Why is there a layer of atmosphere around earth while other planets don't have?
Answers
gravity my friend gravity, when the rms velocities of the gas molecules become more than the escape velocity of the particular planet the gases will not form an atmosphere ...
let me get this simple....
all gases are at all times in continuous motion.... there is drag offered by the earth's surface and force of gravity too.... so... the gases.... we know have some weight and form the atmosphere and thereby giving pressure to the surface.....
escape velocity of the earth is the speed at which any particle will and must escape the gravity of earth and travel into interstellar space.... thus when rms velocity of a gas exceeds escape velocity... no atmosphere will persist on the planet unlike earth.....
If you want it mathematically,... compare b/w rms and escape
escp = √rg (r= distance of object from the center of the earth )
( g= acc. due to gravity)
rms = √(3RT/M) [ R= universal gas const. T= temperature. M =
mass of the gas]
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Cheers
PS>.. forgive me for all my spellin' mistakes.. (I typed in a hurry) :)