NASA's Unexplained Files

Strange, flying objects have been caught on NASA's cameras and astronauts have reported seeing UFOs.

A chunk of the sun seems to have vanished and a dark craft appears beneath the Shuttle Endeavour.

A distant planet shows evidence of an Earth-like atmosphere, while a light suggests the impossible.

Could spaceships be powered by atomic bombs? Can artificial rings encircle an entire star?

What could make a NASA astronaut report seeing a flying saucer above a US Air Force test range?

Images of Mercury show large spider-like formations on its surface; A classifed space shuttle mission almost ends in disaster.