When you walk down a steep hill, the pressure on your knees is equal to three times your body weight.
199
Stephen Hawking once tried to find potential time travellers by throwing a party and only sending out invitations after the party.
17
4.5 pounds of sunlight strike the Earth each day.
27
Airports that are at higher altitudes require a longer airstrip due to lower air density.
39
Stannous fluoride, which is the cavity fighter found in toothpaste is made from recycled tin.
65
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
Scientists aren't sure what color dinosaurs were.
312
The average temperature at 40,000 feet above sea level is -60 F.
56