They call it the Planet Machine. Weighing 1,000 tons and standing as tall as an 18-storey building, the world's biggest optical telescope is designed to see where no-one has seen before. It has been a gleam in the eye of astronomers for nearly a decade and now they are on the verge of seeing the birth of their brainchild - a telescope that for the first time will enable us to watch other Earth-like planets orbit distant suns.The Giant Magellan Telescope (GMT) will be four times bigger than the biggest existing telescope and 10 times more powerful than the hugely successful Hubble Space Telescope.It will use computer optics to eliminate atmospheric interference so that from its mountaintop perch in the bone-dry Atacama desert of Chile it will see further than any terrestrial telescope into the depths of time and space.In addition to seeing "exoplanets" beyond our Solar System, the telescope could quite literally shed light on some of the biggest mysteries of the universe, from the origins of creation to what might happen if time itself comes to an end.The Australian National University announced this week that it is the latest partner to sign up to the consortium of nine institutions dedicated to building the GMT at a total estimated cost of £310m.The largely American consortium is being led by the Carnegie Institution of Washington which built one of the first large telescopes at the beginning of the 20th century that led the great American astronomer Edwin Hubble to discover that the universe was expanding.