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by lmm
2743 days ago
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Why does one want to exclude Ceres? What I don't like about the "cleared its orbit" criterion is that it's something you can't tell from looking at the object itself. If a planet is ejected from its orbit, it becomes a ... well, we don't even have a name for what it would be. (This problem exists for "moon" to a certain extent, but a moon that's thrown out of planetary orbit would become a planet if it was big enough and an asteroid if it wasn't). It's also hard to apply: a lot of extrasolar planets we're discovering will have to be reclassified once we get better at finding smaller bodies, just like in this solar system. |
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Dwarf planet is a helpful term in some contexts but not others. The solar system is a dynamic system, when talking about the whole thing or its evolution it's useful to distinguish between planets and dwarfs.