Talk:Moons of Jupiter/Archive 2

Archive 1

Archive 2

to do

• Add apparent magnitudes
• format refs: done except w/ 28-31
• last name, first name
• rewrite the masses
• ref eccentricities
• play around with the unlinked notes in the table
• no break spaces for units

 Done Nergaal (talk) 06:45, 2 September 2008 (UTC)

Rings

There's no mention of how the moons maintain the rings. Serendi^podous 11:59, 5 September 2008 (UTC)

added a line. Serendi^podous 12:10, 5 September 2008 (UTC)

irregulars image

I've found a nice image with the orbits of teh irregulars above 10km in radius here - figure3. Is it ok to upload it? It would very nicely present the groupings of the outer satellites. Nergaal (talk) 20:36, 5 September 2008 (UTC)

Yes, that's a nice image. Is it not copyrighted? It does suggest that the outer moons may be the shattered remains of a relatively small number of bodies, doesn't it?

Leda

Leda would appear to have ten times the density of other moons its size. Can s.o. confirm the mass and diameter aren't off? kwami (talk) 08:55, 6 September 2008 (UTC)

according to NASA figures, it has a mass of 6 x 10¹⁵ kg and a radius of 5 km, which would, by my calculations, give it a density of 11.5. That seems ridiculous. To be that dense it would have to be made mostly of gold or lead.Serendi^podous 09:10, 6 September 2008 (UTC)

I've subbed it with info from this Fukuoka University page. Seems to produce a more logical density. Serendi^podous 08:27, 8 September 2008 (UTC)

Thanks. I wrote to NASA asking them to fix their page. We should probably place a note on the Leda entry, since the Fukuoka data is rather old. kwami (talk) 10:18, 8 September 2008 (UTC)

Added a commented out link. Serendi^podous 12:16, 8 September 2008 (UTC)

Formation

I can't believe we forgot to put a formation section in here. I'll get on it. Serendi^podous 09:36, 10 September 2008 (UTC)

Actually, come to think of it, the formation section would probably be best in Galilean moons. Serendi^podous 11:06, 10 September 2008 (UTC)

I was planning on having a formation section but as I went through I realized that most of that info is allready covered in the Groups section. Basically Galilean moons formed in situ, while the others were more or less captured and broken asteroids (exceptions noted too). Besides that, the only thing that could be added is detail about the GM part, which as you said, would go in the GMs article better. Nergaal (talk) 16:23, 10 September 2008 (UTC)

There is actually something that this article does not cover at all, and that is explaining how & why the Galileans got to the present resonance. Nergaal (talk) 09:52, 12 September 2008 (UTC)

Does that belong here, or in the Galilean moons article? Serendi^podous 10:21, 12 September 2008 (UTC)

It definitely should be discussed in Galilean moons (which it isn't) and maybe Orbital resonance as well. I would say that a summary sentence or two would be appropriate in this article.

A review of the topic can be found in Peale and Lee (2002)[1], which cites all of the relevant previous papers as well as providing new arguments in favor of a primordial origin for the resonance. I would say that the idea of evolving into the resonance through tidal expansion is still a very viable model, and should be equally discussed. --BlueMoonlet (t/c) 13:08, 12 September 2008 (UTC)

I can't access it from my terminal. Do you think you could add it? Serendi^podous 13:43, 12 September 2008 (UTC)

new horizons

did the probe show anything interesting about the moons besides the volcanoes on Io? Nergaal (talk) 01:07, 16 September 2008 (UTC)

They found lots of interesting things, but nothing revolutionary, as far as I can tell. Serendi^podous 04:55, 16 September 2008 (UTC)

[2]

It's good to have a snapshot of the system every once in a while, just so we know what's normal. Too bad we didn't have Galileo there when Shoemaker-Levi hit. kwami (talk) 05:48, 16 September 2008 (UTC)

I just wanted to make sure that nothing was missing from this list (I am slightly surprised that with its good camera, horizons did not look at any of the smaller moons). Nergaal (talk) 06:03, 16 September 2008 (UTC)

Number of moons in the past

It's worth mentioning that the current moons are believed to be the ones that survived their formation process. New Scientist (7 March 2009) has an article on the subject if you'd like a reference. I would add it myself but am unable to because of semi-protection. The article ("Cannibalistic Jupiter ate its early moons" by Marcus Chown, page 11) gives an estimate of up to 20+ for the number of Galilean moons the planet could have originally had. Recognizance (talk) 22:08, 17 March 2009 (UTC)

The article is available online at http://www.newscientist.com/article/mg20126984.300-cannibalistic-jupiter-ate-its-early-moons.html. Recognizance (talk) 16:35, 18 March 2009 (UTC)

new section

I added a new section on origin & evolution based on User:Recognizance's link. It could use some editing by someone who really knows what they're talking about, and we might want to migrate to here material on origins now scattered through the article.

