Astronomers have uncovered a hidden population of distant stars and galaxies that were formed much earlier than scientists had previously thought, they said on Wednesday.

They used a new type of camera, called SCUBA, to delve deeper into the distant universe and produce images more accurate than even the most powerful optical telescope."We looked at the very distant universe to see if we could see dust in galaxies that could be enshrouding hot young stars," James Dunlop, of the Royal Observatory in Edinburgh, said in an interview.

"What we found is that optical astronomers seem to be missing about 80 percent of the star formations in the early part of the universe - the first billion years."

The findings of the British team, and similar research done at the University of Hawaii, has opened up a new frontier in astronomy which may help scientists answer basic questions of modern cosmology.

"It has ramifications for working out how galaxies formed from the very beginning of the Big Bang," said Dunlop, referring to the theory that the universe resulted from a huge explosion about 15 billion years ago.

Astronomers had thought that star formations peaked when the universe was about three-quarters of its present age. The latest research indicates stars were born billions of years before that.

Until now astronomers used optical wavelengths visible to the naked eye to gauge star formation. They now know that stars born in dust clouds in galaxies were often hidden at optical wavelengths.

Dust absorbs starlight emitted at visible wavelengths by hot young stars and re-radiates it at much longer wavelengths. In very distant galaxies the light is further altered by the expansion of the universe to wavelengths slightly less than a millimeter.

The British and American/

Japanese studies, published in the science journal Nature, used the SCUBA (Submillimeter Common-User Bolometer Array) camera in their research.

The device measures heat emission from small dust particles, allowing astronomers to map a region of the sky in submillimeter wavelengths. They were able to detect the dust-enshrouded galaxies that were obscured by optical wavelengths.

"The recent submillimeter observations have opened up an exciting new era in cosmological exploration comparable to that which occurred with the restoration of image quality with the Hubble Space Telescope," Richard Ellis, the director of the Institute of Astronomy at the University of Cambridge in England, said in a statement.

The British team, led by David Hughes, examined the Hubble Deep Field where the optical orbiting space telescope had taken its best pictures. The American and Japanese astronomers, headed by Amy Barger, concentrated a region called SSA13.