• Apepollo11@lemmy.world
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    28 days ago

    I’d be happy with:

    Pluto = planet

    Anything smaller than Pluto ≠ planet

    Nine planets. Now with clear non-stupid rules.

    • Semjeza@fedinsfw.app
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      28 days ago

      The arbitrary cutoff size being to ensure continuity of the scientific consensus in popular awareness when I was a child isn’t a stupid rule.

      Not even when a larger kuiper belt object is found.

      Not even, when since mass is the primary means of estimating size until we fly a probe out there, we estimate a smaller but much with much more mass object to be larger and we debate a 10th planet yet again.

      • Apepollo11@lemmy.world
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        28 days ago

        Hey, if we find something bigger than Pluto, then by all means let’s call it a planet.

        By any reasonable person’s definition of a planet, Pluto is a planet. It’s a rocky spherical mass that orbits the sun, with a varied terrain of mountains, plains and glaciers. It has days and seasons. It has its own system of moons.

        An additional grievance I have is that, by the IAU’s stupid definition of a Dwarf Planet, Charon should really be called a dwarf planet too. It isn’t a satellite of Pluto in a meaningful sense - both Pluto and Charon orbit a point between them. The other moons also orbit this space between Charon and Pluto.

        So, want to know why it isn’t a Dwarf Planet? Because the IAU class it as a planetary satellite. What’s the formal definition of a planetary satellite then? There isn’t one. It was discussed, but a formal definition was not decided upon. Charon is literally a moon now because it was called a moon before the definition of a planet was changed and dwarf planets were invented.

        I’m all for formal definitions, but the IAUs current rules are just really sloppy. It’s maddening.