The Earth's Core Is as Hot as the Sun's Surface

Thousands of kilometers beneath our feet, the center of our planet blazes with a heat that rivals the surface of a star. This extreme temperature is not just a passive feature; it's the result of two powerful engines. The first is primordial heat, a leftover furnace from Earth's violent formation over 4.5 billion years ago when gravitational energy from colliding space debris was converted into immense thermal energy. Our planet is still slowly cooling from this fiery birth.

The second engine is a constant, slow-burning nuclear reactor. Deep within the mantle and core, unstable isotopes of elements like uranium, thorium, and potassium undergo radioactive decay. As these elements break down over millions of years, they release a steady stream of energy, continuously replenishing the heat lost to space. Scientists determine the core's temperature not by direct measurement, which is impossible, but by studying how seismic waves from earthquakes travel through the planet's different layers.

This incredible internal heat is not just a curiosity; it's the driving force behind much of our planet's geology. It powers the convection currents in the liquid outer core, which in turn generate Earth's protective magnetic field. This field shields us from harmful solar wind, making it a critical component for the existence of life on the surface.