<Tr> <Td> </Td> <Td> 6995292000000000000 ♠ 29.2 × 10 </Td> <Td> 7009125000000000000 ♠ 1.25 × 10 </Td> <Td> 6992369000000000000 ♠ 36.9 × 10 </Td> <Td> 6988108000000000000 ♠ 1.08 × 10 </Td> </Tr> <P> Geoneutrino detectors can detect the decay of U and Th and thus allow estimation of their contribution to the present radiogenic heat budget, while U and K is not detectable . Regardless, K is estimated to contribute 4 TW of heating . However, due to the short half - lives the decay of U and K contributed a large fraction of radiogenic heat flux to the early Earth, which was also much hotter than at present . Initial results from measuring the geoneutrino products of radioactive decay from within the Earth, a proxy for radiogenic heat, yielded a new estimate of half of the total Earth internal heat source being radiogenic, and this is consistent with previous estimates . </P> <P> Primordial heat is the heat lost by the Earth as it continues to cool from its original formation, and this is in contrast to its still actively - produced radiogenic heat . The Earth core's heat flow--heat leaving the core and flowing into the overlying mantle--is thought to be due to primordial heat, and is estimated at 5--15 TW . Estimates of mantle primordial heat loss range between 7 and 15 TW, which is calculated as the remainder of heat after removal of core heat flow and bulk - Earth radiogenic heat production from the observed surface heat flow . </P> <P> The early formation of the Earth's dense core could have caused superheating and rapid heat loss, and the heat loss rate would slow once the mantle solidified . Heat flow from the core is necessary for maintaining the convecting outer core and the geodynamo and Earth's magnetic field, therefore primordial heat from the core enabled Earth's atmosphere and thus helped retain Earth's liquid water . </P>

Where does the heat from the inner core come from
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