One of the first people to make a very accurate measurement of theĬircumference of the Earth was Eratosthenes, a Greek philosopher who Their data is publicly available and can be used for our purpose.Measuring the Earth's Curvature Activity II This website attempts to pair two schools from around the world and help them redo the Eratosthenes experiment as a teaching aid. You can do the calculation yourself without any traveling by using the data provided by. Their outcome will vary a lot even though this experiment does not demand high precision and accuracy.įrom this fact, we can easily conclude the Earth is spherical, not flat. It is not a coincidence that not a single flat-Earther can give us the exact distance to the Sun. The flat-Earth model cannot explain this phenomenon.įurthermore, the flat-Earth model will not produce a consistent result. We can also observe that in near-polar locations, the experiment will result in a very long shadow. On the other hand, using the spherical Earth model, the length of the shadow has a non-linear response. Using the flat-Earth model, the length of the shadow will have a linear response. But we can easily modify his experiment by making measurements in three or more places, and the flat-Earth model is instantly proven wrong. Using the flat-Earth model, they concluded that the distance to the Sun is only 3000-5000 km (1850-3100 mi).Įratosthenes did his experiment by taking measurements in two locations: Alexandria and Syene. Assuming the Earth is flat and sunrays are not parallel, we can determine the distance to the Sun (left picture).Assuming the Earth is spherical and the Sun is very far, we can determine the circumference of the Earth (right picture).

They say the experiment can be applied to the flat-Earth model.įrom the diagram above, both of these statements are right: He did the measurement in Alexandria and timed it to coincidence when the Sun is directly overhead Syene.Ģ222 years after that, some flat-Earthers tried to refute the Eratosthenes experiment. In 205 BC, Eratosthenes successfully determined the circumference of the Earth by measuring the length of the shadow cast by a rod.

Eratosthenes flat earth