Many US sightings peak at a time of space milestones such as the first space probe to Mars and the first landing in the Moon, Prof Impey said. 'Astronomers are looking for physical evidence - reproducible evidence - and this is really in short supply in this field.' These things are well known to astronomers but not to other everyday observers. He said this is probably a combination of 'psychology, wishful thinking and being slightly deluded by familiar things in the night sky'. He agreed that per capita reporting of UFOs in the United States is very high in comparison with other countries. He said he is amused by claims aliens are already on Earth but are concealing themselves and describes such claims as part of the conspiracy theories that are prevalent these days. I think he was onto something when he did that and that's why those movies resonate.' 'It's a psychological phenomenon, a spiritual phenomenon if you like. 'We have elevated aliens to this high status of a modern religion and we've invested them as a repository of our hopes and our fears and our dreams and our longings. Modern media - including hit movies such as ET and Close Encounters of the Third Kind - drew on Biblical stories and director Stephen Spielberg was a clever film-maker who tapped into a need, Professor Impey said. He told The Weekend there is a spiritual aspect to the belief in the existence of aliens. Chris Impey is a Distinguished Professor of Astronomy at the University of Arizona and has penned eight popular science books, and he has even taught cosmology to Tibetan monks. In the wake of the chaotic American elections and a global pandemic, many people have joked that it’s probably about time aliens landed on Earth.

Listen to Chris Impey on The Weekend with Karyn Hay

Los extraterrestres existen