Between the Earth and the Moon

This video is interesting because it shows an estimation error that seems to be quite common, and that may have its origin in the education we receive.

In the video people are handed 2 balls and asked to represent the relative distance between the Earth and the Moon.

(via En Resumidas Cuentas, amazing.es and above all Recuerdos de Pandora)

The diameter of the Earth (which can be calculated with a simple experiment) is approximately 12,700 kilometers.

There is roughly one light-second between the Earth and the Moon (light takes one second to arrive from the surface of the Earth). Since the speed of light is 300,000 kilometers/second, that gives us a distance between Earth and Moon of about 24 Earth diameters.

Basketballs have a diameter of 24 centimeters, so the distance between the representations of the Earth and the Moon would be 5.76 meters. That is 7 or 8 steps, depending on the person’s height (the presenter takes 10 steps).

Some illustrations of the Earth-Moon distance that lead to this mistake: