Out there, in the night sky, you can see a bunch of twinkling stars with your naked eye, or in my case, with my prescription eyeglasses on my face. Our atmosphere makes them twinkle. In space they don’t twinkle.
They twinkle, and they move too. Really quickly it turns out. Right across the sky in a big arc.
I tried to look at Saturn once through an ordinary backyard telescope. I saw it – rings and all. However, it was moving past the field of vision with stupendous rapidity. That means really fast. You’d be surprised. I tried to photograph it, but I needed a long exposure to capture the dim light, and it came out a blur because Saturn moved. It just slid right out of view lickety-split.
Yeah, it’s in orbit around the sun and all, but that’s not the problem. The problem is our dizzying rotation around the Earth’s axis – that pesky little problem that makes a day only 24 hours. At the equator you’re traveling fast and far, and not in a straight direction. We’re spinning like a top. A man in Equador goes 24,901 miles a day at over a thousand miles per hour. In a big circle.
That spinning gyroscope known as Earth is why the sun rises and sets, why the stars spin by above us, and why I couldn’t photograph Saturn that night.
But are we affected by centrifugal force by all this spinning around and around? Well, it turns out that at the equator your weight is reduced by one third of a percent because of it. The further north or south you go from the equator, the less this effect is felt.
Additionally, the earth isn’t a perfect sphere. All this spinning around the axis has warped the shape of Earth. Our planet is fatter at the equator. We call that equatorial bulge. So somebody standing on the equator weighs 1/3 of 1 percent less because of centrifugal force, and another 1/5 of one percent being further from the center mass of the planet.
So if you’re interested in weight loss but diet and exercise isn’t your thing, go to the equator, where you’ll weigh about a half of a percent less than you do at the poles. That explains why Santa Claus weighs more at the North Pole than he would at the equator, and why he lives at the top of the world.