The Main Range is the name for the highest part of Australia, a region of barren but beautiful peaks, in the Snowy Mountains.
It's a desolate, boulder strewn, treeless area prone to very bad weather. It's also one of the best places in Australia to bushwalk.
The dark hill on the right is Mt Townsend, Australia's second highest mountain and in the centre, sunlit and on the horizon, is Mt Kosciuszko, the continent's highest point.
See here for a story about this image and others taken at the same time.