AST251H1 Lecture Notes - Lecture 5: Aurora, Runaway Greenhouse Effect, Escape Velocity
29 Jan 2018
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When the photons hit the magnetic field, they travel to the poles of the earth and they give us some colours like green and blue, and they give us the aurora borealis. The magnetic field is also being stripped away with each photon that hits it. We can even lose an atmosphere by thermal escape where particles in the atmosphere gain energy through heat. If the particles heat up enough and move fast enough, they can reach the escape velocity and escape the earths gravity. The reason why none of the terrestrial worlds have significant amounts of hydrogen gas in their atmosphere is 1) hydrogenn gas was not present inside of the frost line when terrestrial planets form. 3) hydrogen suffered nuclear fusion to become the nitrogen gas in our atmosphere. 4) none of the terrestrial planets have enough mass. The answer is 4, none of the terrestrial planets have enough mass.
