Venus was long thought to have an immobile solid outer shell like Mars or the Moon, but it turns out that the plant is actually more like Earth: it has large tectonic blocks that move like a broken pack of ice on a frozen lake.
"We've identified a previously unrecognized pattern of tectonic deformation on Venus, one that is driven by interior motion just like on Earth," said North Carolina State University professor Paul Byrne. "Although different from the tectonics we currently see on Earth, it is still evidence of interior motion being expressed at the planet's surface."
This suggests that Venus is still geologically active:
"We know that much of Venus has been volcanically resurfaced over time, so some parts of the planet might be really young, geologically speaking," Byrne says. "But several of the jostling blocks have formed in and deformed these young lava plains, which means that the lithosphere fragmented after those plains were laid down. This gives us reason to think that some of these blocks may have moved geologically very recently - perhaps even up to today."
The researchers are optimistic that Venus' newly recognized "pack ice" pattern could offer clues to understanding tectonic deformation on planets outside of our solar system, as well as on a much younger Earth.
"The thickness of a planet's lithosphere depends mainly upon how hot it is, both in the interior and on the surface," Byrne says. "Heat flow from the young Earth's interior was up to three times greater than it is now, so its lithosphere may have been similar to what we see on Venus today: not thick enough to form plates that subduct, but thick enough to have fragmented into blocks that pushed, pulled, and jostled."
Image: NC State University, based upon original NASA/JPL imagery