Layers of Earth

The Earth is made up of many layers, pressure increasing as you go deeper. At the center of the Earth is the core, made of the Inner and Outer Core. The Inner Core has a solid sphere of iron while the outer core is fluid. Extreme pressure causes heat, which makes rocks melt.

The inside of the Earth is warm but cooling, losing heat to space. Radioactive materials help, but they decay too slow to release enough heat.