The population of the Earth has more than doubled since 1950.
151
All of the Earth's continents are wider at the north than in the south - and nobody knows why.
194
An organisation called Mars One is planning to establish a permanent colony of humans on Mars by 2023.
9
A comet's tail always points away from the sun.
2
Jupiter is bigger than all the other planets combined.
254
It 'snows' metal on Venus.
13
There are approximately 3,500 astronomers in the U.S. - but over 15,000 astrologers.
124
