Scientists Uncover Martian Dichotomy: Solving a 50-Year-Old Mystery

After decades of speculation, scientists may have solved the 50-year-old mystery surrounding Mars' 'dichotomy'—a stark contrast between the planet's northern and southern hemispheres. The northern lowlands are 5-6 kilometers lower with a thinner crust compared to the southern highlands, which are ancient, cratered, and magnetized. Known since NASA's Viking orbiter mission in the 1970s, this enigma puzzled researchers for years.

A groundbreaking study published in Geophysical Research Letters suggests the dichotomy stems from internal heat transfer rather than external cosmic collisions. Leveraging marsquake data from NASA's InSight lander, scientists uncovered evidence of ancient tectonic activity. These tectonic plates, now frozen as a "stagnant lid," may have driven mantle convection, shaping the crust billions of years ago.

Geochemical analysis of Martian meteorites bolsters this theory, revealing the planet's thermal history and supporting the idea that mantle convection influenced the hemispheric divide. The southern highlands’ magnetized surface dates back to when Mars had a global magnetic field, while the younger northern lowlands lack such magnetism and are less cratered.

Despite these insights, researchers emphasize the need for further marsquake data and comparative studies to confirm the theory. Future exploration could offer deeper understanding of Mars’ tectonic and thermal evolution.

Adding to the intrigue, a separate Harvard study revealed last year that Mars' magnetic field may have lasted until 3.9 billion years ago—200 million years longer than previously thought. This overlap with an era of abundant surface water suggests Mars once had conditions ripe for supporting life.