A study of Venus found a thinner lithosphere and more than twice as many volcanoes in the north. The result adds a north-south divide to models of how the planet loses internal heat.
Researchers compared Venus's gravity and topography with its geological provinces. The data point to a thinner lithosphere in the north and more than twice as many volcanoes there than in the south. The pattern offers a new way to study how a planet close to Earth in size evolved without plate tectonics.
The international study was led by the Universidad Complutense de Madrid, with participation from the Universidad Rey Juan Carlos. Earth and Planetary Science Letters published the work. Its central link is direct: the thickness of Venus's rigid outer shell tracks the distribution of volcanic structures that release internal heat.
Observations from recent studies indicate that Venus’s surface and interior are not geologically static: the planet shows signs of relatively recent or possibly continuing volcanic activity.
A thinner lithosphere gives heat an easier path out through volcanic activity. Venus is not built the same way everywhere.
Researchers already knew about the BAT anomaly, an unusually active volcanic zone. BAT refers to the elevated regions Beta, Atla and Themis, where volcanoes are concentrated. The new analysis found that the difference extends beyond this zone. The northern and southern hemispheres also differ across the rest of the planet.
The team reached that result by combining geological provinces with geophysical models. Alberto Jiménez Díaz of the Universidad Rey Juan Carlos said the researchers studied lithospheric thickness and the distribution of loads. They used gravity and topography data collected by Magallanes, the NASA probe launched in 1989 that orbited Venus for four years.
The north-south asymmetry is presented as a result that should be tested through independent reanalysis and further examination of the complete peer-reviewed study. If confirmed, it would help explain how Venus loses heat without an Earth-like system of plate tectonics.
The researchers sorted the geophysical data by location. They then compared it with the planet's geological divisions. Statistical tests checked whether the north-south contrast was real or came from one isolated regional anomaly. The analysis found a difference outside the BAT zone too.
That matters because Venus is the terrestrial planet closest to Earth in size, yet its geological history took a different path. It has no system that recycles its lithosphere in the way Earth's plate tectonics does. Volcano locations therefore offer important clues about how Venus cools inside.
ScienceInsights also describes Venus as a world whose surface and interior remain active areas of research. Studies have found signs of relatively recent or possibly continuing volcanic activity. Venus is not a static world.
The study's method also shows why regional measurements matter in planetary science. An earlier data breakdown in another field separated a daily movement from the wider pattern. That same distinction matters when isolated figures can hide a broader trend.
No single explanation yet accounts for the thinner northern lithosphere. Javier Ruiz of the Universidad Complutense de Madrid said the result now needs to be added to models of Venus's evolution. The team is also testing different ideas about how the split formed.
Materials from the Universidad Complutense de Madrid say future models must include the uneven nature of Venus's outer shell. The main point is already clear. Venus loses heat through a planet-wide north-south imbalance. Future models will have to account for it.
