Talk:List of solar system objects by radius

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I'm not sure if I agree with the system of ranking objects that are irregularly shaped. Shouldn't we find the average radius of those objects and use that to rank them? Otherwise, small oblong objects could rank above generally larger but rounder objects. --Patteroast 14:48, 15 Jun 2004 (UTC)

I didn't really use a system when trying to compare and rank irregularly-shaped objects, just more or less did it "by eye". Perhaps there's a better way. -- Curps 17:43, 15 Jun 2004 (UTC)
You could compare for example the average radius - the radius of a sphere that will have the same volume as the moon. If a moon has a volume of V, then the average radius is 3V^{1\over{3}}\over{4\pi}Smartech 19:27, 11 July 2005 (UTC)
That's the same as comparing the volumes.
In my corresponding page, I just referred to it as Solar system by size, thereby sidestepping the whole "radius" issue. When one gets down to the irregular bodies, the ranking necessarily becomes somewhat arbitrary anyway. --P3d0 03:09, July 13, 2005 (UTC)

The following post intended for this page was accidentally posted to a broken link by Smartech on 01:21, 12 July 2005. -- BD2412 talk 01:45, 4 October 2005 (UTC)

And how exactly should this merging be done? Unfortunately, the two rankings are not the same, since some bodies are denser than others. For example Ganymede is lighter than Mercury, even though the former is the smaller body. In any case, there would be two lists, so in my opinion it is a decision on whether to have those two lists in one article or in two. Smartech 01:21, 12 July 2005 (UTC)

Contents

[edit] Radius/diameter

Thanks to User:TheTom for catching my goof. I had a suspicion something was wonky but didn't figure it out, even while changing half the numbers. This brings up an interesting question, though. Why are we charting by radius, when the planet infoboxes and most articles use diameters? I'll add a note inside, though, to future editors, so they don't make the same mistake I did! --Dhartung | Talk 18:42, 31 July 2005 (UTC)

Is there an established precedent such that the infoboxes use diameter? Or is choice of diamter versus radius an aesthetic choice that would be preferable to standardize? --Iamunknown 07:40, 17 September 2006 (UTC)
Not sure, the infoboxes almost always go with diameter. Seems to be largely an aesthetic choice: diameter is probably more intuitive because it immediately gives the approximate "size" of the object. Radius is more convenient if you want to run around calculating volumes and surface areas, but that's a marginal pursuit, I believe. Actually, it always mildly annoys me that this list uses radius, so I'm happy for it to be changed to diameter. Deuar 14:37, 18 September 2006 (UTC)

[edit] Rename

I'd like to rename this article to the following: List of Solar System objects by size. Any objections? --P3d0 21:44, August 3, 2005 (UTC)

Since it's unlikely there would be a different corresponding article, e.. List of Solar System objects by diameter, I don't object. There will be a bunch of redirects to fix, though. --Dhartung | Talk 05:13, 5 August 2005 (UTC)
Keep the "radius" wording, but if you'd like to make a redirect from List of solar system objects by size to this article, go ahead. The problem with "size" is that it's too loosely defined. —Bkell 21:01, 9 August 2005 (UTC)
... or you could go with "volume", if irregularly shaped bodies are causing a problem. —Bkell 21:03, 9 August 2005 (UTC)
The looseness of "size" is why I prefer it. For smaller bodies, there's no easy way to rank them precisely by volume until we go take each body, dip it in a bathtub, and — eureka! — measure how much water it displaces. --P3d0 01:03, August 14, 2005 (UTC)
The looseness of size may make executive decisions for we editors easy, but it makes an unnecessarily confusing, ambiguous, and misleading article for readers. --Iamunknown 07:43, 17 September 2006 (UTC)

[edit] Rank is not a useful column

This list is not exhaustive, and so the Rank column is not useful, and may even be misleading. I would like to remove it. Any objections? --P3d0 01:04, August 14, 2005 (UTC)

