why the planets like the ball's shape?

Answer 1

The rounded shape of planets, stars and other large heavenly bodies is because of gravitational force. Gravity pulls all the matter in the planet towards the centre, and is so strong that the inside of most planets is molten liquid. Since gravity pulls all the matter towards the centre, it becomes a rounded shape, just like soap bubbles are round because of the surface tension force.

The sphere is the shape with the smallest surface area for a given amount of matter, so planets tend towards the spherical shape.

Actually it is not exactlly a sphere but more like an orange (bulging out at the equator) because of the rotation of the planet causing a centrifugal force.

If the body is relatively smaller (like many asteroids and comets), or newer, it is usually not rounded, because either the gravity is too weak to force the matter into a round shape, or it did not have enough time to do so.

Answer 2

Planets (and bigger asteroids and moons) are spheroids because the material they're made of isn't strong enough to resist the force of gravity which tries to pull everything to an "equipotential surface".  The equipotential (equal gravitational potential energy) surface is a sphere for a non-rotating body in isolation - which is only an approximation for lots of bodies in the Solar system.

FYI, energy/distance = force.  If something can get to a lower energy level by moving, there's a force pushing it to move; the force is equal to the energy/distance.

(Yes, I'm a physics nut, however did you guess?)

Answer 3

they are not really like a ball, but a bit lumpy and slightly oval, but the rotation of turning, plus the way the sun hits them makes them look more perfectly round. I think that they got pretty much rounded off by all the rotating they have done for so long.

Answer 4

Because the sun's gravitational pull would allow no other shape.

Answer 5

Just the way god made them.