Geometry of the Earth Long before Columbus, a Greek scholar names Eratosthenes (274-194BC) calculated the circumference of Earth by making some simple observations about shadows at noon and applying some insights from geometry. The size of Earth has been estimated and measured many time since then. The French Academy of Sciences tried to make an accurate measurement in the late 1700s in order to create a new unit of measure, the meter. They proposed to define the meter as one ten-millionth of the distance from the North Pole to the equator. Today we can measure Earth's circumference very accurately using data from satellites and making calculations on computers. The circumference at the equator is 24,901. 55 miles. Earth is not a perfect sphere, however, because its rotation c
22 centuries
20 centuries
18 centuries
16 centuries
About 20 miles
About 40 miles
About 80 miles
About 200 miles
1031 miles
1036 miles
1038 miles
1042 miles
3960 miles
4530 miles
6300 miles
7920 miles
700 miles per hour
7000 miles per hour
10,000 miles per hour
14,000 miles per hour