Why are all planets round ?
Why are all of the planets round? All of the planets are round because of gravity. When our solar system was forming, gravity gathered billions of pieces of gas and dust into clumps which grew larger and larger to become the planets. The force of the collision of these pieces caused the newly forming planets to become hot and molten. The force of gravity, pulled this molten material inwards towards the planet’s center into the shape of a sphere. Later, when the planets cooled, they stayed spherical. Planets are not perfectly spherical because they also spin. The spinning force acts against gravity and causes many planets to bulge out more around their equators.
There is never one that is square. — Walter Irwin, Mannheim, Germany Walter, I like the idea of a planet that’s a cube. For one thing, you might have some REALLY LONG downhill ski runs. But seriously, I would like you to consider the gravity of this question. No, really, gravity is why planets are spherical. Planets are so massive that they have a kind of “self-gravity,” explains Wayne Christiansen, a UNC professor of astrophysics and director of the Morehead Observatory in Chapel Hill. The center of the planet actually pulls the surface in. That force from the center is the same over the entire planet’s surface, so the gravity “pulls” it into a big ball. If a planet were shaped like a cube, its corners would tower over the rest of the planet. Gravity wouldn’t like that. In fact, planets are so large that nothing could possibly keep those towering corners up so high from the center of the planet. Even if they were solid rock, gravity would pull them down.
Nature has a common goal with everything and anything it does. Whatever it does, it does with the least amount of effort and expense of energy. In this universe, the sphere and circle are the most efficient shapes to produce, so, nature takes the easiest road when producing planets. Having enough mass for the gravitational force necessary, nature pulls that mass into the shape of a sphere, and we have spherical planets. The same goes for stars, (there are stars that are bulging due to very fast rotational speeds, but even then, they are considered spheroids).
