why aren't there square planets?

Question

Is there a fundamental rule of physics that requires all planets in the universe to be round - or at least some kind of oval shape?

Answer 1

Gravity is a powerful thing.
When an object gets above a certain mass, since the center of gravity is the center of the object, everything gets pulled equally towards the center in all directions. This pulls the object into a spherical shape -- round. Gravity can be overcome, of course -- the earth itself isn't a perfect sphere, it bulges at the equator and is flatter at the poles, because centrifugal force (the outward force created by our rotation around our own axis) pushes out at the center and flattens near the axes.
Below the "planetary" threshold, objects in space can have odd shapes. Lots of fairly large asteroids have oblong shapes, some are shaped like potatos or squash...but once you get enough gravity, you're gonna have a sphere.

Answer 2

, Planets seem to be spheres, not cubes or cylinders or oddball rocky shapes. Some smaller bodies such as asteroids or Mars moons Phobos and Deimos, do have odd shapes, but larger bodies like the nine planets and most of their moons do look like spheres. That's because of the nature of gravity. You can think of gravity as a force that points inward toward the center of the planet so that every part of the surface is pulled evenly toward the center, resulting in a spherical shape.
Of course, planets are not perfect spheres because mountains and valleys and even skyscrapers are all deviations from the spherical shape. However, as planets get larger, gravity gets stronger, until eventually large objects on the surface are crushed under their own weight. That's why we don't have mountains that are 50 miles high or skyscrapers that are 2,000 stories tall. Planets stay basically spherical because any large deviations get crushed.

Although gravity keeps planets close to spherical, there are other forces that cause deviations from the basic spherical shape. For example, the rotation of the earth once every 24 hours, causes an apparent centrifugal force which creates a bulge at the equator. In fact the earth's diameter at the equator is 7,926 miles while the diameter between the poles is only 7,900.

Answer 3

The reason why is the planets revolve that the crust also move as well, but to slide forward, following the circular motion of planet's movement by the planet's gravitational pull. With many layers on the core above, the gravitational force magnified that able to break the fallen crust to smittereens. The motion of planet's revolvement is also a force too, create a shape of planet's roundness continuously and endlessly.

Answer 4

How do you know there aren't square planets. Depending on how you feel about Pluto we have only accounted for nine planets and a couple dozen moons. The galaxy has millions of stars and there are millions of galaxies and perhaps millions of universes. There are many many planets out there. many sizes.

But to remain a solid mass they need to rotate. Rotation cause gravity and gravity pulls equally in all directions so you get round planets.

At least in our little corner of the universe...

Who knows how the laws of physics may work elsewhere?

Answer 5

Gravity pulls things into round shapes, like the orbits of the planets. Planets are molten at first, so think of each molecule of molten rock as a planet. They all sort of hover like they were orbiting the center, and therefore make a sphere. When the planet cools, it stays that way.

Answer 6

There is a univeral law which states that everything likes to be at the lowest energy state possible. Thermodynamics states that. When masses coalesce into a larger mass in zero gravity the lowest energy state occurs when they form a spherical shape. That is why planets are round, and also why liquid you see floating in zero gravity is round.

Answer 7

i will in easy terms assume that the form of planet could have been built by way of an infinitely stepped forward (and insane) civilization. In the form of undertaking, the north and south poles may be set arbitrarily to in spite of its preliminary circumstances have been. i might assume that it would be set to 2 opposing faces particularly than 2 opposing corners. that ought to furnish lots extra effective day / night cycles. this might advise those residing on the north and south pole faces may be screwed ... yet hi, you desperate to stay there interior the 1st place. The axis may be desperate by way of drawing a immediately line from the midsection of the north pole face in the process the centre of the cube to the centre of the south pole face. i might assume the sunlight(s) and moon(s) might nevertheless be around. What may be interesting may be the gravity of the planet. The power of gravity may be extra effective close to the centre of the face as adversarial to the corners, when you consider that they may be nearer to the centre of gravity.

Answer 8

If a body is massive enough, gravity and surface tension will wear down protrusions Impacts from meteorites help in this process, as well.

Answer 9

Yes--gravity. It pushes evenly from every angle--the only possible shape is round(ish).

Answer 10

Oh, don't worry, we will have square planets just as soon as you have a square head.