I understand that the Earth’s core is full of very hot liquid rock, but why is it hot and why does it stay hot?
What is the heat source?
In: Planetary Science
Most of the heat of the Earth’s core is left over from Earth’s formation.
All those chunks of rock banging together at high speed generated a lot of heat, and the crust of the Earth itself is an incredibly good insulator keeping all that heat in there.
Volcanoes and tectonic movement all serve to release that energy, but the total amount released is minuscule compared to how much is down there.
Another important factor is the Theia impact. It is currently believed that the moon was formed by the impact of a mars sized object with Earth. This re-liquefied much of the planet at a critical time in its formation and may explain why Earth’s core is still molten when similarly sized Venuses core is nearly solid.
Much of what makes Earth unique from our magnetic field, tectonic movement, the axial tilt (the seasons), the tides, and even the speed of the rotation are possibly all the result of our moon and how it was formed.
The Earth’s core also contains a lot of radioactive material like Thorium and Uranium. The constant radioactive decay of these materials is constantly re-heating the core.
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