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Mars may be hiding a split personality. New research suggests the Red Planet’s southern interior is hundreds of degrees hotter than its northern half — and may even be partially molten deep below the surface. The finding could rewrite what scientists thought they knew about Mars’s interior and its long-running debate over whether the planet still has any volcanic life left in it.
The conclusion comes from combining seismic data gathered by NASA’s InSight lander with models of how heat moves through the planet’s rocky interior. Rather than a uniform interior, Mars appears to have a fundamental asymmetry baked in — a temperature divide between its hemispheres that reaches all the way down.
The ancient split
Planetary scientists have long noted that Mars’s two hemispheres look different from orbit: the south is ancient, heavily cratered highlands, while the north is smoother, lower-lying terrain. The new work suggests that this surface contrast is not just skin-deep. A hotter southern interior could have helped thicken and stiffen the southern crust while keeping the deep south — against all expectations — partially molten today.
Why it matters
A partially molten Martian interior would be big news. It would reshape estimates of how much heat the planet still produces, influence the hunt for any lingering volcanism, and change models of how Mars cooled after its violent youth. It also has implications for the planet’s missing magnetic field, which shut down billions of years ago — possibly because the interior dynamics that powered it changed in ways this new asymmetry helps explain.
For future missions — human or robotic — understanding the planet’s inner workings is more than curiosity. Interior heat shapes everything from quakes to the stability of underground ice that explorers may one day rely on.
Featured image: topographic map of Mars’s Tharsis region, based on NASA Mars Global Surveyor data (CC BY-SA 4.0). Source: ScienceDaily.
