How the Moon Affects the Shape of Our Planet
There was a time when people believed that the earth was flat. Of course, it’s not. It’s not perfectly round either, though. It’s true! Earth is an oblate spheroid. It is squished at the North and South poles and bulging around the equator. And this bulge means that from the center of the earth to sea level is about 21 kilometers (13 miles) more at the equator than it is at the poles. We have gravity — and the moon — to thank for that.
But even as a semi-sphere, the earth isn’t perfectly symmetrical. It is more of a lumpy bumpy sphere. That’s because mass isn’t distributed evenly within the earth, so gravity affects the different densities in different ways. There are some other factors that also influence the shape of our planet. Tectonic plates shift, and once in a while, meteors crash into the earth and alter the planet enough to measurably change its shape. Glaciers melt and move. The oceans eat away at and build the shores they flow between. The primary force when it comes to Earth’s shape, though, is gravity. And one of the biggest influences on this planet’s gravity is the moon. That is because the moon is Earth’s closest neighbor.
As the moon orbits Earth, gravity pulls on it. The side of the earth that is closest to the moon has a stronger gravitational pull, so it also bulges out a little more than the opposite side (the side farthest from the moon.) The results are pretty interesting. Consider this: Mount Everest is the highest point on Earth above sea level, but Ecuador’s Mount Chimborazo is actually the highest place on Earth. And it is because it sits near the equator where the moon’s gravitational pull is strongest.
