There are three types
of planets in our solar system. On the one hand we have rocky worlds like Earth
and Mars have a solid surface on which to put your feet and consist of 'rocks'
(silicates and metals). Then there are gas giants like Jupiter and Saturn, composed
mainly of hydrogen and helium (and actually should be called "Giant
fluid" because most of its interior hydrogen is a liquid or metallic).
Finally we have the ice giants,
