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    No One Actually Knows What a Moon Is
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    No One Actually Knows What a Moon Is

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    1. Joshau-k on

      The whole classification system of sub-stellar spacial objects needs a do over.

      You get nonsense like rogue planets and double planets technically not being planets. Meanwhile the ‘dwarf’ adjective is used in contradictory ways.

      Orbit is clearly not a fundamental property, yet it’s treated like one in our classification system. 

      Once you separate out the physical composition and formation history from orbit, then classifying types of moon orbits into short and long term categories is much simpler

    2. A_N_T on

      I, in fact, ***do***. It’s the big round thing in the sky at night. Checkmate, astrologists.

    3. manicdee33 on

      FWIW “Quasi-” is a (borrowed) prefix in English meaning that something is almost but not quite the thing described. So “quasi-moon” is a great description for an asteroid that shares an orbit with a planet/dwarf planet/planetoid but isn’t actually in orbit around the larger object.

      At some point there needs to be a scale: at what point are two bodies satellites of each other, and does the relationship rely on relative mass/volume? Are the Earth and Moon in a planet/moon relationship or is this a binary planet system? Is the definition based on where the barycentre is, or just on the jive of it?

      What about a system with harmonic resonances where the barycentre is sometimes inside, sometimes outside the largest of the bodies in the relationship?

      Is a rubble-pile asteroid ever going to class as a satellite, or always a captured asteroid?

      Does the relationship have to be stable for a certain period of time to be a planet/moon relationship? Is that decades, centuries, millennia, more?

    4. ChiefLeef22 on

      If this is about that quasi vs mini-moon thing again, no we DO know what a moon is, people are just confused. Tony Dunn encapsulated really well with a simple explanation:

      Simple test:
      Delete the Sun.
      – Still orbiting Earth, even years later? Mini-moon (bound), like 2024 PT5.
      – Gone forever? Quasi-moon, like 2025 PN7.

    5. FUThead2016 on

      Nobody knows what a moon is, ok? Nobody. Some people say it’s made of cheese, some very smart people. But it’s a war zone over there on the moon. You got the crazy people from the Dark Side .There’s a Dark Side, not many people know this, and it’s got no electricity and all the bad people live there. And they wanna come over here to the Lighter side. They say oooo it’s just two small steps for mankind, but it’s not, ok? It’s a huge leap if you’re gonna come over to the Light side. And we gotta stop those lunatics. They’re lunatics.