jun 1, 240 BC - Earth's Circumference

Description:

This marks the year that the Earth's circumference was first measured, with Eratosthenes of Cyrene being the one to accomplish it. He came to realize that if he knew the distance between two cities, Alexandria and Syene, then he could approximate the circumference of the Earth, and his method worked very accurately. While there is some disagreement on the distance of Eratosthenes' calculations, swinging wide between 24,000 and 29,000 miles, the Earth's circumference has been found to be 24,900 miles, which isn't that far off from the lower end of the debated range. As such, Eratosthenes' calculation of the Earth's circumference was a major milestone in mathematics, and the method he used for his approximation is still in use to this day.

Added to timeline:

Date: