Big Bang: The Universe was created between 10 billion and 20 billion years ago from a cosmic explosion. Called the Big Bang, this theory explains why distant galaxies are travelling away from us at great speeds and why the universe is expanding all the time.

Eye on Sky: Man has been fascinated by the heavens and stars from the earliest times. Some of the oldest written material on astronomy came from Egypt, China and Mesopotamia (circa 3000 BC).

Greek Geek: As early as 6th century BC, Greek mathematician Pythagoras speculated that the earth is a sphere.

Awesome Neptune: It takes the earth 365 days to revolve around the Sun, right? But since its discovery in 1846, Neptune, the 8th planet in our solar system, has made only about three-quarters of one revolution around the Sun.

The Sun Next Door: The Sun is 93 million miles from earth. But it’s still 270,000 times closer than our next nearest star Proxima Centauri!

Space Jaunt: The Universe is such a huge place — we have only just explored a tiny corner of it. Our own galaxy Milky Way is 100,000 light years across. (1 light year is 10 trillion km). So to explore just this one galaxy we’ll need much more advanced spaceships than we have now. Scientists say future modes of superfast space travel — capable of shooting us across light years at mind-boggling speed — may include solar sails, ion engines, nuclear-powered spacecraft, or, believe it or not, space elevators!

Looking for ET: The search for life in outer space began way back in 1960. There is the Search for Extra-Terrestrial Intelligence (SETI), in California, US, that trains its highly sensitive radio wave receivers to pick up signals from aliens from distant planets. So far, no one has called in.

It’s A Bird, It’s A plane, It’s A UFO! We haven’t got proof of the existence of ETs yet. But, hey, there are plenty of fascinatingly mysterious alien-related stuff around to chew on. There have been loads of UFO (Unidentified Flying Object) sightings, for instance. (There was one in Calcutta recently!) In the most famous incident of them all, in 1947, in Roswell, New Mexico, US, certain debris of a “flying object” were recovered. The US military claimed a top secret research balloon had crashed. But many people believe that actually, an alien spacecraft had crashed and that the government had tried to cover it up.

Mars Attacks! On October 30, 1938, a radio dramatisation of H.G. Wells’s The War of the Worlds, directed by Orson Wells, had thousands of people in New York rushing out of their home and fleeing in terror. They thought planet Earth had really been taken over by the Martians!

Man on Mars? In 1976, NASA’s Viking 1 spacecraft orbiting Mars spotted the shadowy likeness of a human face on the planet. It appeared to be an enormous head staring back at the cameras from a region of the Red Planet called Cydonia. Sadly, it turned out to be just an eroded Martian landform. But to this day, ET-lovers believe it's proof that life existed on Mars once.

Space Junk: There are thousands of pieces of debris flying around the earth — bits of waste from all the satellites, space shuttle launches, probes etc. They hurtle around the globe at speeds of up to 25,000 miles per hour. NASA frequently has to replace windows on the space shuttle that have been damaged by objects as small as a flake of paint. Do we have to pollute the environment wherever we go? That’s something for you to ponder when YOU become an astronaut.