Radioactivity isn't all bad
In fact, I'm very glad
That geoneutrinos
In earth's deep infernos
Keep us warm just like a rad.

From ELUSIVE PARTICLE FOUND

Gratta said about half of the Earth's heat represents the primordial temperature that remains as the planet slowly cools from the heat of its formation some 4.5 billion years ago. But the rest must come mostly from the radioactivity of Earth's interior rocks, and this can be measured by measuring the energy spectrum of the antineutrinos, he said.