Mastodawn

There is a remarkable difference between #mars ' southern and northern #hemisphere that was not well explained. Travel over the southern hemisphere and you'll find lots of craters and frozen flows of volcanic lava. Then you go downhill, losing 5-6 kms altitude (which could be fun to do by bike maybe) and you enter the northern hemisphere. These lowlands are mostly flat and almost free of craters. We think there might have been an ocean there.
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Marcel-Jan Krijgsman Jan 21, 2025

But why is the difference so big between these two hemispheres? There are two theories. One is a giant #impact . Another is a difference in heat transfer through the rising of warmer and sinking of cooler material inside Mars' mantle.
#MarsInsight landed conveniently close to the border of these two hemispheres. Its seismometer detected quakes and impacts in both hemispheres and scientists were able to detect the distance and speed of these waves. /2