Talk:List of Solar System objects by size

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Sorting by Mass

I notice that when we sort the list by mass the exponent is ignored. Is there anything we can do about this? It makes it difficult to compare a 2.1×10²⁰ kg body to a 8.8×10¹⁹ body. -- Kheider (talk) 19:36, 5 December 2008 (UTC)

I'm not sure, but it might work if we use the exponent template {{e|20}} or {{e|19}} instead of spelling it out. Serendi^podous 19:40, 5 December 2008 (UTC)

I don't think the sort program is that smart so I am filling the M_Earth column for the known masses so that the list can be sorted by mass. I am currently leaving out the assumed^A masses since they are just guesses. -- Kheider (talk) 18:44, 6 December 2008 (UTC)

Mass list added

The entire mass list is now incorporated into the big list. Now I want to go over the list and condense it (there's no point in having two different measurements of the same value (km or kg vs Earth) in separate columns), add Surface gravity, type of object and sphericity. Serendi^podous 18:04, 6 December 2008 (UTC)

I think we should keep both of the Mass columns. One for common use (kg) and one for wiki-sorting (M_Earth). If you currently sort the Mass kg column you will see that Ceres is the most massive at 9.5. :-) -- Kheider (talk) 19:29, 6 December 2008 (UTC)

I've made a request on the Lists talk page. I hope we can figure out how to do it. If worst comes to worst we can change kilograms for yottagrams (×10²¹ kg). Serendi^podous 20:00, 6 December 2008 (UTC)

Ouch. I notice NONE of the columns are sorting properly. -- Kheider (talk) 11:18, 7 December 2008 (UTC)

Yeah, I noticed that too; I reverted everything. Shame. If I want this merge to work, then this list is going to have to be really wide. Serendi^podous 11:21, 7 December 2008 (UTC)

This merge is still a good idea because a sortable list is better and all the data could be kept in one list. Besides when I think of masses I think in kg, not yg. If we wanted to we would keep the assumed^A asteroids from cluttering the "sorting by mass" by not inserting a M_Earth value for them. I realize that for objects beyond Saturn, including most of the smaller moons of Uranus and Neptune, "assumed masses" is the only way we can really do a complete list.-- Kheider (talk) 11:46, 7 December 2008 (UTC)

Red Links

Should we remove the red TNO links? Their radii (200-264) appear to be taken from Johnston. With an article like this I prefer TNOs with a better estimated size, ie "Johnston #" and the Spitzer list. -- Kheider (talk) 17:59, 8 December 2008 (UTC)

I'm sure Johnston used a source to cite it. And he lists his sources on his page. We could always create their pages. Serendi^podous 19:32, 8 December 2008 (UTC)

Yes and no. On Jonhston's page, objects marked with a # next to the diameter have actually been professionally estimated. All other bodies are "assumed to have an albedo of 0.09". I looked at the red link TNOs, they are all assumed albedo 0.09 (per Johnston). I don't mind assumed albedos for the largest bodies, but these red links are basically small unknown TNOs. -- Kheider (talk)

I've had a think and I have decided that I agree. They should go. The only one I think we should keep is the last NEA, since I'm sure that one's radius can be determined fairly accurately.Serendi^podous 11:51, 9 December 2008 (UTC)

Given their large radii and potential as dwarf planets, I added 2005 UQ513* 462, 2007 UK126* 439, 2003 UZ413* 303 (all assumed albedo 0.09) to the list. -- Kheider (talk) 18:09, 9 December 2008 (UTC)

If Chiron is on this list, then shouldn't Charilko, which is bigger than Chiron, also be on this list? Serendi^podous 20:24, 9 December 2008 (UTC)

Yes we need to list the largest centaurs, just as we need to list the largest dwarf planet candidates. With that in mind I also believe that we should list 1995 SN55 that could turn out to be the largest known centaur. -- Kheider (talk) 17:25, 10 December 2008 (UTC)

Radius

Currently * symbolizes "Radius is known only very approximately". We need more tags for radius. Should ^R be used for "Objects that have been determined by various methods, such as optical (Hubble), thermal (Spitzer), direct imaging via spacecraft." This would be good for say Eris, Haumea, 2002 TC302, Orcus, MS4, AW197, GV9, AZ84, UX25, TL66, DE9, Huya. We could also have a ⁹ label for all the basically unknown "assumed albedo 0.09" objects. The * will also be good smaller moons like Sycorax.

