The Amazing Greeks! Eratosthenes It wasn’t until the mid-20th century that we managed to launch satellites into space and determine the exact kilometers of the circumference of the Earth: 40,030.2 kilometers. But how, then, could the ancient Greek mathematician, Eratosthenes, manage to find pretty much the exact same number, without having any pictures of Earth from space or even proper measuring tools? Amazingly, Eratosthenes didn’t have much more than a stick and his brain when he made the ama