# Talk:307261 Máni

Where did the old diameter of ~1386 come from?  Now that I check the history logs I see that User:Michaelbusch kept re-instating it in place of wild guesses. User_talk:68.186.106.251 was the 1st to insert it on 11 Sept 2006 :-) Kheider 06:48, 8 November 2006 (UTC)
With abs mag (H)=3.8, even assuming an albedo of 0.04 in 2006 would have resulted in a diameter of only 1150. -- Kheider (talk) 18:52, 6 January 2010 (UTC)

Needs an image (even though it will just be a dot!)Fig (talk) 13:33, 14 March 2015 (UTC)

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@Nrco0e: Regarding your addition Calculated from the projected elliptical dimension of 842 × 688 km, or triaxial dimension of 842 × 842 × 688 km. The mean diameter of 787 km is derived from the cube root of the product of the given triaxial dimensions., I wonder where you take the information about the triaxial dimensions from. The occultation does not give triaxial dimensions; it gives an elliptical cross section 
  
    
      
        a
        ⋅
        b
      
    
    {\displaystyle a\cdot b}
  
, which may be assumed to be from a triaxial object with volume 
  
    
      
        a
        ⋅
        b
        ⋅
        b
      
    
    {\displaystyle a\cdot b\cdot b}
  
 (it almost certainly isn't, but whatever). It is almost never 
  
    
      
        a
        ⋅
        a
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        b
      
    
    {\displaystyle a\cdot a\cdot b}
  
 for large bodies, even though this is possible. Do you have any source for why it should be the rare one (or the not-so-rare one, for that matter)? If not, I suggest to completely remove all of this, including the mean diameter. The source just doesn't give this information, and a lot of the assumptions must be WP:OR. Renerpho (talk) 04:43, 16 November 2019 (UTC)
There is one more mathematical quirk here: The fit 842 × 688 km is done with just two chords (four points), which is not enough to define an ellipse (even assuming that the two chords had perfect accuracy, which they don't).[1] So, those numbers must come with considerable uncertainty (hundreds of km's in each axis, if I should guess; the uncertainty is not specified). Having a mean diameter based on a triaxial shape based on those numbers is questionable. Renerpho (talk) 04:48, 16 November 2019 (UTC)

Successful observation of a stellar occultation tonight, which was actually streamed live via Youtube. The occultation is starting near the 39:43 minute mark, and took about 23 seconds. The prediction details can be found here. Note that this is the first of three occultations by 2002 MS4 this summer, the other two coming up on August 8th and August 12th. Renerpho (talk) 01:26, 28 July 2020 (UTC)

Cool! We're getting a lot of occultation data, so hopefully we'll see tighter numbers. — kwami (talk) 06:14, 21 June 2022 (UTC)

Isn't Ceres the largest known planetoid without a moon? This google search says that it is just another term for asteroid and Ceres is the largest known asteroid. (I don't think 2002 MS4 is an asteroid)108.46.173.109 (talk) 12:38, 1 May 2021 (UTC)

'Planetoid' is synonymous with 'minor planet'. Ruslik_Zero 17:36, 1 May 2021 (UTC)

We are giving a 3-sigma uncertainty of abt. 14 days for the perihelion date. This may be a sensible thing to do, but right now the article doesn't say what that reason is. The reference gives dtp=4.6936 days (1-sigma), and there has to be a good reason not to follow that. We could point here for why 3-sigma is a reasonable choice for some data, although I still don't see why we don't just give the 1-sigma value from the source.Renerpho (talk) 05:39, 21 June 2022 (UTC)

Uncertainties are generally assumed to be 1 sigma unless stated otherwise. We don't state otherwise, so I changed it to 1 sigma. If there's a reason for 3 sigma, that can be restored with the reason added. — kwami (talk) 06:11, 21 June 2022 (UTC)

Is it known if there are any yet suggested? I don't even know where you'd start to look, but it seems odd that there aren't even any proposed ones from some time in the last 21 years. Or might it just be left as a number forever, as a deliberate piece of astronomical weirdness, seeing as it's now been so long? (How long did Albion run before being named, again?) 51.219.168.15 (talk) 13:31, 9 May 2023 (UTC)

There's always going to be a largest unnamed object, so in that sense it doesn't matter. Often ppl will hold off naming an object until they know enough about it to decide on an appropriate (as opposed to arbitrary) name, or until someone has something or someone to commemorate. There's a whole string of small, unremarkable asteroids named after students who won an annual science competition, but there are more stringent guidelines for these objects. If someone discovers something notable about MS4, we might get a name then. — kwami (talk) 04:47, 10 May 2023 (UTC)
Albion took just over 25 years to get a real name. Double sharp (talk) 16:07, 10 May 2023 (UTC)
Naming a common dwarf planet (as there are hundreds if not thousands of them) is not really a high priority or of scientific value. As I have known many of these objects by their "license plate numbers" for numerous years, I often find them getting a name making it more difficult to remember which one someone is talking about. -- Kheider (talk) 08:44, 11 May 2023 (UTC)
Too bad we can't find mythological names like 'Orten' or 'Emsephor'. — kwami (talk) 10:54, 11 May 2023 (UTC)
No, but already in the first thousand some of the final names alluded to the provisional designation. Consider 572 Rebekka = 1905 RB, 573 Recha = 1905 RC, 574 Reginhild = 1905 RD, 575 Renate = 1905 RE. Double sharp (talk) 16:37, 11 May 2023 (UTC)
Exactly what I was thinking, but harder to do that within the naming reqs of the IAU. — kwami (talk) 08:27, 12 May 2023 (UTC)
Salacia and Varda got named, so naming similarly-sized MS4 and AW197 isn't really that unreasonable in my opinion. Especially since they were discovered so early. Double sharp (talk) 16:54, 11 May 2023 (UTC)
The discoverers had no naming interest in it, probably.  I would like to propose the name Jingwei.Chinese goddess.±  — Preceding unsigned comment added by 文爻林夕 (talk • contribs) 11:11, 15 June 2023 (UTC)

