Timeless Red Earth:
The background represents Australia's red earth, and the two symbols (placed so as to provide antisymmetric tension) represent various pairs of opposites - Sun vs Stars, Traditional vs Futuristic, Convex vs Concave, Day vs Night.
In addition, the Sun represents successive waves of migration (the First Australians at the centre, then the First Fleet, European migration, New Australians, and future migrants), and the Stars represent the Southern Cross