Pluto and Charon

[Catastrophe]

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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[Catastrophe]

Charon (moon) - Wikipedia

Pluto - 9th Planet - First Dwarf Planet - First Dwarf Planet with 5 moons.

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[Pogo]

Yeah, I’mnot sure that they have ever defined at what point does a planet/moon or dwarf planet/moon becomes a double. I guess it would have to with the difference between the geographic center and the barycenter.

 

[Catastrophe]

Personally, I think the centre of gravity (barycentre) being outside either object is a major factor. Of course, if they were of equal mass, the cog would be in the middle of the distance between them.

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[Catastrophe]

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