Airports that are at higher altitudes require a longer airstrip due to lower air density.
39
The gas that gives rotten eggs their distinctive foul smell may slow ageing and block damaging chemical reactions inside cells, according to scientists in China.
5
Optical illusions occur when what the eyes see conflicts with what the brain expects.
75
Sound travels about 4 times faster in water than in air.
408
Your brain is 80% water.
525
Because heat expands the metal, the Eiffel Tower always leans away from the sun.
79
A cubic yard of air weighs about 2 pounds at sea level.
31