This would give us:
* Radius is known only very approximately
^R Radius has been determined by various methods, such as optical (Hubble), thermal (Spitzer), or direct imaging via spacecraft
⁹ Unknown radius, generic assumed albedo of 0.09
-- Kheider (talk) 23:34, 10 December 2008 (UTC)

At some point we're going to have to go a lot farther than that. We are going to have to provide an individual reference for every established radius and note any radius that is derived from other properties, such as albedo. I know it will be tedious, but that's how these things work. Serendi^podous 10:22, 11 December 2008 (UTC)

I think this merge may be a lost cause

The sortbot simply can't handle so many terms. It can sort the mass figures alright going up, but not down, even when all the figures are regularised. Serendi^podous 12:32, 11 December 2008 (UTC)

Maybe we should split the list in half, one for bodies above 100km in radius, one for bodies below 100 km in radius. Serendi^podous 12:36, 11 December 2008 (UTC)

Heck, I'll just try it. Serendi^podous 14:52, 11 December 2008 (UTC)

I did it and it worked! Yay! One thing; while I was sorting out the over 100s from the under 100s, I noticed that 283 Emma's radius seemed remarkably big for something of its mass. Are you sure it wasn't 48, rather than 148? Serendi^podous 15:23, 11 December 2008 (UTC)

Looks good. Yes, 283 Emma (Binary) has a density of 0.83 per BAER. BAER is the source for current volumes and masses of the asteroids. This is why I tagged it with a (M)ass known. This is also part of the reason I like keeping the M_Earth for objects with known masses. Otherwise you don't know when you have a 8 Flora (Density 7+) or an Emma. -- Kheider (talk) 15:39, 11 December 2008 (UTC)

Baer

I figured Baer (as a source) would be coming up. Baer just gave a presentation at the AAS Division of Planetary Sciences meeting in October. This is why I have been busy playing with the masses of the asteroids so much. Baer also put out a paper in 2007.  :-) -- Kheider (talk) 15:50, 11 December 2008 (UTC)

I just realised a second problem

Now that the tables are split, many objects in the lower table actually higher masses and surface gravities than those in the upper table. I wonder if the merge is worth this or whether we're better off with the three old tables. Serendi^podous 17:28, 11 December 2008 (UTC)

• One master table to maintain is better than 3 "very generic" tables. And for the most part it appears sortable.
• I still doubt the gravity entries for the smaller objects with assumed diameters and masses (Below Miranda @ surface gravity.) Those with known masses are (assumed) ok.
• Since the start of this project I figured this master table may get split into two sections, kind of like planet vs dwarf planet. :-) There will always be little rocks with more mass than a chunk of styrofoam.
• I am still comparing various sources for the diameters of the smaller moons: JPLSSD, Sheppard, NSSDC. Things get pretty wild around Sycorax (diameter 150-190).
  -- Kheider (talk) 18:29, 11 December 2008 (UTC)

Mass and radius are now in

All that remains is surface gravity. Since there are about 100 entries to input (starting at Elara) I would very much appreciate it if someone else could help in shouldering the load. Serendi^podous 16:05, 11 December 2008 (UTC)

• According to surface gravity, Sycocrax has a radius of 75km (Sheppard/NSSDC), but it claims it has a mass of 5.4×10¹⁸! Ouch, that would require it to have a density of 3. I think Sycorax probably has a density of 1.3 to 2. But if the original entry showed a radius of 95km (JPLSSD) with a density of 1.5 then we would get a mass of 5.38×10¹⁸. Crud, even the original entry shows a radius of 75. :( -- Kheider (talk) 19:29, 11 December 2008 (UTC)
• For Caliban, a radius of 36km and mass of 7.4×10¹⁷ requires a density of 3.8. Ah, I see. They took their mass estimates straight from the (April 2007) wiki articles, and if those numbers were a mix match of different edits to the mass, radius, etc... you get weirdness. -- Kheider (talk) 23:03, 11 December 2008 (UTC)

Bugger. Since it would appear that adding any more figures from that list would be more dangerous than not doing so, I'll just go ahead with the merge. I guess I'll have to do what I usually do: drag Ruslik over here to do the calculations. Serendi^podous 19:47, 11 December 2008 (UTC)

