eli5 Where does the earth’s core get the energy to generate heat from?

Question

The suns energy is from fusion, fine makes sense.

But the core is a hot spinning liquid metal generating tremendous amounts of heat. Why hasn’t it cooled down? How is it replenishing its energy?

In: Planetary Science

Answer 1

Gravity generates immense pressure on the core, and that pressure generates heat. The Earth itself absorbs solar energy which contributes only slightly.