Mars's Interior is 400°C Hotter Under Southern Hemisphere

The planet Mars is a cold and dry world completely devoid of life, but billions of years ago things were much different. This is when Mars had a much warmer interior than it does today, resulting in active volcanism that replenished its atmosphere, a magnetic field that protected the planet from harmful solar and cosmic radiation, and a surface of flowing liquid water. But due to Mars’s small size, the interior cooled far faster than Earth’s has cooled, leading to a loss of volcanism