I sorta like it, but I can't see keeping track past (say) Pluto. I agree it's potentially very misleading for the lower end of the list. Then I can't think of a good argument for only having it for part of the list. Primarily, it's going to be a pain to maintain as more TNOs are discovered and others, like 2003 UB313, have their diameter pinned down. --Dhartung | Talk 01:28, 14 August 2005 (UTC)
I'm not sure why the Rank column is 'not useful'... this is a list of objects by size, correct? Going from largest to smallest? In which case, the size-ranking is of interest. --Firsfron 03:46, 27 August 2005 (UTC)
As I said, it's not useful because the list is not exhaustive. The rank we present is meaningless, aside from listing where an item appears in our list. There's absolutely no reason to believe, for instance, that Mercury is the 11th-largest body in the solar system, since we could discover a larger TNO at any time. This problem becomes even more pronounced as one moves downward in the list, at which point there are even known bodies that are not in our list. I have started by removing the ranks after Europa, since the relative ordering of Triton and UB313 are not known. --P3d0 16:27, August 27, 2005 (UTC)
According to Dave Jewitt, we could discover something larger than Jupiter at any time, too: "a planet of Earth's mass could exist undetected if it were more than a few 100 AU away, and even a Jupiter (300 Earth mass planet) could exist at distances only slightly greater." (from the Kuiper Belt Page: http://www.ifa.hawaii.edu/faculty/jewitt/kb.html ) However, there is ample evidence that Jupiter is the 2nd largest body in the solar system, and that Mercury is the 11th-largest body in the solar system: in over three hundred years of telescopic astronomy, we haven't discovered anything larger.
Does the possibility of something existing that is larger than Jupiter mean Wikipedians can never create a list including the rankings of known objects by size, because there might be something larger? Of course not. Many resources, including books and web-sites, refer to the size-ranking of various bodies: check here for Mercury , here for Jupiter, and here for Europa (official NASA site, BTW). If NASA's ranking planetary bodies by size, there's no reason Wikipedia can't. --Firsfron 22:27, 27 August 2005 (UTC)
The potential to find new objects is secondary; I'm sorry I focused on it in my remarks, because it was a spurious argument that seems to have utterly distracted you from my main point, which is that our list is not exhaustive. Even if it could be made exhaustive, which I doubt; even if we could find some means to include every known solar system object in the list, and keep it up to date with new findings; the sizes of most of them will never be known with enough precision to allow them to be ranked. The whole concept of the ranking is fundamentally futile beyond about 15th or so.
Having said all that, if you would like to use a ranking you find in another source, and cite it, be my guest. Wikipedia is all about collecting knowledge from credible sources. --P3d0 03:26, August 28, 2005 (UTC)
Hmmm. Yes. I believe you said that, once or twice. "You keep using that word. I do not think it means what you think it means." ;) Exhaustive: from Dictionary.com : very thorough; exhaustively complete. I'm not exactly sure how you think this list of objects could be more thorough or complete. If you think the list is incomplete, I wonder why you don't add the information you have (with suitable citation, of course). If it's just that you believe that more objects exist out there, yet undiscovered, I think I already addressed that: there's always the potential for larger objects (than Mercury or Jupiter) to exist, but we haven't found any, in the last three hundred years. And even if we do, it's really not too hard to update the list. Meanwhile, these are the largest objects known to exist, outside of fringe speculation and conjecture. If you're basing your objection to rank based on speculation, I don't know what to tell you: I've taken a look at your edits on other pages, and they seemed really sound, so your argument here seems quite puzzling.--Firsfron 13:05, 28 August 2005 (UTC)
Please, just for one moment, consider the possibility that I'm not an idiot. Maybe, just maybe, I have a point, and that is this: 1) there are upwards of 5000 bodies currently known in the solar system; 2) most of them are very small and their sizes are only known to one significant figure, and 3) this makes a ranking of 90% of the bodies impossible and meaningless. --P3d0 16:09, August 28, 2005 (UTC)
I don't think you're an idiot, P3. In fact, I thought I pretty much said that above, when I said I liked your earlier articles. I'm not sure why you thought I didn't think you weren't intelligent, as my post tried to indicate something else entirely.
I'd like to address these new points, P3, but I wish you would have mentioned them earlier. Anyway, back to your new points, which weren't mentioned earlier.
And I wish you had asked, or found out for yourself, rather than assume I was mistaken.  ;-)
1) there are upwards of 5000 bodies currently known in the solar system; 2) most of them are very small and their sizes are only known to one significant figure, and 3) this makes a ranking of 90% of the bodies impossible and meaningless.
There are certainly 5000 bodies currently known in the solar system. Most of them are very small and their sizes are not all certain, true. However, you're off on point three: the list we are discussing doesn't contain 5,000 bodies. It contains the largest bodies known. You say this makes a ranking of 90% of the bodies impossible and meaningless, but in point of fact, the 90% of the bodies were never on this list. Only the largest bodies were on this list, and their ranking according what's currently known. Astronomy is an ever-evolving field, and our knowledge of heavenly bodies is always expanding; that doesn't mean that a list of solar system bodies, or even a ranking of known solar system bodies, is meaningless: as I said earlier, more than one resource, even NASA sites, cite size ranking, so obviously it's important to some people. Certainly the high school student who is writing a report on Saturn might find it useful to mention that Saturn is the third-largest body (known) in our solar system, and that's where a ranking might be useful, and not at all meaningless. Cheers! --Firsfron 16:42, 28 August 2005 (UTC)
