Talk:List of gravitationally rounded objects of the Solar System

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Featured listList of gravitationally rounded objects of the Solar System is a featured list, which means it has been identified as one of the best lists produced by the Wikipedia community. If you can update or improve it, please do so.
Article milestones
DateProcessResult
January 31, 2009Featured list candidatePromoted

Days[edit]

Shouldn't synodic day lengths be added to the tables? 76.66.196.229 (talk) 11:42, 6 February 2009 (UTC)[reply]

Accepted dwarf planets[edit]

Actually, Ckatz, per you revert edit line "not our place to second-guess this; the people who created the category also get to populate it", I'm not second guessing. What we have listed under dwarf planets are not dwarf planets, but bodies named as dwarf planets. We have an entire section of likely dwarf planets which have not been named as such. If the category "dwarf planet" is defined by what the IAU names a dwarf planet, then we need to make that explicit in the intro. But all our refs say otherwise: that a body is a dwarf planet because of geological and orbital parameters, regardless of its recognition. No IAU publication I've seen says "the people who created the category also get to populate it," they assume that the category is populated by the objects themselves. Therefore we need to inform our readers that we likely know of many other dwarf planets which aren't on this list, which looks misleadingly comprehensive. kwami (talk) 19:40, 6 February 2009 (UTC)[reply]

There are currently only five objects in the Solar System that are categorized as dwarf planets. We are not misleading the readers as there is a section below it that clearly indicates other potential candidates. --Ckatzchatspy 20:52, 6 February 2009 (UTC)[reply]

This article needs a better name[edit]

This is the article one goes to to get orbital and physical info on the planets. It needs a name that gives people some idea of what it is. Nobody, looking for information on the radius of Mercury, is going to search for "hydrostatic equilibrium." Serendipodous 22:11, 20 February 2009 (UTC)[reply]

Yes, it's very awkwardnessfull. Any suggestions?
But why should people need to come here for the dimensions of Mercury? kwami (talk) 07:19, 7 April 2009 (UTC)[reply]
Two years and neither discussion nor resolution? Yes, it's a ridiculous title. Ideas:
  • List of round solar system objects
  • List of major solar system objects
  • List of planets, dwarf planets and satellites in the solar system
Or a combination of the above, such as, List of major solar system objects (planets, dwarf planets and satellites)
The title doesn't have to be exact but descriptive and search-engine friendly. Petersburg (talk) 01:37, 29 March 2011 (UTC)[reply]
"Major" is judgemental, by which I mean that it depends upon the perspective of the person doing the search. Why is Mimas major, but not Proteus or Pallas, which are larger? From another perspective, I could reasonably cut the list of major objects at Uranus, or Mercury. The third doesn't fly, either, since it isn't a list of satellites, only those in H-E (and "major satellites" has the previous problem). "Round" could work, with "spheroidal" and "ellipsoidal" (and H-E) also redirecting, except that you then have to explain away coincidental roundness. Maybe "gravitationally rounded"? Tbayboy (talk) 03:36, 29 March 2011 (UTC)[reply]
"gravitationally rounded" is as awkward as "hydrostatic equilibrium", and "hydrostatic equilibrium" is what is important about these objects. -- Kheider (talk) 03:42, 29 March 2011 (UTC)[reply]
The idea is that it searches better for casual readers, since they're more likely to look for "round" than "H-E". There's probably a better way to get that kind of search to work, though. Tbayboy (talk) 14:15, 29 March 2011 (UTC)[reply]
But none of those titles are very accurate. The asteroid 2005 YU55 is round, but surely you don't mean to include a 400 meter object? Major solar system bodies generally only refers to the Sun and Planets. Hydrostatic equilibrium is the definition of significance. Maybe those pages can be re-directs? -- Kheider (talk) 03:40, 29 March 2011 (UTC)[reply]
So no objections against using the title List of planets, dwarf planets and satellites in the solar system? Accurate, descriptive and search-engine friendly. Petersburg (talk) 12:19, 29 March 2011 (UTC)[reply]
See objections above! The page does not include a "list of satellites" (which implies all), but only of "satellites in hydrostatic equilibrium", so that title is not accurate. If you correct it, you're back to H-E in the title, and you don't need the rest, so you're right back to what we have now. Tbayboy (talk) 14:15, 29 March 2011 (UTC)[reply]
Didn't notice that, sorry. This is an article for the public, right? How many people know what "hydrostatic equilibrium" means? 1 out of 100 at best. It's a terrible title. That expression needs to be substituted with something descriptive even if it is not 100% accurate. So "round" or "major" or other suitable terms can be used. The other problem is searching for planets, dwarf planets and satellites. This article will not be listed due to its title.
Of course the other question is whether the grouping of objects is appropriate. What is the case for having a list of solar system objects in hydrostatic equilibrium? The Solar System portal lists planets, minor planets and moons as categories. The term is not even mentioned there. If we are to keep this grouping, my suggestion would be List of major planets, minor planets and moons and adjust the content. It's clear that we are struggling with coming up with a good title so the content might be the culprit. Petersburg (talk) 10:41, 30 March 2011 (UTC)[reply]
A List of major planets, minor planets and moons would have roughly 500,000 entries. Serendipodous 12:55, 30 March 2011 (UTC)[reply]
You misunderstand. The meaning is: major (planets, minor planets and moons). Or: major (planets, dwarf planets and satellites). That is: major planets, major dwarf planets and major satellites. Same list. Petersburg (talk) 12:03, 31 March 2011 (UTC)[reply]
Major planet is already a classification (a synonym for planet, basically, as distinct from minor planet). The term "Major minor planet" is therefore an oxymoron. Serendipodous 12:38, 31 March 2011 (UTC)[reply]
Hydrostatic equilibrium is a significant natural transition, a visible marker of where geology begins to happen (perhaps that should be in the lead). You say "public", but I think you mean "neophyte". Many wikipedia pages require some understanding of the subject (some require a lot!), and this is one of them. I think the page you want is List of solar system objects, which is introductory level. Tbayboy (talk) 15:56, 30 March 2011 (UTC)[reply]
Public = neophyte = laymen & laywomen. Wikipedia is not a scientific treatise, it is meant as a compendium of basic knowledge for the public. List of solar system objects has no useful information in it beyond a list while this one does. One shouldn't need a dictionary for understanding titles. Not sure why you're so hung up on this silly title and at the same time provide no suggestions for improving it. Petersburg (talk) 12:08, 31 March 2011 (UTC)[reply]
It would be Planets, dwarf planets, and "major" moons of the Solar System. Besides "major" being vague, there's nothing to suggest these form a coherent class of objects. I agree the current title is inaccessible, but I can't think of anything better, and no-one has suggested anything that's much better. What we need is an accessible synonym for 'hydrostatic body'.
I should also not that we've already had this discussion. We had it years ago when this article was under construction, and changed names about 6 times. I don't like this title, I don't think anyone likes this title, but it's the title that best fits the contents, and there aren't any other titles that work. Serendipodous 12:44, 31 March 2011 (UTC)[reply]
Maybe List of rounded bodies of the Solar system, where we explain in the lede that rounded (as opposed to the inadequate "round") means rounded under gravitational relaxation? — kwami (talk) 12:40, 31 March 2011 (UTC)[reply]

