Our planet has a hot core that heats the surrounding mantle, which carries that heat up to Earth's rigid outer rocky layer, or lithosphere. The heat is then lost to space, cooling the uppermost region of the mantle. This mantle convection drives tectonic processes on the surface, keeping a patchwork of mobile plates in motion. Venus doesn't have tectonic plates, so how the planet loses its heat and what processes shape its surface have been long-running questions in planetary science.

The study looks at the mystery using observations the Magellan spacecraft made in the early 1990s of quasi-circular geological features on Venus called coronae. Making new measurements of coronae visible in the Magellan images, the researchers concluded that coronae tend to be located where the planet's lithosphere is at its thinnest and most active.

"For so long we've been locked into this idea that Venus's lithosphere is stagnant and thick, but our view is now evolving," said Suzanne Smrekar, senior research scientist at NASA's Jet Propulsion Laboratory in Southern California, who led the study published in Nature Geoscience.

Just as a thin bedsheet releases more body heat than a thick comforter, a thin lithosphere allows more heat to escape from the planet's interior via buoyant plumes of molten rock rising to the outer layer. Typically, where there's enhanced heat flow, there's increased volcanic activity below the surface. So coronae likely reveal locations where active geology is shaping Venus's surface today.