Mysterious crown-like features on Venus may finally have an explanation

Scientists have proposed a new explanation for Venus’ giant, crown-shaped geological features, known as coronae.

A close up of Venus in space. (Image credit: NASA/JPL-Caltech)

The mystery behind Venus’ giant, crown-shaped geological features, known as coronae, may finally have an explanation: A “glass ceiling” in Venus’ mantle is trapping heat and driving slow, shifting currents that might lead to the formation of the crown-like surface features, scientists propose in a new study.

“On Venus, there is a pattern that is telling us something,” Madeleine Kerr, a doctoral candidate at the University of San Diego’s Scripps Institution of Oceanography and the study’s lead author, said in a statement. “We think what we found is the key to unlocking the mystery of the origin of these coronae.”

Venus and Earth are considered “twin” planets because they have roughly the same size, bulk density and distance from the sun. However, the planets’ surfaces indicate that they diverged on their evolutionary paths, leading to two substantially different worlds. One such difference is these coronae, which are unique to Venus.

Scientists have mapped more than 700 coronae across Venus’ surface, and they span a wide range of sizes and features. Yet their origin is still a puzzle, given that Venus is covered in a single, continuous crust — unlike Earth, which has shifting tectonic plates.Some hypotheses link the formation of Venus’ larger coronae — those bigger than 310 miles (500 kilometers) in diameter — to mantle plumes and tectonic processes such as subduction and the delamination of denser parts of the planet’s crust, the research team wrote in the study, published Sept. 16 in the journal PNAS. The smaller coronae — those with a mean diameter of about 124 miles (200 km) — on the other hand, can be attributed to smaller hot upwellings in the mantle, like blobs of wax rising in a lava lamp.

A series of green and orange blobs over a green background with a bar scale of 1000 km labeled.

“The current state of knowledge of the planet Venus is analogous to the 1960’s pre-plate tectonic era because we currently lack an equivalent unifying theory capable of linking how heat transfer from the planet’s interior gets manifested into the tectonics and magmatic features observed on Venus’ surface,” David Stegman, a professor of geosciences at the University of San Diego’s Scripps Institution of Oceanography and one of the study’s authors, explained in the statement.

Now, Stegman and his colleagues believe they may have found a crucial piece of the puzzle.

Cold material that sinks from the surface and hot material that rises from deeper inside both encounter a barrier at a depth of about 370 miles (600 km) — what the team calls a “glass ceiling.” Most rising hot plumes aren’t strong enough to break through this barrier, so they get deflected and spread sideways underneath it. Only the largest plumes can penetrate all the way to the surface, where they form huge volcanic rises. The material trapped beneath this ceiling stays warm, but it doesn’t melt — so it acts like a hidden reservoir of heat in the mantle.