If we're going to use rounded, we may as well use gravitationally rounded. Serendipodous 12:50, 31 March 2011 (UTC)[reply]

Sounds good to me: List of gravitationally rounded objects of the Solar System. That does seem more accessible. — kwami (talk) 13:07, 31 March 2011 (UTC)[reply]

It is also important to note that every object on this page may some day be known as a full blown planet, depending on how the definition of a planet does or does not evolve. There are currently 541,000 minor planets. -- Kheider (talk) 16:12, 30 March 2011 (UTC)[reply]

Agree that either List of rounded bodies of the Solar System or List of gravitationally rounded objects of the Solar System would be much better choices than the current one. Views? Petersburg (talk) 12:43, 1 April 2011 (UTC)[reply]
Anyone? Petersburg (talk) 21:41, 3 April 2011 (UTC)[reply]
No objections, so I'm moving it to Serendipodous's suggestion. — kwami (talk) 00:04, 4 April 2011 (UTC)[reply]

Ganymed?[edit]

Why did someone add the ~30 km diameter asteroid Ganymed to the potential dwarf planets list? I'd fix it, but I'm terrible with Wiki tables and I'm just on my way to bed. --Patteroast (talk) 06:32, 7 April 2009 (UTC)[reply]

Reverted. kwami (talk) 07:17, 7 April 2009 (UTC)[reply]

The 1036 Ganymed article says, "produced images of the asteroid, revealing a roughly spherical object." Of course this is a coincidental shape and not a result of true hydrostatic equilibrium. The tiny moon of asteroid 243 Ida also has a (coincidental) "roughly spherical shape" :-) -- Kheider (talk) 14:53, 7 April 2009 (UTC)[reply]

So are a lot of river rocks. The list could get quite lengthy ... kwami (talk) 15:59, 7 April 2009 (UTC)[reply]

Pictures[edit]

The pictures of dwarf planets are a mixture of real images and artists conception. Is this OK or is the Wiki way to have real images for all.

Carlwev (talk) 19:14, 14 September 2009 (UTC)[reply]

Real images are preferred, but artist's conceptions are sometimes all there is. Serendipodous 20:13, 14 September 2009 (UTC)[reply]

Luna[edit]

Shouldn't "the Moon" be identified by it's name like the other satellite objects? Lonelyksdem (talk) 20:01, 17 November 2009 (UTC)[reply]

The Moon's name is "the Moon" (capital M). Serendipodous 20:05, 17 November 2009 (UTC)[reply]

Vesta[edit]

Since Hubble determined that Pallas appears to not be in equilibrium, which almost certainly excludes Hygiea as well, Vesta is of interest as the only DP candidate in the inner Solar System, so IMO it should definitely be on the list. The article makes clear that there are many others in the outer SS, and that it's impractical to list them all, but we can and IMO should list them all (all one of them) in the inner SS. kwami (talk) 20:57, 22 November 2009 (UTC)[reply]

When did this happen? And why does it necessarily exclude Pallas and Hygeia from consideration? Have they been officially dropped? Regardless, the title of the subsection is "largest dwarf planet candidates". I picked largest as a criterion because it was objective and measurable. If you feel there is another criterion that could include Vesta then fine, but please make sure the criterion is objective and consistent. Serendipodous 21:03, 22 November 2009 (UTC)[reply]
Grey areas... I agree 4 Vesta is a strong dwarf planet candidate, but that is pending confirmation of Hydrostatic equilibrium (vs what I believe is just currently a theory). Until it is more official I am also somewhat concerned about potentially confusing the general public. -- Kheider (talk) 21:14, 22 November 2009 (UTC)[reply]
[edit conflict] A Science article just came out that Pallas is partially differentiated by not completely, and is somewhat irregular in shape. (Hygiea, of course, is substantially less massive than Pallas -- though I suppose if it's icy enough, it might still be a DP.) Vesta is thought to have achieved equilibrium, but to no longer be in it; unlike icy bodies, rocky bodies can't easily reachieve equilibrium if they get whacked after they cool. So we think we know the situation with Vesta; the only question really is a matter of definition, whether it's a DP or an ex-DP. With the KBOs, we can only assume that they're in equilibrium, because we can't resolve their surfaces well, so they're a different kind of candidate. kwami (talk) 21:16, 22 November 2009 (UTC)[reply]
I am also afraid of being wrong, what if Wikipedia assumes Vesta is in HE, and then Dawn or whatever proves that it is not? -- Kheider (talk) 21:23, 22 November 2009 (UTC)[reply]
Wrong how? If we assumed Vesta were in HE, we would count it as a DP, not as a candidate. It appears to be in HE (or to have once been in HE), but that is not demonstrated, hence the candidacy. kwami (talk) 01:59, 23 November 2009 (UTC)[reply]

I think now would be a good time to revise the list anyway; Varuna is apparently not nearly as large as originally thought, and 2002 TC302 need to be included. Serendipodous 21:33, 22 November 2009 (UTC)[reply]

Vesta is often called the smallest terrestrial planet. I think Vesta article should be brought to FA. Ruslik_Zero 10:25, 23 November 2009 (UTC)[reply]
We could, but in 2 yrs it will be almost entirely obsolete. kwami (talk) 10:52, 23 November 2009 (UTC)[reply]
We could push it to the main page just before Dawn arrives. Ruslik_Zero 10:55, 23 November 2009 (UTC)[reply]
Yeah, we will be getting a lot of hits.
I just hope a few years later our Pallas article is obsolete! kwami (talk) 11:26, 23 November 2009 (UTC)[reply]

Objects that made the list while other didn't[edit]

Obviously more objects will get included on this list as time passes, but I find the current content to be missing a few objects. . Haumea makes the list by virtue of its dwarf planet status even tho it is of irregular shape. . Proteus (420km) dos NOT make the list even tho it is larger than Mimas (397km) and the reason given is that Proteus has an irregular shape. . I also don't see Vanth (660km). . Does anybody see reason to make the change and add columns for Proteus and Vanth ? —Preceding unsigned comment added by Skiz nem (talk • contribs) 20:58, 11 October 2010 (UTC)[reply]

It's not due to regular shape. It's due to hydrostatic equilibrium. Haumea is in hydrostatic equilibrium, but stretched out by its rapid rotation. Proteus would be in hydrostatic equilibrium, but is too cold. Vanth is too small to be in hydrostatic equilibrium, so is not included. Serendipodous 21:03, 11 October 2010 (UTC)[reply]

"Vanth is too small to be in hydrostatic equilibrium" at 660km but Mimas is large enough at 397km ? Does the size needed to be in hydrostatic equilibrium vary that greatly by temperature ? — Preceding unsigned comment added by Skiz nem (talk • contribs) 21:58, 12 December 2010 (UTC)[reply]

The cited value for Vanth's diameter is 280 km. Oh, wait, yeah, I see, someone called the diameter the radius. Common mistake there. Serendipodous 22:17, 12 December 2010 (UTC)[reply]
The shape of a small candidate probably has more to do with composition/density then temperature. -- Kheider (talk) 02:52, 13 December 2010 (UTC)[reply]
In the case of Proteus though, it would appear to be temperature, as Proteus's composition is similar to that of Mimas, which is spherical. Serendipodous 10:38, 13 December 2010 (UTC)[reply]

Obliquity of the ecliptic value[edit]

I've corrected it to 23.44°. The source, JPL's planetary fact sheet was wrong, and I have informed the author of the site. This is not just a new, improved figure, or one that is in dispute. This has been the value since late 1917. Saros136 (talk) 22:39, 13 November 2010 (UTC)[reply]

move?[edit]

Move to "List of planetary-mass objects in the Solar System"?

