From the Earth to the Moon in 270 BC

e=mc2andallthat

The brain is wider than the sky,

For, put them side by side,

The one the other will include

With ease, and you beside.

Emily Dickinson

How did human beings first work out the distance from the Earth to the Moon?

Aristrarchus of Samos (310 BC – 230 BC) figured out a way to do so in terms of the radius of the Earth in 270 BC. Combined with Eratosthenes’ measurement of the radius of the Earth (c. 240 BC) it enabled people to calculate the actual distance to the Moon. The ancient Greeks used a measurement of distance called stadia (singular: stadium) but we will present the measurements here in terms of kilometres.

Magic with a shadow, not with mirrors

Aristarchus used the fact that the Moon passes through the Earth’s shadow during a total lunar eclipse, which happen once every two to three years on average.

What…

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About e=mc2andallthat

Gethyn Jones BSc, PGCE, MCCT is a physics teacher of over 29 years experience who still enjoys teaching (well, most of the time anyway). He lives in London with his lovely wife and two rescue cats. Please follow him on Twitter @emc2andallthat
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