🌋 The mystery of Venus's coronae finally solved?

Venus, our planetary neighbor, displays strange geological formations on its surface in the shape of coronae that have intrigued scientists for decades. These circular structures, called coronae, dot the Venusian landscape and may finally reveal their secrets thanks to a new study exploring the mysteries of the planet's interior.

The coronae of Venus exhibit great diversity in size and characteristics, with more than 700 structures identified across the surface. Unlike Earth, where the crust is fragmented into moving tectonic plates, Venus has a continuous and rigid outer shell. This fundamental difference makes the origin of these coronae even more enigmatic, as they might be linked to deep movements within the planet's mantle. Researchers have long hypothesized that mantle plumes – columns of hot material rising from the depths – could be the origin of these formations.



The study published in PNAS reveals the existence of an invisible barrier at about 600 kilometers deep (approximately 370 miles), which scientists compare to a "glass ceiling." This interface separates the upper and lower layers of the Venusian mantle, preventing most hot plumes from rising to the surface. Only the most powerful ones manage to cross this obstacle to create the large volcanoes observed, while weaker plumes are deflected laterally and spread beneath this barrier, forming a heat reservoir.

The computer models developed by the team show how "drops" of cold rock from the base of the Venusian crust can trigger a chain reaction by sinking into the hotter mantle. This process generates pockets of hot material that rise toward the surface, thus creating the diversity of observed coronae. Madeleine Kerr, a doctoral student at the University of San Diego, emphasizes that this discovery could be the key to understanding the origin of these mysterious geological structures.

David Stegman, a professor of geosciences and co-author of the study, compares the current state of knowledge about Venus to the period before the theory of plate tectonics in the 1960s. Researchers estimate that this mechanism works when Venus's mantle is 250 to 400 kelvins hotter than Earth's, but the duration of this thermal state remains uncertain. Future three-dimensional studies incorporating rock melting and different mantle compositions will be needed to refine these models.


This research opens new perspectives for understanding how Venus's internal heat shapes its surface. The interactions between mantle plumes, the deep barrier, and the stagnant crust could explain not only the coronae, but also the volcanic activity and overall geological evolution of this planet often referred to as Earth's "infernal twin."

The planetary mantle and its movements

The mantle is the intermediate layer between a planet's core and crust, composed of solid rocks but capable of deforming very slowly over geological time scales. On Venus, this layer extends about 3,000 kilometers thick (approximately 1,860 miles) and is the site of convection movements where hot materials rise and cold ones descend.

These movements are fueled by internal heat from the radioactive decay of elements and residual heat from planetary formation. Mantle convection is an essential driver of geological activity, but on Venus, it occurs differently from Earth's due to the absence of plate tectonics.

The high viscosity of Venus's mantle rocks and extreme temperature conditions alter the dynamics of these currents. Mantle plumes, which are narrow columns of abnormally hot material, play a particular role in transporting heat toward the surface.

Understanding these processes helps explain why Venus, although similar in size to Earth, exhibits such distinct geology with its vast volcanic plains and unique coronae.