Eratosthenes Experiment 2019

The English School, Cyprus and EMP-CELP School, Mozambique share experimental data to work out the circumference of the Earth.

Many cultures realised that the Earth was round thousands of years ago.  In 240 B.C., the Greek astronomer Eratosthenes made the first reliable measurement of the Earth’s circumference by comparing shadows formed in the cities of Alexandria and Syene.

The Astronomy Club conducted a similar experiment on 21st March, which is a special day called the “Vernal(Spring) Equinox.” At equinox the Sun shines directly on the equator and the length of day and night is nearly equal. 

We contacted the EMP-CELP school on the other side of the equator in the capital of Mozambique, as they share a similar longitude to The English School and they joined us as part of the project http://eratosthenes.ea.gr/ to perform the experiment and share data. 
By measuring the size of the shadow of a 1-metre stick at local mid-day at both schools and then using simple trigonometry we figured out that the circumference of the Earth from pole to pole is 39200 km with an uncertainty of 2.2%. 

We are pleased to say that this overlaps with the accepted value of 40 008 km https://www.space.com/17638-how-big-is-earth.html.

The Astronomy Club will carry out the experiment again on September 23rd on the Autumnal Equinox and we will attempt to share data with more schools on our longitude.
If you are interested in participating, please contact Ms. Katie Demetriou or any member of the astronomy club.  

Here is a link to the article written by   EMP-CELP School, Maputo, Mozambique http://www.epmcelp.edu.mz/index.php/noticias/140-maos-na-ciencia/2049-ciencia-da-teoria-a-pratica-alunos-redescobriram-que-a-terra-e-redonda

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