Add Yahoo as a preferred source to see more of our stories on Google. Donald Trump's pledge to release official files relating to UFOs has intrigued conspiracy theorists who suspect the US government ...

A NASA image from Mars has reignited an old question online: are some of the strange patterns on the Red Planet really signs ...

Elon Musk has turned a long-running joke about being an extraterrestrial into a central part of his public persona, even as he argues that humanity may be the only intelligent life in the universe.