This view of Australia's Lake Eyre was taken by the space shuttle in 1990. The lake covers about 3,600 square miles and is the lowest point in Australia at about 50 feet below sea level.

The Lena River, some 2,800 miles long, is the easternmost of the three great Siberian rivers that flow into the Arctic Ocean and is one of the largest rivers in the world.

High above the African continent, tall, dense cumulonimbus clouds, meaning 'column rain' in Latin, are the result of atmospheric instability.