Scientists Discover Hidden Heat Anomaly Deep Beneath Mars's Southern Hemisphere

Planetary scientists have identified a major thermal divide inside Mars, with gravity data suggesting that the mantle beneath the planet's southern hemisphere runs 200 to 400 degrees Celsius hotter than the north and may be partially molten. The findings, published in the journal Nature on August 27, were led by Alexander Berne, a Caltech PhD graduate now a postdoctoral researcher at the University of Arizona.

Berne's team built a model that uses subtle variations in Mars's gravitational field to infer the structure and temperature of the planet's interior without needing a lander at every location. The resulting picture points to a hemispheric asymmetry that has puzzled scientists for decades: Mars's crust, magnetic signatures, and even its early water history differ sharply between north and south, and a hidden pocket of extra heat could help explain why.

Researchers say the anomaly may connect to unusual magnetism recorded in iron-rich minerals in the southern highlands, since a warmer, partially molten layer could have sustained a stronger local magnetic field earlier in the planet's history. The team plans further modeling to test whether the heat source is linked to Mars's ancient core dynamo or to a more localized geologic process, and the results are expected to inform how future missions target subsurface studies of the planet.