More than a dozen men have stood on the surface of the moon, but only three have been to Challenger Deep in the Marianas Trench, the deepest known spot in the ocean.
17
An earthquake on Dec. 16, 1811 caused parts of the Mississippi River to flow backwards.
243
The warmest temperature ever recorded on Antarctica was 3 degrees F.
175
Even Antarctica has an area code. It's 672.
58
The Amazon rainforest produces more than 20% the world's oxygen supply.
182
In one day, a full grown redwood tree expels more than 2 tons of water through its leaves.
56
One cubic mile of seawater contains about 50 pounds of gold.
79
The North Atlantic gets 2.5 centimetres (1in) wider every year.
119