Why doesn't the sky fall?

[John Pavlick]

I'll drink to that!!!

John Pavlick
http://www.idseng.com
 

> -----Original Message-----
> From: discussion-request at nsrca.org
> [mailto:discussion-request at nsrca.org]On Behalf Of john tarpinian
> Sent: Monday, August 15, 2005 7:07 PM
> To: discussion at nsrca.org
> Subject: Re: Why doesn't the sky fall?
> 
> 
> The sky has fallen, its resting on the ground.
> 
> --- Wayne Galligan <wgalligan at goodsonacura.com> wrote:
> 
> > SO..... in other words... Newtons theory about the
> > apple falling on his head about sums it up....
> > right?
> > 
> > WG
> > 
> >   ----- Original Message ----- 
> >   From: randy10926 at comcast.net 
> >   To: discussion at nsrca.org 
> >   Sent: Monday, August 15, 2005 4:35 PM
> >   Subject: Re: Why doesn't the sky fall?
> > 
> > 
> >         At the top of a planet's atmosphere,
> > particles are running around in all directions, at
> > all of the various speeds corresponding to the
> > kinetic temperature, and to the predictions of the
> > Maxwell-Boltzmann distribution. Some of the
> > particles will be headed upwards, some downwards,
> > and some sideways. Some of them will be moving
> > slowly, some at an average speed, and some very
> > quickly. Whether a planet will hold onto an
> > atmosphere will depend upon the motions of those
> > particles which happen to be moving upwards at a
> > much higher than average speed. If those particles
> > are moving upwards at less than the planet's escape
> > velocity (the speed which an object must be
> > traveling at in order to escape the planet's
> > gravity, and go off into space), then the particles
> > will follow curved paths which are ellipses with a
> > focus at the center of the planet, and will go up
> > for a while, and then fall back into the atmosphere.
> > (This discussion assumes that we are in the very
> > outermost reaches of the atmosphere, where there is
> > so little gas that the particles don't collide with
> > other particles very often. If we were talking about
> > a lower region, the particles would be deflected
> > from their paths, and change their energies, so
> > frequently that any discussion of motions which
> > resemble orbital motions would be pointless.)
> >         However, if the particles were moving
> > upwards faster than the planet's escape velocity,
> > they would follow hyperbolic paths which would take
> > them out into space, never to return. Of course,
> > only those particles which happened to be heading
> > upwards at very high speeds would follow such paths,
> > but as already discussed, there is a continual
> > shuffling of particle motions and speeds, and as a
> > result, in a short while, particles which did not
> > originally have such motions would end up with
> > motions identical to those particles which had been
> > lost, and then those particles would also be lost.
> > 
> > 
> >   Simple ain't it.
> > 
> >   Randy
> > 
> >     -------------- Original message -------------- 
> > 
> >     I thought it was time to stir the pot while we
> > wait for the results from the Worlds.
> >     Can anyone explain why gravity doesn't pull all
> > the air molecules down to earth?  Are they lighter
> > than space?  What is their mean speed?
> >     I don't think this will help answer the
> > weathervaning question and won't help us fly any
> > better but I thought it might be fun.
> >     Jim O
> 
> 
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