I know that many people are going to disagree with me on this. I suspect that Pluto's basic compostion is basaltic, with nitrogen ice on the real surface, pssibly including methane ice and dry ice as well. The ices sublimate when to form a very thin atmosphere when Pluto is close to perihelion like it was between 1979 and 1999. Ulttaviolet sunlight turns the color of hydrocarbon ices to reddish-brwon. When baslat oxidizes, it turns reddish brown. That's what explains the red colors of Mars and it's sands.

http://1.bp.blogspot.com/_RpTRoam5eOc/SbMwMS5K6EI/AAAAAAAALgo/IqS8FEpNqvY/s400/Pluto.jpg

http://www.google.com/search?q=hubble+pluto+images&hl=en&rlz=1T4GPCK_enUS400US400&prmd=ivns&tbm=isch&tbo=u&source=univ&sa=X&ei=WAWyTfz_CurX0QGL462FCQ&ved=0CBoQsAQ&biw=955&bih=472

The people who say that Pluto is a big snowball of ice and rocks or is a comet do not understand the processes of planetary formation and chemical differentiation. In other words, they don't understand what they are talking about.

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