Space travel is all well and good, but returning home to Earth provides another set of problems. Get ready to be quizzed about Yuri Gagarin's crash landing, cutting-edge shuttlecraft, and orbital space flight. Your quiz starts now...

Strange flying objects have been caught on NASA’s cameras and astronauts have reported seeing UFOs. Some 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 seen 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 Space Shuttle Endeavour. Hubble spots thousands of unidentified objects traveling faster than light. Are we being watched?

A distant planet shows evidence of an Earth-like atmosphere, while a mysterious light suggests an atmosphere on the Moon. Have we found evidence of a crashed alien ship in the asteroid belt? 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?

What could make a NASA astronaut report seeing a flying saucer in the skies above a US Air Force test range? How have the swirling gases of Saturn formed a perfect Hexagon that has hovered above the planet’s pole for 30 years?

Scientists explore how the universe might have developed.

One astronomer believes she may already have heard alien communication.

Some strange-but-true phenomena may make time travel a reality.

Morgan Freeman explores how life as we know it was created.

Hadron Collider findings could validate theories about what we are made of.

Black holes are the most-powerful objects in the universe.

Today, scientists think the universe is primarily made of dark matter.