The white Southern Cross on blue, as well as existing dimensions, is retained as it is strongly identified by Australians as a national symbol.
Add is the gold disc which is suggestive of the significance of indigenous Australians and the country they have long been guardians of. The 'Sun' is also appropriate as a national symbol. It symbolises the 'Sunburnt Country' as well as being a bold, optimistic and uplifting form that looks boldly and confidently to the future. The yellow disc also represents the wattle flower which has had a longstanding status as a national symbol. Yellow (or gold) is also a colour that has commonly been used a colour that identifies Australians internationally.
The Black panel and White trim provide some structure to the flag and can be seen to represent a chronology of the country, where there has been a long aboriginal guardianship with a more recent European involvement in building the nation. Together, with optimism and confidence we take the nation into the 'blue sky' of possibilities.