Your brain is 80% water.
525
Only 12,000 years ago there was a species closely related to modern humans called Homo floresiensis that had been living on an Indonesian Island. They used fire and rather advanced tools, yet were only about 3 feet tall and weighed around 25kg.
15
The Earth's atmosphere weighs about 5.5 quadrillion tons.
108
It takes a photon 170,000 years to travel from the core of the Sun to the surface, but only 8 minutes to travel the rest of the way to Earth.
6
Aluminum used to be more valuable than gold!
84
For every gallon of sea water, you get more than a quarter pound of salt.
45
A cesium atom in an atomic clock beats over nine billion times a second.
43
Iron weighs more after it rusts.
68