In: Physics
Write a brief note on why Earth's magnetic field may have allowed it to keep its atmosphere whereas Mars’ lack of a comparable field may have contributed to its loss of an atmosphere.
Sun continuously releases charged particles from its upper atmosphere (corona) out into the solar system, this emmision is known as solar winds. This stream of charged particles are very energetic and when it interacts with the particles in the atmosphere, it gives them enough energy to escape from the planet's gravity. For example, on mars, the solar wind particles strikes it at about 1,000,000 mph (447,000 m/s, or about 0.15% the speed of light), an incredibly fast rate. So, the bottomline is that the solar wind is harmful for atmosphere. This is why Mars currently loses about 100 grams of atmosphere every second.
But, when there is presence of magnetic fields, the charged particles get deflected by lorentz force and that's why on Earth they funnel into the poles, creating beautiful Aurora sites. So, Earth's Magnetic field indeed helped us in protecting our atmosphere over these billions of years.