# Why are planets spherical in shape?

I know they are not always exactly shperical in shape, the earth has a difference accross the equator of 43km compared to pole to pole. But basically they are spherical, wouldnt a big bang produce lots of crappy unequally shaped things like asteroids etc???

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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.

Source(s): Aerospace Engineer in NASA for the past 15 years.

Gravity is the key. You may be aware that Jupiter, our largest planetary neighbor in the solar system, is almost all gas (there is a small core of non-gaseous material). Understanding that Jupiter is a ball of gas, wouldn't it be bizzare if it had a shape other than a sphere? Think also of a bubble blown by a child (or your inner child) through a loop. Even very large ones (which are the most fun) seem to seek rest in a spherical shape, even if breezes batter and deform it from time to time. Matter seems to seek to balance internal forces. It would be scary to look up at Jupiter and discover that it had morphed into a doughnut shape or a large tube shape.

When we are talking about collections of matter that are planet-sized, the same general idea holds. Taking a mass equal to that of the earth, and of similar materials, you could attempt in your mind to construct a pillar with a 1,000 kilometer diameter. But you wouldn't get too far before the pillar's mass would exert so much gravitational force that the whole thing would come crashing in. Even if you braced the pillar while building it, the inner sections would eventually crumble and/or melt long before you finished. Eventually, all the mass would find its way to balance out the gravitational forces.

• 4 years ago

hmmmmmmmmm they probable morphed that way after being in area see you later shifting around and because they're basically going around in circles the began to get that around shape. i don't think of its because of the fact if it grew to become into sq. we would not fall of i advise come on who's fallen off a flat floor. And if that grew to become into the ingredient of not having a sq. planet so why did we get a around one? we could fall of less difficult and the sole reason we are nevertheless on earth is as a results of the fact gravity.

• quasar
Lv 5

Gravity and rotation gives the spherical shape..

• Tom S
Lv 7

Only energy came out of the Big Bang, other stuff came about later. So, when you blow soap bubbles how many different shapes do you get?

Because that is the blueprint of the universe,spherical and disk shaped,don't you watch "The universe"on History channel?

Source(s): Me and the Television
• Dude
Lv 7

THis is asked every single day here

go to any search engine and type

why are planets round?

and you will get thousands of hits from real scientists