Thread: Source of Earth's internal heat

I have read that the earth's internal heat is attributed to radioactive decay and residual heat from the Earth's formation. This feels intuitively wrong, or to be more specific, inadequate, to me. The, admittedly casual, reading I have done does not even mention what I would see as a significant input to the heat of the Earth. That is tidal friction. Not the oceanic tides but the tides within the core of the earth. The Earth moon system revolves around a barycenter beneath the Earths crust. The earth itself revolves on its central axis. These are different rotational motions, they have to generate stress and continuous flexing of the Earth's rock. Such flexing has to generate heat. Does anyone know how much heat? Or rather does anyone know how we might calculate how much heat is generated within the Earth by tidal stress?

This abstract sets out the numbers, which turn out to be about 10% of so of heat from radiative decay but you'd have to check my math on that last part.
ScienceDirect - Deep Sea Research Part I: Oceanographic Research Papers : Abyssal recipes II: energetics of tidal and wind mixing

Originally Posted by Lynx_Fox

This abstract sets out the numbers, which turn out to be about 10% of so of heat from radiative decay but you'd have to check my math on that last part.
ScienceDirect - Deep Sea Research Part I: Oceanographic Research Papers : Abyssal recipes II: energetics of tidal and wind mixing

I think, maybe, you did not link to the correct paper.

Lord Kelvin calculated age of Earth planet from calculations based upon gravitational compression. He was wrong. If venerable sir wishes to reinvent such a square wheel, who is Prince to intervene?

Prince WILL point out that radioactively decaying substances are relatively common in crust of Earth planet, and that being heavier elements could reasonably be expected to exist in greater concentration at depth. Earth planet has greater gravity than Moon and proportionately greater effect upon Moon accordingly. Is interior of Moon molten?

No.

Intuitively wrong? Hardly.

Nice question though.

Earth planet has greater gravity than Moon and proportionately greater effect upon Moon accordingly. Is interior of Moon molten?

The tidal heating on our moon has nearly stopped because it is gravitationally locked to earth, and its orbit nearly circular.

And I did link to the wrong paper.

Tidal forces must generate some heat, although I've no idea what percentage it contributes to the total. Probably small, but not zero. The Earth's rotation might add some heat too; again, I've no idea how much except to say it'd be small in comparison to the radioactive decay and residual heat components.