Venus Has a Single Solid Crust... But It's Surprisingly Thin

A new study suggests that unseen geologic activity may lurk just below the thin crust of Venus.

We’re slowly unraveling the mysteries of Earth’s strange twin.

Our nearest neighbor is only slightly smaller than the Earth… but that’s just about the only thing the two planets have in common. Permanently shrouded in a thick atmosphere, the surface is subjected to a punishing atmospheric pressure more than 90 times that of Earth at sea level, and temperatures reaching 460 degrees Celsius. This has also made Venus difficult to explore, to say the least, with the late Soviet Union’s Venera missions lasting for just hours on the surface.

Certainly, exploring enigmatic Venus is hard. A reminder of this literally came home this month, when the failed Soviet Venus lander Kosmos-482 reentered on May 10th over the Indian Ocean region, after more than half a century in Earth orbit.

Now, a recent NASA-funded study published in Nature: Communications suggests that the interior of Venus may be equally strange as well.

Earth has an active surface and crust, with tectonic plates crashing together and rising and sinking back into the interior in a process known as subduction. In contrast, we see that Venus has no surface fault lines suggesting individual plates, with the crust of Venus instead seeming to be fused in one single piece.

Contrasting interiors of Venus versus Earth. Credit: JAXA.

NASA’s Magellan mission created a radar map of the surface of Venus in the 1990s. Venus, however, is not dormant, but features vast active structures called coronae. These are circular surface features, thought to be caused by plumes of hot material pushing against the surface. Think bubbling cheese, on a piping-hot pizza. Though modern Earth has no direct analog, geologic coronae are thought to have been a feature common on early Earth. Evidence for modern volcanic activity on the surface of Venus includes the Maat Mons and the Ozza Mons regions.

The Artemis Corona feature on Venus. Credit: NASA/Magellan.

Another recent study out earlier this month lends support to the idea that these circular coronae are still actively reshaping the surface of Venus.

This then presents a mystery, as Venus seems to lack a tectonic plate cycle, but somehow still remains volcanically active. What researchers in the study propose is a mechanism of crust metamorphism, coupled with rock density and melting cycles. Researchers ran models and simulations of the interior of Venus and came up with a surprising result: this activity limits the crust-mantle boundary to a depth of 25-40 miles (40 to 65 kilometers) at most… a surprisingly thin result. For context, we know that Earth’s crust is on average 3 to 44 miles (5-70 kilometers) thick (that’s oceanic, versus continental).

Crustal density and thickness for Venus, versus various basalt compositions and thermal gradients used in the study. Nature/Creative Commons

"We are currently working on understanding the composition of the Venusian highlands since they do show similarities to Earth's continental crust, which would give us some insight on the geological evolution of Venus," Julia Semprich (Open University, United Kingdom) told Universe Today. "Modeling the interior with our new crustal densities would also be an option."

"This is surprisingly thin, given the conditions of the planet,” says Justin Filiberto (NASA-JSC Astromaterials Research and Exploration Science Division) said in a recent press release. “It turns out that, according to our models, as the crust grows thicker, the bottom of it becomes so dense that it either breaks off and becomes part of the mantle or gets hot enough to melt.” This could, in turn drive a recycling of material in the interior, and drive volcanic activity.

What we really need are direct measurements of Venus, in a dedicated seismology mission along the lines of NASA’s Mars InSight. Next up in the mission pipeline for Venus are the European Space Agency’s Envision set to study the surface and atmosphere of the planet, and NASA’s VERITAS (Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy) and DAVINCI (Deep Atmosphere Venus Investigation of Noble gases, Chemistry and Imaging) missions, set for the early 2030s. As of writing this, the future of DAVINCI, VERITAS and much of NASA’s planetary science efforts is in doubt, thanks to proposed budget cuts.

"New missions will focus on high-resolution radar and emissivity maps allowing us to get better constraints on topography (and) crustal thickness as well as surface features and compositions," says Semprich. "The best way to answer the question whether Venus has plates would be to use seismometers to map the interior, and this seems not very likely in the near future."

For now, why Venus and Earth took two divergent paths remains a mystery. Venus transitioned from dusk into the dawn sky in early 2025, where it still dominates as the morning star.

Looking east on the morning of Saturday, May 24th. Credit: Stellarium.

Certainly, our sister world doesn’t give up its secrets easily. A new series of missions could give us key insights, into the interior workings of our inner solar system neighbor.