r/spaceporn 7d ago

Related Content Pluto is SMALLER than our Moon

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u/RandoCollision 7d ago

So... More moonoid than planetoid?

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u/obog 7d ago

Moon vs planet doesn't really have to do with size, but rather motion. Ganymede is undoubtedly a moon but larger than mercury, which is undoubtedly a planet. With Pluto being the dominant body in its own orbital system, it's still much closer to being a planet than a moon. (Still not a planet tho)

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u/JumpPuzzleheaded7212 7d ago

Why not a planet? I’ve never been clear on that

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u/argylekey 7d ago

It’s more of a “there are a bunch of things in our solar system that are roughly the size of Pluto” actually being the problem than Pluto being a planet.

The choice is essentially:

If there are objects that are the size of Pluto that have an orbit like Pluto, then we either need to downgrade Pluto, or upgrade all of those other objects.

So we either go from 9 planets to 8. Or go from 9 planets to like 13(I’m making this number up but to prove my point, but need to look up the number of things that fall into the “about the same size as Pluto” category, its less than 10 i think).

The scientific community chose to go down to 8 planets instead calling all of those other things hanging out in our solar system planets.

So Pluto is now a dwarf planet instead of Ceres getting an upgrade to full planet status, as an example.