Talk:List of solar system objects by mass

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[edit] Trustworthy sources for data

I started this page with the expectation that it would be relatively easy to find masses for the planets and their moons, and a few of the major asteroids and planetoids and so forth. The masses of the planets are fairly well known, but I had a ridiculously difficult time trying to find good, reliable sources for the masses of moons (especially those of Uranus and Neptune). I tried NASA's Solar System Exploration page, which appears to give pretty good values for most moons. As I started updating the masses to match those given by SSE, however, I noticed that the masses of many moons (31, in fact) are given as 8×1017 kg. It appears that SSE is using this number to indicate an uncertain or unknown mass rather than simply saying "unknown," which makes me question the accuracy of the other numbers. Until I can resolve that, I'm going to avoid using SSE values, so if anyone knows of other reliable sources, please post them here or update the page yourself. --Bkell 22:42, 19 Mar 2004 (UTC)

I think those moons are listed at that number because they're all rounded to around the same size. Most of the newly discovered moons have very little known about them. I've seen orbit sizes changed by more than ten million kilometers in months. At this time, we only have very rough estimated of thir size, and the masses are probably inferred from estimating the mass of a sphere of that size with a guessed density. Anyway, I admire the effort put into this page, I've always wanted to try something like this myself, but I'd never been able to find enough reliable info on objects under the size of Ceres. --Patteroast 00:00, 6 Apr 2004 (UTC)

[edit] Formatting

I originally started this page as a table, and then moved to an ordered list, since it seemed to me that it would be nice to be able to quickly ascertain a given object's rank in the solar system. Curps changed it back to a table today, which has its benefits, among them the fact that the masses are nicely aligned. The problem is that now the ranks are gone.

I realize that assigning rankings to some of the objects lower in the list is somewhat misleading, since it's very likely that there are larger objects in the solar system that just aren't in the list because their masses aren't well known. But I think it would be nice to have rankings for at least the first few objects; after all, I think we're fairly certain that Earth is the sixth most massive object in the solar system, so it would be nice for it to be labeled "6".

Perhaps we can just add another column down the left side of the table for the rank. Any opinions out there? —Bkell 03:50, 14 Apr 2004 (UTC)

[edit] Other sources, cutoff size for mass, and capitalization of "Solar"

While looking for masses for 31 Euphrosyne and 65 Cybele, I found some interesting sources which I will not be able to wikipediate all the useful content from today. These masses are given in terms of Solar masses, not in kilograms, and so will need to be converted.

--Arkuat 23:33, 2005 Jun 23 (UTC)

My impression was this page is not supposed to list all bodies in the solar system, rather those with mass greater than 1 billion metric tons (1015 kg). If you think that lighter bodies should be added, start with Jupiter's natural satellites, Saturn's natural satellites, Uranus's natural satellites and Neptune's natural satellites. Smartech 8 July 2005 14:42 (UTC)

1015 kg sounds like a good cutoff to me, in that we really shouldn't add anything less massive than that until we're all confident that the list is complete for more massive objects (which seems unlikely given the recent discovery of objects such as Sedna). And by the way, oughtn't this article be titled "List of Solar system objects by mass"? It's only a case quibble, so I hesitate to do a "Move this page" without discussing it on the talk page first. --Eric Forste 9 July 2005 08:19 (UTC)

Yes, well technically the article should be named "List of known Solar system objects", because obviosly, we dont know all of them and most likely never will, or at least it looks like we never will now. But the point is, that applies to all articles more or less, because things are not fixed. Smartech 00:49, 11 July 2005 (UTC)

Sorry, I wasn't clear. I just meant that Solar ought to be capitalized instead of spelled "solar". --Eric Forste 04:23, 11 July 2005 (UTC)

