Credit: Giant Magellan Telescope - Carnegie Observatories

ASK ASTRONOMERS WHERE the next frontier in space research will be and the answer is unanimous: a giant telescope due to be built on a remote mountain top in Chile.

With up to 30 times the resolving power of current telescopes, the Giant Magellan Telescope promises to answer some of astronomy's most fascinating questions.

The history of astronomy is marked by technological leaps that led to new discoveries. Galileo revolutionised astronomy with his 37-millimetre telescope, as did Edwin Hubble with his two-metre optical telescope, and his namesake, the Hubble Space Telescope, with its 4.2-metre telescope and view from space.

New telescopes are being built all the time. So why build another, and what's causing the buzz?

A world consortium of astronomy organisations plans to build the Giant Magellan Telescope (GMT) on a mountaintop near the village of Residencia in Chile's Atacama Desert. It will cost US$600 million and should be ready by 2016.

With a resolving power ten times sharper than Hubble and five times sharper than its replacement, the James Webb Space Telescope, the GMT is a big step up in terms of power. Composed of an array of seven mirrors, each 8.4 m in diameter (some of the largest ground-based telescopes currently have a diameter of 10 m), it will have the capacity of a telescope with a diameter of 24.5 m – far larger than any telescope built so far.

"THE BIGGER THE BUCKET, the more rain you catch, and the bigger the telescope, the more light you catch," says astronomer Matthew Colless, director of the Anglo-Australian Observatory in Sydney, who earlier this month gave a talk on the GMT to a bunch of astrophysicists at the Australian Institute of Physics Congress in Adelaide.

"The GMT can collect five to six times as much light as current telescopes. It will also produce sharper images, and be able to focus on objects two-and-a-half to three times smaller than current telescopes," he says.

The key is to use both capabilities – collecting lots of light and resolving very small objects – together. This will give the GMT 30 times the power of current telescopes. And that's a pretty big jump. It will, for example, be enough to allow the GMT to look the Universe's first stars, follow the formation of galaxies within a few million years of the Big Bang, and for the first time look directly at extrasolar planets, for a start.

"We are confident that it will have a great impact on our understanding of extrasolar planets, black holes and early star and galaxy formation," says astrophysicist Pat McCarthy, from the Observatories of the Carnegie Institute in Washington. "The great advantage offered by the next generation of telescopes is the combination of enormous collecting area and great angular resolution.

"Current infrared space telescopes, such as the Spitzer Telescope, are limited by the poor angular resolution in the infrared," he adds. With its large diameter, the GMT will have the high angular resolution needed to probe the structure of dense star-forming regions in the infrared and see directly into regions of massive star formation."

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