Evidence suggests that Mars may have had life at some point in the past. The difference between Earth and Mars is that during formation, Earth's inner core of solid iron and nickel with an outer core of other hot metals moving fairly quickly created a strong magnetic field which shielded (and shields) the atmosphere from being bombarded with cosmic and solar radiation, which prevents the atmosphere from being stripped away rapidly... Mars on the other hand doesn't have a strong magnetic field and so this led to rapid deterioration of it's atmosphere.
Now, Mars has a very thin atmosphere comprised mostly of CO2 (98%) which is, obviously, not a good support for life. However, scientists have reason to believe that before a lot of Mars' atmosphere was stripped away, life could've been present there due to conditions which would be similar to Earth's. You may ask how this could be as Mars is not in the habitable zone of our solar system and so water should've taken a solid (ice) form on the surface. However, Mars has a much higher % of CO2 in it's atmosphere than Earth, which gives us reason to suggest that it had a high % in the past too. This means that the greenhouse effect upon the planet's lower atmosphere (troposphere) and surface would be much greater than here on Earth. This would compromise for the less solar radiation reaching the planet and would've made it much warmer- about Earth's average surface temperature (15°C). So water would've been able to take a liquid form on the planet's surface which is the staple ingredient for supporting life! Additionally, we know that the compounds and elements contained within the soil from Mars suggests past life- carbon compounds etc.
Thanks for reading!
All critiscm and comments appreciated! But please go easy, I'm only 16 and starting my A-levels very soon (Chemistry, Physics, Maths and Geography if you were wondering)...
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