About half of Earth's internal heat comes from the radioactive decay of isotopes such as uranium-238, thorium-232 and potassium-40, rather than from heat left over from the planet's formation.

Is it true that about half of Earth's internal heat comes from the radioactive decay of isotopes such as uranium-238, thorium-232 and potassium-40, rather than from heat left over from the planet's formation?

Yes. A reference overview states Earth's heat flow comes from radiogenic decay and primordial heat in roughly equal amounts, naming uranium-238, thorium-232 and potassium-40; geoneutrino measurements also support a substantial radiogenic contribution.

Verdict: SUPPORTED · 3 sources for, 0 against · Last checked 2 Oct 2026

The private library was unavailable for some searches in this check. Missing library results are not evidence against the claim.

Earth's internal heat budget. (n.d.). en.wikipedia.org. https://en.wikipedia.org/wiki/Earth%27s_internal_heat_budget

Is radioactive decay the cause of the high temperature of the Earth's core?. (2011). skeptics.stackexchange.com. https://skeptics.stackexchange.com/questions/5537/is-radioactive-decay-the-cause-of-the-high-temperature-of-the-earths-core

Consortium, L., :, Cabrera, A., Chen, M., Mantovani, F., Serafini, A., Strati, V., Apilluelo, J., Asquith, L., Beney, J. L., Bezerra, T. J. C., Bongrand, M., Bourgeois, C., Breton, D., Briere, M., Busto, J., Cadiou, A., Calvo, E., Chaumat, V., & Chauveau, E. (2023). Probing Earth's Missing Potassium using the Unique Antimatter Signature of Geoneutrinos. arxiv.org. https://doi.org/10.48550/arXiv.2308.04154