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I am doing a school project and need to know...

Will the Earth's mantle or core ever cool? If so, how?

Thank you!

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    $\begingroup$ Does Could earth's core lose its heat? answer your question? Or do you need to also know about the mantle cooling too? (although that's likely a similar answer) $\endgroup$ – hichris123 May 24 '16 at 3:04
  • $\begingroup$ It's absolutely answered in the question you've linked, but the question isn't exactly the same. Flagged anyway for review by mods. $\endgroup$ – Ben MS May 24 '16 at 3:20
  • $\begingroup$ The Earth's core is cooling, and has been cooling for a long, long time. Evidence: The Earth has a solid inner core (which couldn't exist if the core wasn't cooling), and it has a magnetic field (which couldn't exist without a high heat flux through the outer core). $\endgroup$ – David Hammen May 25 '16 at 15:23
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Yes. It is kept heat by slowly (very slowly) decaying radioactive elements. They are: Uranium (238) and Thorium (232). The half life of the first is 4.4billion years, the second around 14billion years.

They heat the surface even now, it is around 0.2K warmer.

As they decay, this temperature will be lower amd lower.


Extension: On the most populer models (and David Hammen's comment :-) ), the uranium and the thorium is in the crust and in the mantle, and not in the core. Despite that, their radioactive decay heats the Earth.

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  • $\begingroup$ Most geophysicists think there is very little uranium and thorium in the Earth's core. Both are incompatible lithophile elements. $\endgroup$ – David Hammen May 25 '16 at 15:18
  • $\begingroup$ @DavidHammen 1) Ok, but chemistry in 6000K and some 100000 bar isn't a little bit different? 2) Any idea, what heats the core then? 3) They are also the heaviest elements, any idea where could they are? 4) What is with their ores? They are mined in large quantities. They are not incompatible? $\endgroup$ – peterh says reinstate Monica May 25 '16 at 21:55
  • $\begingroup$ @DavidHammen I've read a little bit about this and you've right. I extended my answer, please consider a vote change. $\endgroup$ – peterh says reinstate Monica May 28 '16 at 4:13

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