Is it possible that extraterrestrial beings visited our ancient ancestors? Known Universe: Decoding the Skies : http://channel.nationalgeographic.com/series/known-universe/4502/Overview Subscribe: http://bit.ly/NatGeoSubscribe About National Geographic: National Geographic is the world's ...

What would aliens on other planets actually look like? Subscribe: http://bit.ly/NatGeoSubscribe About National Geographic: National Geographic is the world's premium destination for science, exploration, and adventure. Through their world-class scientists, photographers, journalists, and ...