Why the Earth Is Round
Our never-thought to ask question for today is: Why is the earth round? Why not a cube? A cube? No,that's silly. Is it? Why?
Because…,because really big things like to be round for some reason. Exactly right.And that reason is gravity.
Think of it this way. Suppose the earth were a cube. Then some points on its surface would be farther away from the center than others. The corners, for example, would be much farther out than the rest.
Since gravity works equally on everything, there would be a tendency to pull those uneven places down. The surface would even itself out. The only geometrical object in which every point on the surface is the same distance from the center is a sphere.
But wait a minute,I've seen pictures of asteroids that have all sorts of crazy shapes.Why aren't they round?
Only because they aren’t big enough for gravity to be a determining factor. If an asteroid were to suddenly become as big as a moon, it would indeed rearrange itself gradually into a sphere.