First, the 35 or so bodies we have listed are not the 35 largest known bodies. They are the 35 bodies that people felt like adding to the list. That is why I keep saying the list is not exhaustive (though that could be fixed). Second, out of just these 35 bodies, the rankings of more than half of them are uncertain. Thus, even if you don't want to consider all 5000+ bodies, my points still stand with just these 35. Our rankings for most of them are meaningless. --P3d0 21:44, August 29, 2005 (UTC)
First, the 35 or so bodies we have listed are not the 35 largest known bodies. Not true. According to [[1]] the KBO on our list are the largest objects. Also compare with [2]. Neither site lists any KBOs that are larger than any on our list, so this isn't a case of the list here being inaccurate because people 'felt like adding bodies to the list'. As far as I can tell, Wikipedia's list here agrees with the findings on both of these sites, which I might add are run by professional astronomers. See also my talk page or yours for further comments. --Firsfron 04:37, 30 August 2005 (UTC)
I concur with the elimination of a ranking number past 15, and I've added an editorial note to that effect inside the article (with a see talk). I think it's OK to have it there, at least partially, because it's something that a casual reader might expect.
Regarding Jupiter: It's certainly possible for a Jupiter-sized object to exist on a very long orbit of the Sun, if hypotheses about a brown dwarf companion have any validity. --Dhartung | Talk 05:06, 28 August 2005 (UTC)
Hypotheses about brown dwarf companions to the sun are always interesting, of course, but doesn't that sort of fall into the category of speculation? --Firsfron 13:10, 28 August 2005 (UTC)
I was just responding to the over-certainty in the earlier comment. In fact, I think it's more certain that we will discover planetary bodies at least as large as Europa -- in other words, our Top 15 is by no means finished -- and remains possible that we will discover very distant gas giants at least as large as Neptune, so that the Top 5 might even change one day. That doesn't change my view that down past 1500km there are going to be objects too numerous (er, hyperbole) to count, let alone definitively rank. In fact, I think these are complementary views. --Dhartung | Talk 23:49, 28 August 2005 (UTC)
That doesn't change my view that down past 1500km there are going to be objects too numerous (er, hyperbole) to count, let alone definitively rank. While I agree there are still many bodies left to be discovered, some of which could be quite large, if the Main Asteroid Belt is any example, most of the larger objects in the Kuiper Belt have already been discovered (the first four asteroids discovered represent a majority of the mass of the entire main belt). In the past twelve years, we've discovered less than a dozen objects in the 1000 km range, which works out to less than one per year. That average doesn't really support claims of many large ("too numerous to count") objects in the range of 1500 km, and even if we discovered a large object every year for the next hundred years, we'd only have to update the list once a year.--Firsfron 18:30, 29 August 2005 (UTC)
David Jewitt, who discovered the first TNO, beleives that the Kuiper Belt contains some 70,000 objects larger than 100km, and is 300 times more massive in aggregate than the asteroid belt. [3] There are only 230 asteroids that large; and we're not necessarily counting objects in the Oort cloud (of which one is on our list already). Most of these are icy and dark. I don't think the history of asteroid belt astronomy is necessarily an excellent match; the first several TNos aren't even on our list, and it was only 1998 when we discovered the first of them (Ixion) and that's now the smallest listworthy object. So I still think there are a lot of them out there, and I don't think that 2003 UB313 is the upper bound; the odds are simply against it. Anyway, my argument has little to do with updating the list regularly; if anything, Wikipedia is in a better position to keep an updating ranking than NASA or anybody, because they publish static pages, while ours might be updated within minutes of an announcement. I'm just concerned that the ranking ceases to be useful after a certain point, because we simply don't know the mean radius value on which it is based to a reliable degree of accuracy. --Dhartung | Talk 19:54, 29 August 2005 (UTC)
the first several TNos aren't even on our list, and it was only 1998 when we discovered the first of them (Ixion) Actually, of course Pluto and Charon are TNOs that are on our list, so of course Ixion wasn't truly the first. I do certainly agree with you that the Main Belt discoveries may not be, as you say, an 'excellent match', however even with the great probability of thousands of objects in the 100 km range, the rate of discovery of larger, 1000-km-scale, objects (less than one per year during the past twelve years) doesn't really support the idea of vast numbers of 1000km+ objects. I certainly also agree with you that the ranking ceases to be useful after a certain point, but strongly disagree at where that point has, IMHO, arbitrarily been placed. There were less than 40 rankings on the list, and the majority were removed because the rankings 'were not useful' or something, based on the perception that the list was not accurate at its lower end. {P3d0 -- I removed rankings after after Europa because the relative ordering of Triton and UB313 are not known.} There are, however, no other bodies that belong in amongst these ones, according to [4], which is updated as new large discoveries are made. I also agree that Wikipedia has a better chance of remaining up-to-date than NASA's site or other places. --Firsfron 05:03, 30 August 2005 (UTC)
I'm glad we agree on some things! (And yes, I do fall into the Pluto=TNO camp.) Putting it quite simply, speaking only of the known bodies, after #15 is where we start to get bodies whose mean radius is not known with any certainty. 2003 UB313 could be 16th through 19th, depending; Orcus could be 19th through 36th, by my count. Given that, assigning ranks is purely arbitrary. Cheers. --Dhartung | Talk 06:27, 31 August 2005 (UTC)