I only added a link to the popular summary. The original article on the evolution of Europa is here.[3] kwami (talk) 00:22, 19 March 2009 (UTC)

Okay, this is going to need some work. I removed some nonsense from recent edits (such as "trapped in the gravitational field"), but what's left is contradictory. For example, we claim that the early galileans spiraled into Jupiter, but then say that new moons formed from their debris. We also claim that a large mass "passed through" the disk, but never say where it came from--the solar disk, perhaps? kwami (talk) 10:31, 19 March 2009 (UTC)

By "newly accreted debris" I meant new material that accreted by Jupiter from Solar nebular (not debris of moons). Ruslik (talk) 11:09, 19 March 2009 (UTC)

You mean material pulled in from the Solar nebula to replace that depleted by the accretion of the moons? kwami (talk) 11:20, 19 March 2009 (UTC)

Yes. Ruslik (talk) 11:25, 19 March 2009 (UTC)

Fantastic. The idea of such a section occurred to me while I was reading the article, but it had been mentioned on the talk page (and was already at FA status) so I didn't want to mess with it. But this definitely improves the article. I do think it belongs earlier in the article though. Recognizance (talk) 16:48, 20 March 2009 (UTC)

Another thought with respect to organization: The naming section as a subsection of the discovery section. Moons are named as they're discovered, so the two are inherently related. I can go either way on it though so I refrained from making the change on my own. Recognizance (talk) 16:59, 20 March 2009 (UTC)

??? = Jupiter L Herse

USGS Astrogeology has a news item up about a newly named moon of Jupiter, discovered in 2003 by Gladman et al. Unfortunately, there are multiple unnamed moons fitting that description and I can't find any info on which one it is. Link here. Can anyone else find out more so we can start the name-changing spree on related articles and lists? --Patteroast (talk) 04:52, 11 November 2009 (UTC)

It is S/2003 J 17. Ruslik_Zero 13:20, 11 November 2009 (UTC)

Classify Trojans as Moons?

The Jupiter Trojans, such as 624 Hektor (~1.4×10¹⁹ kg) are technically in orbit around Jupiter at a distance of ~5.2 AU. Should these be included as moons? If they were then 624 Hektor would be the 5th largest moon of Jupiter. If they are not included as moons they should still be mentioned as objects of relevance to the article. --Tediouspedant (talk) 13:02, 18 February 2010 (UTC)

They're not in orbit about Jupiter. They're in orbit about the Sun in resonance with Jupiter. We wouldn't say that Pluto is a moon of Neptune. kwami (talk) 13:16, 18 February 2010 (UTC)

Using JPL's Orbital simulation (Java) and zooming out with a timestep of say 10 days, you can clearly see that Hektor orbits the Sun and not Jupiter. -- Kheider (talk) 18:45, 18 February 2010 (UTC)

Pluto does not remain a constant distance from Neptune, but 624 Hektor remains a constant distance (~5.2 AU) from Jupiter [See correction below --Tediouspedant (talk) 15:43, 19 February 2010 (UTC)]. Viewed from Jupiter 624 Hektor would be seen to follow a circular orbit around the planet just like its nearer moons. As 624 Hektor forms an equilateral triangle with Jupiter and the Sun it consequently orbits both bodies simultaneously. This can be seen from JPL's orbital simulation. There may be a convention for not including Trojans as moons but your comment does not provide a reason for this. --Tediouspedant (talk) 23:36, 18 February 2010 (UTC)

Being seen to follow a circular orbit around Jupiter is not the same as orbiting Jupiter. Even over a short simulation (2010-2050) Hektor can easily vary from 7.1AU from Jupiter (2017-Aug) to 4.3AU from Jupiter (2049-Jul). -- Kheider (talk) 00:50, 19 February 2010 (UTC)

Assuming that an orbit is a cyclical motion resulting from gravitational attraction then 624 Hektor IS orbiting Jupiter (as well as the Sun) and not just appearing to do so. Thanks for the correction on distances. If the cyclical variations in distance between Jupiter and 624 Hektor are mapped out then they will almost certainly reveal an elliptical orbit which is entirely concordant with it being classified as a moon. All the moons of Jupiter have somewhat elliptical orbits. The only reason that I can think of for not counting a Trojan as a Moon (or Pluto as a planet) is linguistic convention. Can anyone provide a reference to such a convention? --Tediouspedant (talk) 15:41, 19 February 2010 (UTC)

The Sun is about 1047x times more massive than Jupiter. Jupiter Trojan Hektor is not a moon because when it librates 7.1AU from Jupiter, it is at most 5.4AU from the Sun. The orbit around the Sun is the DOMINATE and obvious one. "Linguistic convention" can also be thought of as categorization based on common characteristics. Hektor is really no more a moon of Jupiter than Pluto is a moon of Neptune, or 3753 Cruithne is a moon of Earth. -- Kheider (talk) 18:13, 19 February 2010 (UTC)

not dwarfs

Comet Ganymede?

