Mars is far less balanced than researchers long assumed: deep inside the planet lies a huge temperature divide. According to a new study, the Red Planet’s southern half is roughly 200 to 400 degrees Celsius hotter than the north – and in places even partially molten.
The finding comes from a team led by Alexander Berne, who began the work during his PhD at the California Institute of Technology (Caltech) and now researches at the University of Arizona. Experts from Brown University and NASA also took part. The results appeared on 27 August 2026 in the journal Nature.
Measured over decades from gravity data
To peer inside the planet, the team used a method called tidal tomography. The researchers analyzed tiny velocity changes in three Mars orbiters – Mars Global Surveyor, Mars Odyssey and the Mars Reconnaissance Orbiter – that circled the planet for decades. From the minute variations in the gravity field, they reconstructed the interior structure. Seismic data from the InSight lander mission support the picture of a warmer southern half.
Why it could solve several Mars puzzles
The asymmetry could shed light on several long-standing questions: the planet’s unusual magnetism, its seismic behavior and clues to its early water history. Where the heat comes from, however, remains open. Candidates being debated include a giant impact in the north, rising mantle flows in the south, or thick rock layers trapping heat.
A model, not a direct look
An important caveat: these are model-based inferences drawn from gravity and seismic data, not a direct measurement inside the planet. Berne stresses that scientists usually assume planetary interiors are largely spherically symmetric – Mars shows that need not be true. For now, the cause of the divide remains an open question.
Sources: Caltech (press release), phys.org, ScienceDaily (study in Nature, 27 Aug 2026).
