Plate Tectonics on Exoplanets

via National Geopgraphic, a new Harvard study theorizes that our planet is on the small side of rocky worlds where plate tectonics operates. Plate tectonics, the theory which describes the "drift" of continental landmasses on the Earth's crust, is believed to play a large role in keeping the planet sutible for life.

"Tectonics—the continent-shifting forces that build mountains and fuel volcanoes—recycle Earth's crust by drawing it underground, where it melts and later re-emerges as magma, pointed out Diana Valencia of Harvard University. That helps keep carbon dioxide levels in the atmosphere more or less stable, as excess gas is removed from the atmosphere by reacting with fresh rocks in a process called "weathering." The carbon dioxide is later returned to the atmosphere via volcanic gases."

This makes it more likely that we will find a terrestrial counterpart in our search for habitable worlds elsewhere, given that it's easier to find large worlds than small ones. Larger worlds are more likely to have warmer interiors, producing the convection currents in the planetary mantle responsible for the cracking of the planetary crust into interactive segments. On Earth, it is thought that the process is enhanced by the amount of liquid water in our planetary oceans. Large planets with water might have continental plates moving up to ten times faster than our planet.