NASA's Unexplained Files

The Sun's Evil Twin. Witnesses photograph two suns in the sky over Indonesia - is this the first sighting of the Sun's dark twin that could spell imminent danger to Earth?

Secret Aliens. Geologists discover alien deposits on the Earth's surface - and the answer could shed light on the cause of the greatest extinction in its history.

Stonehenge On Mars. A NASA probe captures an image of a familiar structure on the surface of Mars. What made 'Mars Henge'? Plus, how did an Apollo astronaut get sick on the Moon?

The Sun's Evil Twin. Witnesses photograph two suns in the sky over Indonesia - is this the first sighting of the Sun's dark twin that could spell imminent danger to Earth?

Secret Aliens. Geologists discover alien deposits on the Earth's surface - and the answer could shed light on the cause of the greatest extinction in its history.

Stonehenge On Mars. A NASA probe captures an image of a familiar structure on the surface of Mars. What made 'Mars Henge'? Plus, how did an Apollo astronaut get sick on the Moon?

CIA's Secret Revenge. When the Soviet Union unveils its own space shuttle, the CIA hatches a revenge plot. Plus, a missing nuclear weapon could threaten a NASA base in the Arctic.

Saturn's Death Star. A NASA spacecraft suffers a malfunction in orbit - can its lone astronaut make it back to Earth? Plus, new evidence emerges over Yuri Gagarin's mysterious death.

CIA's Secret Revenge. When the Soviet Union unveils its own space shuttle, the CIA hatches a revenge plot. Plus, a missing nuclear weapon could threaten a NASA base in the Arctic.

Saturn's Death Star. A NASA spacecraft suffers a malfunction in orbit - can its lone astronaut make it back to Earth? Plus, new evidence emerges over Yuri Gagarin's mysterious death.

Pluto's Stranger Things. Did Apollo astronauts hear unexplained transmissions on the far side of the moon? Plus, an astronomer spots a strange disturbance in Martian atmosphere.

Rise Of The Planet Killer. Apollo 12 astronauts bring back something alive from the moon. Plus, NASA track an asteroid heading towards Earth and make a shocking discovery.

A President's Close Encounter. Geysers are discovered on a frozen moon, NASA redirects a probe on a mission to find proof of life, and a future US President is eyewitness to a UFO.

The Earth Next Door. Astronomers detect a potentially habitable planet tantalizingly close to Earth. A chance discovery at NASA reveals a top secret military space program.

Curse Of The Full Moon. Two cosmonauts fight for their lives, trapped inside a capsule in a frozen lake. NASA astronomers are spooked when the full moon affects their experiments.

Did Earth Have Two Moons?. A startling discovery suggests the hellish clouds of Venus may be the origin of life on Earth. Plus, did the Earth once have two moons?

Mystery Of The Invisible Planet. A probe mysteriously malfunctions as it enters deep space. Astronomers find evidence of an invisible planet in a distant solar system.

Did Earth Have Two Moons?. A startling discovery suggests the hellish clouds of Venus may be the origin of life on Earth. Plus, did the Earth once have two moons?

Mystery Of The Invisible Planet. A probe mysteriously malfunctions as it enters deep space. Astronomers find evidence of an invisible planet in a distant solar system.

The Earth Next Door. Astronomers detect a potentially habitable planet tantalizingly close to Earth. A chance discovery at NASA reveals a top secret military space program.