Tuesday, September 20, 2011

Noon Day project measurements begin this week- September 19, 2011

Carl Sagan tells the story (6.5min)
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.
Doing the measurements
Follow me on Twitter (Hashtag #noondaymeasure) as I recreate the experiment that Eratosthenes did. I hope to do my measurements on September 22 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.


  1. Rain, clouds continue to postpone my measurements.

    As of today there are 39 participating classes from Australia (1), Canada (1), France (7), India (9), Malaysia (2), Philippines (4), Romania (1) and USA (14).

    One class in Australia has posted their data.

    The weather doesn't look good for me for at least a couple of more days. Fortunately, the measurements are still relatively accurate for a least another week. Even if you do them later than that you can compensate for the passage of time with a little bit of math.

  2. I can't believe that its Oct 4th already and I still haven't seen any direct sunlight at the time of day when the sun is highest in the sky. The forecast is for sunny weather, so I hope to measure on Thursday 11/6. In the meantime 69 classes have signed for the project from the following countries: USA (23), Poland (12), India (9) France (7), Phillipines (5), Malaysia (3), Venezuela (2), Romania (1), Puerto Rico (1), Canada (1) and Australia (1) and 13 of them have posted their data.
    It's still not too late to join in the fun. Since I'm also measuring late, I'll share my strategy for compensating for the late data with you after next Thursday. I'm looking forward to seeing the sun. It's been a while.

  3. I did my measurements on Thursday 10/6/11 at high noon (sun at its zenith) and got 46 degrees for my sun angle. Usually if I do the measurement at the equinox (~9/21) it is closer to 41 degrees which just happens to be my latitude. The fact that my sun angle is now 5 degrees bigger that it was on 9/21 tells me that the lengths of my shadow are getting longer due to the fact the the sun does not reach as high in the sky as as it did at the time of the equinox which is what happens as we move closer to the winter solstice when the shadow length at "high noon" peaks.

    If you would like to learn more about the Noon Day project you can send me an email at ihor@dmcpress.org and/or read my article in L&L-ISTE