Earth’s internal structure and heat sources drive plate motion, essential for life on Earth.
The Earth is composed of several layers, starting with the crust, which is the surface we walk on, and continuing to the mantle, outer core and inner core. The inner core is the hottest part, reaching temperatures as hot as the surface of the sun. As a professor of earth and planetary sciences, Shichun Huang studies the insides of our world. Scientists use seismic waves, or sound waves produced by earthquakes, to image the Earth’s internal structures. The lithosphere, which is about 60 miles thick, is the upper part of the mantle and the crust combined. The lithosphere is divided into several large blocks called plates, which move very slowly over time. This movement is what triggers earthquakes and volcanic eruptions, and it is also a critical factor driving the evolution of life on Earth.
The heat that drives the plate movement comes from two sources. The first is the heat that Earth inherited during its formation 4.5 billion years ago, when collisions and mergers between bits of rock and debris produced an enormous amount of heat. The second is from the decay of radioactive isotopes, which are distributed everywhere in the Earth and release a steady stream of energy that converts to heat.
Without the Earth’s internal heat, the plates would not have been moving and the Earth would have cooled down. This would have made the world uninhabitable, and life as we know it would not exist. The internal heat of the Earth is essential for the evolution of life and the formation of new lands and oceans. The next time you feel the Earth under your feet, take a moment to appreciate the heat that lies beneath it.