The winner of the Eratosthenes Photo Contest September 2019 has been announced!

Welcome to the Eratosthenes Experiment platform!

  • Register by creating your account. If you have already created one in the past, just log in and check "Yes" in the "I want to participate in Eratosthenes Experiment March 2020" participation box.
  • Come in contact with a registered school at the same longitude with you (this info will be provided to you by the organizing team)
  • Join efforts with the matching school and record your data
  • Calculate the circumference of the Earth
  • Submit your data

The Eratosthenes experiment March 2020 will take place on the March equinox day, Friday the 20th of March (see here). You can perform the experiment in collaboration with another school on the same longtitude, if no other schools can be found on the same longitude -  for your matchup – you can consider the existence of a virtual school on the equator with experimental data 0 (shade of a one-meter stick measured at local noon). This way you can also have an accurate outcome by conducting the experiment by yourself. Schools that register till Tuesday 10th of March 12:00 CET will receive on Thursday 12th of March an e-mail with the coordinates of potential matching schools along with the information (email) of their contact persons, so that they can communicate and arrange their match-up during the day of the experiment. Schools that register till Monday 16th of March 12:00 CET, will receive an email during the same day (after 16:00 CET).
If you would like to perform the experiment by yourself on a date other than the 20th of March, you can use this simulator to find the exact angle from your school to the place where the sun rays are perpendicular to the ground.
The Eratosthenes Experiment March 2020 is organised with the collaboration of the Hellenic Mathematical Society. 

The Eratosthenes Experiment is organized under the support of the International Astronomical Union (IAU) and the European project spaceEU.


Contest Winners


Ellinogermaniki Agogi
Research & Development Department
Dimitriou Panagea Street
GR 15351 Pallini


The Eratosthenes Experiment is endorsed by IAU, the European project spaceEU, OSOS Project and the Hellenic Mathematical Society





  • Dr. Angelos Lazoudis
  • Phone: +30.210.8176795
  • Email: