How is the core of the Earth kept hot?

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Discussion Overview

The discussion revolves around the mechanisms that keep the Earth's core hot, exploring the contributions of radioactivity, gravitational friction, and residual heat from the Earth's formation. Participants examine the relative importance of these factors and consider additional influences such as tidal forces from the Moon and Sun.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant asserts that the mantle is kept hot by radioactivity, questioning if the same applies to the core.
  • Another participant confirms that while the core is not primarily heated by radioactivity within it, heat from radioactive decay in the mantle and crust contributes to the core's temperature.
  • A participant inquires about the potential heat contribution from tidal forces exerted by the Moon and Sun.
  • One participant summarizes a source that identifies four sources of heat within the Earth, attributing up to 90% of the heat to radioactive decay, with additional contributions from gravitational friction, residual heat from formation, and latent heat from solidification of molten materials.
  • The same participant suggests that tidal forces are included in the gravitational friction component of heat generation.

Areas of Agreement / Disagreement

Participants generally agree that radioactive decay is a significant source of heat, particularly in the mantle and crust, but there is no consensus on the extent of heat contributions from tidal forces or the exact proportions of each heat source.

Contextual Notes

There are limitations regarding the specific contributions of each heat source, and the discussion does not resolve the influence of tidal forces on the overall heat budget of the Earth.

Forestman
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I know that the mantel of the Earth is kept hot by radioactivity, but is this also true for the core?
 
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Yes.

Addendum. Most of the radioactivity is in the crust and the mantle; but this is still generating heat which contributes to keeping the core hot. For lots more detail see Probing Question: What heats the Earth's core? at physorg.com

So the core is not being kept hot by radioactivity in the core; the energy from decay in the mantle and crust is more important. I had to look this up also.
 
Last edited:
Thanks sylas.
 
does the Earth gain significant heat from the moon and the suns tidal pull?
 
The link that sylas provided list 4 sources of heat within the earth.

Up to 90% of the heat is from radioactive decay.
About 5 to 10% is from friction caused by gravity.
About 5 to 10% is residual left over from the original formation of earth.
A small amount is latent heat released when molten materials turn into solids.

As I understand it, tidal push and pulls are part of the 5 to 10% gravity friction portion.
 

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