this post was submitted on 19 Mar 2024
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Astronomers are a little unsure of the applicability of this index, but NASA's Planetary Protection Officer is all in favor.

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[–] teft@lemmy.world 6 points 8 months ago

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.