There could be 36 alien civilisations in the Milky Way which are actively communicating by broadcasting radio signals into space, according to new research.
No direct evidence has been found for any intelligent extraterrestrial lifeforms, but a study led by the University of Nottingham puts a number on how many civilisations we should be looking for.
Their estimate is based on the assumption that intelligent life would evolve on other planets in the same way that it has done on Earth, and the paper is published in The Astrophysical Journal.
The research estimated the number of what the scientists call Communicating Extra-Terrestrial Intelligent civilisations (CETI) – or alien civilisations like our own which broadcast radio signals into space.
Professor Christopher Conselice, an astrophysicist at Nottingham, explained: “There should be at least a few dozen active civilisations in our galaxy under the assumption that it takes five billion years for intelligent life to form on other planets, as on Earth.”