The article contains the following sentence: "The Galilean satellites are spheroidal in shape, and so would be considered dwarf planets if they were in direct orbit about the Sun." But Ganymede is larger than Mercury, and Mercury is a fullfledged planet, not a dwarf planet. I believe, though I don't have the figures, that the other three are also near Mercury's size. If they were in direct orbit around the sun, they would be classified as planets as well. CharlesTheBold (talk) 04:26, 16 June 2009 (UTC)

It is more complicated than that:

• (1) Mercury (3.3E+23 kg) is more massive than Ganymede (1.4E+23 kg). It is mass (not volume) that helps an object dominate its region.
• (2) It would also depend on how far the object orbits from the Sun. The further from the Sun, the more massive it needs to be to dominate the region.
• (3) If Ganymede got too close to the Sun it might look a lot like a comet. -- Kheider (talk) 05:57, 16 June 2009 (UTC)

Either way, claiming they would be dwarf planets seems OR to me, since they might indeed be planets depending on circumstances. So the quoted sentence should be reworded in my opinion.--Roentgenium111 (talk) 16:24, 2 June 2011 (UTC)

Naming

This article provides some interesting facts about the naming of the moons of Jupiter, but now about its system of rendering Greek: is there any reason for Callirrhoe (moon) versus Kallichore (moon), both with Καλλι- in Greek. Does anyone know? Fransvannes (talk) 10:39, 2 February 2011 (UTC)

I dunno. Maybe the discoverers thought the word looked better if spelt the way they chose? Double sharp (talk) 02:59, 24 March 2013 (UTC)

---

(regarding Refrance number 23)

from: http://galileo.rice.edu/sci/observations/jupiter_satellites.html (6th paragraph down...) The naming of the satellites provides an interesting example of how such matters were handled before the foundation of the International Astronomical Union in the twentieth century. As their discoverer, Galileo claimed the right to name the satellites. He wanted to name them after his patrons and asked whether they would prefer "Cosmic Stars" (after Cosimo II) or "Medicean Stars." They opted for the latter, and through much of the seventeenth century they were known by that name. In his notebooks, Galileo referred to them individually by number, starting with the satellite closest to Jupiter, but he never had occasion to refer to them in this way in print.

the rest of these paragraphs goes on to explain the naming in more detail, should this be added to this section of the article? May 5 2011 —Preceding unsigned comment added by Jessycormier (talk • contribs) 03:35, 15 May 2011 (UTC)

Current number of natural satellites?

Is the current confirmed number 62 or 63? The main article starts off with saying there are 62, but the table shows 63, is there one that is listed but unconfirmed? Sethhater123 (talk) 02:08, 19 September 2008 (UTC)Sethhater

Also, the NASA website seems to state that there is 62 and not 63 satellites : http://solarsystem.nasa.gov/planets/profile.cfm?Object=Jupiter&Display=Moons G0rth0r (talk) 02:21, 8 February 2009 (UTC)

It seems that S/2000 J 11 has gone missing from reading that moon's article.--Roentgenium111 (talk) 21:19, 18 October 2010 (UTC)

Two more so now 65!

http://www.minorplanetcenter.net/mpec/K11/K11L06.html If anyone has access to the IAU circulars, if/when one appears for these a check would be useful. 202.7.182.10 (talk) 09:14, 2 June 2011 (UTC)

I'd say "now 64" (if this is confirmed), given my above comment on S/2000 J 11.--Roentgenium111 (talk) 16:21, 2 June 2011 (UTC)

April 2012: The opening paragraph states that there are 66 moons, which is in agreement with the Table information, but the final paragraph of the Discovery section states that there are (only) 63 moons. I realize that this information can change but I think that it's a minimal requirement for an encyclopedic article about the moons of Jupiter to get the number right, or at the very least be self-consistent. Someone seems to have dropped the ball here. nagualdesign (talk) 09:06, 20 April 2012 (UTC)

An MPEC has been issued today giving the recovery of S/2000 J11 last year by Sheppard et al. see http://www.minorplanetcenter.net/mpec/K12/K12R22.html Andrew W 202.7.182.10 (talk) 08:07, 11 September 2012 (UTC)

