Radioactive decay releases heat, and early in the planet's history there were many radioactive elements with short half lives. These elements long ago decayed into stable materials, but they were responsible for the release of enormous amounts of heat in the beginning.
Radioactive decay: Radioactive decay releases heat, and early in the planet's history there were many radioactive elements with short half lives. These elements long ago decayed into stable materials, but they were responsible for the release of enormous amounts of heat in the beginning.