We could either remove the section on the Sun, or leave it in for comparison purposes, but this would take care of the titling issues, and also make the article a more convenient target for links (say in planet, in the planemo section). — kwami (talk) 16:54, 6 February 2012 (UTC)[reply]

Don't really see the difference between this and using Basri's definition. Since Basri's definition of "planemo" is an object in hydrostatic equilibrium that doesn't fuse, all it really does is add another layer of explanation. Serendipodous 20:32, 6 February 2012 (UTC)[reply]
I think it would be useful because we talk about 'rounded' bodies in many other articles, and we never mean stars. In such cases we could link here for examples, but people might object if we only mean PMOs and this article isn't restricted to PMOs. The only extra layer of explanation would be "isn't a star", and because we could link to the planemo section of planet for explanation, it would actually mean fewer layers of explanation here. I think it would also be a more accessible title than "gravitationally rounded", which can convey the false suggestion that the objects are round, and in itself therefore requires more layers of explanation. — kwami (talk) 21:27, 6 February 2012 (UTC)[reply]
See the previous discussion on "This article needs a better name". "Planetary-mass objects" is okay for accuracy, but I think it's a stretch for the layman looking for "big, round things" including satellites, since the "planetary" suggests (to the naive reader) "not a satellite". I.e., it's moving away from a descriptive title to a technical term title -- back towards the H-E problem (although not as bad as that one). Also, how does a name change make linking more convenient? The planemo section can link to this article as is; the caveat is already in the lead. Tbayboy (talk) 16:36, 9 February 2012 (UTC)[reply]
Perhaps you're right. — kwami (talk) 16:52, 9 February 2012 (UTC)[reply]

New complication: Methone appears to be gravitationally rounded, and I don't think we want to start adding bodies like that. Also, we should probably merge with List of planetary-mass objects in the Solar System, which seems more accessible in its layout to me. — kwami (talk) 22:16, 22 May 2012 (UTC)[reply]

This WAS merged with that page. But Dojarca obviously unmerged it. The layout would be rather difficult to maintain with lists as long as this page's, and I would rather keep the information than lose it for the sake of layout. And can someone please explain to me why any article needs "surface area system summary" or even how that could be determined to any satisfactory degree? Serendipodous 22:51, 22 May 2012 (UTC)[reply]
I don't know why anyone would need it, but it's easy enough to calculate, since they're ignoring gas giants. I suppose the surface area of the galileans compared to that of Earth might be of some interest to someone. — kwami (talk) 02:25, 8 June 2012 (UTC)[reply]
I feel List of gravitationally rounded objects of the Solar System should be the main article as it already has a much greater amount of data, tables and references, the term gravitationally rounded more accurately describes the objects than planet-mass, which would only confuse the reader into thinking that the article is solely on planets , also surface area is calculated by the simple formula 4 x pi x radius squared. – Phoenix B 1of3 (talk) 01:20, 8 June 2012 (UTC)[reply]
Many asteroids are gravitationally rounded to some degree, yet not in HE. And then of course there's Methone. 'PMO' is the accurate term, though accessibility is an issue. — kwami (talk) 02:13, 8 June 2012 (UTC)[reply]
Methone should be discounted, it is definitely roundish, but at a mere one mile across it most certainly has not reached hydrostatic equilibrium, as for the name I am leaning towards gravitationally rounded which would imply hydrostatic equilibrium as it inquires the object is large enough for its gravity to be strong enough to conform everything into a spheroid, such would exclude methone as its shape is merely the result of the way the dust settled, not pressed into shape by strong amounts of gravity. But if the proper name is planetary-mass objects perhaps we should further elaborate on it in the introduction, planetary-mass objects is an unlikely search term for someone unfamiliar with the topic as most would assume that it simply implies the planets and not there larger satellites. Also though too long to be a proper title, List of gravitationally rounded objects of the Solar System to have achieved hydrostatic equilibrium would be a good description of what qualifies to be included as such in this list. – Phoenix B 1of3 (talk) 17:43, 8 June 2012 (UTC)[reply]
That's the way the dust settled ... due to gravity. So it's gravitationally rounded. The accurate title would be list of Solar System objects in hydrostatic equilibrium, but that has accessibility issues. (Methone's surface is in HE, but presumably not its sub-surface. The IAU def speaks of rigid-body forces.) — kwami (talk) 22:54, 8 June 2012 (UTC)[reply]
List of Solar System objects in hydrostatic equilibrium sounds very fitting and proper for an article title, we'll just need to create some layman term redirects to the article, the redirects would make it more accessible. – Phoenix B 1of3 (talk) 23:23, 8 June 2012 (UTC)[reply]
I agree, especially, as Kwami pointed out, because there are many asteroids that are somewhat gravitationally rounded but are not in HE. --JorisvS (talk) 10:43, 9 June 2012 (UTC)[reply]
Note that "... in H-E" was the title of this article, and it was changed to the current after some discussion. The current title is trying to strike a balance between technical accuracy and approachability. The content, however, is intended to be "bodies in H-E", as the lead indicates. Tbayboy (talk) 15:15, 9 June 2012 (UTC)[reply]
Yes, that's always been the problem. The history of the articles has shown that even some of us editors have not understood what HE is, thinking for example that a body cannot be in HE unless it is round—though the current title doesn't do much to clarify that point. — kwami (talk) 15:37, 9 June 2012 (UTC)[reply]

Merge[edit]

That merge tag has been up there for months. Can we just merge it back? It was only recreated out of spite. I've made a full case here. Serendipodous 07:46, 28 October 2012 (UTC)[reply]

I like the layout of the other one better in some ways, but I don't think there's anything to actually merge. If there is, it can be added later or suggested here. Turned into a redirect. — kwami (talk) 08:04, 28 October 2012 (UTC)[reply]

Naming thread from [List of planetary-mass objects in the Solar System] fork[edit]

Appears that Methone may be in HE, and assuming that we don't want to start adding bodies like that, I renamed the article to PMO's. — kwami (talk) 22:05, 22 May 2012 (UTC)[reply]

Merge thread from [List of planetary-mass objects in the Solar System] fork[edit]

This article already was merged with List of gravitationally rounded objects in the Solar System, but was deliberately de-merged by a user who contested the merge in the first place. The reason it's redundant is because it was created to be. Serendipodous 09:50, 14 September 2012 (UTC)[reply]

We could still add the internal structure to that list. --JorisvS (talk) 09:55, 14 September 2012 (UTC)[reply]
What for? Without a key the pictures might as well be of split gobstoppers. Serendipodous 08:49, 24 October 2012 (UTC)[reply]

This article should be merged back to List of gravitationally rounded objects in the Solar System. It was recreated by a spiteful editor who didn't like that her list was merged and lost a debate on the issue.

