Earthed

Planets >>>>>>>>?

I was wondering can anyone tell me why/how all the planets, and moons we see in the solar system are round?



I have always wanted to know why every one is a sphere?????



I dont require a very, very technical answer, just the basics,,,,,



Thanks

Public Comments

1. It uses less energy to be round. That's the simple answer.
2. They arent perfect spheres - that have mountains and valleys and lots and lots of irregularities. But, gravity pulls the same in all diriections, so that causes roundness: squashed in all directions.
3. A sphere is the easiest form to be created, due to gravity.
4. I always think it is for cosmic symmetry - it just looks nicer - but the real answer probably has more to do with rotation. Round things spin and orbit easier - don't you think?
   
   
   
   Peace!
5. You can credit 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.
6. basically its beause a large mass like a planet exerts a lot of gravity, the gravity eventually pulls it into a rougly spherical shape.. A body has to have sufficient mass to do this to be called a planet (as well as orbiting a star)
7. actually they are spherical. ever roll show on the ground as a kid? got a big snow ball right. well when the planets were forming their gravity pulled in other matter as the planet spun. this matter joined up with the planet creating a bigger planet with more gravity that pulled in more mater etc etc.
   
   just like new layers of snow clinging to the snow ball.
8. There is now twelve official planets in our solar system (see BBC news link below). All are spherical due to gravity pulling equally on every part so a natural ball shape is formed.
9. First of all they r not really spheres....They r not exactly of any shape.....
10. Under the circumstances of our solar system, milky way, and universe as far as we know/see/detect it is simply the most efficient form to carry the most mass in the least possible volume. In this way it also gives the celestial objects the biggest possible balance.
11. Gravity
    
    
    
    The planets were formed by the actions of gravity. As the early solar system cooled the planets started to form. At first they were collections of gas and dust. Eventually they formed a ball or spherical shape. The did this because the force of gravity was even on sides and pulling toward the center.
    
    
    
    To contain a mass the sphere is the most efficient space. It can hold more mass, per volume, than any other shape. Gravity tried to pull all the matter together into the smallest shape possible--this creates a spherical shape.
    
    
    
    Rotational energy, magnetic forces, the actions of a nearby body, and a lot of other forces act to deform the spheres, but in general the planets and moons are just big spheres.
12. Let's imagine a big croud, of any size of shape you want.
    
    Why is the crows there? Well, everyone wants to know it seems
    
    People in the center can only see other people, so they know that they are very near something, so they just mingle about.
    
    People at the edge see lots of people towards a center, so they want to go towards the center. As the beging to push in, more people at the edges see people going in, so they start to gi in as well. Eventually, all sides are puching equally towards the center, trying to see what's going on.
    
    What happens when all sides are pushing equally? Well, that's a circle. You can have the same thing with squares, or triangles, where the corners are farther away from the center than the edges.
    
    
    
    Gravity works much the same way. If you have a cloud of dust, the center pieces, are no problem.
    
    But t the edges, gravity attracts a few pieces to the center. Then, because there is more dust in the center, more particles are attracted, euqually, from all direction. And so on etc.
    
    
    
    Just remember that this isn't perfect. Mountains form, erosion occurs, even the spin of a planet can effect the final shape (spin too fast and you get an elipsoid, but such a fast spin may not be sustainable without introducing energy), can all effect the topography.
    
    
    
    Cheers.
13. 2 Major reasons
    
    1) rotation
    
    2) gravity
    
    
    
    Initially when planets are formed they are either gas or solids. The solid one were in semi solid form due to bombardment of other objects and internal heat etc.so the rotation combined with gravity shaped them in to a sphere. The sphere is the most efficient shape in which more mass can be packed in less volume. Nature knows it!!!
14. taeylor is right... A sphere is the lowest energy configuration of any geometrical shape... its the same reason bubbles are spherical...
    
    
    
    However, the reason is simple... gravitation pulls towards a bodies center of mass radially, thus all mass is pulled directly at the center of a massive body like a planet or moon... however, many others here are right to say that Earth, and pretty much every other planet and moon, are not perfect spheres and have differing mass concentrations...
    
    
    
    This is what cause tectonic plate shifts of the Earths crust... it is in fact trying to balance itself out, and even out its mass distribution, and of course with its spin creating a stronger force (centrifugal) than gravity it makes it a slow and very drawn out process... Chances are Earth will never reach a perfectly spherical shape...
15. 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.
    
    
    
    Planets are round because their gravitational field acts as though it originates from the center of the body and pulls everything toward it. With its large body and internal heating from radioactive elements, a planet behaves like a fluid, and over long periods of time succumbs to the gravitational pull from its center of gravity.
16. Anything will try to do everything in the least amount.
    
    
    
    For planets (and any astronomical entity), that means it will try to pack its mass in as small a space as possible. The shape that does this is a sphere.
17. Planets and some moons are very massive, and therefore they exert a great bit of gravity. The gravity is so strong that all lumps of bumps are diminished and all you're left is a rough sphere.
18. The object spins causing gravity. Gravity pulls material towards its centre which makes a planet spherical.
19. can float around better