NASA's Unexplained Files

Strange flying objects have been caught on NASA's cameras and astronauts have reported seeing UFOs. Some of the odd shapes and lights can be identified; others remain a mystery. We'll reveal NASA footage and interview the astronauts and scientists.

Astronaut Leroy Chao's spacewalk is interrupted by bright lights flying past. A flying saucer photographed from the Apollo capsule, dark shapes caught on camera shadowing the shuttle...the ideas are science fiction, but the incidents are science fact.

The Viking Lander may have found life on Mars, so why don't we know about it? What is the most destructive force in the universe? How could a Starship be spotted in the Aurora Borealis? And what are NASA's mysterious Moon Pigeons?

A chunk of the sun appears to have vanished. An ominous dark craft beneath the Shuttle Endeavour. And Hubble spots thousands of unidentified objects travelling faster than light. Are we being watched? Or could we ourselves be aliens from another world?

A distant planet shows evidence of an Earth-like atmosphere, while a mysterious glowing light suggests the impossible - an atmosphere on the Moon. Have we found evidence of a crashed alien ship on the asteroid belt, and why are there blueberries on Mars?

Could spaceships be powered by atomic bombs? Can artificial rings encircle an entire star? why was Neil Armstrong's transmission feed cut off when he spotted strange lights on the Moon? And how can lightning talk to itself?