I have a problem reconciling something. According to Newton's shell theorem, at any point within a solid sphere, for the purposes of calculating the gravitational force exerted on you, the mass that is outside your own radius to the center can be ignored since it cancels out, and the net force from any mass outside your radius is zero. I understand this theorem, and it makes complete sense. What I have a problem with is if this is the case, then what is causing the enormous amount of pressure that causes the Earth's core to remain solid? What causes the pressure in the sun's core that allows fusion to occur? Can someone please reconcile these two concepts for me. It seems to me, that the farther you get to the center, the LESS force there is from gravity. In other words, if the mass OUTSIDE your radius exerts a net force of ZERO, then WHAT is pushing DOWN on you in the core? What is compressing the core? I hope this isn't a dumb question. First time posting in this forum. That would be a rough start!!