The heat at the Earth's core primarily originates from the decay of radioactive materials, a process that has been ongoing since the planet's formation. While the pressure from overlying rocks contributes to geothermal heat, it is not the main source; radioactive decay remains dominant. Geothermal energy is technically a non-renewable resource, but the potential energy we can extract is minimal compared to the Earth's age. Unlike the sun, where gravitational collapse leads to fusion reactions, the Earth's heat generation is fundamentally different, relying on radioactive decay rather than atomic fusion. Thus, while geothermal energy can be harnessed, it is not an infinite resource.
