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

>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?

The energy mainly come from the movement, but you are right, it is cooling down, and movement is reducing. Other than radioactive decay it’s not replenishing it’s energy, and even that probably doesn’t contribute much.

So in the past it was really hot with lots of movement, and it is cooling down just quite slowly.