As for data loss, there are three pieces of data that this page contains that the merged page does not:

  • The order of the objects from the Sun. Although not represented visually on the other page, the information is contained in text. Any attempt to convey it the way this article does would be rendered cumbersome due to the larger amount of data in each row.
  • Images of the interiors of the planets. These images mean nothing without some kind of key or supplementary text, and so can be discounted.
  • The combined surface area of gas giant systems. Aside from being pointless, this figure is impossible to cite, as the surface areas for the smallest moons are not known. Serendipodous 07:56, 28 October 2012 (UTC)[reply]
We know the approximate surface areas of all planemos out to Neptune, and this is a list of just planemos, so your last point is not true. As for it being pointless, yeah, it's not much of a loss.
It would be easy enough to order by distance from the Sun. The only problem is using rows, but we could always arrange the existing columns by distance. We could have a double header, say, with "Terrestrial system" (top line) containing Earth and the Moon (2nd line), etc. — kwami (talk) 08:21, 28 October 2012 (UTC)[reply]
Do you not think that would be confusing? Perhaps you could create a trial on your userpage, and we can see how it would look. Serendipodous 08:24, 28 October 2012 (UTC)[reply]
Here's what I imagine the terrestrials would look like: [1] (I didn't bother to include Ceres, but it would just be the next column.) Presumably all moons would have the same background color. — kwami (talk) 08:56, 28 October 2012 (UTC)[reply]
Personally, I prefer the current format, because it a) allows people to link directly to "planet" or "moon" or "dwarf planet", b) is less confusing (the alternate format makes the Moon seem like a terrestrial planet) and c) allows for more information, as moons of various planets or gas giants vs terrestrials can all have their own colours. Serendipodous 10:44, 28 October 2012 (UTC)[reply]

(a) is a consideration, assuming people actually do that. Do they? Can you provide such a link? (b) Anyone confused by this would be confused by the article anyway. The article is not about planets, and the Moon is a terrestrial body. (c) isn't a valid point: We can color-code the moons any way we like, so we could keep the current colors. — kwami (talk) 19:28, 28 October 2012 (UTC)[reply]

a) As a matter of fact, I just did. b) Not sure what you mean. The current format keeps the various categories separate. I don't see how anyone could be confused by it c) You said yourself just above that all the moons would have to be the same colour to differentiate them from the planets in the alternate scheme. Serendipodous 23:50, 28 October 2012 (UTC)[reply]
a) is this really the best we can do for a list of Solar planets? what about Planet#Solar System? If the link in that list is the only reason for keeping them separate, it's not much of an argument.
b) anyone finding their way here should already know what a planet is. This isn't likely to be anyone's first stop. How could they be confused? Especially when planets are color coded as planets?
c) I said 'presumably'. I'm hardly claiming ownership. I see no point in having different colors for the moons, but if others do, why not? Maybe a different color for ice moons?
— kwami (talk) 01:59, 29 October 2012 (UTC)[reply]
a) because the other list has more information. Also, you're being needlessly antagonistic. Anyway, unless you're planning on actually doing this, I really don't think we should continue this discussion. If you are planning on doing this, we shouldn't continue this discussion here, because we'll need input from others. Serendipodous 06:44, 30 October 2012 (UTC)[reply]
What in the world did I say that was antagonistic, apart from not holding your opinion? — kwami (talk) 08:01, 30 October 2012 (UTC)[reply]
Describing my points as not valid or saying I've made "not much of an argument". True, perhaps, or not, but either way not necessary to make your point. Serendipodous 08:09, 30 October 2012 (UTC)[reply]

Excessive precision[edit]

Could we reduce the precision of the rotation period, orbital period, and eccentricity to 3 digits in the tables? The large number of digits make these entries difficult to quickly scan and compare values. A reader desiring greater precision can follow the link to the main article on the object to get it. Three digits seems to be enough precision to differentiate between the entries and short enough to quickly scan.--Wikimedes (talk) 17:59, 26 January 2013 (UTC)[reply]

"Once in HE"[edit]

The text of this article was recently changed to reflect a new source that says that most of Saturn's large moons are technically not quite in HE. We continue to include these here, and I think for good reason: they are clearly gravitationally rounded. However, the article now also (correctly) mentions Phoebe as an object that was once in HE but is no longer. Because this body was gravitationally rounded (although battered out of a 'round' state), should it be included? I tend to say 'yes' because its case is only marginally different from that of most other large Saturnian moons, but I'm interested in any good counterarguments. --JorisvS (talk) 23:25, 24 February 2013 (UTC)[reply]

Weren't all metal-rich asteroids once part of HE bodies? I.e., you need the differentiation to separate the metals out from the lighter elements. So any large asteroid (obviously Vesta, but also, say, Davida) might be the largest part (the remnant core) of a HE object, and thus be said to once have been in HE. No solid body is in perfect HE (mountains and craters), so it's really a question of how close it has to be, and how localised the deviation. The currently listed objects all need close analysis to decide the issue, Phoebe and friends don't. I'm not sure where the line should be, but there's currently a clear gap between Mimas and Phoebe or Vesta. (Although I suspect that a good look at all those TNOs will blur the distinction into silliness.) Tbayboy (talk) 05:27, 15 January 2014 (UTC)[reply]
Actually I think we should include all objects that we know were once in HE. We know that Iapetus and friends are not in HE, although they once were: we also know that Phoebe is not in HE, although it once was. Of course we should note that Iapetus is still quite roundish now, while Phoebe isn't, and perhaps put Phoebe in a separate section on this page because of this: but I think that, given its past history, it should be there, along with Vesta and friends. Double sharp (talk) 06:34, 31 May 2014 (UTC)[reply]
We don't "know" that any of these ever were HE. Even determining current HE is very difficult without a probe in the area taking lots of measurements. I don't think we should include these objects in the tables. However, an addendum list might be nice, for curiosity's sake. Just a simple list of links, no table (or just a very simple table), of objects that are nearly round, or are round (like Methone) but don't fit the dwarf planet criterium of overcoming rigid body forces (which I think was the motivation for this page).
What I don't like about the idea, however, is the problem of sourcing the list. Do we have references that claim likely past-HE for objects? Vesta and Phoebe should be easy to get, but are there any others? Pallas, Proteus, Janus, Methone... Tbayboy (talk) 14:38, 31 May 2014 (UTC)[reply]
OK, we don't know that they were in HE, but they probably were. Double sharp (talk) 04:44, 1 June 2014 (UTC)[reply]
Those moons of Saturn were earlier believed to be in HE, until Cassini took many precision measurements and it was determined that they are actually not in HE. Because their inclusion in this list makes sense, this list was renamed to say "gravitationally rounded", which they clearly are. Now, we also know that Vesta and Phoebe were gravitationally rounded, just like those round non-HE moons of Saturn. The only difference is really that Vesta and Phoebe experienced lots of impacts that battered them out of a visibly nicely round shape. The same, AFAIK, cannot be said of any of the others, some may still look pretty rounded, but that is different from knowing that they were once in HE and had their rotational shape frozen in and/or were battered out of a nicely round shape. Tiny Methone is very much in a category of its own, with possibly a few other small satellites of Saturn. If and when other objects turn out to be like Vesta and Phoebe (or rather when a source for this turns up, in Wikispirit), they can of course also be added. --JorisvS (talk) 11:17, 7 February 2015 (UTC)[reply]

Moons of Mars, Phobos and Deimos, unlisted, why?[edit]

