Why is life not possible on Venus and Mars?

Life as we know it cannot exist on Venus and Mars due to their extreme atmospheric conditions and lack of liquid water. Venus has a runaway greenhouse effect with surface temperatures around 450°C (850°F)—hot enough to melt lead—and crushing atmospheric pressure 90 times greater than Earth's. Its thick carbon dioxide atmosphere traps heat so effectively that Venus is actually hotter than Mercury, despite being farther from the sun. Mars faces opposite challenges: its thin atmosphere (less than 1% of Earth's pressure) cannot retain heat or support liquid water on the surface. Temperatures average -60°C (-80°F), and any liquid water would quickly evaporate or freeze. Additionally, both planets lack protective ozone layers and magnetic fields comparable to Earth's, exposing their surfaces to harmful solar and cosmic radiation that would destroy organic molecules essential for life.