: justice, prudence, temperance and fortitude. The number of points on the stars of the Southern Cross on the modern Australian flag differs from the original competition-winning design, in which they ranged between five and nine points each, representing their relative brightness in the night sky. The stars are named after the first five letters of the Greek alphabet, in decreasing order of brightness in the sky. In order to simplify manufacture, the British Admiralty standardised the four larger outer stars at seven points each, leaving the smaller, more central star with five points. This change was officially gazetted on 23 February 1903.
Before 1901, what is now Australia was six separate British colonies. The Union Flag, as the flag of the British Empire, was first used on Australian soil on 29 April 1770 when Lieutenant James Cook landed at Botany Bay, and it was again used at the start of European settlement of the country on 26 January 1788. This was the original Union Flag introduced in 1606 that did not include the Saint Patrick's Saltire, included from 1801 after the Acts of Union 1801. It is the second version post 1801 that is depicted on the Australian Flag. It was often used to represent them collectively, and each colony also had its own flag based on the Union Flag. As an Australian national consciousness began to emerge, several flag movements were formed and unofficial new flags came into common usage. Two attempts were made throughout the nineteenth century to design a national flag. The first such attempt was the National Colonial Flag created in 1823–1824 by Captains John Nicholson and John Bingle. This flag consisted of a red cross on a white background, with an eight-point star on each of the four limbs of the cross, while incorporating a Union Flag in the canton. The most popular "national" flag of the period was the 1831 Federation Flag, also designed by Nicholson. This flag was the same at the National Colonial Flag, except that the cross was blue instead of resembling that of St. George. Although the flag was designed by Nicholson in 1831, it did not become widely popular until the latter part of the century, when calls for federation began to grow louder. These flags, and many others such as the Eureka Flag (which came into use at the Eureka Stockade in 1854), featured stars representing the Southern Cross. The oldest known flag to show the stars arranged as they are seen in the sky is the Anti-Transportation League Flag, which is similar in design to the present National Flag. The differences were that there was no Commonwealth Star, while the components of the Southern Cross are depicted with eight points and in gold. This flag was only briefly in usage, as two years after the formation of the Anti-Transportation League in 1851, the colonial authorities decided to stop the intake of convicts, so the ATL ceased its activities. The Eureka Flag is often viewed as the first "Australian" flag as it was the first notable example of a design that had the Southern Cross while excluding the Union Flag. The Murray River Flag, popular since the 1850s, is still widely used by boats that traverse Australia's main waterway. It is the same as the National Colonial Flag, except that the white background in the three quadrants other the canton were replaced with four alternating blue and white stripes, representing the four major rivers that run into the Murray River.