There was some physicist who said that the volume of a planet (or another space body) doesn't matter because the force it exerts is the same if its volume is higher or smaller.

 

For example, the force between Earth and Sun doesn't depend on the volume of Earth or Sun, only depends on their masses and the disance center-center. So... I don't remember who said this and what said exactly.

 

So if someone know it, it would be vere nice from him to tell me :DD

 

 

P.S.: I hope you to understand my poor English >.<

This is the shell theorem and I believe it was first proved by Newton.

 

• A spherically symmetric body affects external objects gravitationally as though all of its mass were concentrated at a point located at the centre of the object.
• If the body is a spherically symmetric shell, then no net gravitational force is exerted by the shell on any object inside the shell.

Edited October 31, 201312 yr by ajb

It is also known as Gauss's law, which is mentioned in ajb's link

Agree with AJB - although Gauss' explanation can be an easier and more intuitive read.

 

x-posted with swansont