More than a third of Americans believe in Aliens

More than a third of people in the U.S. believe aliens exist - and more than 10 per cent of the population believes they have seen an alien ship in the sky.

The study from National Geographic Channel found that 80 million Americans - or 36 per cent - are certain alien spaceship exist, and of those who believe, 79 per cent are convinced the White House has kept information about other lifeforms a secret.

If an alien knocked on the door, 22 per cent would try to befriend the alien, 15 per cent would run away, 13 per cent would lock their doors, and, reassuringly, only 2 per cent would try to inflict bodily harm.

A mock-up of a UFO flying over an American road: up to 10 per cent of Americans believe they have seen something strange in the skies

Furthermore, 55 per cent believe there are real-life Men in Black-style agents who threaten people who spot UFOs.

Brad Dancer, senior vice president of research and digital media for National Geographic, said: 'We wanted the pulse on people's opinions. 'We wanted to get a sense of how Americans view UFOs, what people believe and how mainstream pop culture may or may not be playing into their opinions on it.'

In total, 17 per cent of Americans had no belief in UFOs, 36 per cent think they do, and 48 per cent are not sure.

Turning to aliens vs politics, almost 65 per cent think Barack Obama would so a better job at an alien invasion over his opponent Mitt Romney. On a slightly less realistic note, 21 per cent would handle the Hulk, 12 per cent would call Batman, and eight per cent would call Spider-Man.

The survey was commissioned for an upcoming National Geographic Channel series, Chasing UFOs.