The telescope will conduct a year-round survey

It will conduct a year-round survey, scanning all of the Milky Way galaxy visible in the Northern Hemisphere.

Seti is an exploratory science to scour the cosmos for signatures of technology built by alien beings.

Some experts believe alien societies are at least as likely to use light for communicating as radio transmissions.

Sending laser signals across the cosmos would be a very logical way for ET to reach out

Bruce Betts, Planetary Society

It has been installed at the Harvard Smithsonian Center for Astrophysics at Oak Ridge Observatory.

"The opening of this telescope represents one of those rare moments in a field of scientific endeavour when a great leap forward is enabled," said Bruce Betts, director of projects at the Planetary Society, which funded the telescope.

"Sending laser signals across the cosmos would be a very logical way for ET to reach out; but until now, we have been ill-equipped to receive any such signal."

Bright flashes

Astronomers have been using radio telescopes to look for transmissions from an extraterrestrial intelligence since the 1960s.

But some scientists believe that alien civilisations might opt for visible light to communicate.

Previous searches have used radio telescopes to search for signals

Using only present-day terrestrial technology, a bright, tightly focused light beam, such as a laser, can be 10,000 times as bright as its parent star for a brief instant. Such a beam could be easily observed from enormous distances.

"This new search apparatus performs one trillion measurements per second and expands 100,000-fold the sky coverage of our previous optical search," said the optical telescope's project director, Paul Horowitz of Harvard University, Massachusetts.

The telescope's custom processors will process the equivalent of all books in print every second. As the telescope scans strips of sky, it employs a custom-built "camera" containing an array of detectors that can detect a billionth-of-a-second flash of light.

It has been funded by the Planetary Society with support from the Bosack/Kruger Foundation.