I have been starting to compare the mass and gravity figures to what are given in the main articles and most of them do not deviate too much. But yes, I think I trust the main articles to be more up to date. And we really only want 3 sig figs for smaller bodies. If Ruslik works on it, I would have him start with bodies that have a known mass/radius (JPLSSD) instead of the assumed densities. -- Kheider (talk) 20:31, 11 December 2008 (UTC)

List of named Solar System objects

This list contains a number of objects that we might want to include in the bottom list. Serendi^podous 12:26, 13 December 2008 (UTC)

Maybe. But I am trying to stay away from adding too many poorly known objects (with radii<20 km) that have assumed masses. I have even given some thought to removing asteroids 141 Lumen through 100 Hekate since they are little known asteroids with assumed masses. We have enough quality asteroids with known masses for the list, IMO. -- Kheider (talk) 18:51, 14 December 2008 (UTC)

The list no longer exists.--Roentgenium111 (talk) 00:16, 16 January 2010 (UTC)

Kheider

could you link to your sources? Lists need to have some form of referencing, even if it's not as rigorous as the referencing for an article. Just posting them at the bottom should be enough. Serendi^podous 22:56, 15 December 2008 (UTC)

Problem of Mass Unit?

It appears to me that masses given are in Kg x 10 to the 24th but unit shown in heading is Gm x 10 to the 24th(Yg).Dspacenut (talk) 17:26, 18 February 2009 (UTC)

The top list gives its values in 10^21 kg (Yg). The bottom two lists give mass values in 10^18 g (Eg). Serendi^podous 22:50, 18 February 2009 (UTC)

Volume in Earths

My calculations are giving completely different values to the numbers listed. Can someone check please? Serendi^podous 21:38, 3 March 2009 (UTC)

Having a quick look at Mercury, Venus, Jupiter and Neptune using http://nssdc.gsfc.nasa.gov/planetary/planetfact.html I don't see a problem. Which objects did you see a problem? -- Kheider (talk) 22:50, 3 March 2009 (UTC)

Could you have a look at Charon and Umbriel? Serendi^podous 07:36, 4 March 2009 (UTC)

Umbriel: Volume of a sphere with radius 584.7 km = 837,313,109.4 km³ / 1,083,207,317,374 km³ = 7.7E-04 = 0.00077 Earth
Charon: Volume of a sphere with radius 603.5 km = 902,704,853.6 km³ / 1,083,207,317,374 km³ = 8.4E-04 = 0.00084 Earth
-- Kheider (talk) 14:22, 4 March 2009 (UTC)

Right. So they're wrong on the page. The list claims the volumes are 0.095 and 0.092 x10^9 km^3.

Which is not only the wrong value but appears to be off by a factor of ten. For me, 837,313,109/10^9 is 0.837, not 0.0837.

Which means I have to manually go through the entire list and redo the whole thing.

Bugger. Serendi^podous 14:41, 4 March 2009 (UTC)

This list claims that Charon has a volume of 0.87*10^9 = 870,000,000. Though it should be closer to 0.9*10^9, I do not see where it is off by a factor of ten. It also depending on how the original author rounded and what estimated radius they used. Heck even the Charon article claims radius 603.5 ± 1.5km while Planetary Satellite Physical Parameters shows 603.6 ± 1.4. The radius of Charon to Earth is 604/6378=0.0947 (which is what this article shows.) -- Kheider (talk) 15:37, 4 March 2009 (UTC)

OK, I've been reading the wrong columns. God this is painful. But still, it means that OR10's volume is going to be misplaced when it's added, unless I redo all of the volume figures. Serendi^podous 18:14, 4 March 2009 (UTC)

Are the "Mean Radius" and "Volume" columns supposed to be related by the formula V=4/3*pi*R^3 ? Currently they aren't because Eris's R is greater than Pluto's, and Pluto's V is greater than Eris's. —Preceding unsigned comment added by 92.225.99.73 (talk) 11:17, 24 August 2009 (UTC)

Ceres

MPEC 2006-R19 : EDITORIAL NOTICE says:

• "Ceres, Pluto and 2003 UB313 were identified as members of this new category"
• "It should be noted that, just as some of the numbered objects that have exhibited cometary activity also have designations in the catalogue of numbered periodic comets, the numbering of "dwarf planets" does not preclude their having dual designations in possible separate catalogues of such bodies."

