Astrophysicist Neil deGrasse Tyson, 67, explained how any alien visitor from another planet would likely look very different ...

The government gave no analysis of the files, suggesting it is up to Americans to draw their own conclusions.

New government UFO files reveal Apollo 17 astronauts saw 'Fourth of July' like flashes and other strange phenomena during a 1972 mission to the moon.

Videos in this batch show unidentified aerial phenomena but offer few clues to existence of alien life ...