The idea that aliens may have visited the Earth is becoming increasingly popular. Around a fifth of UK citizens believe Earth has been visited by extraterrestrials, and an estimated 7% believe that they have seen a UFO. The idea that aliens may have visited the Earth is becoming increasingly popular. Around a fifth of UK citizens believe Earth has been visited by extraterrestrials, and an estimated 7% believe that they have seen a UFO. Astrobiology Phys.org – latest science and technology news stories