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This year the experiment will take place on the 21st of March, one day after the spring equinox day. Thus, for your matchup – if no other schools can be found on the same longitude- you can consider the existence of a virtual school on the equator with experimental data 0 (shade of a one-meter stick measured at a certain time). This way you can also have an accurate outcome by conducting the experiment by yourself.

Please keep in mind that we will provide you with a list of schools (and their contact persons) that are located at a longitude very close to that of your school.

Ask your students to calculate the circumference of the Earth and submit your value in the Submit Your Data area.

  1. Find the time of your local noon at your location. Please use the web-based NOAA Solar Calculator or Solar Calculator or the Stellarium software (A short guide for using theStellarium software to calculate your local noon at your location can be found here in English and in Italian).
  2. Take a one-meter stick (H= 1 meter, see figure below) and place it vertically to the ground. Ask your students to measure the length of the stick to make sure it is one meter long.At the time scheduled to conduct the experiment, ask your students to measure the length of the stick’s shadow (length S in the figure below). Repeat the measurement 5 times and write their values down in the form found in the Submit Your Data area in the website.
  3. Provide to the students the value for length (L) of the third side of the triangle in the picture below or ask them to calculate it themselves by using the Pythagorean Theorem (L2=S2+H2). Write the value in your notebook.
  4. Calculate the distance using Google Maps between your school and the school you have matched up with. (A short guide on how to perform the measurement using Google Earth can be found here in English and in Italian. An alternative method using the interactive mapmaker can be found here). Provide the students with the value of this distance between the two schools. Write the value in your notebook.
  5. In case of a cloudy weather please follow the instructions here on how to get a measurement of the Earth's circumference 

Ask your students to calculate the circumference of the Earth and submit your value in the Submit Your Data area.

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The Eratosthenes Experiment 2018 is organised with support from the European Commission in the context of the Seventh Framework Programme (FP7). This Website reflects only the views of the Ark of Inquiry consortium members, the Commission cannot be held responsible for any use that may be made of the information contained herein.



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Ark of Inquiry


  • Dr. Angelos Lazoudis
  • Phone: +30.210.8176795
  • Email: angelos@ea.gr


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