Q&A: General Astronomy and Space Science
Where did the energy come from that caused the newly created
Earth to be in a molten state?
The core of the Earth was heated by two sources of energy: the
release of gravitational energy as the material settled into the
central core, and radioactive decay of potassium, thorium and
uranium. These decays led to heating by energetic particles
released in the nuclear fission process. Most of the helium
found in the Earth is also a result of this process--helium
nuclei are one of the primary products of the fission or
spitting of heavy nuclei into two lighter ones.