The Surprising Ways Mars is Hostile to Life

I would argue that Mars cooled down faster because it was NOT hit by an object similar to Earth was. Which created a unique core mix (allot less uniformed) and a stronger and longer lasting magnetic field. 



Earth == Correct star size (Sun), green zone range to said star, core mix because of pre moon hit, comparably overly large moon with a gyro stabilizing effect and large amount of water (both need for life and T-plates). That is what it takes to create complex life (mammals etc) and its like winning the lotto 10x times in a row.


Mars is too small, but Venus is about Earth size (ca -10%), has a thick atmosphere because its large enough (not the kind you would want to be in though), but still doesnt have a magnetic field. Why? Because of the core mix, I would argue. The MAJOR problem with this is that most planets in the Universe do NOT have a Earth like core mix and if we are talking planets in the green zones of their stars, there are even fewer. Earth is most likely if not guaranteed 1 in a trillion.