Mars' Southern Half Is Weirdly Warm Underground. The 'Thermal Anomaly' Might Explain Why the Planet's Hemispheres Look So Different
Researchers used a novel technique to figure out what's going on inside the Red Planet. The work suggests that the interior of the southern hemisphere is hundreds of degrees hotter than that of the northern hemisphere and partially molten
We haven't written up this one. Smithsonian has the full story — the link below goes straight to it.