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Why is the moon listed in the table as NOT being in hydrostatic equilibrium? (It's certainly not stated as such in the quoted reference.) — Preceding unsigned comment added by PaulxSA ( talk • contribs) 07:16, 18 November 2019 (UTC)
If all stars were called “suns,” as they only occasionally are, the same problem would obtain, and indeed Sol is an alternative name of our home star. Mucketymuck ( talk) 06:19, 3 December 2023 (UTC)
The IAU requirement for hydrostatic equilibrium ("has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape") can't be read too strictly or else Mercury and Venus must not be planets since they are far from being in hydrostatic equilibrium. [1] Instead the parenthetical "nearly round" part must be given weight. So the claim that the hydrostatic requirement is strict should be removed, and the right hand column of the table is inappropriate. Pulu ( talk) 17:58, 10 February 2023 (UTC)
References
I am not sure about the (uncited) discussion of the TNO moons. It seems to be making the old argument (e.g. Brown's list of candidate dwarfs) that since Mimas is round, TNOs that small should be in HE. But now we suspect (Grundy) that the situation is different and that TNOs as large as Varda probably can retain enough porosity to not be DPs. Yes, Vanth and Ilmarë would get some tidal forces from their parents, which an iceball floating out on its own would not. But if Varda itself isn't in HE, can we seriously claim Ilmarë might be? The error bars don't even take it to Mimas' diameter. I guess the density matters, and we don't know it well. Double sharp ( talk) 16:26, 4 July 2021 (UTC)
In fact, the low albedos of Dysnomia (~0.04) and Vanth (~0.08) also raise suspicions that they are not solid either. Note that Dysnomia is not too far from Varda in size! Double sharp ( talk) 12:28, 2 September 2021 (UTC)
This article seems to be written as an oppostional diatribe to the IAU definition for what is a planetary mass object. The goal of the IAU definition was to help define "dwarf planets" as spherical in shape and exclude "asteroids" (other than Ceres), not get into an argument. In general, objects of 400km+ in diameter are candidates for gravity to be strong enough to 'round' it. The Moon is nearly spherical, hydrostatic equilibrium or not. Ryoung122 17:04, 22 June 2023 (UTC)
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Why is the moon listed in the table as NOT being in hydrostatic equilibrium? (It's certainly not stated as such in the quoted reference.) — Preceding unsigned comment added by PaulxSA ( talk • contribs) 07:16, 18 November 2019 (UTC)
If all stars were called “suns,” as they only occasionally are, the same problem would obtain, and indeed Sol is an alternative name of our home star. Mucketymuck ( talk) 06:19, 3 December 2023 (UTC)
The IAU requirement for hydrostatic equilibrium ("has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape") can't be read too strictly or else Mercury and Venus must not be planets since they are far from being in hydrostatic equilibrium. [1] Instead the parenthetical "nearly round" part must be given weight. So the claim that the hydrostatic requirement is strict should be removed, and the right hand column of the table is inappropriate. Pulu ( talk) 17:58, 10 February 2023 (UTC)
References
I am not sure about the (uncited) discussion of the TNO moons. It seems to be making the old argument (e.g. Brown's list of candidate dwarfs) that since Mimas is round, TNOs that small should be in HE. But now we suspect (Grundy) that the situation is different and that TNOs as large as Varda probably can retain enough porosity to not be DPs. Yes, Vanth and Ilmarë would get some tidal forces from their parents, which an iceball floating out on its own would not. But if Varda itself isn't in HE, can we seriously claim Ilmarë might be? The error bars don't even take it to Mimas' diameter. I guess the density matters, and we don't know it well. Double sharp ( talk) 16:26, 4 July 2021 (UTC)
In fact, the low albedos of Dysnomia (~0.04) and Vanth (~0.08) also raise suspicions that they are not solid either. Note that Dysnomia is not too far from Varda in size! Double sharp ( talk) 12:28, 2 September 2021 (UTC)
This article seems to be written as an oppostional diatribe to the IAU definition for what is a planetary mass object. The goal of the IAU definition was to help define "dwarf planets" as spherical in shape and exclude "asteroids" (other than Ceres), not get into an argument. In general, objects of 400km+ in diameter are candidates for gravity to be strong enough to 'round' it. The Moon is nearly spherical, hydrostatic equilibrium or not. Ryoung122 17:04, 22 June 2023 (UTC)