How Would You Measure The Circumference of Earth

  Have you ever wondered how large our world is?
One of the earliest attempt to measure our Earth was made made by Eratosthenes, a Greek
Mathematician ,about 2,300 years go.The Earth is obviously large for anyone to measure
using a tape or piece of string.so howdoes we measure the circumference of our Earth.
  Eratosthenes did this by determining the angle of th sun from 2 different places .Then he measured th distance between the 2 places.Using these measurement,and advanced knowledge of
geometry and mathematics,he measured th distance around the globe was between
28,000and 29,000 miles(45-47,000 Km)
     That was awfully close to thecorrect values of about 24,860miles(40,008Km)