aug 24, 271 BC - Greek mathematician and geographer Eratosthenes
Description:
proved that the Earth was round, and made a remarkably accurate calculation of its circumference and its tilt (as well as devising a system of latitude and longitude, and, possibly, estimating the distance of the Earth from the Sun).Added to timeline:
Date:
aug 24, 271 BC
Now
~ 2299 years ago