I have been watching the TV series The Planets - why are all planets globes when there is no friction in space

Answer 1

they all spin and rotate around the sun creating gravity

Answer 2

When the inner rocky planets were formed and gravimetric forces exerted their pull on the rocks surrounding the would-be planets the rocks grinded together and friction caused them to heat as they came together. Each planet would eventually become a mostly molten rock. Liquid, when in the presence of a vacuum will form a mostly spherical shape. Another factor that helped the planets become spherical was the rotation of them, as the molten rock and other materials were spun they stretched and, without the assistance of gravity, would have been pulled apart, but gravity kept the planet together and so it pulled the molten surface into a sphere. The outer gas giants were also formed by a similar process, except in place of molten rock, there was gas. The gases that make up our outer planets were flung out by the rotation, but only as far as their immense gravity would allow. Some gases lay low in their atmosphere, some on the very boundry between the atmosphere and space itself. This primarily depends on the weight of the gas and element in question. Hope, this sheds some light on this.

Answer 3

What has the planets being spherical got to do with friction or no friction?

The planets are spherical because their immense gravity pulls them into that shape.

A sphere, as you will notice, has every part of its surface the same distance from its center. Just think, if a planet was cube shaped, the corners would be much further away from the center than the middle point of the sides, and the immense gravity would try to pull everything so it was equal distance from the gravitational centre.

It has nothing to do with its passage through space.

Answer 4

In continuation of the above response: even silicate rocks do not have infinite strength to retain their shape. In very massive objects, the force of gravity exceeds the force necessary to crumble and then shape the rock (which occurs when the object becomes very massive). When this happens the object becomes an approximate spheroid, and if the object spins about an axis of rotation like the Earth, then it will bulge about the equator, which is called an oblate spheroid.

My explanation may be easier imagined by considering any of the very large asteroids in the asteroid belt, such as Ceres.

The mistake of thinking that an external source applies a friction on Earth which results with Earth becoming a round object, just like a pebble in a stream eventually becomes round, is not applicable and should be avoided. But you did present a good, logically sound question.

Answer 5

i don't think friction has anything to do with the shape of a planet. its all to do with gravitational fields and strengths that pull all constituent parts of a planet together with the same amount of strength, thereby resulting in the planet have a globe-like shape.

Answer 6

Since each planet is so massive, they each have a large gravitational pull on themselves. Over millions of years, this pull toward the center of mass of each planet has shaped the planets into near spheres.

Answer 7

The key factor here is gravity. Planets are massive so they end up as spheres (to the closest approximation). Asteroids, on the other hand, have small masses so they end up as potato-shaped objects.

Answer 8

For the same reason a water droplet is a globe or sphere in o gravity. It ocuppies the smallest volume.

Answer 9

I believe that the reason for this is that in space there is pressure. this pressure exerted evenly around objects will make them round. Oddly enough this pressure is GRAVITY. Gravity causes the mass to to become round because it is exerted evenly to itself through out the mass. Hope this helps. Will.

Answer 10

because there is friction in space the speed of energy traveling in a medium is governed by the medium.and thats all space is. a medium.

Answer 11

There IS friction in space...