The Moons of Mars, Phobos and Deimos are not writed in the list-table of natural satelites in the solar system in this article, that is a mistake... I think, I dont know, or are those in another space category?--Feroang (talk) 03:21, 15 January 2014 (UTC)[reply]

Read the article title: neither Phobos nor Deimos come close to qualifying. Tbayboy (talk) 05:31, 15 January 2014 (UTC)[reply]
Yes, there _is_ another space category: Phobos and Deimos are listed on the page List_of_moons. That article does not need to care whether the moon is gravitationally rounded or not. jimswen (talk) 21:06, 24 February 2014 (UTC)[reply]

Crazy or sensible symbols[edit]

@JorisvS and Serendipodous: As per your disagreement about the special characters (a.k.a. "crazy" symbols) used to label different categories, I have a suggestion to make. Here's what I learned from your edit-comments:

  • J: remove unnecessary symbols
  • S: the symbols were added for b/w printers/ colour blind people as per the FLC
  • J: there must be a better way than the odd-looking symbols that make reading the names more difficult
  • S: There may be, but until there is, stop endangering this list's featured status.
  • J: fine, I'll leave the crazy symbols alone for now...

First of all I'd like to acknowledge the effort that has been put into the article. Whoever crafted the tables in this article has gone through great pain to do such a nice work. As for the special characters used in the tables (e.g.* for terrestrial planets. ° for gas giants, and † for ice giant) there is actually a simple solution to replace them: all one has to do is to mention the name of the satellite/planet/dwarf planet together with their category in the text, and there is no need for these symbols anymore.

Today I amended the text for the planets, and it now reads: Planets are both large enough to have achieved hydrostatic equilibrium and have cleared their neighborhoods of similar objects. There are four terrestrial planets (Mercury, Venus, Earth and Mars) and four giant planets, that can be divided further into two gas giants (Jupiter and Saturn) and two ice giants (Uranus and Neptune). When excluding the Sun, the four giant planets account for more than 99 percent of the mass of all bodies in the Solar System.

If that information was given in the text, printers and color-blind reader would have no need for these symbols. In fact, I don't even see a reason to use a legend anymore (little table). As far as my experience goes with visually impaired readers, the accessibility of a website does not improve when separate legends and special characters are introduced (rather on the contrary). I think the rule, that less is sometime more applies here. Another issue I'd like to raise is the too heavy coloring of the tables in section Satellites that potentially render a black-and-white print-out unreadable.

For all these reasons I strongly suggest to remove the "special" symbols from the tables and reconsider the usage of the legends and the coloring of some tables. I could/would do these amendments but for obvious reasons one of you should do the necessary expansions in the sections text. What do you think? Cheers, -- Rfassbind -talk 02:15, 7 February 2015 (UTC)[reply]

Isn't a much simpler and clearer solution to just add a row that says to which planet the satellites belong? --JorisvS (talk) 11:19, 7 February 2015 (UTC)[reply]
Yes, for section satellites (with a total of 19 displayed moons) that's likely much simpler indeed. For all other tables, mentioning the names and categories in the text seem easy and straightforward to me. However, for consistency reasons, one might to opt for one way or the other. Both alternatives (textual or tabular) seem better than the current usage of an additional legend-table and exotic symbols.
Maybe Serendipodous could confirm whether or not these changes would negatively affect the featured list criterias (FLC) he mentioned. To me, if accessibility was of such great concern, then why aren't there any "alt"-attributes accompanying the many images in the first place? Cheers, -- Rfassbind -talk 12:59, 8 February 2015 (UTC)[reply]
I honestly have no idea; the demand to put the symbols in took me by surprise, and I don't know if the rules have changed since then. Serendipodous 10:43, 9 February 2015 (UTC)[reply]
True, for the planets and dwarf planets, it is easily mentioned in the text. Nevertheless, an additional row like the one I proposed for the satellites can also easily accomodate the planets and dwarf planets. Moreover, a Ceres vs. plutoids division is not a very useful one. Better would be a row to indicate which population the dwarf planets belong to: Asteroid belt, Kuiper belt, or scattered disc. "Plutoid" can then still be mentioned in the text. --JorisvS (talk) 10:14, 9 February 2015 (UTC)[reply]

Hi Serendipodous, thx for the reply. I went through the article's history and I saw, that in 2008, there was a lot of action happening:

So let me assure you that my intention is to improve the article only as long as I have your consent, since I've seen now all the effort you have put into the article and I respect you too much for this.

  • You started to add those "crazy symbols" on October 9, 2008 and unfortunately there are no edit-comments at all (nobody seemed to care about explaining their intentions in those days). So, unfortunately, I'm still in the dark about the requirements for the symbols. In any case, hundreds of edits followed in the next few months (mostly by you on notes and citations, as well as on the dwarf planets, syntax and links, math-formulas, moon Proteus) and the article got its featured list star on January 31, 2009.

So what's your say, Serendipodous? Remove the crazy symbols (and legends?) and replace them by a textual or tabular form? If so, what are your thoughts on that? -- Thx and cheers, -- Rfassbind -talk 16:59, 9 February 2015 (UTC) PS: JorisvS also mentioned the "plutoids division", and I mentioned the color and table-sizes, and missing alt-tags as well. But I think it's better just to talk about the "crazy symbols" for now. OK?[reply]

The request was made here; the request was made at a time when I was getting ambushed by requirements like alt-text at FAC so I assumed the same applied. However, when I look at the FLCR, there doesn't seem to be anything about accessibility. Serendipodous 17:26, 9 February 2015 (UTC)[reply]

Instead of a funny symbols for planets, how about a digraph (pre-super-scripted, in place of the existing symbols): Ea Ju Sa Ur Ne Pl. Or, the Unicodes for the actual astro symbols (♃ etc), but I think that might be a code too far. I still like the colours, although they could be lightened so that they are effectively white on printers. Don't need the Ceres/Plutoid distinction. Tbayboy (talk) 18:33, 9 February 2015 (UTC)[reply]
Thx, Tbayboy good idea, but I think it's not only the "funny" symbol but also their location (in front of the object's name) that is perceived as rather distracting. Besides that, I think the term "plutoid" is confusing, and I also like the colors and I agree with lightening some of them, but let's hear first what Serendipodous proposes, because, I think, his opinion is important. Cheers, -- Rfassbind -talk 22:06, 9 February 2015 (UTC)[reply]
Thx, Serendipodous, your link was very helpful. Correct me if I'm wrong, but from what I can see, the crazy symbols were a direct consequence of the little legend tables you had added previously. If we use textual or tabular representations for the categories, there is no need for the legend-tables, hence no need for the crazy symbols as well. Now, we all know these tables and symbols are part of the article for almost 7 years, and one might get accustomed to them, but as a professional web developer who has worked with visually impaired people (including a blind programmer friend of mine) I can assure you that these tables are most likely perceived as confusing when read by an interpreter. So my question is: could you live with the removal of the symbols and legends in place of the proposed alternatives? Because if that is not the case, I will stop here, as I've gone through hundreds of your edits this afternoon I saw how much work you have put into this featured list, and I really think that it is you who has to decide whether or not we should do an overall revision after seven years. With great respect and acknowledgement for your excellent work on this list, Rfassbind -talk 22:06, 9 February 2015 (UTC)[reply]

