(276-195BC)
Eratosthenes was a Greek mathematician who used his skills in the world of astronomy. He was the first person to begin thinking about the geography and size of the Earth. This motivation led him to literally discovering the circumference of the Earth using two poles in different cities, sunlight, and some simple calculations. The number he found was between 39,690KM and 46,620KM. This number is still fairly accurate to even today's technological standards.
A model showing Eratosthenes' experiment. Eratosthenes was the first to devise such an experiment, and it proved largely successful even to this day!
