Exploring Plate Tectonics: Is Earth the Sole Planet in Our Solar System with This Unique Feature?

Plate tectonics shape our planet in fascinating ways. They create mountain ranges, cause earthquakes, and slowly shift continents around. Interestingly, Earth seems to be the only place in our solar system with active plate tectonics. So, what makes Earth special?

According to Bradford Foley, a geodynamicist at Penn State, we don’t have all the answers yet. He describes this as one of the big mysteries in geophysics.

Earth’s outer layer, called the lithosphere, is made up of about 15 large, moving plates. These plates are always changing position—sometimes they collide, other times they pull apart. Scientists aren’t sure how this division happened, but certain geological features help keep the plates moving.

Foley explains that for a planet to maintain plate tectonics, it needs something called a convective mantle. This is where cold, dense material sinks into the mantle at subduction zones and new material rises where plates spread apart. Without this process, there wouldn’t be enough energy to drive the movement of the plates.

However, simply having convection isn’t enough. The lithosphere must be thin enough to break into plates, yet dense enough so those plates can sink into the mantle, according to Geoffrey Collins, a geologist from Wheaton College.

There’s also the interesting effect of water. Russell Pysklywec, a geophysicist at the University of Toronto, notes that water can help lubricate rocks. When water interacts with these rocks, it might aid the movement of tectonic plates at subduction zones, especially where tectonic plates meet and overlap.

All these factors combined could explain why Earth is unique in displaying plate tectonics. A study from 2022 showed that Jupiter’s moon Europa once had signs of “plate-tectonic-like” activity. Its icy crust seemed to break into plates, but because ice is less dense than water, these plates behaved differently than Earth’s. They didn’t sink into an ocean but rather floated on it.

Europa’s activity is limited and shows up as small patches across its surface. Collins explains that these patches might turn on and off, making it quite different from Earth’s continuous tectonic activity.

On Mars, the situation is different again. This planet has a “stagnant lid.” Although it has a convective mantle, its surface isn’t divided into plates. Instead, it’s covered by one solid plate, creating a different geologic environment altogether.

Studying Earth alone makes it tough to pinpoint the exact reasons for plate tectonics. If we had many rocky planets with varying conditions, we could gather more insights. For now, Earth continues to stand out as a unique case in our solar system.