Seeing that S/2000 J11 was observed multiple nights over multiple years, sounds like a recovery to me. -- Kheider (talk) 17:36, 11 September 2012 (UTC)

???? the article starts off with a claim of 67 confirmed moons, and then later on that is reduced to 63 moons in the 'Discovery' section. Should not the article at least agree with itself? Note this discrepancy was reported above in April 2012 when the counts were 66 and 63, Suggest the count be reduced to 63 in the opening paragraph Edantu (talk) 12:05, 2 June 2013 (UTC)

This article received the FL star on 14 September 2008 when it was stated that there were 62 confirmed moons (S/2000 J 11 was lost at the time). It was the discovery section that needed to be updated. Four moons have been discovered post-2003, so we have 63+4=67 moons. 16 have been discovered but not yet named since 2003. -- Kheider (talk) 14:37, 2 June 2013 (UTC)

Color the groups of satellites in the table?

In the Moons of Saturn article, the different satellite groups (Inuit, Gallic, etc.) in the table are colored. If a satellite is in this group, it's colored this color, if it's in that group, its a different color, etc. We should do something like this in the Moons of Jupiter article, e.g. color the Ananke group one color, the Carme group another color, etc. What do you think?

Good idea. nagualdesign (talk) 18:00, 8 July 2013 (UTC)

roman numbering

Roman numbering was at first by distance, and now in order of naming, not order of discovery, correct? — kwami (talk) 16:37, 6 February 2012 (UTC)

I always wonder when I see Roman numerals if it would be wise to change them to Arabic numerals, regardless of historical doting. The year of discovery column has the majorly relevant info. Friendly Person (talk) 17:29, 10 July 2013 (UTC)

No, the Roman numerals are the official usage, and we already have a column with Arabic numerals. Double sharp (talk) 16:31, 19 July 2013 (UTC)

Sorting by orbital period

The sorting doesn't work for me (IE11): it sorts lexicographically instead of numerically. Double sharp (talk) 14:14, 3 June 2014 (UTC)

A new moon name and some questions

I can't read the CBET myself, but other sources confirm the recent change that S/2000 J 11 has finally gotten a friggin' name! Making the changes now to that. However, how should we handle S/2010 J 1 and S/2010 J 2, which apparently received official Roman numeral designations, but not names? --Patteroast (talk) 09:28, 10 March 2015 (UTC)

I'd expect the names to be coming soon; it wouldn't be a first, as Helene got its Roman numeral (XII) before its name. In the meantime, the provisional designation or "Jupiter [Roman numeral]" would both work as article titles, I think. Cool about S/2000 J 11, incidentally! These Jovian and Saturnian irregulars haven't been getting names for a while... Double sharp (talk) 13:08, 12 March 2015 (UTC)

“0.003 percent” + “99.999%” > 100% !

> … with the remaining 63 moons and the rings together comprising just 0.003 percent of the total orbiting mass.

> … Galilean moons … contain almost 99.999% of the total mass in orbit around Jupiter

These don’t obviously reconcile. One could perhaps argue that “almost 99.999%” could mean 99.997%, but in that case why not just say the smaller number. I do not know which of the two obvious possibilities is correct, if either, but the current text seems wrong.

And, separately, let’s use “%” to save a squabble about “percent” versus “per cent”. JDAWiseman (talk) 13:50, 14 June 2015 (UTC)

[replying to self] The tables on this page give totals of 39,310,972.2021001 and 39,309,900, for a result of 99.9972725119%. The rings might slightly lower this. So I’m changing the “almost 99.999%” to “about 99.997%”. And also changing the “percent” to “%”. JDAWiseman (talk) 16:03, 14 June 2015 (UTC)

S/2010 J 1, S/2010 J 2, S/2011 J 1, S/2011 J 2

Is there any RS for their group assignments? Some time ago, I provisionally (with appropriate question marks, although somewhat OR-ishly) put S/2011 J 1 as its own group, S/2010 J 2 as an Ananke group member, and the other two as Pasiphae group members, hoping to later be corrected. However they seem to have stood. Am I right, or has nobody found a RS assigning these four most recently discovered moons to groups? (Sheppard just puts them with the other unnamed moons, except S/2000 J 11 which he puts in the Himalia group.) Double sharp (talk) 13:32, 3 June 2014 (UTC)

OK, I found a source giving S/2010 J 1 as Carme group and S/2010 J 2 as Ananke group (http://www.space.com/16111-jupiter-smallest-moon-discovered.html), but nothing on the other two yet. Double sharp (talk) 08:28, 19 July 2015 (UTC)

How are these sourced in the table? --JorisvS (talk) 08:50, 19 July 2015 (UTC)

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Repeated vandalism 2016May05

Repeated vandalism today (5^th May 2016), sometimes big (deleting lots of text) and sometimes small (changing a number). Be not afraid to revert. JDAWiseman (talk) 19:17, 5 May 2016 (UTC)

orbital Inclination of Galilean sattelites

In the List, I assume that the column for inclination is for orbital inclination, although the reference system is not mentioned.