[edit] To rank or not to rank

The previous discussions have become quite voluminous, so let's see where we stand.

Can we agree on these two points?

  • The list currently does not contain all known solar system bodies. It does not even contain all known bodies in the size range it covers. This could be fixed if we wanted to do so.
  • The size of most solar system bodies is known only approximately. Therefore, rankings beyond a certain point are meaningless. (Note: I have currently pegged this at number 15, because we currently don't know whether Triton is larger or smaller than 2003 UB313.) This point will increase over time, but the large majority of known solar system bodies will always be unrankable.
In light of the new statement on 2003 UB313's diameter in the 2/2 Nature by Bertoldi et al., I have (1) changed the radius to reflect the latest figures, (2) placed 2003 UB313 higher than Triton on the list, (3) removed the "15" ranking from Europa (since it is possible that 2003 UB313 is larger than Europa). RandomCritic 14:30, 1 February 2006 (UTC)

I see a few possible courses of action. Please add more to the end of the list if I have forgotten any.

  1. Remove the Rank column. (This was my original proposal.)
  2. Include ranks only for those bodies unaffected by known omissions and ranking uncertainty. Leave the Rank column blank for all other bodies. (This is the list's current state.)
  3. Include only bodies unaffected by known omissions and ranking uncertainty. Include ranks for all bodies in the list.
  4. Include rankings for all bodies in the list, despite ranking undertanty. Fix known omissions by adding the missing bodies.
  5. Include rankings for all bodies in the list, despite known omissions and ranking uncertainty. (This was the state of the original Rank column.)

It's only #4 and #5 that I really object to. #3 seems to exclude a large number of interesting bodies (like Pluto).

My original proposal was #1, but having read other people's arguments, I think I'd now prefer #2. --P3d0 18:20, August 31, 2005 (UTC)

If we're voting, then Option 2 is my preference. I think it's a reasonable compromise between readers' expectations of some sort of ranking in a list "by N", and the known unknowns. --Dhartung | Talk 07:04, 1 September 2005 (UTC)
I'm fairly happy with Option 2, if we're putting it to a vote. 1-16 have all been visited by probes and their sizes are well-known (since the 1980's, in fact), so there's little controversy on their respective sizes and rank in size. Having said that, the current Wikipedia article on 2003 UB313 lists its radius as anywhere up to 2,500km. --Firsfron 16:31, 1 September 2005 (UTC)
I'm neutral, but while we're talking about the rank coloumn, did anyone notice that the images are overlapping the numbers? :| 66.134.206.66 20:11, 4 February 2006 (UTC)

[edit] Wrong radii?

