The distance of the eight planets in the solar system with the sun from near to far,in turn,are:mercury,Venus,earth,Mars,Jupiter,Saturn,Uranus,Neptune.Not far from our earth from the sun is not close,this makes the earth won't be hot,like mercury is not as cold as Neptune.And this is for the survival of life on earth provides a good condition.
This is very difficult to express clearly concrete to abstract understanding.
If volume and density is not so,for example,would not exist in the close to the sun,and close to the density and mass of the sun must satisfy this condition.,of course,why is this condition such as the upstairs said composition and condition of various factors,it is difficult to a one-time finish.