The reference coordianate system should be identified; it might be:

a) the equatorial plane of the primary (planet)
b) the orbital plane of the primary
c) the orbital plane of the Earth (the ecliptic)
d) The invarient plane of the Solar system

The citation for the inclination of several satellites, including all the Galileen satellites, is [37], but this reference does not contain orbital information, only orientation! 

I have the background to correct this, but not currently the time to dig through the literature. Perhaps the person who entered the values can correct the citation. Real experts would be the NAIF group at JPL.

I found the reference below ; the inclinations I get, in degrees, are

0.027   0.467   0.178   0.272

these average 0.03 different than in List. However, the reference plane is still unclear.

---

Astron. Astrophys. Suppl. Ser. 129, 205-217 (1998) Galilean satellite ephemerides E5 J.H. Lieske Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., MS 301-150 Pasadena, 91109 California, U.S.A. e-mail: jay.lieske@jpl.nasa.gov

Table 1: . Matrices for precession from B1950 to J2000 Eq. (5): Lieske matrix from R1(−εJ2000)R3(L0)R1(−JA)R3(−L)R1(εB1950)

0.9999256795268940 −0.0111810778339439 −0.0004859930159015 0.0111810775053504 0.9999374894281627 −0.0000272382503387 0.0048599309149990 −0.0000271030297995 0.9999881900987267

Table 2. Definition of theory parameters $/varepsilon$ 21 c11 4756 $10^{-7}$(1 + $\epsilon_{21}$) Primary sine inclination of Satellite I 22 c22 81490 $10^{-7}$(1 + $\epsilon_{22}$) Primary sine inclination of Satellite II 23 c33 31108 $10^{-7}$(1 + $\epsilon_{23}$) Primary sine inclination of Satellite III 24 c44 47460 $10^{-7}$(1 + $\epsilon_{24}$) Primary sine inclination of Satellite IV

25 IJ 3.10401(1 + $\epsilon_{25}$ ) Inclination of Jupiter orbit to Jupiter equat

---

That the satellite nodes are disperse indicates that the reference plane for inclination is the Jovian equator

The actual me is Hugh Kieffer, hkieffer@charter.net OldMartian (talk) 16:05, 15 March 2017 (UTC)

All inclinations are relative to the Jovian equatorial plane as is specified in the second paragraph of the leading section. Ruslik_Zero 19:48, 15 March 2017 (UTC)

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A link for more info about Jupiter's new moons, including discovery images.

http://www.skyandtelescope.com/astronomy-news/two-new-satellites-for-jupiter/

8.40.151.110 (talk) 23:01, 6 June 2017 (UTC)

Order of the list needs to be updated.

A few irregulars were recovered and given better orbital elements, whose values have been added to the table by User:Renerpho.

Unfortunately, the revised distances have flipped a few of them out of sequence and the numbering on the left column doesn't quite match.

The order of the outer irregulars needs to be reassessed and updated. 8.40.151.110 (talk) 20:17, 9 June 2017 (UTC)

EDIT: Also, the orbital periods need to be checked to make sure that they have the same order as the distance and the numbering list. All three - distance, orbital periods, and the list - should have the same order. 8.40.151.110 (talk) 20:19, 9 June 2017 (UTC)

 Done Double sharp (talk) 14:40, 11 June 2017 (UTC)

Is Aoede's high eccentricity correct?

The article lists a value over 0.6, which is unusually high.

