jun 21, 240 BC - Measuring the Circumference of the Earth
Description:
The achievement that Eratosthenes was best know for was measuring the circumference of the earth. He did this by using 2 shadows (A well and a pole) in Syene (now know as Aswan) and Alexandria. It is believed that he did this in 240 BC based on an astronomer named Cleomedes crediting him with doing it. We also know that he calculated the circumference between June 20 - 22 because that is the summer solstice which means the sun would be directly above the well.Added to timeline:
Date:
jun 21, 240 BC
Now
~ 2267 years ago