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
Mars had an oxygen-rich atmosphere around 4 billion years ago
13
There are 5 to 10 times more stars in the known Universe than there are grains of sand on all the world's beaches, but a single grain of sand has more atoms than there are stars in the known Universe.
20
41% of the moon is not visible from earth at any time.
103
The Earth gets 100 tons heavier every day due to falling space dust.
673
The last time that the Sun was in its current position in space around the Milky Way, dinosaurs ruled the Earth.
10
The heart of an astronaut actually gets smaller when in outer space.
216