Rfassabind, I'm not sure what you mean by "in the text"; in the text above the table, or in text in the table? Either way I don't see how it could work. Serendipodous 07:15, 14 May 2015 (UTC)[reply]

"officialness has no bearing on scientific categories"[edit]

Guys, we really need to talk about this. The rulings of the IAU or the International Botanical Congress or the IUPAC may seem arbitrary but they do have a scientific purpose; they ensure that any scientific paper, from wherever in the world, employs consistent terminology so that other reviewers hoping to replicate the paper's results start from the same position. Yeah it's true that the International Botanical Congress's definition of a berry has little or nothing to do with our definition of a berry, but it is nonetheless the definition every botanist has to use. Serendipodous 10:49, 19 March 2015 (UTC)[reply]

These categories have been conceived by scientists and of course there is a purpose. But inclusion into those categories is not a matter official recognition, nor of whether a list is maintained. The IAU nevertheless carries weight and so does the list that they have, and that is why we have a separate section for the IAU five. It is not a matter of "officialness", but of the weight the IAU carries, and this should be reflected properly in the section header. --JorisvS (talk) 13:37, 19 March 2015 (UTC)[reply]
How do you define "official"? Astronomy is not a state, and states shouldn't rule on scientific matters. What would be official in this case? Serendipodous 14:08, 19 March 2015 (UTC)[reply]
The heading for Planets doesn't say "Planets recognized by the IAU", so why not simply "Dwarf Planets" for the heading? The paragraph under each explains the definition. Does the heading really need any kind of disclaimer? DinoSlider (talk) 15:08, 19 March 2015 (UTC)[reply]
Planets are different because everyone agrees about the category that contains the major eight, even Alan Stern, who includes dwarf planets and round satellites under the term planet, but not the category. However, there is considerable discussion about which objects can and should be considered dwarf planets given our knowledge and even which could be but about which we have insufficient data. Some accept more objects as dwarf planets than others, which is why we do need to specify.
@Serendipodous: official as in #3: "approved by authority": it is not like dwarf planets are dwarf planets because of IAU recognition. They are dwarf planet because they fit the definition. If there is insufficient data to be relatively certain (which is the case for nearly all dwarf planets; of which up to several hundred may have been discovered already), they are possible dwarf planets. --JorisvS (talk) 17:39, 19 March 2015 (UTC)[reply]
One astronomer's opinion does not make a dwarf planet either. Just because one, or even a number of astronomers think there is enough evidence to declare an object a dwarf planet, that doesn't mean there is. Serendipodous 17:54, 19 March 2015 (UTC)[reply]
I'm not saying it does. --JorisvS (talk) 18:18, 19 March 2015 (UTC)[reply]
So who decides whether a dwarf planet fits the definition or not? Serendipodous 20:45, 19 March 2015 (UTC)[reply]
Astronomers by analyzing the data on these objects. Like in any scientific endeavor, with a paucity of data they will most likely disagree, but as more data is gathered, more and more astronomers will agree. For most, if not all, non-IAU-listed objects this will be a long time. But that does not matter when we simply focus on the IAU-listed ones. --JorisvS (talk) 20:59, 19 March 2015 (UTC)[reply]

I didn't say to focus on the IAU listed ones. I am simply unhappy with the phrasing "according to the IAU", because that implies there is some other authority with whom it does not accord. Serendipodous 21:31, 19 March 2015 (UTC)[reply]

Okay, so how do you suggest to phrase it? --JorisvS (talk) 21:38, 19 March 2015 (UTC)[reply]
I liked it the way it was initially phrased. Serendipodous 21:43, 19 March 2015 (UTC)[reply]
But "official" isn't right either, even more so. What about "IAU-listed dwarf planets" or "Dwarf planets listed by the IAU"? --JorisvS (talk) 21:53, 19 March 2015 (UTC)[reply]
There are other authorities: Every peer-reviewed author can be taken as an authority. Brown, Tancredi, Sheppard, Stern: they're all authorities. They disagree with the IAU not because there's any real debate, but because the IAU has not been addressing the issue. It's like we're claiming a body is only "possibly" an asteroid because it's not included in a well-respected list published in 1980.
BTW, we speak of IAU-list DPs and "possible" DPs. We forget that the IAU-list bodies are also possible DPs. The IAU has said as much: Haumea and Makemake were named as DPs not because they IAU was certain they were, but because they felt that their H gave them sufficient leeway to be reasonably certain. They did, however, say that if it should turn out that Haumea & Makemake are *not* DPs, they will be reclassified by keep there names. Given what we now know about HE of icy bodies, it's very possible that Haumea and Makemake are not DPs. Once Dawn and NH verify that Ceres and Pluto are in HE (assuming they can), and given the assumption that if Pluto is a DP then Eris probably is too, then we will have 3 DPs (Ceres, Pluto, Eris) and a whole bunch of possible DPs (everything else). It would be nice if we didn't continue to dumb things down, as if we knew. We don't.
Membership in categories is determined by scientific consensus, not official decree. Brown has complained about the unscientific role the IAU has taken on as gate-keeper of what is a DP, as if the definition of a DP were whatever the IAU says is one. No astronomer accepts that standard. We shouldn't either. — kwami (talk) 23:38, 19 March 2015 (UTC)[reply]


While I don't see a great difference in the two phrasings, I favour the original "official". The definition is not scientific: you can't take the definition, look at an object, and determine if it's a DP or not for a large number of the candidate objects. The problem is that the definition doesn't specify "how round is round" (i.e., how much deviation from pure HE is allowed). (It also doesn't specify "how clear is clear", orbit-wise, but nature gave us a big gap to put the line in, so it hasn't been an issue.) The list of planets tells us that Mercury is a planet, even though those billions-year-old craters haven't relaxed themselves away. The lists give some guidance to the interpretation of the definition text. The DP list tells us that whatever the definition of "round" is, it should encompass those objects (notably, Ceres and Haumea). So officalness has bearing as guidance towards the fulfilment of footnote 2 (the process to separate the categories) and the establishment of a truly scientific definition, and so it should be prominent.

The argument about "official" is a silly word game. If the IAU is not official, then there's no definition in the first place.

Aside: From the IAU news release at the end of the conference:

Currently a dozen candidate "dwarf planets" are listed on IAU's "dwarf planet" watchlist, which keeps changing as new objects are found and the physics of the existing candidates becomes better known.

