Ozone layer is also protected by the magnetic field. If the magnetic field of the earth were as weak as the planet mars, the solar wind would strip away the ozone layer which is our natural filter from the sun. Allowing the full rays of the sun in, means all life would die. The UV rays of the sun are deflected by the ozone layer. Full amount of UV rays would kill everything, basically sterilizing all life. UV rays are the most damaging to life because they alter DNA to the point life cannot exist. Example: The reason welders have to wear eye protection is because the welding light produces intense UV rays similar to the sun. Staring at a welding light for just 5 minutes can damage you eyes to the point you can become blind. Now imagine that same type of light coming at you from the sun several 1000 times more intense. And because UV light alters DNA, it’s one of the main causes of skin cancer. So having a planet filter like the ozone layer, is a must have. A must have that mars does not have.