Eratostheness
How long the earth’s circumstance?
Geometry sun’s position
Plato “The earth’s circumference is 400,000 stadia.”
≒ 74,000
1 stadium = 185m
True Circumference is 40,000 Km
Plato’s guess was 85% larger than the true circumference.
Archimedes: circumference of Earth is 300,000 stadia
Archimedes: Look at the geometry of a sphere and find a clever way to calculate the circumference
