The entire Pluto system is interesting on a wider level, but not least is the Pluto/Charon barycentre - which depends on the masses of dwarf planet and satellite - or are they joint dwarf planets?
Pluto's moon Charon sports a red polar cap that forms as seasons change | Space.com Forums
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Pluto's moon Charon sports a red polar cap that forms as seasons change | Space.com Forums
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