I wonder if that list is maintained. Tbayboy (talk) 01:34, 20 March 2015 (UTC)[reply]

No. That's just wrong. And the definition is scientific, though of course there may be marginal cases. Again, you're confusing the definition of a DP with determination of which bodies fit that definition. You might be able to get away with the "official" definition of a DP, but even there it would be clearer to say the IAU definition. But there is no official set of DPs. Also, "round" does not need to fit Haumea: if Haumea is not "round", then it's not a DP, per the IAU itself. Calling them "official" is a mockery of science. "Bureaucratic" word be a better term.
I agree that we should use the IAU definition of DP, as that's the most widespread. But knowledge does not hold still: We should determine whether a body is a DP based on a preponderance of sources, not according to whether the IAU gave its blessing 7 years ago. — kwami (talk) 05:01, 20 March 2015 (UTC)[reply]

Article ordering[edit]

Shouldn't the section on dwarf planets be before the section on satellites? You have Charon listed before Pluto the way it is now. It doesn't seem natural to have satellites first. Fyunck(click) (talk) 06:54, 14 May 2015 (UTC)[reply]

The problem is the final "likely dwarf planets" list. Since that list by definition will never end, it's best to keep it at the bottom, and the dwarf planets list really only works above it. Serendipodous 07:19, 14 May 2015 (UTC)[reply]
I agree with the "likely dwarf planets" being best at the bottom, but I have no idea why you would say the dwarf planets list really only works above it. It seems out of synch to me being anywhere except right below the planet listing. Does everyone at the Astronomy Project agree with the current order where moons of dwarf planets get listed before the dwarf planets themselves? Fyunck(click) (talk) 09:22, 14 May 2015 (UTC)[reply]
Contentwise it is actually more like a subsection of the section "Dwarf planets" rather than an independent section (despite it having the L2 header). Maybe it is best given an L3 header. --JorisvS (talk) 09:32, 16 May 2015 (UTC)[reply]

Largest non-gravitationally rounded entries[edit]

Technically Iapetus should not be in the list. Can there be a sentence in the intro listing the largest bodies that are not in this list? Nergaal (talk) 16:35, 28 August 2015 (UTC)[reply]

Also, the likeliest DP is IMO a tad too long. Just looking at List of possible dwarf planets, I think only 2007 OR10, Quaoar, Sedna, Orcus, 2002 MS4, and Salacia should be listed, as Ixion, Varuna, 2005 UQ513, and 2007 UK126 don't even appear to be the next largest ones. Nergaal (talk) 16:42, 28 August 2015 (UTC)[reply]

Yes, the list here is a bit dated. I support your list. There appears to be a significant drop-off in estimated size after Salacia. — kwami (talk) 17:27, 29 August 2015 (UTC)[reply]
Iapetus is clearly gravitationally rounded. It's just no longer technically in hydrostatic equilibrium. It has every business being here. As for the 'possible DPs' listed, something like that makes sense, though maybe we could better change the dwarf planets section not to myopically focus on those listed by the IAU. Template:Dwarf planets also lists objects accepted by Brown and Tancredi, and we could do something similar here. --JorisvS (talk) 11:10, 29 August 2015 (UTC)[reply]
Sounds good. What did you have in mind? Should we merge the lists, maybe limited to the objects Nergaal mentioned? — kwami (talk) 17:27, 29 August 2015 (UTC)[reply]
Note that the other Saturn moons (except Titan and Rhea) might not be in HE, either, by the same paper that says that Iapetus isn't. The Iapetus result shows that it is not easy to determine. You need a probe up close taking lots of pictures and getting gravitational data (to know whether or not the body is differentiated) to know for sure, and even Cassini wasn't enough to finally decide Mimas, Enceladus, Dione, and Tethys. Even Rhea's shape might be coincidental, and might not be in current HE: it might have de-spun before "freezing", whereas more distant Iapetus took longer to de-spin and froze before it completed. "Rounded" is the best we can do.
The DPs were the next largest at the time the tables were last edited to add/remove bodies. And many of the numbers are garbage, anyway, since the error bars are large and the mass is often just a guess. I think there should be a separate, simpler, row-based table for the bodies with poorly known properties (which would include Makemake and OR10), containing only H, orbital properties, and a measured size if there is one. In other words, an easy to maintain table for the more volatile information. Split the tables by the data quality. Tbayboy (talk) 17:46, 29 August 2015 (UTC)[reply]
Sounds good to me.
We were only able to detect this for the Saturnian moons because they are in a strong gravitational field and subsequently experience significant tides. Although the Pluto–Charon system has about the same rotational period as Rhea, the gravitational field is much lower, and neither are scalene as Rhea is. It is thus probably impossible to confirm that Pluto is in HE based on its shape, which is essentially spherical, only that is was in HE after the event that created Charon, though given the geological activity on the body I double anyone seriously doubts it's in HE. Close obsersation of Haumea and Varuna should be enough to establish whether they're in HE (or at least haven't spun down since entering HE), but for other possible DPs, even a dedicated orbiting probe might not be enough to answer the question. Thus the IAU definition of DP is entirely impractical, and a stand-in parameter or a redefinition will need to be found if we're ever going to be able to use the term intelligently. The whole point of the term was to sneak Pluto back into planetary status through the back door; since that effort failed, better IMO to abandon the term altogether and return to the more ambiguous term "planetoid" for any reasonably rounded object (e.g. for anything that looks like a world or which we expect might look like a world if we were to get close), and stop pretending we know what we're talking about. — kwami (talk) 19:35, 29 August 2015 (UTC)[reply]
Indeed the current definition is impractical. It would be best to redefine HE → gravitationally rounded. Much easier to measure. And that also applies to Vesta and Phoebe, really. As for the term, "dwarf planet" has, I think, taken hold, and it has the advantage of being useful in languages where the normal word for "asteroid" is "planetoid". Regardless, for the time being we're stuck with the current situation. What we can do is improve this list, focusing on "gravitationally rounded", with the title already being accurate. --JorisvS (talk) 20:33, 29 August 2015 (UTC)[reply]

Unreliable masses of TNOs[edit]

The TNOs Makemake, Ixion, Varuna, UQ513, OR10 and Sedna have no moon, so their mass can only be guessed. Please everybody, don't add unreliable masses in such a case, better put a question mark, or a lower and upper limit with reference. Thanks & regards, Herbmuell (talk) 03:20, 28 January 2016 (UTC)[reply]

All unreferenced masses are calculated assuming Pluto's density, as noted in note F. Serendipodous 19:30, 28 January 2016 (UTC)[reply]
Actually it uses 2. Pluto's has since shrunk to 1.86. :-) Tbayboy (talk) 00:04, 29 January 2016 (UTC)[reply]
Then they probably need to be changed. Serendipodous 00:23, 29 January 2016 (UTC)[reply]

I'm thinking of changing the masses and densities of those objects to ? I was once researching the radii and masses of the larger Solar-System objects when I found these unsupported masses stated here. Lpetrich (talk) 18:53, 19 March 2017 (UTC)[reply]

Exospheres and atmospheric composition[edit]

For bodies with only exospheres, should we really list a atmospheric composition? Listing the components of the Moon's "atmosphere" for example gives the mistaken impression that it has a permanent atmosphere like Earth and Mars when it doesn't. I think for bodies like Mercury or the Moon, it's better to list "none", or maybe "exosphere only". Oiyarbepsy (talk) 05:43, 11 May 2016 (UTC)[reply]

First sentence should describe the title[edit]

Are gravitationally rounded objects of the Solar System the same thing as planets? I think this should be clarified early as per WP:LEAD. I Made an attempt, but not being super familiar with this topic, I expect it will be corrected.

