Edition 10 of the Astronomy On-line Newspaper

Preliminary Report About the Eratosthenes Project

The Astronomy On-Line Collaborative project invites you to measure the circumference of the Earth, using the method that the ancient Greek astronomer Eratosthenes first introduced around 200 BC.

From November 7th the project Eratosthenes started in collaboration between Danish, Greek, Italian, Czech, Finland and Sweden groups of Astronomy On-Line.

6 groups from Denmark, 21 from Greece, 1 from Italy, 1 from the Czech Republic, 2 from Sweeden and 1 from Finland participate at the moment.

The problem in that project is the bad weather in northern Europe that does not always allow measurements to be taken.

Groups in both Greece and Denmark have measured the sunlight-shadows of 1m ruler at the instant the sun passes the local meridian.

Until now we have results from three measurements that give a circumference of the Earth of 39,900 km, 41,000 km and 42,000 km - exactly what Eratosthenes found!-to be compared with the real value 40 074 km.

This coincidence is of course merely a question of luck - we estimate the real accuracy to be within 10 percent. In the method we used an ordinary Road Map to measure the North-South distance between Greece and South Denmark and not of course the camel of Eratosthenes!

Other schools are eagerly invited to join our group - estimating the diameter of our Globe.

Only equipment needed : a shadowkeeper ("gnomon") - size 1 meter or equivalent.

You only have to measure the following conditions on local Noon:

Shadow length and time for local noon. Ensure the surface is horizontally correct levelled.

When you report your measurements then also give in your location. All details are available in the main document.

Join us!

More results to appear soon!

The Erathostenes Groups with Students from Greece, Students from Denmark, Students from the Czech Republic, Students from Italy, Students from Finland, and Students from Sweden.


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Last update: Nov 17, 1996