Hi all. As said in my intro, I'm here to ask a few questions (not for homework) that I was unable to find answers for in the Great Googleverse, neither did I wish to ask them in Yahoo Questions. Even though science (especially astronomy and cosmology) interests me, I've never had the chance to properly study it myself, save the programs on Discovery Science lol, so for all accounts and purposes I'm a layperson. These questions may sound ridiculously silly and newbie-ish but I hope someone has the patience and good nature to take the time to answer them.
(I love my disclaimer! I cannot bear to let it go!!)
My question this time is a hypothetical secanrio concerning the Earth's atmosphere:
1. Imagine the atmosphere thinned milennia ago. What could have caused this to happen, and how? (I'm guessing something to do with the magnetosphere and gravity?)
2. If it were any thinner (how much thinner I do not know), could it sustain life? What sort of life?
3. What would happen to the Earth under a thinner atmosphere?
Again, thanks for your patience and help.