Also I'm confused why the title just doesn't say planets of the solar system. Am I missing something here? ThanksDig Deeper (talk) 07:39, 23 November 2016 (UTC) Dig Deeper (talk) 07:39, 23 November 2016 (UTC)[reply]

According to the WPs definition of Planet, a dwarf planet isn't a planet, although it has planet in its name. From a linguistic point of view, that's a sad thing. But then there are many funny names in astronomy. Gravitationally rounded objects = planets and dwarf planets, that's how I understand it. --Herbmuell (talk) 08:18, 23 November 2016 (UTC)[reply]
Also, the Sun is not a planet, and moons are not planets. Serendipodous 08:24, 23 November 2016 (UTC)[reply]
Wow, you guys are fast! Thanks for you quick responses.
So the part that confused me when I first landed on this page (on a mobile device) is why is the article talking about planets for the first few lead sentence when the article is about GROs.Switching to desktop view, now I can see all the pics and it's more clear. I think the problem still remains. Can we have a definition on these GROs and perhaps cut out some detail on what defines a planet? This is, after all a list. Thanks. Dig Deeper (talk) 08:41, 23 November 2016 (UTC)[reply]

"This is a list"[edit]

The wording of the lead goes against WP:THISISALIST ("If the page is a list, do not introduce the list as "This is a list of X" or "This list of Xs..."") and should be amended. Lizard (talk) 00:04, 15 January 2017 (UTC)[reply]

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Symbols for satellites - source?[edit]

Where do the symbols €, ₤, $, ₩, ₦ and ¶ for satellites of Earth, Jupiter, Saturn, Uranus, Neptune and Pluto come from? I tried to find a source, but all I find are 3rd party articles that eventually lead back to this Wikipedia article. If there is an official source for these, great - then it should be cited. If not then I see no reason to use these symbols. Why not use the official symbols for the planets instead? Renerpho (talk) 17:56, 22 July 2018 (UTC)[reply]

They are not used here as official symbols, but rather just as a key for the table, comparable to the keys used earlier in the article. That said, if you know how to technically replace them with the planet symbols, I would certainly see it as an improvement-- more clear and intuitive. Go for it! A2soup (talk) 18:42, 22 July 2018 (UTC)[reply]
I went ahead and did it myself. I like it, thanks for the suggestion! A2soup (talk) 18:55, 22 July 2018 (UTC)[reply]

Surface Pressure[edit]

Any reason we don't list surface pressure? Seems to fit with gravity, surface temperature, and atmospheric composition. Nfitz (talk) 00:11, 23 March 2019 (UTC)[reply]

Titan?[edit]

The article for Titan states that it is gravitationally rounded. Why isn't it on the list? Cynthia-Coriníon 16:11, 30 August 2019 (UTC)

Look again: it's in the satellites section. Tbayboy (talk) 16:20, 30 August 2019 (UTC)[reply]

Moon in hydrostatic equilibrium[edit]

It says:

"Several of these [satellites] were once in [hydrostatic] equilibrium but are no longer: these include Earth's moon and all of the moons listed for Saturn apart from Titan and Rhea.[citation needed]"

I personally know nothing about this, but according to some tidbits found on the Internet, at some nitpicky level, pretty much NONE of Solar System bodies are technically in exact "hydrostatic equilibrium", which, if true, would somewhat invalidate the whole usefulness of such a criterion. Or, if a "near enough" approach is adopted, then is the Moon also not "near enough"? It looks pretty round to me. 2A00:23C5:4B91:AB00:B43B:4214:20F:399 (talk) 21:04, 30 April 2020 (UTC)[reply]

Question about orbital periods[edit]

I have a question about the orbital periods given for the major planets. Those are given in days and years (the latter being defined as 365.25 days on the linked wiki page). However, that ratio doesn't match. For instance, the numbers for Earth give a ratio of exactly 365, while the other planets give ratios in the range of 365.20 to 365.37 days. Why is that? Additionally, one might assume that , but that doesn't match, either: The periods for Mercury to Mars are a little bit too large, the periods for Jupiter to Neptune are a little bit too small. What am I missing? Renerpho (talk) 07:20, 25 February 2021 (UTC)[reply]

Ganymede's axial tilt[edit]

I'm not sure where "0.33" comes from, since the paper being cited does not have that figure. Is it from reading the graphs in Fig. 3?

But also, that paper shows varying inclinations and obliquities for all four Galilean moons, so it seems the figures we have may be wrong. The text gives:

Io Europa Ganymede Callisto
Inclination 0.0041° ± 0.0073° 0.468° ± 0.023° 0.204° ± 0.074° 0.15°–0.70°
Obliquity 0.000405° ± 0.00076° 0.0965° ± 0.0069° 0.155° ± 0.065° [not stated]

The values for Callisto's obliquity are not stated, but on the graph it seems to go between 0.1° and 1.8° over 2000 years. Double sharp (talk) 08:38, 8 August 2022 (UTC)[reply]

Looks to me like it's from the figure, yes. I would interpret the uncertainties as the standard deviation, not the maximum deviation (which is only given in the figure). Note: I corrected one of the values in your table, I hope you don't mind. Renerpho (talk) 01:45, 9 August 2022 (UTC)[reply]
@Double sharp: I forgot to tag you. Renerpho (talk) 01:46, 9 August 2022 (UTC)[reply]
Regarding Callisto, quote: The most extreme case is Callisto, where the inclination oscillates from 0.15° to 0.70° with a 580 year period, and the obliquity spans a range 3-4 times as large, with the same dominant period. The range is 0.55, and 3-4 times that would be 1.65-2.2. That is, varying between 0(?) and 1.65-2.2 degrees. I don't know why no concrete values are given, but if I'd have to hazard a guess, I'd blame the fact that there is quite a strong secular component to how the obliquity changes (there is a linear trend downwards over the time period studied), and the period at which it oscillates is quite slow. So just taking the values from that time period and computing mean and standard deviation would be crude. Renerpho (talk) 01:54, 9 August 2022 (UTC)[reply]

Titan seems to have nonzero obliquity too. Maybe the assumption that all the satellites have 0 obliquity should be retired... Double sharp (talk) 06:37, 9 August 2022 (UTC)[reply]

@Double sharp: Nothing in this universe has 0 obliquity. Claiming all of them to be 0 is sketchy, especially with no sources whatsoever. I'd call 0.3° pretty close to 0 though. Nothing like Earth's moon. I suggest to replace all the 0's by ≈0, and call it a day (except where actual non-zero values can be cited from the literature, like for the ones we've discussed here). Renerpho (talk) 17:31, 9 August 2022 (UTC)[reply]
@Renerpho: Yeah, that sounds good to me. They are probably all close to 0 anyway, even if not exactly there. For now I only found non-zero values for the Galileans and Titan, so it'd be those, I suppose. Double sharp (talk) 03:59, 10 August 2022 (UTC)[reply]
Oh, also found Triton. Double sharp (talk) 04:00, 10 August 2022 (UTC)[reply]

@Renerpho: I added all the values I found above, and replaced all the 0's with "≈0". I guess that's still a bit odd for Callisto, given that it's probably going to have the largest range of all the Galileans. Double sharp (talk) 11:34, 28 August 2022 (UTC)[reply]

@Double sharp: Agreed. I suggest to add a note to the Callisto value, stating something like "Callisto's obliquity is varying between 0 and about 2 degrees on time scales of thousands of years". The article already has a "notes" section. Renerpho (talk) 18:04, 28 August 2022 (UTC)[reply]
@Renerpho: Okay, done. :) Double sharp (talk) 07:17, 29 August 2022 (UTC)[reply]

We CANNOT measure the "mass" of any of these objects[edit]

See Talk:List_of_Solar_System_objects_by_size#We_CANNOT_measure_the_mass_of_any_of_these_objects, from Jamescobban (talk) 22:54, 19 April 2024 (UTC)[reply]

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