Does the distance of the sun from the earth change during the different seasons?

I remember learning in grade school that the sun or the earth is 93 million miles away from each other. I’m wondering if because of the temperature changes that certain regions of the earth go through if the distance between the sun and the earth changes. Because for it to become colder the earth moves [...]

Why is the chemical composition of the Earth and the other terrestrial planets so different from the sun?

Why is the chemical composition of the Earth and the other terrestrial planets so different from that of the sun? Why is the chemical composition of Jupiter and other Jovian planets more similar to the sun’s?