The article itself lists 0.4311. So who's correct? 8.40.151.110 (talk) 20:24, 13 June 2017 (UTC)

Sheppard gives 0.432. I'll change it. Double sharp (talk) 23:43, 13 June 2017 (UTC)

new moons LIV through LIX

The MPC for 9 June 2017 gives:

• Jupiter LIV = S/2016 J 1
• Jupiter LV = S/2003 J 18
• Jupiter LVI = S/2011 J 2
• Jupiter LVII = S/2003 J 5
• Jupiter LVIII = S/2003 J 15
• Jupiter LIX = S/2017 J 1

None have received names, just like Jupiter LI (S/2010 J 1) and Jupiter LII (S/2010 J 2) back in 2015. Presumably the discoverers have declined to name these tiny moons, as the improbable alternative is that we somehow exhausted Zeus' numerous conquests and offspring. Double sharp (talk) 06:20, 13 June 2017 (UTC)

I'll also need to update their group assignments now that their orbits are more secure; all are Pasiphae group members except Jupiter LVII, which is a Carme group member. Additionally, S/2003 J 16 has been recovered and is an Ananke group member; perhaps that might soon be Jupiter LX. Double sharp (talk) 07:31, 13 June 2017 (UTC)

 Done, at least the more obvious ones. Double sharp (talk) 14:19, 13 June 2017 (UTC)

OK, I think I've fixed all the links (I tested it by looking for "what links here" on Jupiter LV, one of the older ones). Double sharp (talk) 15:54, 13 June 2017 (UTC)

I've also updated the names in the articles accordingly, e.g. "S/2003 J 15 is..." to "Jupiter LVIII is..." 8.40.151.110 (talk) 16:51, 13 June 2017 (UTC)

Thank you! Double sharp (talk) 23:44, 13 June 2017 (UTC)

Mass

I think some mention should be made in the lead of the extreme mass imbalance in the Jovian system. I've done a calculation (will need to be checked) that the total mass of all the 59 non-Galilean satellites combined comes to 1.07x10^19, or 0.02 percent the mass of Europa, the smallest Galilean. Serendi^podous 09:50, 5 September 2008 (UTC)

The small moons don't even show up.

Yes, good point. Jupiter really does have four moons and a bunch of rocks. Something like a pie chart would be good for all the gas/ice giants. kwami (talk) 09:59, 5 September 2008 (UTC)

I'm not sure a pie chart would work for Jupiter. On a scale of 10,000 to 1, you'd basically have to point to the line between Ganymede and Europa and say, "All other moons." :-) Serendi^podous 10:15, 5 September 2008 (UTC)

Yeah, but we can have a chart for all the planets, and when it comes to Jupiter, just say that the others are so tiny they don't even show up. It might still get the point across in a way that raw numbers wouldn't. kwami (talk) 10:37, 5 September 2008 (UTC)

I get the same mass for all the small moons, but that comes out to only 0.003% the total. The others are 22%, 12%, 38%, 28%. kwami (talk) 10:18, 5 September 2008 (UTC)

I was measuring against Europa only. Serendi^podous 10:20, 5 September 2008 (UTC)

My brilliance at work! Anyway, I made a pie chart. Will upload in a minute. kwami (talk) 10:33, 5 September 2008 (UTC)

Nice coincidence how the masses of Io & Callisto are equal to Europa + Ganymede.

The seven 'dwarf planet' moons. Mimas doesn't show, let alone the small moons.

Now Saturn looks very different. I was surprised to see that even Mimas doesn't show up, and that I had to enlarge the chart to see Enceladus. kwami (talk) 10:53, 5 September 2008 (UTC)

Great charts! We may need to create a separate section on mass to put them in though. Serendi^podous 11:03, 5 September 2008 (UTC)

Updated pie chart to make it look more encyclopedic (less like an Excel chart). stewartIM —Preceding undated comment added 02:18, 7 July 2018 (UTC)

2 comments on the pie chart:

Personally I think a pie chart is a poor way to represent that masses of Jupiter's moons... Pie charts are supposed to represent fractional proportions and its not clear what this is all a fraction of, and I'm not sure if a fraction is relevant unless it's with respect to something useful. What does the % actually refer to (it doesnt say on the article)?

wrt "Those smaller than Europa are not visible at this scale, and combined would only be visible at 100× magnification"... Are you sure? If MS excel made this picture 100x larger would it print out a segment for the low mass moons? I wouldn't think so.

It is a fraction of the mass in orbit around Jupiter. And it does say that in the article. Serendi^podous 07:02, 8 September 2013 (UTC)

The Uranian system

The Uranian system is rather similar to the Jovian one; there we have Ariel + Oberon = Umbriel + Titania, with Miranda being largely negligible. Furthermore, the masses of Uranus I through IV are about the same fraction of that of Uranus as the masses of Jupiter I through IV are to those of Jupiter. For this reason it would actually be possible to do a Galileo-style tour of the Uranian satellites (source), unlike the situation at Saturn where you can only really use Titan (the same is true at Neptune with Triton). Double sharp (talk) 13:50, 21 July 2017 (UTC)

New moons, now 79

Data is now available in MPEC's O08 through O18 and on Scott Sheppard's MOONS OF JUPITER page. Agmartin (talk) 15:58, 17 July 2018 (UTC) Including Valetudo.

