# How does earth core remain molten?

• Heat from when Earth first formed and accreted. The heat hasn't been lost yet.
• Frictional Heating by material from the denser core sinking into the center of the Earth.
• Heat expelled from decaying radioactive substances.
May 2, 2018

When radioactivity was discovered and the immense amount of energy that can be generated through radioactive decay, the age of the earth was extended backwards to match the half-life of Uranium 238. The amount of energy produced by radioactive decay is based on the famous equation $E = M {c}^{2}$