Are we alone in the universe? Consider mysterious "extraterrestrial" radio signals. Unexplained gases on other planets.

Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.” – Arthur C.

One pilot's offhand description in 1947 started a national obsession that never quit.

From the Greys to the Nordics, these aliens appear frequently across abduction stories and science fiction tales.

Vanity Fair reports from the Capitol Hill conference, where members of a sprawling community of national security experts and ...