We should not yet be using the name Valetudo, as it is only proposed. That moon is listed for now by its provisional designation S/2016 J 2. Double sharp (talk) 08:39, 18 July 2018 (UTC)

Are the uncertanities necessary in the table?

Nergaal (talk) 06:13, 18 July 2018 (UTC)

I think they are helpful, as it alerts the reader to the fact that the numbers are not known very precisely for the five lost moons (which is, after all, why they were lost in the first place). Double sharp (talk) 08:38, 18 July 2018 (UTC)

Yes, but is completely ruining the table format. Is there a way to break those numbers into multiple rows? Nergaal (talk) 14:50, 18 July 2018 (UTC)

Actually, I was just about to bring up a request to use the orbits with the uncertanties, rather than the current primary ones. Some of them differ quite a bit, and judging by assumption of group membership, the ones with uncertainties seem to be a lot more accurate. exoplanetaryscience (talk) 19:08, 18 July 2018 (UTC)

I notice that Sheppard's page is splitting the Ananke and Pasiphae groups based on semi-major axis which would make the uncertainties relevant if this page is going to use it for group assignments. Agmartin (talk) 19:18, 18 July 2018 (UTC)

Well, apparently they are actually split in semimajor axis. here's a crappy illustration I made of their inclination vs semimajor axis. Carme to right, Pasiphae at top, Ananke at bottom. It's pretty clear that there's somtehing wrong with 2017 J6, and 2003 J2 and 12. exoplanetaryscience (talk) 19:53, 18 July 2018 (UTC)

The Pasiphae group is more of a catch-all term for "We don't know what group the moon is in yet." It's like the null group, Sheppard also calls it the "No Strong Clustering Irregulars". Many moons have been reclassified from Pasiphae to Ananke recently. Dreigorich (talk) 20:41, 18 July 2018 (UTC)

That's probably because they've been vastly overclassifying objects that clearly belong to other groups as Pasiphae. For instance, Aoede is in the Carme group, not Pasiphae. exoplanetaryscience (talk) 23:05, 18 July 2018 (UTC)

Perhaps. It might be a recategorization when the observations constrain the orbit enough to know for sure. Dreigorich (talk) 23:16, 18 July 2018 (UTC)

With Themisto, Carpo, and now Valetudo not fitting in a prograde group I'm now wondering how many of the retrograde satellites are singles rather than members of the groups they have been assigned to. I note that Carme and Ananke have compact groups near the largest objects. The Carme group has a halo around this, though that might be due to the limited observations since I didn't see that when I plotted the JPL data. Agmartin (talk) 17:36, 19 July 2018 (UTC)

Aoede has a rather eccentric orbit for a Carme group member, though. Last year when Jupiter LIV through LX were numbered 8.40.151.110 and I were engaging in some OR on our talk pages regarding classifying the moons into groups, though of course none of it went into the mainspace. ^_^ Double sharp (talk) 06:36, 19 July 2018 (UTC)

Yep. I remember that. That was actually me before I registered on Wikipedia. Dreigorich (talk) 14:27, 19 July 2018 (UTC)

Other proposed families

Recent article Cladistical Analysis of the Jovian and Saturnian Satellite Systems identifies an Iocaste family by albedo and eccentricity and proposes a Sinope family. Agmartin (talk) 19:24, 17 August 2018 (UTC)

Interesting. I don't think this will distort things too much, though. The idea of an Iocaste group is interesting, but I disagree with the merging of the Ananke and Carme groups, although both overlap with Pasiphae quite a bit. One thing is that if we discover a moon with orbit similar to Iocaste's family, we might not know whether it's in the Iocaste group or the Ananke-Carme group. Dreigorich (talk) 03:42, 30 August 2018 (UTC)

new moons LXI through LXXII

From MPC 111804 (dated 25 September 2018):

• Jupiter LXI = S/2003 J 19
• Jupiter LXII = S/2016 J 2
• Jupiter LXIII = S/2017 J 2
• Jupiter LXIV = S/2017 J 3
• Jupiter LXV = S/2017 J 4
• Jupiter LXVI = S/2017 J 5
• Jupiter LXVII = S/2017 J 6
• Jupiter LXVIII = S/2017 J 7
• Jupiter LXIX = S/2017 J 8
• Jupiter LXX = S/2017 J 9
• Jupiter LXXI = S/2018 J 1
• Jupiter LXXII = S/2011 J 1

as well as:

• Neptune XIV = S/2004 N 1

Double sharp (talk) 06:22, 30 September 2018 (UTC)

And now from the IAU Working Group for Planetary System Nomenclature:

