Mars had an oxygen-rich atmosphere around 4 billion years ago
13
The Earth weighs around 6,600,000,000,000,000,000,000 tons (5,940 billion billion metric tons)!
221
Any space vehicle must move at a rate of 7 miles per second in order to escape the earth's gravitational pull.
121
There are approximately 3,500 astronomers in the U.S. - but over 15,000 astrologers.
124
41% of the moon is not visible from earth at any time.
103
Earth is the only planet in our solar system that's not named after a god or goddess.
17
All of the Earth's continents are wider at the north than in the south - and nobody knows why.
194
The earth travels through space at 660,000 miles per hour.
189