Iron weighs more after it rusts.
16
Airports that are at higher altitudes require a longer airstrip due to lower air density.
39
Approximately 70 percent of the earth is covered by water. Only 1 percent of this water is drinkable.
65
Columbia University has developed an artificial tree that passively soaks up carbon dioxide from the air using "leaves" that are 1,000 times more efficient than true leaves that use photosynthesis.
15
A cubic yard of air weighs about 2 pounds at sea level.
31
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