IAU Questions and Answers on Planets says:

• "Ceres is (or now we can say it was) the largest asteroid" (clear as mud. So what was the first asteroid discovered? 2 Pallas?)
  

-- Kheider (talk) 12:00, 8 March 2009 (UTC)

Kheider, thanks for adding the "in the asteroid belt" part. I actually intended to do something along those lines, but forgot for some bizarre reason. (The "DP in the asteroid belt" format is consistent with what we are doing in other articles involving Ceres; keeping the "asteroid" status somewhat ambiguous in the absence of any definitive statement.) It also with how we don't identify Ceres as the xth planet discovered; identify it as a DP and leve the rest as background. --Ckatz^chat_spy 19:26, 8 March 2009 (UTC)

Surface gravity

It can be argued that we don't need surface gravity measurements for those objects under 20 km, but why leave the field there while removing the title? That makes no sense. Serendi^podous 12:16, 8 March 2009 (UTC)

Because the small objects aren't in gravitational equilibrium (i.e., they are potatoes), the surface gravity will vary depending upon where on the surface you are doing the measuring. The value computed from the mass and mean radius is really just a theoretical upper bound. This applies to the 20-200 km objects, too. For example, one of those dog-bone asteroids will not have anywhere with a surface gravity near the value computed from the mass and mean radius. So I think surface gravity should be dropped from the under 20, and probably from the 20-200, too, since it isn't any actual surface gravity on the object. Tbayboy (talk) 15:47, 8 March 2009 (UTC)

Very well. But the problem is that many of the mass calculations for the smaller objects were obtained by assuming sphericity and then a likely density. I would prefer a cited mass figure if one can be found, but that isn't always possible. Serendi^podous 11:42, 9 March 2009 (UTC)

density?

i was thinking of adding density to the tables, as this is also an interesting attribute. Then people could sort a list, showing for example that the average density of Earth is higher than the Sun.

I thought i would ask before doing so, is there a reason that density is not included? Is it because mass and volume are provided?

I think density is important enough to be included. Sorting by density would be a lot different that sorting by either mass or volume, it paints a whole different picture. —Preceding unsigned comment added by 203.219.216.45 (talk) 15:17, 22 April 2010 (UTC)

Good point. Will get onto it eventually. Serendi^podous 20:12, 24 April 2010 (UTC)

repetition

-- object 140 Siwa is repeated; around 55 km radius. ........ Well spotted. Serendi^podous 20:12, 24 April 2010 (UTC)

Trojan 4348 Poulydamas albedo

A Jupiter Trojan discovered in 1988 that's over 100km in diameter? Forgive me if I'm doubtful. — kwami (talk) 01:26, 31 May 2010 (UTC)

Just curious because of the "1988", but what exactly makes you doubtful? Anyway, looking at the IRAS source documents, the diameter is calculated from the absolute magnitude using an assumed albedo of .01, whereas other entries in the Wikipedia table with unknown albedos use the standard .09. Note that using that assumed .01 albedo, the source also lists 9 Metis as 737 km, Irene as 730, Euterpe as 529, etc. With .09, Poulydamas would have a diameter of 64 km. Tbayboy (talk) 23:28, 31 May 2010 (UTC)

It's the same size and distance as 624 Hektor, but took another 80 years to find? That just set my BS detector off. And, as you note, the albedo assumption applied to Metis and Irene make them the protoplanets rather than Vesta and Pallas. Of course, maybe Poulydamas is unusually dark and so just escaped notice, but our article on it mentions nothing about it being tied with Hektor as the largest known Trojan. — kwami (talk) 00:21, 1 June 2010 (UTC)

With absolute magnitude H=9.2, 4348 Poulydamas generically (one size fits most) should have a diameter of around ~60km. Assuming a generic trojan albedo of 0.06 would yield a size of ~80km. An albedo of 0.02 (624 Hektor has an albedo of 0.025) would still only place Poulydamas at 135km. In 2004 the European Asteroidal Occultation Network listed it pre-occultation as 48km in diameter. Trojan 2456 Palamedes H=9.6 has an albedo of 0.03 giving it a size of 91km. Asteroid 1049 Gotho is H=12 with a very dark albedo of 0.01 (size=51km), but he is a rare breed. -- Kheider (talk) 00:54, 1 June 2010 (UTC)

