Mars had an oxygen-rich atmosphere around 4 billion years ago
13
In space, astronauts cannot cry properly, because there is no gravity, so the tears can't flow down their faces!
175
Astronomer Percival Lowell believed that he was the first person to observe canals on Venus, but because of a faulty adjustment of the eyepiece on his telescope, he was in fact looking at the blood vessels in his own eye.
4
The Earth weighs around 6,600,000,000,000,000,000,000 tons (5,940 billion billion metric tons)!
221
The temperature of the earth's interior increases by 1 degree every 60 feet down.
115
The earth travels through space at 660,000 miles per hour.
189
Earth is the only planet in our solar system that's not named after a god or goddess.
17
