Talk:Dwarf planet

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Outdated[edit]

"On March 6, 2015, the Dawn spacecraft began to orbit Ceres, becoming the first spacecraft to orbit a dwarf planet. Later in 2015, the New Horizons is expected to fly by Pluto.

After Ceres, the next-most-massive body in the asteroid belt, Vesta, might also be classified as a dwarf planet, as its shape appears to deviate from hydrostatic equilibrium mainly because of massive impacts that occurred after it solidified. The definition of dwarf planet does not address this issue. Data from the Dawn probe, which orbited Vesta in 2011–2012, may help clarify matters."

I'm assuming there is other information that is outdated with the new Pluto measurements from New Horizons. Jameswrjobe53 (talk) 02:19, 15 July 2015 (UTC)

I removed the Vesta comment. Pluto's size was correct, just an error in the error bar. I haven't looked into the derived numbers (density, albedo, gravity, etc.). Tbayboy (talk) 02:38, 15 July 2015 (UTC)
And I fixed the tense in the other statement. I also removed the {{outdated|date=July 2015}} hatnote. It's a complete overkill, especially since this is a featured article and there is already a hatnote {{Current related||New Horizons{{!}}''New Horizons''. Rfassbind -talk 09:58, 15 July 2015 (UTC)

Mimas[edit]

Mimas is known not to be in hydrostatic equilibrium despite its roughly round shape.--Reciprocist (talk) 15:27, 9 October 2015 (UTC)

So? The article says it is not in hydrostatic equilibrium. By the way, why are moons of saturn being discussed in the dwarf planet article? Huritisho 17:13, 9 October 2015 (UTC)
I've just removed info related to moons of Saturn. The paragraph I removed was entirely about moons, and it added nothing of value since it contradicted itself (first, it was taking into account Mimas was in hydrostatic equilibrium, but later, it turns out it was not). That's just fluff. Huritisho 17:26, 9 October 2015 (UTC)
Saturn's moons are discussed because Saturn has 7 large spherical moons and we know them better than any other set of moons in the Solar System. I think deleting that content might be a bad idea. -- Kheider (talk) 17:28, 9 October 2015 (UTC)
Good. But discuss them in Moons of Saturn. That size and mass section (now called "hydrostatic equilibrium") is already long enough. Also, there is a "main article" link, so the section should be just a summary. Huritisho 17:42, 9 October 2015 (UTC)
The point of mentioning them is to sketch our knowledge about when objects can be expected to be round and which of those can be expected to be in hydrostatic equilibrium. The Saturn system is the only system that can provide us with examples relevant to the trans-Neptunian region. --JorisvS (talk) 12:48, 10 October 2015 (UTC)
Blanking the information about moons probably just makes it more difficult for the reader to know about examples of HE. Because of Cassini–Huygens we know a great deal about the Saturn system. I may revert you because other people do not agree that all of this belong at HE. See: Talk:Hydrostatic_equilibrium#Article_too_focused_on_astrophysics. -- Kheider (talk) 13:28, 10 October 2015 (UTC)
I've been thinking of re-writing the last couple of paragraphs. They confuse the idea of gravitational relaxation with having a particular shape (the shape is a consequence of the relaxation, and so a necessary condition, but not a sufficient condition), misunderstand Cole's work, and add in Lineweaver-Norman (which is a bit different from Cole and more directly relevant to DP-ness). Including the empirical evidence from the well-observed moons belongs here, too, since it's the closest data we have to what the transition might be like in the trans-Neptunian zone. And little Methone illustrates that even equilibrium is not sufficient, that DP-ness requires the equilibrium to be due to the breaking of the material bonds. Tbayboy (talk) 16:48, 10 October 2015 (UTC)
I strongly disagree with re-adding information about the moons of Saturn, but if that's a consensus, then what can I do. Huritisho 17:24, 10 October 2015 (UTC)
Since the page is "dwarf planet", not "moons of Saturn", I'd tend to disagree, too, but...I can see a need for explaining. I'm just not sure this is the place for it. Isn't hydrostatic equilibrium the place, if anywhere? There, the examples can be used without straying too far afield. TREKphiler any time you're ready, Uhura 18:03, 10 October 2015 (UTC)
Other than the potential for tidal forces acting on a moon, there is very little difference in the physical characteristics of a dwarf planet and a large spherical moon. -- Kheider (talk) 19:08, 10 October 2015 (UTC)
"there is very little difference in the physical characteristics" It's not the characteristics that are at issue, really. It's what's being discussed that is. The similarity seems better handled at a page designed for dealing with the common issue than at one intended for something quite different in objective. TREKphiler any time you're ready, Uhura 20:27, 10 October 2015 (UTC)
The problem is that it isn't hydrostatic equilibrium (the section is poorly named as well), it is having "sufficient mass for its self-gravity to overcome rigid body forces". Hydrostatic equilibrium (and the commensurate shape) is a consequence of that. The section is not about explaining HE, it's about explaining the requirements for how HE might be attained in this specific context. Also, it's not about the moons of Saturn, it's about the well observed objects that straddle the boundary between rigid and plastic; where they're from is coincidental, and Vesta, Pallas, and Proteus should be mentioned, as well, so not just moons of Saturn. Since this is specific to DP, and not used elsewhere, I think it is a better fit here than in the hydrostatic equilibrium page. A separate page might work, too, like with clearing the neighbourhood, but it might be small to be a page of its own, and I don't see an obvious name for it. Tbayboy (talk) 02:55, 11 October 2015 (UTC)
"A separate page might work" That makes sense to me, more than trying to shoehorn it in here. Let's not make this page more complicated than it needs to be. TREKphiler any time you're ready, Uhura 03:50, 11 October 2015 (UTC)

Alphabetization[edit]

I've been using {{DEFAULTSORT:}} to alphabetize dwarf planets and other minor planets by their given name (if they have one), rather than by their minor planet number (MPN); because in most contexts minor planets, at least the bigger, better known ones, are usually called by their given name only, e.g. “Vesta” rather than “4 Vesta”. Thus, {{DEFAULTSORT:Sedna}} or {{DEFAULTSORT:Salacia}} (see Sedna, Salacia). (Obviously, the articles “Ceres (dwarf planet)”, “Eris (dwarf planet)”, or “Pluto”, because of the article title, need no DEFAULTSORT.) Also, the given name can begin with any of 26 characters (discounting accented vowels, etc.), whereas the MPN can only begin with one of 10 characters (assuming MPN < 100,000 means that the first character is 0). Thus, alphabetizing by given name results in more possible initial characters, preventing clutter in the alphabetic lists. Okay?--Solomonfromfinland (talk) 23:35, 30 November 2015 (UTC)

RR245[edit]

Is 2015_RR245 sufficiently official to be listed on this page? JDAWiseman (talk) 19:17, 14 July 2016 (UTC)

Most are not listed here. I don't see why it would be special enough to mention here. Note, though, that officialness is a non-reason. --JorisvS (talk) 19:29, 14 July 2016 (UTC)

a dwarf planet is not aplanet — Preceding unsigned comment added by 63.134.173.4 (talk) 18:23, 15 August 2016 (UTC)