| |
 Way Back When
The Rotation of the Earth Was Proved
 Way back when, in January of 1851, Jean Bernard L`eon Foucault (pronounced Foo-KOH) proved the rotation of the earth. He was a French physicist who was born in Paris, France, on September 18, 1819. To prove that the earth rotates (turns), he invented a device called a pendulum, which is an object that hangs from something and swings. It was already known that the earth travelled around the sun. Scientists believed that the earth spun as it circled the sun, but they had no proof.
In his experiment, Foucault hung a 62-pound iron ball on a 220-foot-steel wire. The wire was attached to the dome of the Patheon, a famous building in Paris. He made the ball swing. If the earth did not rotate, the ball would swing back and forth. If the earth did rotate, the spinning would cause the ball to travel in a circle. The ball traveled in a clockwise circle, so the earth rotated. In 1855, Foucault won the Copley Medal of the Royal Society of London for his experiment. Models of the pendulum he created are called Foucault Pendulums.
Earths rotation is why we have days and nights. As the earth turns, it seems like the sun is rising, moving across the sky and setting. Actually, the earth is moving, and areas of the globe move closer or farther from the sun. It takes 24 hours for the earth to complete a turn.
Depending on where a Foucault Pendulum is, it will rotate differently. In some areas, it will turn clockwise, but in other areas, the pendulum will travel counterclockwise. Also, the angle of how far the pendulum will lean from its suspended point will change depending on the location. As well as proving the earths rotation, Foucault measured the speed of light and helped improve telescopes.
Ashley Genova is a freelance writer from Fayetteville, NC. Source: Britannica Encyclopedia Online. http://www.britannica.com/eb/article-9035012; Britannica Encyclopedia Online. http://www.britannica.com/eb/article-9035014.
|
 |
