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xkcd #2908: Moon Armor Index
(imgs.xkcd.com)
Alt text:
Astronomers are a little unsure of the applicability of this index, but NASA's Planetary Protection Officer is all in favor.
Finally, Earth is Number One again (well Number Two if you count Pluto, that is)
That was why we told pluto it couldn't be in the club anymore.
Pluto-charon shouldn't count since it is more akin to a binary planetary system than a planet-moon system. Charon and Pluto are so close in size that the system has a barycenter outside of Pluto. This means instead of Charon orbiting a point inside Pluto, Charon and Pluto orbit a point about 800 km above Pluto's surface.