Interstellar space is unforgivingly vast, but the emptiness has some advantages. The lack of atmosphere means there is no aerodynamic drag.

Barack Obama's insisting the USA doesn't have little green men or alien spaceships locked up in an underground bunker somewhere ... but, if they ever visit Earth, he's volunteering to lead the ...

As the Pentagon throws open its extra-terrestrial files, Disclosure Day depicts encounters of an even closer kind.

A Pentagon release of new UFO footage has revived the question of whether aliens could realistically travel to Earth.

In a world easily startled by sensationalism, Tyson offers a cool, gentle voice of reason amid the unchecked fascination with alien visitation.