There are up to 38,000 alien civilisations with the potential to make contact with Earth, scientists at Edinburgh University have claimed.

The researchers have predicted there are likely to be at least 361 inhabited planets in the Milky Way, but say there could be more than 37,000.

Building upon developments in the Drake equation, a formula devised byUS scientist Dr Frank Drake in the 1960s to estimate the number of civilizations in our galaxy, the team examined the combination of stars and planets needed to form a life supporting solar system, and the likelihood of life surviving long enough to develop into an intelligent civilisation.

Taking a new approach, they constructed computer model of the galaxy which was then subjected to certain hypotheses in order to ascertain the likelihood of extraterrestrial life existing on other planets – with interesting results.

The first scenario assumed that it is difficult for life to be formed but easy for it to evolve, and suggested there were 361 intelligent civilisations in the galaxy.

A second scenario assumed life was easily formed but struggled to develop intelligence. Under these conditions, 31,513 other forms of life were estimated to exist.

The final scenario examined the possibility that life could be passed from one planet to another during asteroid collisions, which gave a result of 37,964 intelligent civilisations in existence.

Duncan Forgan, who led the study, points out that picture the team have developed is still incomplete. He also makes the point the alien civilisations could be totally unrecognisable to us: "Life on other planets may be as varied as life on earth and we cannot predict what intelligent life on other planets would look like or how they might behave."

A further impediment to confirming the team's hypothesis is the distance these civilisations could be from our planet – even if communication was possible it could take them 30,000 years to make contact.

With previous studies putting the number of possible intelligent civilisations anywhere between less than one and a million, this study has important implications for our understanding of the likelihood of life beyond the solar system.

The study was funded by the Science and Technology Facilities Council and Scottish Universities Physics Alliance, and is published in the International Journal of Astrobiology.