How Did the Greeks Figure Out the Size of the Earth?
The Greek Eratosthenes, who lived around 250 B.C., was the first man we know of to figure out the size of the earth. Yet he never traveled around the earth, nor did he have any of today’s measuring equipment. How, then, did he do it? Eratosthenes used Euclid’s principles of geometry to solve the problem. First he learned that at
