Human life could exist on up to 1,000 planets a leading British professor of astronomy has told an Irish conference.

Professor Ian Morison is professor of astronomy at Gresham College in London and has been studying the universe for over forty years, using radio telescopes. He was speaking at the Sligo Institute of Technology.

He explained that intelligent life is likely to be very rare with the human race probably making up the only one of its kind in this  galaxy.

 He said the most optimistic astronomer would admit that life could exist on no more than 1,000 planets in the universe.After 60 years of actively searching for signs of extraterrestrial intelligent life scientists and explorers have found nothing.

His tall was entitled "Are we alone? The Hunt for Extraterrestrial Intelligence" as part of Science Week Ireland.

Despite this, he added that more simple forms of life such as single celled organisms and bacteria are probably fairly widespread. He suggested that even somewhere as close as Mars may have living organisms hidden under its surface or perhaps evidence of extinct simple life from the past.

Following recent discoveries that Europa, Jupiter’s moon, has a liquid water ocean, it is very possible that simple life might be found there, as this would be the ideal environment for its development.

Prof Morison was involved in a collaborative effort to search for extraterrestrial intelligent life between 1998 and 2003. The study, known as "Project Phoenix” undertook 820 distant star systems but still obtained no evidence of the existence of alien intelligence.

The problem is that the distance between us and distant galaxies make it extremely unlikely that the presence of extraterrestrials living in distant galaxies will ever be confirmed.

Morison pondered the question; "Somewhere out there an ET will exist, but the question is will we be close enough to find him?”