eli5/ Why is there magma at the center of the earth? What does it do? How does it stay so hot for millions of years without “losing” its temperature?

Question

eli5/ Why is there magma at the center of the earth? What does it do? How does it stay so hot for millions of years without “losing” its temperature?

In: 13

Answer 1

Earth has formed billions of years ago when a lot of dust particles lumped together due to gravity. All these collisions released a lot of heat, so Earth was quite hot in the beginning and didn’t have a solid surface. Eventually it cooled down enough for the solid crust to form, but down there it’s still hot. It cools very slowly because it’s so large, and also because there is radioactive decay at work, adding significant amount of heat.