During our journey in Crete we calculated the distance Earth -Moon with a coin and our dear friend Thales:

The problem was : 

"Hold a coin at arm’s length so that it perfectly hides the Moon.

Deduce the distance Earth- Moon given the ratio of the Moon to the Earth is around 1:3."

We took a coin and extended our arms with the coin in our hand. We're measured the distance between our eyes (point O) and the coin (AB). We had to cheat a little because the smallest coin we had was too big! We aligned two persons and found 1.4 meters.
 

 

Then we measured the diameter of the coin (0.016 m) and searched for the diameter of the Moon on the Internet.

 

                     

We looked for the value of the segment MN.We knew: lines (DO) and (EO) intersect at O. Lines (AB) and (OF) are parallel. We used the intercept theorem, also sometimes called Thales' theorem :

The distance between M and N is almost the same as between O and E.
We can conclude that the distance which separates the Earth and the Moon is approximately 303 975 000 meters,
This is about 303 975 kilometres.

Eulalie

 

Thales was born in Milet, in -624 BC and he died in the same city in -547 BC.

More than a simple mathematician, Thales was a universal scholar, curious about everything, astronomer and philosopher, and very observer.

Thales would have learnt his knowledge in geometry of his travels in Egypt.

He invented the process to calculate the height of pyramids; he stood his cane vertically, and noticed that the length of the shade of its cane was exactly equal to its height, and he deducted that from it he should be the same for pyramids.

 

 

 

 

 

 

 

 

 

Myrtille