spacedaily.com
Around 240 BCE, the Greek mathematician Eratosthenes calculated the circumference of the Earth using only two sticks, two cities in Egypt, and the angle of their shadows at noon on the summer solstice — and his result came within about 2 percent of the modern measurement, in one of the most elegant pieces of reasoning in human historyEratosthenes of Cyrene, born around 276 BCE in what is now Libya and serving from his mid-thirties onward as the third chief librarian of the great Library of Alexandria, performed one of the most consequential calculations in the history of science with a pencil, a stick, and an idea. The idea was that the Earth […]
