How Big Is the Earth? Eratosthenes Figured It Out With a Shadow 2,200 Years Ago With Just a Stick!

About 2,200 years ago, with no plane and no satellite, Eratosthenes measured the whole Earth with a stick and its shadow. Two cities about 800 km (500 miles) apart, one small angle of 7.2°. How close did he get? JOIN OUR MATH COMMUNITY 👇    / @think_again_tv