The capitalization is fine, I had already gotten it the first time ;) If you read about the (assumed) Zipf distribution of bodies in the solar system, it is clear that the smaller the dimensions, the lower the percentage of total bodies that we know of. Smartech 05:03, 11 July 2005 (UTC)
Why should "solar" be capitalized? It isn't capitalized in the solar system article. Yes, we're discussing a particular planetary system, but we aren't saying "the Sol system". Words such as "solar" and "lunar" usually aren't capitalized. —Bkell 20:59, 9 August 2005 (UTC)

It shouldn't be capitalized; I was wrong. Someone will have to put up a request for deletion on the redirect at List of solar system objects by mass, and I haven't gotten around to that yet. This shouldn't be fixed by a copy-and-paste between the two articles because of the effects that will have on page history. --Eric Forste (Talk) 02:14, 13 August 2005 (UTC)

[edit] Interwiki .fr

The French version of this article has added several large TNOs that may not have independent articles in the English wikipedia yet, and in any case probably don't have masses listed yet. Personally, I'm more interested in the missing large asteroids, but I may get around to working on these TNOs someday. In the meantime, I thought I'd mention it here in case someone else would like to do that. --Eric Forste (Talk) 02:14, 13 August 2005 (UTC)

[edit] Pallas

Hi Arkuat/Eric,

Concerning minor planet Pallas: it is typically depicted as non-spherical, and roughly football-shaped (N. American football, obviously). Wikipedia lists its dimensions as 570×525×482 km, which is egg-shaped rather than spherical. Ceres is the only asteroid which is known to be round. Cheers!--Firsfron

[edit] Minor correction

I have change the listed mass of Icarus from 1.0 to 2.9, as this is the mass listed on the "Icarus" page both in Wikipedia and on "http://www.answers.com/topic/1566-Icarus". I have never changed any-thing in Wikipedia before and is therefore not accustomed to the procedure, so I would like to apologize beforehand if this correction has been unwarranted...

allan N

No worries, you did the right thing. Thanks for noticing and correcting the problem! DenisMoskowitz 19:26, 10 November 2005 (UTC)

I have changed the listed mass of 243 Ida to reflect the value given on article 243 Ida. Also moved it to the appropriate place in the list. I have changed the listed mass of 90482 Orcus to reflect minimum estimated mass as listed in the article 90482 Orcus. Also moved it to the appropriate place in the list. I have changed the listed mass of 704 Interamnia to reflect value given in the article 704 Interamnia. Also moved it to the appropriate place in the list. I have changed the listed mass of 22 Kalliope to reflect value given in the article 22 Kalliope. I have changed the listed masses of 1620 Geographos and 1862 Apollo to reflect value given in respective articles. Also they have been moved to new appropriate place in the list. Abyssoft 21:35, 5 July 2006 (UTC)

[edit] Spheroid or not?

I have changed some of the Zettagram range table. If we give the dimensions of a body in descending order as a×b×c, then a characteristic feature of the so-called irregular-shaped bodies which have not relaxed due to gravity is that b is significantly less than a. If a and b are much the same, but c is significantly smaller, it is indicative of an oblate spheroid with an equatorial bulge. You get this for all the planets e.g. Saturn has a big bulge. A classic case is Vesta (578x560x458 km) v.s. Pallas (570x525x500 km), where Vesta mainly has lots of flattening because it rotates fast, but Pallas seems to be clearly irregular around the equator. Proteus is apparently another oblate spheroid being about 215x213x197 km. [stuff I learned reading Slyuta et al, Icarus Vol. 129, p. 401 (1997)]. Deuar 11:30, 13 November 2005 (UTC)

Here is the problem with classifing objects such as Proteus and Vesta as 'oblate spheroids': they aren't round! Objects such as Saturn and Ceres are roughly rounded: they're oblate spheroids because two of their axes are fairly close in size, and the third axis is fairly smaller, like a slightly deflated ball.
Vesta and Proteus, on the other hand, are only as spherically oblate as smashed-in pumpkins: Proteus has three giant craters which cover the majority of its surface: in the accompaning article, you can see it looks more like a slightly rounded brick than a sphere. Compare to the photographs of Mimas or Miranda, which are spherically oblate.
Vesta is also not really spherically oblate: take a look at the HST photo. At first appearances, it does resmble a very deflated ball, but take a look at the color spectrograph, which reveal giant irregularly shaped craters, one of which covers a huge portion of the surface.
These two objects are like floating potatoes in space: they aren't spheres and they're not oblately spheroid, any more than your average rock is.--Firsfron 20:35, 14 November 2005 (UTC)

