Why are planets round?

Question

why cant they be sausage shaped or oval or just ramdom lumps like a boulder on earth would be

Answer 1

when the planets are formed, they are ina liquid state. due to surface tension, matter in its liquid state takes the shape of speres.

Answer 2

So they can fit in a telescope eyepiece, and as we all know. Isaac Newton invented both gravity and the telescope. Planets are also round because they are made of play dough.

Answer 3

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 4

Everything is made up of atoms, the earth is made up of trillions maybe even more of these atoms.. therefore, round.

Answer 5

good question. remember that the core of a planet is extreamily dense, and has a very strong gravitational pull. it is because of this gravity that the planet shapes itself as a sphere. the matter wants to be pulled down as much as it can into the core of the earth. the sphere is the most compact shape that exists, therefore, as a result of the planets own gravity, the planet becomes a sphere. some planets do have a very slight oval shape to them, and are elongated at the equator. this is sometimes because although the gravity from the core was strong, it wasn't strong enough to make all matter pull towards it and form a sphere. sausage shaped celestial bodies would be considered planets. one reason is because in order for a celestial body to become a planet, it has to be in the shape of a sphere as a result of its own gravity. second of all, this wouldn't be large enough to be the largest object in its obit, and would end up being considered an asteroid.

so to sum it all up, planets are shaped like spheres as a result of there own gravity, and as a result they are shaped into a sphere, the most compact shape.

Answer 6

The smallest ones (like asteroids and some of the moons of the solar system) are indeed like irregular boulders.  The larger a body gets, the stronger its own gravity works on its constituent material.  If you imagine a body of solid rock, it has a certain material strength.  At a certain mass, gravity will pull harder on the rock than it can withstand and its shape will alter towards a sphere, which is the shape you would get if gravity overwhelmed all other influences.  The enormous gravity of a neutron star (where the mass of the sun occupies a sphere about 10km in diameter) makes them the most perfect sphere in nature.  Rocky bodies in our solar system start to tend towards spheres at a diameter of about 200 miles.

Answer 7

I think it's because of the gravity that gets exerted onto it...the gravity is so strong that it just pushes it into the shape of a ball..kind of like the pressure you would put on a lump of Play-Doh to turn it into a ball, but on a much bigger scale.....

I read that they weren't perfectly round though...Earth at times resembles a pear, and Jupiter is more of an Oval.

Answer 8

I think it's something to do with gravity, or  because of the way they spin around...

Answer 9

Since gravity pulls toward the center of the planet or star, everything gets pulled down into a sphere.

Truthfully, planets and stars are not really perfect spheres. They spin, so they bulge out a little around the equator.

Answer 10

Because as particles clump together, they start to exert a lot of gravity. Now gravity pulls in each direction equally. If the planets were square or another shape, that would be a different story. Now if you look at a square, and think of something at the center, you'll notice some parts of a square are closer to that center than others, the corners are not the same distance as the mid square.

The only way you could get that via gravity is if it didn't pull as hard in every direction. Gravity draws everything inward evenly.

Answer 11

Planets are not round,but  spherical.

That is the smallest volume in which we can enclose maximum stuff!

Now gravity pulls to center and make them spherical if the size is more than 800kilometers. If it is small,it will not be spherical