Around 240 BC, Eratosthenes, a Greek mathematician, calculated the Earth’s circumference from Alexandria, Eygpt. Eratosthenes’ experiment was one of the most important experiments in antiquity and his calculation of the earth’s size was accepted for hundreds of years afterwards. It was, in fact, the most accurate estimate until humans were able to go to the Space.

To repeat this historical experiment in the framework of International Year of Light (IYL2015), Cosmic Light project, groups in Alexandria, Egypt and Andinean Region in South America invite students and schools around the world to take measurements between 15 to 17 June 2015.

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