Neptune's moon Proteus is one of the largest non-spheroids in the solar system. Kheider 19:03, 18 October 2006 (UTC)

[edit] Naming of sun

Is there a reason the sun is listed in Spanish instead of English? (sol) | Phaldo 16:56, 1 January 2006 (UTC) |

See the Sol article. Ardric47 02:06, 27 February 2006 (UTC)

[edit] cutoff mass for TNOs

I would suggest cutting off all trans-Neptunian objects at the 1020 kg point, barring something really notable. The suggested cutoff corresponds to a diameter of 457 km (assuming the usual density guess of 2.0 g/cm<sum>3). While the population of TNOs is poorly sampled at all size ranges, this cutoff at least corresponds to about the size at which icy satellites compress to a spheroid from self-gravity. Deuar 18:42, 7 February 2006 (UTC)

[edit] 2003 UB313

Added information on this "10th planet". Mass is estimated on the basis of size measurements and assuming it is very similar in composition to Pluto (ref: http://www.gps.caltech.edu/~mbrown/planetlila/index.html):

Estimated mass of 2003 UB313 = Pluto's mass * [(2003 UB313's diameter)/(Pluto's diameter)]3 = 1.305*1022*(3000/2306)3 = 2.873*1022 ~ 2.9*1022 Aquirata

Updated mass estimate on 2003 UB313 to reflect latest diameter estimate (2400 km vs 3000 km). However, I notice that the mass for Pluto in this article and the Pluto article aren't in agreement: 12.9 Yg vs 13.05 Yg. I used the 13.05 Yg value (same as the original mass estimate and the Pluto article) and rounded up 14.0 Yg, but thought I'd bring the discrepency to everybody's attention. --Pfhreak 02:13, 13 April 2006 (UTC)
Aren't they saying now (i.e. since the revised size measurements) that the composition of 2003 UB313 is different from that of Pluto? Ardric47 03:51, 13 April 2006 (UTC)
I think the revised size estimate is simply based on a new measurement by the Hubble Space Telescope (http://www.gps.caltech.edu/~mbrown/planetlila/index.html#size). With that, the new estimate for how much sunlight the planet reflects was upped to 86%, but composition is still thought to be similar to that of Pluto: "Pluto, we know, has a density about midway between ice and rock, thus we think that it is made of about half and half ice and rock on the inside. The new planet, being about the same size and the same surface composition as Pluto, is probably close to the same." (http://www.gps.caltech.edu/~mbrown/planetlila/index.html, under the heading 'What is the planet made out of?' - about halfway through the article) Aquirata 23:59, 16 April 2006 (UTC)
Using Pluto's mass as 13.05 Yg, I get 14.7 Yg. Hence, i'm rounding up to 15 Yg. Deuar 12:26, 22 April 2006 (UTC)

[edit] Graph showing relative masses

Added graph showing relative masses of selected objects today in the front matter. It is very revealing to see this in graphical form rather than trying to get a feel from the actual numbers. The list includes all objects listed from the Sun to 3 Juno. The decision to have the cut-off at Juno was made for the following reasons:

  • The list includes the four major asteroids
  • The graph is roughly symmetrical to the Earth as the Sun is just about as many Earth masses (330,000) as the Earth is Juno masses (200,000)
  • This list divides nicely into three approximately equal sets: 1) Sun to Moon, 2) rest of the objects in Yg range, 3) Ceres to Juno
  • It's hard to include more objects without sacrificing legibility

The graph will need to be updated only in case of a major change in the main lists. It is an Excel chart, which is relatively simple to update. Aquirata 14:00, 15 May 2006 (UTC)

Looks great! Graphs like this shouldn't be uploaded in the JPEG format, however; please see Wikipedia:Preparing images for upload for more information. Could you make a PNG version of this graph and upload that? —Bkell 07:14, 16 May 2006 (UTC)

Thanks for your comment. Will replace the file with a PNG version today. Aquirata 10:32, 16 May 2006 (UTC)

I have replaced the bar graph with what is known in the business as a "dot plot", while keeping, I hope, to the spirit of Aquirata's original. Del C 17:27, 6 October 2006 (UTC)

[edit] fantastic work, wikipedians!

