The Goal of the Noon Day Project is to have students measure the circumference of the earth using a method that was first used by Eratosthenes over 2000 years ago. Students at various sites around the world will measure shadows cast by a meter stick and compare their results. From this data students will be able to calculate the circumference of the earth.
Watch as Carl Sagan describes some of the background surrounding Eratosthenes' experiment in this 6 1/2 minute video.
Follow me on Twitter (Hashtag #noonday) As I recreate the experiment that Eratosthenes did. I hope to my measurements on March 17 weather permitting.
There is some good background material on the measurement at the Noon Day project site hosted by the CIESE (Center for Innovation in Engineering & Science Education) - Stevens Institute of Technology in Hoboken, NJ.