Why doesn't the sky fall?

[J.Oddino]

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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.f3a.us/pipermail/nsrca-discussion/attachments/20050815/75c201a5/attachment.html