I just want to say that this article is so much more helpful than the last time I edited it. You folks make wikipedia fun for me. --arkuat (talk) 04:53, 20 May 2006 (UTC)

[edit] Mass vs delta-vee

Is anyone else interested in working on a list of solar system objects ranked by the quotient of mass/delta-vee-from-Earth? Respond here or on User_talk:Arkuat --arkuat (talk) 05:55, 5 June 2006 (UTC)

So this list looks interesting to work on, but I'm wondering about several issues:
  1. PR: I can see that this is roughly a ranking of "How interesting is it for the effort required to get there". Do you have by any chance a catchy title for the list, and any ideas on where to link it up with other solar system articles?
  2. Technical 1: How would we go about calculating the delta v? is it for a flyby, orbit (if so, how close), do we include getting out of Earth's gravitational well, or just the Sun's gravity, what about the gravitational well of a gas giant when it comes to calculating Δv to their moons. Also, delta vee will tend to depend on the date that you set out, for example if the bodies are nicely aligned with their perihelion, Earth's aphelion, etc. delta-v may be smaller. It starts to look complicated ;-) (which is not necessarily a major discouragement).
  3. Technical 2: This is a somewhat arbitrary quantity. On what basis do we prefer M/Δv to M/(Δv)^2 or R/Δv, say. This might bear some thought...
Deuar 15:46, 20 June 2006 (UTC)

[edit] petagram range

I notice that some of the objects in the "Petagram range" table are actually smaller than 1×1012 kg. Perhaps we should rename this section or change the blurb at the top to be consistent with what we want there. Matter of fact, what do we want there? Currently there is a couple of NEOs distinguished by either being the first of their orbital class or by being radar imaged from Earth. Deuar 12:06, 15 June 2006 (UTC)

The petagram section of this list is the only list of NEOs ranked by mass on wikipedia that I know of, so I think what we want here is a short list of the most massive known NEOs in that order. It's true that there are lots of petagram-range objects in the main asteroid belt that would be ignored, but is that so wrong? (The objects that turn out to be less than 1×1012 kg ought to be removed, of course.) --arkuat (talk) 23:50, 18 June 2006 (UTC)

Sounds good to me. No tears will be shed for the main belt asteroid hordes either (you might notice that run-of-the mill asteroids are excluded even in the exagram range). A final issue is should a "Teragram range" be made for those objects of interest below 1×1012 kg, or should they be left out. Personally, I reckon just give them the chop. Deuar 13:27, 19 June 2006 (UTC)

Yeah, I don't think we want a teragram range. The list sections we do have are all incomplete, as it is, what with all the TNOs popping up. (This is why I want a list ranked by mass divided by delta-vee-from-Earth.) If it weren't for the "near-Earth" aspect (I am interested in keeping track of the most massive NEOs!), I'd get rid of the petagram range list too. --arkuat (talk) 06:18, 20 June 2006 (UTC)

[edit] Minor Planet Removals

52 Europa

Concerning minor planet 52 Europa (1948 LA), due to the large uncertainty as to the actual mass; I move to have it removed from this list until it's mass is in better confidence. Abyssoft 21:23, 5 July 2006 (UTC)

951 Gaspra

Concerning minor planet 951 Gaspra (SIGMA 45; A913 YA;1955 MG1), due to the large uncertainty as to the actual mass; I move to have it removed from this list until it's mass is in better confidence. Abyssoft 21:57, 5 July 2006 (UTC)

