The only moon in the solar system as far as I know that has an atmosphere worth mentioning is Titan (saturn). IIRC its about twice the density of earths, the other moons atmospheres are close to vacuum.
And for pluto and charon: at this moment there's quite a discussion about whether pluto is even worthy of having a planetary status. It's a very small world (2370 KM across), even far smaller then our own moon (3500 KM across) . Charon is half the size of Pluto. They found a lot of space rocks like pluto, even one that could be more than half it's size (800 to 1300 KM) and they keep finding more. Follow this link for information:
http://news.bbc.co.uk/hi/english/sci...00/1054157.stm
Re: Moons
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