The Universe And Your Solar System

Are the planets gradually becoming perfect spheres?

Just as a rock becomes a gemstone in a rock tumbler, a rough or ridged object becomes smooth or perfect in shape after being exposed to the same constant force for a long period of time. Is this the case with the planets in our solar system? As the celestial bodies orbit the sun they are exposed to the same movement year after year. By looking at the pictures of the planets in a science book or from the readings of a satellite, you can see that they indeed are spherical. When the big bang occured they could not have been perfectly-shaped like that. Therefore, they must be gradually turning into perfect spheres, correct?

The increased centrifugal force at a rotating planet’s equator can make a planet bulge around the middle. Atmosphere and oceanic friction slow down rotation slowly but surely over geologic time, though.

Then there’s internal forces within a planet that affect the shape of the surface, but the energy that makes the core hot enough to do all that has to diminish slowly but surely, it seems.

Cosmic collisions between a planet and an asteroid here or there can add energy back, but in the grand scheme I think it’s a general rule that they get rounder.

Jupiter – Solar system in pictures