2060 Chiron

Concerning minor planet 2060 Chiron (1977 UB; 95P/Chiron), due to the large uncertainty as to the actual mass; I move to have it removed from this list until it's mass is in better confidence. Abyssoft 21:23, 5 July 2006 (UTC)

2685 Masursky

Concerning minor planet 2685 Masursky (1950 VO; 1973 QF;1975 XJ5; 1977 KU;1981 JN) due to the large uncertainty as tot he actual mass; I move to have it removed from this list until it's mass is in better confidence. Abyssoft 21:44, 5 July 2006 (UTC)

You know, there are actually dozens of bodies in the list whose mass comes from various estimates rather than accurate measurements. These are all those whose mass value is preceded by a tilde "~". Their true mass is likely to vary by about a factor of two both ways. The largest of these is Sedna, all the way up at number 22 on the list.
I do not think that it is a good idea to remove them.
  1. While their exact values are uncertain, their true position on the list is not going to be far from the present "provisional" one. Unless someone cares a lot whether, 52 Europa, say, is number 30 or 35 on the list, this uncertainty is not a problem. Note how teh Zettagram and lower ranges do not have a rank column, for this very reason.
  2. The objects in question are unambiguously marked. Perhaps this marking could be made more conspicuous than just the the tilde, and a explanatory note placed somewhere prominent. This would reduce some possible confusion.
  3. Most importantly, in my opinion, this is possibly the most complete list of solar system objects on the wikipedia that includes a physically meaningful and visually appealing comparison for them. As such it gives a good and fairly unbiased comparison of the types of objects, their relative sizes, and gives some idea regarding their numbers. At present, it is pretty complete at least down to about 1×1019 kg, and still quite representative much further down. Removing objects with uncertain masses will bias the list towards moons, against asteroids, and very much against TNOs, giving a skewed impression of the denizens of the solar system.
In brief: it is more misleading to remove some objects, making their presence invisible to a reader, than have them close to their true position but with a little uncertainty. Deuar 22:04, 5 July 2006 (UTC)

The above 4 contained large uncertainties listed in the main articles associated with them. Albeit, there are several in the list that are estimated, these estimates are indicated in the respective articles and do not state an uncertainty. This expresses confidence in the figure listed.

List of uncertainties in %: 52 Europa, ~34.6; 951 Gaspra, ~33.3; 2060 Chiron, ~7.7; 2685 Masursky, ~37.5

Of these 2060 Chiron is the only one with an uncertainty of less then 10%. I would not be opposed to the idea of keeping a body listed should it have a confidence greater then 90%, and the mass listed be the median of the uncertainty. Abyssoft 00:29, 6 July 2006 (UTC)

How about just listing the uncertainty, so that the reader can be aware that the given mass might be substantially wrong? —Bkell (talk) 10:26, 6 July 2006 (UTC)
Writing the uncertainty would be more professional, although I worry that it may turn out messier for the reader. That's why the tildes have been used. Deuar 19:12, 6 July 2006 (UTC)
I completely agree with Deuar, if anyone cares. Any object more massive than an exagram, the mass of which is known within a factor of two, ought to be listed, and I think the ~ is sufficient notification, since the actual error bars will be found on the linked article describing the object in question. --arkuat (talk) 19:09, 7 July 2006 (UTC)

[edit] Should we have artist's impressions?

Until recently, all the images in this list have been "real" data taken by cameras or gleaned by other methods, however since a recent edit we now have artists impressions for three bodies: 2003 EL61, 90377 Sedna, and 50000 Quaoar. Before the number of artist's impressions grows it would be good to come to some consensus on whether we want them or not. Off the top of my head, some arguments for:

  • eliminates ugly white space

and against:

  • Artist's impressions tend to be misleading -- they have rarely turned out to be close.
  • Having only real data gives a good indication at a glance of how much is known about the object: good images, rough pixelly images (e.g. 1 Ceres, Himalia), not properly resolved (e.g. 2003 UB313), very little (all the empty image boxes). With the artist's impressions, one could be forgiven for thinking we know as much about Quaoar and Sedna as about Saturn's and Uranus's moons which are right next to them on the list.

