Eratosthenes' experiment to measure the radius of the Earth was replicated. A gnomon was constructed and its shadow length was measured at midday along with the sun's angle. Calculations using the shadow length, sun's angle, and distance between measurement points allowed students to determine the circumference and radius of the Earth, replicating Eratosthenes' original experiment from over 2000 years ago.

1. Measurement of the radius of the Earth
Level: 3º ESO
Group: 3º Bilingual
Work Group: ______________________________________________
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1. Eratosthenes’s experiment

2. 2. Experiment at I.E.S. Llanes (26th March 2009).
3. Making a gnomon.
What it is and what it is for:

3. Drawing to explain how we used it:
Report: How we made the gnomon

4. 4. Writing down data at the School playground.
5. Calculation of the distance to Parallel 40°
a) With an Atlas :
b) Taking into account the Meridian
c) Taking into account the Parallel
6. Calculation of the angle of sun rays
MEASURMENT SHADOW LENGTH TIME

5. a) Measuring the Tangent
b) Measuring on the place with a protractor
7. Photo gallery

6. a) Measuring the Tangent
b) Measuring on the place with a protractor
7. Photo gallery