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?

Did our universe come into being by chance or was it created by a God? The latest science shows that the four forces governing our universe are finely tuned, leading many to believe that something must have calibrated them.

They are the most powerful objects in the universe. Astronomers now think there are billions of them, swallowing planets and stars in violent feeding frenzies, and that reality may take place on a two-dimensional hologram at the edge of the universe.

Einstein's Theory of Relativity says time travel is possible if you're going forward in time. But finding a way to travel backwards requires breaking the speed of light. Now strange-but-true phenomena like quantum nonlocality may make this a reality.

Cosmologists agree: our universe is 13.7 billion years old. Using cutting-edge technology, scientists can take a snapshot of the universe a mere heartbeat after its birth. But if the universe was born, where did it come from?

Everywhere we look on Earth, in the most hospitable environments and in the most extreme, we find life. Yet we have only ever found life on our planet. How did the stuff of stars come together to create life as we know it? What do we mean by 'life'?

Aliens almost certainly do exist. So why haven't we yet met E.T.? We're only just developing instruments powerful enough to scan for them. One astronomer believes she may have heard a hint of their first efforts to communicate.

Our understanding of the universe has drastically changed over the last 100 years. It's on the verge of another seismic shift from LHC findings. What we find could validate theories about how the world works and what we're made of.