Heat from collisions and radioactive isotopes keeps Earth’s core and mantle hot, driving plate movement and making life possible.
Have you ever wondered how the inside of the Earth stays boiling hot for billions of years? Henry, age 11 from Somerville, Massachusetts, certainly did. To answer this question, we must first understand the structure of the Earth. The Earth is made up of several layers, starting with the crust and going down to the inner core. The deeper you go, the hotter it gets, with parts of the core reaching temperatures as hot as the surface of the Sun.
Geoscientists use a technique called sonography, similar to the one used by doctors for imaging structures inside the body, to image the Earth’s internal structures. Seismic vibrations reveal what’s below the surface, such as rocks and large and small blocks called plates. These plates are not static and move, sometimes just a tiny fraction of inches over a period of years, and other times more suddenly, causing earthquakes and volcanic eruptions.
The heat that drives plate movement comes from two sources. One is the heat that Earth inherited during its formation 4.5 billion years ago. The other is the decay of radioactive isotopes, distributed everywhere in the Earth, such as uranium-235, which is used as a fuel in nuclear power plants.
Without the Earth’s internal heat, the plates would not have been moving and the Earth would have cooled down, making it uninhabitable. So, the next time you feel the Earth under your feet, take a moment to appreciate the heat keeping it alive.