Happy Earth’s Rotation Day!

“Any person, brought into the presence of this fact, stops for a few moments and remains pensive and silent; and then generally leaves, carrying with him forever, a sharper, keener sense of our incessant motion through space.”–Leon Foucault

Generally speaking, holidays are created to commemorate important events or people. So a fun holiday was invented to commemorate one of the most basic facts of life on our spheroid planet–the Earth’s rotation. If the Earth did not rotate at approximately the rate it does, life as we know it would not exist.

Something that has puzzled me is the question about whether it is possible for an orbital object, like a planet, to not rotate. On the one hand we could compare such a planet to our Moon. One lunar hemisphere always faces the Earth. It appears not to rotate. In reality, the Moon’s rotational cycle equals the Moon’s orbital cycle. In other words, the Moon rotates on its axis. If the Earth behaved in a similar manner, that is, if one hemisphere constantly faced the Sun, the duration of rotation would equal the duration of the orbit. One day would equal one year. It doesn’t take much consideration to understand that our planet’s environmental dynamic would be radically different than what it is now.

Conversely, if the Earth rotated at a much higher speed, the lengths of our days and nights would be shorter. This would affect climate and weather in ways that I cannot fathom. The main difference would be that there would be more days in each year. Life would have evolved much differently if Earth’s days were much shorter in duration.

So, why was January 8th selected as Earth’s Rotation Day? It was chosen because on January 8, 1851, physicist, Leon Foucault demonstrated the theory that Earth rotates on an axis. He suspended a weighted brass sphere from the top of the ceiling of the Paris Pantheon. He noted that the plane of the pendulum’s swing rotated relative to our planet’s rotation. Nowadays, many science museums and planetariums display their own Foucault Pendulums so people around the world can witness the experiment.

To you and yours, Happy Earth’s Rotation Day!

Ciao

The Blue Jay of Happiness quotes Renaissance polymath, astronomer, mathematician and Roman Catholic canon, Nicolaus Copernicus. “I shall now recall to mind that the motion of the heavenly bodies is circular, since the motion appropriate to a sphere is rotation in a circle.”