Okay, these radius figures are all wrong. For example, it list Pluto's diameter as being 1195, when it's really 1430. That's just one example, as they all seem to be wrong. What's up with that?

What do you mean? I see Pluto's radius in the table as 1153 not 1195. This is directly from the Pluto article. Note also that it's the radius not the diameter that's tabulated, and in any case a diameter or radius of 1430 for Pluto is way out. Do you have any other examples? Deuar 10:55, 30 April 2006 (UTC)
(1153x2)x1.6 = c. 1430 (1433 might be more accurate). Get it? Rich Farmbrough 23:16 10 May 2006 (UTC).
Well, I understand that 2×3=5, but i'm getting a bit lost with these bigger numbers! Deuar 10:47, 11 May 2006 (UTC)

[edit] Name change

I moved this article from Geological features of the solar system, keeping in line with the lower-case usage at solar system. Please see Talk:Solar_system/Archive_001#Solar_System_vs_Solar_system and Talk:Solar_system/Archive_001#Requested_move (with discussion) for rationale. — Knowledge Seeker দ 22:10, 14 May 2006 (UTC)

[edit] Recommend change

In the chart, the earth's moon is called "moon". Is not the name for earth's moon suppose to be "Luna"? —The preceding unsigned comment was added by 64.31.11.2 (talk • contribs).

See Moon. In English, Luna is basically a romantic or fanciful name. The Earth's moon is generally called the Moon. --Dhartung | Talk 23:14, 17 June 2006 (UTC)

[edit] Why radius?

Why we use radius, not diameter?--Nixer 09:17, 15 July 2006 (UTC)

Why use the diameter? Why not use radius? --Iamunknown 07:39, 17 September 2006 (UTC)

[edit] ranking

With the smaller uncertainty in 2003 UB313, it looks like Triton can be confidently ranked 16th largest of the known bodies. Deuar 15:04, 24 August 2006 (UTC)

[edit] Thumbnails to wide?

Is it just my system, or a common view? Looking at the list, the thumbnails of the planets (etc) overlap onto the list od radii, partially obscuring the first digit.86.16.42.154 00:00, 25 August 2006 (UTC)Darkson

You were the second complaint. It turns out that the center syntax in the image tag for that column was causing an overlap in Internet Explorer, a bug not visible in Firefox. When I removed it there seemed to be no ill effects at different browser sizes in either software, so I hope that fixes it for everyone.--Dhartung | Talk 02:50, 25 August 2006 (UTC)

[edit] Eris and Pluto

It's odd that Pluto is listed by its numbered designation while Eris is listed as simply Eris. This is presently the reverse of the titles of their respective Wikipedia articles. Considering the heightened state of awareness over these two names, I recommend either using the same format for both names, or following the naming of the main articles for these two dwarf planets. There has been enough debate over this already to justify such a change. 69.136.238.165 23:05, 14 September 2006 (UTC)

Both those articles have been subject to page-move wars, so that's not really an arbiter. Right now there's a requested move discussion taking place on Talk:136199 Eris#Requested move.--Dhartung | Talk 01:57, 15 September 2006 (UTC)
I suggest removing the numbers from all minor planets to make their names more readable. --Greg K Nicholson 05:19, 16 September 2006 (UTC)
I took the liberty of removing the '1' from the name of Ceres -- to be consistent both with the naming of other dwarf planets, and with the name on Ceres' own page which has already been thoroughly discussed over there. Anyway it's nearly impossible that anyone would think the name refers to the goddess in the context of this list. Montalto 18:05, 6 November 2006 (UTC)

[edit] Merge proposal

Proposal to merge content from List of planetary bodies into this article: 1. Because the objects treated are effectively the same. 2. Because the basis for determining a "planetary body" is not sufficiently different from the criteria for inclusion in this list to potentially result in a different set of inclusions, and therefore the two articles will be near-duplicates. RandomCritic 21:44, 3 November 2006 (UTC)

I disagree, basically because I think there's an added value in having a list that's ordered.Junuxx 16:04, 5 November 2006 (UTC)
I think I disagree as well. I think the other article should not be a list by size but an alphabetical list by type. --Dhartung | Talk 18:33, 5 November 2006 (UTC)
I also disagree and will rework the list and change the order of the objects.--Planemo 18:53, 5 November 2006 (UTC)
Disagree as well − both orderings are valuable. Deuar 18:15, 9 November 2006 (UTC)
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