Eratosthenes Experiment 2015

Eratosthenes Experiment 2015

Welcome to the Community for the Eratosthenes Experiment 2015-19 for the Measurement of the Earth's Circumference! For details on the event and the latest photo contest, please see here and here.

Guidelines for participation 


  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 the Stellarium software to calculate your local noon at your location can be found here).
  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 lengthofthestickto make sure it is one meter long.

  3. At the time scheduled to conduct the experiment, ask your students to measure the length of the stick’s shadow. Repeat the measurement 5 times and write their values down in the form found in the Submit Your Data area in the website.(this area will be activated on the day of the Eratosthenes Experiment, 24/09/2018).

  4. Provide to the students thevalue for length (L)ofthethirdsideofthetriangleinthepicturebelow or ask them to calculate it themselves by using the Pythagorean Theorem (L2=S2+H2). Write the value in your notebook.

  5. 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 can be found here). Provide the students withthevalueofthis distance between the two schools. Write the value in your notebook.

The experiment will take place on the 23rd of September 2019. 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 data using your Eratosthenes website account. If you dont have one already. you can create easily here


Created on: 04.03.2015
Last visited: 12.08.2022