Bill Duke., Age 9, Of Montgomery., Ala... For his question:

Why is it hot inside the earth?

The deeper we dig into the earth, the hotter it becomes. We know that the core of the earth is very hot, maybe as hot as the face of the sun. But science cannot explain altogether why this should be so. Experts offer us several guesses based on good reasons.

We think that the young earth may have been a ball of seething gases and red hot liquids. The crusty surface may have cooled and trapped some of this heat inside the new planet. The top layers of rock crushed down with terrific weight., and this pressure would cause the layers below to become hot. Radioactive materials may also add heat to the depths of the earth. Maybe these three reasons working together cause the terrific heat inside our planet.