As for me, as you can probably guess, I much prefer having an empty space to indicate very little available data because it arouses a strong sense of curiosity about the object in me.
However, what does everyone else think? Deuar 14:42, 23 August 2006 (UTC) I have no qualms about having artists' impressions given that they are properly documented as such. Abyssoft 01:47, 25 August 2006 (UTC)

I've gone and distinguished them from the other images by a dark grey bakground (with a note in the header). Deuar 18:03, 4 September 2006 (UTC)

[edit] would it be possible to have a grams column ?

wonderful page there are two columns for mass: yotta and kilo. Would it be possible to have a column in plain old grams, which, after all, is the unit of weight before we start with metric prefixes or scientific notation to scale it. This would make direct plugins of these numbers into other formulas more likely to be accurate. Thanks.

I believe the mass unit that is the widely used standard (at least in astronomy) is kg, rather than g. Deuar 12:37, 25 August 2006 (UTC)
Yes, the kilogram, not the gram, is the SI base unit of mass. The gram is actually a derived unit. —Bkell (talk) 13:01, 25 August 2006 (UTC)

[edit] spurious brackets and units

Just wondering − why do we have brackets around all the numbers in the mass column, and why do we repeat "kg" despite pointing out in the header that it's in kilograms? I'm tempted to remove this, but don't want to charge off into such a tedious business if its going to be reverted ;-) Deuar 17:57, 4 September 2006 (UTC)

I haven't figured out the reason for all the parentheses (brackets) yet either, so go ahead and remove them. I'd say hold off on removing the "kg"s. My experience with teaching science to adolescents is that we must abhor naked numbers, and taking away the kg's would render all those numbers absolutely nude. Besides, it would be prejudicial against those of us who prefer daltons as a unit of mass. I'm still ruminating over your excellent remarks about the mass-vs-deltavee proposal. --arkuat (talk) 07:53, 10 December 2006 (UTC)

Ah then, with luck I'll attack those parentheses on a day when I need some tedious fiddling to calm the mind :) Thanks for a reply to such a stale post; by the way, I'm still finding m-Δv kind of interesting. Deuar 18:15, 11 December 2006 (UTC)

[edit] Solar System Mass

In the Solar System article, it says: "Jupiter and Saturn account for more than 90% of the system's remaining mass"

However, with the figures in this article you can calculate that Jupiter and Saturn account for less then 10% of the solar system's mass (not counting the Sun).

LEitK 03:19, 5 January 2007 (UTC)LEitK

The figure for the whole of the solar system mass does look a bit too high. If you add up all of the figures barring the Sun, you'd get something like ~92% for Saturn & Jupiter combined - with Neptune & Uranus making up ~7% of the remaining. Richard B 03:51, 5 January 2007 (UTC)
I removed "Solar system" from table until this discrepency is resolved. The difference is far too vast for the information to remain until verified. Serendipodous 13:28, 9 January 2007 (UTC)

I would say the previous Solar system mass (2,019,390,000 Yg) was almost certainly the error. The Jupiter mass in the Jupiter article is, rightly, about 0.1% of the Sun's (makes sense since J has a tenth of the radius of the Sun, and a similar density). We should just be able to add them all up. Incidentally, there is a discrepancy between the solar mass given here and at Sun. Both, predictably, without a reference − Aaaargh! The largest component whose mass is unknown is the weight of all the Trans-Neptunian objects. This should be of the order of around ten Pluto masses i.e. about 1e23 kg. Since this is apparently less than the uncertainty in the solar mass, it can be completely ignored. Before we add them, up, though, we should check for consistency with the individual articles. Deuar 13:53, 9 January 2007 (UTC)

→ so I get 1.991104×1030 kg Deuar 14:14, 9 January 2007 (UTC)

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