Since you've bumped the size down to 24km, below the 100-km limit of the table, shouldn't it just be deleted, and the info moved to the Poulydamas article? — kwami (talk) 09:04, 1 June 2010 (UTC)

I moved it down. Serendi^podous 09:11, 1 June 2010 (UTC)

Distance from Sun column

I think we should add a distance from Sun column that would make it easier to find bodies so that the object can be sorted to follow the more common pattern of Sun, Mercury, Venus, Earth, Moon, Mars, etc.

--TimeHorse (talk) 15:42, 15 June 2010 (UTC)

Ultimately, the plan is, once (if) this article ever gets to FL then to go onto List of Solar System objects and do a complete workup of their orbital elements, from semi-major axis to eccentricity to argument of perihelion. Serendi^podous 16:38, 15 June 2010 (UTC)

Density of 20000 Varuna

With radius of 310 km, mass of 0.37x10²¹kg, Varuna has density of 2.965g/cm³, but the source here (abstract / PDF) tell me that it has density of 0.992g/cm³. Newone (talk) 03:37, 4 August 2010 (UTC)

Ok, changed the values for Varuna and Haumea to that source. Fotaun (talk) 16:05, 3 March 2011 (UTC)

Binary/trinary

Just curious, why are these listed as part of the descriptors for some of the dwarf planets? I was under the impression that the terms usually referred to a situation where the object and its moon are close in size. --Ckatz^chat_spy 20:23, 18 September 2011 (UTC)

Not for asteroids. E.g., see Johnston. It's probably just tradition, back to when they had little idea of the sizes. Tbayboy (talk) 21:57, 18 September 2011 (UTC)

Technically even Charon is only a satellite. (B=Binary companion / S=satellite) See also (90) Antiope and (93) Minerva on the list. -- Kheider (talk) 00:00, 19 September 2011 (UTC)

Thanks for the quick replies, and for clearing it up. --Ckatz^chat_spy 08:46, 19 September 2011 (UTC)

File:2003 EL61.jpg Nominated for speedy Deletion

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Using non-free images in the list

The images of 2867 Šteins (File:Steins-Rosetta.jpg) and 25143 Itokawa (File:Itokawa4.jpg) were removed for being non-free and lacking a rationale (WP:FUR). From where I stand including an image where possible adds to the list. Is there any way we could get these back in? --JorisvS (talk) 15:34, 3 January 2012 (UTC)

Sorting

Putting DP first messes up sorting by KBO, SDO, asteroid, etc., and does not even provide sorting by DP. (We can't sort by DP, as WP editors disagree as to which objects qualify as DPs: There are numerous sources that Sedna is a DP, for example, but that's not reflected in the sorting.) Also, the lists further down all sort by KBO, SDO, asteroid, so listing DP second makes the various lists consistent. — kwami (talk) 00:55, 11 February 2012 (UTC)

Reverted, and no, you disagree. The column sorts perfectly well for dwarf planets. --Ckatz^chat_spy 03:53, 11 February 2012 (UTC)

If it sorted, then the DPs would be listed together. But they're not, because we can't agree on which are DPs, because you refuse to accept any sources which disagree with your POV. We can, however, agree on which are KBOs and the like. And since that's how the other tables sort, that's how they should all sort. — kwami (talk) 05:30, 11 February 2012 (UTC)

I think the root problem is that the "type" column contains multiple axes of information. With the "shape" column, they try (inconsistently) to contain info about what the composition of the body is (star, gas, ice, rock), its dynamic status (sun, dominant body, satellite, small body), its dynamic group/location (e.g., planet, main belt, centaur, cubewano, detached, etc.), and its shape (H-E, unknown, potato). (Even more, with the binary indications and so on.) No matter how you arrange it, the sort will be wrong from some perspective. It doesn't help that the DP definition is a combination of dynamic status and shape, which are properties independent of each other. Anyway, reorganising those two columns into three or more that are focused on well defined, single axis properties is what's needed to improve the sorting. Tbayboy (talk) 06:41, 11 February 2012 (UTC)