Polling shows that nearly half of Americans now believe aliens have visited this planet—and that the number who aren't sure ...

Giorgio A. Tsoukalos talks about the Alien Astronaut Theory & the new episodes of "Ancient Aliens" on The History Channel.

Everyone loves a good alien invasion story, preferably one with city-sized ships and physics-defying tech. There's just one big problem with that. The Milky Way is estimated to contain 100 to 400 ...