Today, the lede section was changed[2] from

2002 MS4 is large enough that astronomers consider it a possible dwarf planet.

to

2002 MS4's topographic features are among the tallest and deepest known for Solar System bodies, suggesting that it is not a dwarf planet.

I've reverted that, for now, because no explanation was given, and we are lacking a source (and so WP:PROVEIT applies). As I understand it, the October 2023 publication noted that such a topographic feature is possible, under certain assumptions about the object's internal structure; compare (307261) 2002 MS4#Topographic features. I read that to mean they're compatible with hydrostatic equilibrium. My questions are:

What's the current consensus among astronomers?
What examples do we have for the claimed "original" consensus, that astronomers consider it a possible dwarf planet?
Do we have evidence yet that the consensus has shifted since we learned of that large topographic structure? Renerpho (talk) 18:09, 30 November 2024 (UTC)
For the first point, it's ambiguous; there's no strong consensus in the literature. The classification of 2002 MS4 as a dwarf planet is completely irrelevant to Rommel et al. (2023)'s occultation/topography paper as it is not their focus. Presenting Rommel et al.'s findings of massive topographic features as evidence against hydrostatic equilibrium (which is not discussed in depth in the paper) is therefore WP:SYNTHESIS.
Second point, see the citations (with page numbers) for the line Because of its large size, it is considered a dwarf planet candidate by astronomers. in the article body for specific examples of sources calling 2002 MS4 a possible dwarf planet. Note that out of the 4 sources, one (Peng 2023) calls 2002 MS4 a dwarf planet. Being an individual person's master's thesis, I don't think this source should be authoritative on what can call 2002 MS4. Some other groups like Cook et al. (2023) and Zemouri et al. (2022) merely call 2002 MS4 a "large KBO".
Third point, no. I could only find one paper published after Rommel et al. that mentions 2002 MS4; this 2024 arXiv review paper on TNO occultations by Ortiz et al. merely calls 2002 MS4 a "large TNO".
Nrco0e (talk • contribs) 18:54, 30 November 2024 (UTC)
@Nrco0e: Thanks! Mike Brown[3] has also called it "nearly certainly" a dwarf planet. We're not necessarily looking for people who categorically call it a "dwarf planet"; merely for those considering it a "dwarf planet candidate" or "possible dwarf planet", or those who contradict that possibility.
@Kwamikagami: Maybe we should change the sentence in the lede to "2002 MS4 is large enough that some astronomers consider it a possible dwarf planet", to indicate a lack of clear consensus? Renerpho (talk) 19:47, 30 November 2024 (UTC)
The point on SYNTH is well taken.
Brown hasn't updated his site in a decade, so I'm not sure we should count him any more than we do e.g. Tancredi. I'm not aware of any recent lit that considers objects smaller than Salacia to be likely DPs, though it would be interesting if there were. — kwami (talk) 11:11, 1 December 2024 (UTC)
@Kwamikagami: The last update to Brown's website is from May 5, 2023, about 18 months ago (a few months before the paper on 2002 MS4's occultation was published). This means Brown is using an outdated size estimate for it. It's WP:TOOSOON to tell whether he'll change his mind about it with the next update, or when that may be. If he does, he'll probably move it to his "highly likely" category. Renerpho (talk) 15:08, 1 December 2024 (UTC)
AFAICT he hasn't updated the larger bodies in much longer than that, though it's been a while since I checked. The 'updated daily' statement hasn't been true for at least a decade, which suggests he's not taking very good care of the site. — kwami (talk) 21:19, 1 December 2024 (UTC)
I've added the word "some" to the sentence in the lede, as proposed previously. Any objections? Renerpho (talk) 15:20, 1 December 2024 (UTC)
The wording 'consider it a possible dwarf planet' seems odd to me. As if 'possible dwarf planets' were a classification of objects like SDOs. I kept 'some astronomers' but tried different wording for the rest. I'm not particularly happy with that, but I can't think of anything better. — kwami (talk) 21:57, 1 December 2024 (UTC)
I agree yours is better; also, perfect is the enemy of the good. Renerpho (talk) 08:10, 2 December 2024 (UTC)

So the symbol I made was removed from the Wikipedia page because of it being new and not widely spread. I don't disagree with why it was removed, but what should I do to make the symbols more widely known so it could be added to the page? Pluto2181930 (talk) 20:26, 4 September 2025 (UTC)

@Pluto2181930: Make a proposal to have them added to unicode, like the other dwarf planet symbols.[4] Renerpho (talk) 22:00, 4 September 2025 (UTC)