Astronomy's next big thing

By Christine McGourty BBC science correspondent

The Owl (Overwhelmingly Large Telescope) is an awesome project which requires international effort to make it happen.

It would open an enormous new window on the Universe

Dr Roberto Gilmozzi

This huge telescope - its main mirror would be more than 100 metres across - would have a predicted resolution 40 times better than the Hubble Space Telescope and a sensitivity several thousand times greater.

It would be sited at an altitude of 5,000 metres and would be operated almost as a space observatory, with a base camp for the human operators nearby at a lower height of no more than 3,000 metres.

The European Southern Observatory organisation, the prime mover behind the project, is currently negotiating rights to a site with Chile, the would-be host country.

Eso members have been discussing the Owl project at their Council Meeting in London.

Big revolution

The preferred site would be in the Atacama Desert, which is said to be the driest in the world, making it a perfect location for astronomy. Already, telescopes are located there from the US, Europe and the Eso's newest member, the UK.

Owl is currently in the design phase, with the cost and timescale still to be fixed. But the aim is to take advantage of the latest developments in telescope technology to make the next giant leap forward in observing.

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The mirror, much like the US 10-metre Keck telescopes in Hawaii, would be made of 1,500 hexagonal segments and would use some of the clever computer techniques - active and adaptive optics - that further improve resolution.

Those involved believe the Owl could revolutionise ground-based astronomy.

'Sounds half-crazy'

Roberto Gilmozzi, director of Eso's Paranal Observatory, the site of the Very Large Telescope (VLT), in Chile, told BBC News Online: "At first sight it seems half-crazy. This is a telescope with a primary mirror the size of a football field.

"But it is something within reach of current technology and it has freed astronomers from the old straitjacket which is the belief that every new generation of telescopes will be twice as big as the previous one.

"Now, we can go beyond this. Owl would have the same resolution as the VLT, but in the VLT Interferometer the maximum light you can see is the sum of the light coming from the four telescopes.

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"With a telescope that has 10 times the collecting area of every telescope ever built, you would be able to go down several thousand times fainter than the faintest thing you see today with those telescopes."

He added: "It would open an enormous new window on the Universe, allowing you to detect the presence of oxygen if there is any on Earth-like planets around nearby stars.

"It would allow you to see exploding stars out to the edge of the Universe. It would really be a 'quantum' jump in our understanding of the Universe."