Some folks have a kind of middle-torso bulge known affectionately as "love handles." Well, if you are such a person, take heart: the entire planet suffers from this same indignity. In fact, any rotating body will have a tendency to bulge in the middle, as long as it’s made of a non-rigid substance. A spinning bowling ball stays round, but not a spinning water balloon. Though it seems pretty solid to us, the earth qualifies as a non-rigid body. Considered from a far-enough vantage point, Earth’s molten interior, its oceans, and its shifting plates make it more like a water balloon than a bowling ball. And sure enough, the earth’s spin causes it to bulge.