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
When the earth first formed, it was liquid rock and metal. It was very very hot. Over time the surface cooled and became solid but was still very hot. The surface cools and heat from the center moves to the surface where it is colder. Because rock is a great insulator of heat, this takes a long, long time.
Radioactive material that was denser then rock sank into the core, and that material releases heat as it decays to other materials. Keeping the core hotter then if it didn’t have said material.
It took millions of years for the surface to cool from liquid rock to solid rock. And it took millions more for it to cool enough for h2o gas to turn to liquid water. The cooling is a long and slow process, heat from the sun heats the surface and slows down the cooling as well.
The solid crust of the earth has been getting slowly thicker over billions of years as the earth slowly cools and has it gets thinker slows down heat loss even more as a insulator.
Eventually the core will cool and solidify but that still billions of years away.
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