Science Buddies: "Ask an Expert"

Hi,
My question is how do you measure the circumference of the earth? I been having trouble figuring it out? If you can help I would appriate it and Thank you.

If you do a Google search on "measure the circumference of the earth" you will find many references to the first attempt to measure this by Eratosthenes in ancient Greece, as well as the many refinements in measuring techniques that have occurred since then.