The Panama Canal, opened in 1914, required the excavation of 170 million cubic meters of earth.

The Sahara Desert is roughly the same size as the continental United States.

The Sahara Desert experiences dramatic temperature changes.

The Earth is about 4.5 billion years old.

Mount Everest is not the closest point to space — that title goes to Mount Chimborazo in Ecuador due to Earth's equatorial bulge.

The Great Wall of China spans thousands of miles.

The Himalayas continue to rise due to tectonic movement.

The Caspian Sea is the world's largest inland body of water and is classified as a lake despite its salt water.

The longest cave system in the world is Mammoth Cave in Kentucky.