An ancient Greek astronomer named Eratosthenes was the first man to measure the size of the Earth accurately. His method was very simple: he measured the angle made by a shadow cast from a vertical st...An ancient Greek astronomer named Eratosthenes was the first man to measure the size of the Earth accurately. His method was very simple: he measured the angle made by a shadow cast from a vertical stick in two different cities on the same day and time. With the help of another teacher, you can recreate Eratosthenes’ experiment and your students can measure the size of the Earth for themselves! All you will need is two yardsticks, a protractor, a magnetic compass, and a bit of string.
