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Q & A: losing the earth's atmosphere

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Most recent answer: 01/02/2013
Q:
why earth cant loss atsmophere(climate) in vaccume universe?
- Mangesh (age 20)
mumbai.mahrashtra,india
A:
The Earth can indeed gradually lose its atmosphere. Fortunately any molecule needs to get many times the typical thermal energy at typical atmospheric temperatures to escape. That means that it happens at a very slow rate. The Boltzmann probability of reaching some energy falls off exponentially in the ratio of that energy to the typical thermal energy scale, kT. kT is about 4*10-14 J in the atmosphere. The amount of energy needed for a nitrogen molecule to escape the Earth's field is about 10-18 J. So the fraction that are escaping at any time is something like exp(-2500), a very small number.


 Mike W.

(published on 01/02/2013)

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