Why is the earth´s core still hot, if by the time it has been around it would be colder?

Question

Is there some nuclear activity inside? Is there some insulated layer?

Answer 1

Both nuclear activity and insulation play a role. Given that the surface of the planet is not red hot, you can reasonably conclude that there is considerable thermal resistance between here and that molten core. Also, we receive enough solar radiation to keep the average temperature nearly 300K. So there's a very large thermal mass and a very slow cooling rate. There is also heat being generated in the core by radioactive decay. Because gravity sorted things out when the whole planet was fluid, most of the uranium settled into the core.

Answer 2

some residual nuclear decay, but also the extreme pressure from the overlying mantle and crust plays a part, another major reason is simply angular momentum, as the Earth ages, it's rotation rate is gradually slowing due to the loss of angular momentum from interactions with the magnetic field and gravitational pull of the sun, this loss manifests as a heating up of the core, much like a brake pad on a car heats from friction....

Answer 3

It is not known why the earth's core is hot, but there are lines of evidence. The changing thickness of the earth's crust indicates a constant cooling, which indicates that the heat was created at the beginning of the earth's formation. The core is too hot for it to cool down quickly and the cooling happens slowly. Also the changing thickness could heat it up in some cases.

Answer 4

The Earth's crust is forty miles thick, this offers great insulation value and the heat of the core is raised by gravitational tides of the moons gravity being converted into energy within the Earth.

Answer 5

Yes, it is well insulated..several thousand miles of mantle, which is rather hot itself thanks to the initial heat caused by the accretion and all the asteroid impacts, compression and radioactive decay. And theres also the crust to keep it all nice and toasty inside. You'd be warm too if you had a banket that thick.

Answer 6

The first poster is right. There are a lot of fusion reactions(nuclear bomb like ....) within our earth core which keep temperature high due to massive energy released (Fusion is caused by the pressure done by the external layers of the earth). When everything is fused (to iron), since we are not a massive star, the core will slowly become colder then... then.... go read about it and be sad o_o.

Answer 7

It remains hot due to radioactive decay of uranium and potassium in the Earth's interior.

Answer 8

http://en.wikipedia.org/wiki/Earth#Internal_structure

read about the inner core section

Answer 9

Have read that the gravitational forces of the sun and jupiter have something to with it.

Answer 10

Good question. It would seem that for 100 to 500 million years it would cool and solidify. Something fishy is going on.