• Jupiter LXII = Valetudo

Double sharp (talk) 13:45, 5 October 2018 (UTC)

new moon LX

The MPC for 5 October 2017 gives:

• Jupiter LX = S/2003 J 3

S/2003 J 9, S/2003 J 16, and S/2003 J 23 have also received some new observations and may soon be Jupiter LXI, LXII, and LXIII (though maybe not in that order). Double sharp (talk) 10:45, 8 October 2017 (UTC)

S/2003 J 19 and S/2011 J 1 have since also been recovered. Double sharp (talk) 00:29, 18 September 2018 (UTC)

Since S/2003 J 9, and S/2003 J 16, and S/2003 J 23 have so far not been numbered, I guess I overoptimistically interpreted the "L??" numbers on Sheppard's page. Mind you, this paper reports that S/2003 J 16 at least has been observed in 2011 (which is later than its 2003 discovery), and sometime in 2017 (example) it became the only one with an "L??" listed and coloured in on Sheppard's page. The Minor Planet Center still lists all the unnumbered 2003 moons as having been last observed in 2003, though. Double sharp (talk) 13:59, 5 October 2018 (UTC)

Amalthea

Hello,

Amalthea group is included in the Regular satellites section, but there is this note: Observations suggest that at least the largest member, Amalthea, did not form on its present orbit, but farther from the planet, or that it is a captured Solar System body. If that was the case, would that mean it would become an irregular satellite? I think it should be better explained. I lack the knowledge for this; I'm asking because ca:Satèl·lits de Júpiter is about to become an FA and this question popped up. Cheers--Arnaugir (talk) 10:46, 8 October 2018 (UTC)

@Arnaugir: Irregularity depends on a satellite's orbit as well as its origin. Amalthea orbits very close to Jupiter and hence solar perturbations are not significant enough for it to be considered irregular. Double sharp (talk) 13:52, 8 October 2018 (UTC)

Mass order in table showing up incorrectly

When you click to order the moons by mass, Amalthea comes up top even though it is actually 6th in mass. This is beyond my very limitied skills to fix. Thanks LastDodo (talk) 10:46, 13 August 2019 (UTC)

Orbits and distance ordering

I've updated the list with JPL-HORIZONS orbital elements based on the epoch JD 2459200.5 (17 Dec 2020). Keep in mind that these only reflect the nominal state of the irregular satellite orbits on that epoch since they strongly vary over short timescales (i.e. Cyllene's eccentricity growing from 0.4 to 0.6 from 27 Apr 2019 to 17 Dec 2020). I would prefer using Jacobson et al.'s (2017) time-averaged mean orbital elements over a 1000-year numerical integration, however their list is quite outdated as several moons have since been discovered or recovered. Nrco0e (talk · contribs) 20:58, 1 January 2021 (UTC)

Table column - "Absolute magnitude" - mislabelled?

One of the columns on the list is labelled as "Abs. magn." and links to the page on Absolute Magnitude (a measure of brightness standardized to a distance of 10pc). However, the values reported in this column are absolutely not believable. For example, Ganymede is listed to have an absolute magnitude of -2.1. Were this the case, Ganymede would be ~7 orders of magnitude brighter than the Sun, which has an absolute magnitude of 4.8!

The values given (at least for Ganymede, the only one I checked) also does not correspond to the similar Apparent Magnitude (related to Absolute Magnitude, this is a standard of brightness related to what we actually measure from Earth). Ganymede's apparent brightness, as reported and cited on the Ganymede page on Wikipedia, is ~4.6, still a far cry from the -2.1 reported in this list.

I also note that none of the values on this list have any citations given whatsoever. 73.242.233.70 (talk) 23:01, 1 July 2021 (UTC)adjsmith

Planets (H) and stars (M) do NOT use the same scale for absolute magnitude. Pluto has an absolute magnitude (H) of -0.7. -- Kheider (talk) 23:09, 1 July 2021 (UTC)

I see. I rarely work in these units in my day-to-day (although I'm an astronomer, I work with bodies well outside our solar system). Thanks for the clarification. It might be worth editing the Abs. magn. link to direct to the correct section of the Absolute Magnitude page. — Preceding unsigned comment added by 73.242.233.70 (talk) 13:52, 2 July 2021 (UTC)

table format

the moons of saturn uses a diff format eg mass units and diam is give in % of moon could you guys talk and see if harmonizing the formats is a good idea ? thank you also masses times 10^16 seems a bit nonintuitive for the higher mass moons - maybe a diff mass unit ? and organized with moon of saturna nd moons of uranus ? — Preceding unsigned comment added by 2601:192:4700:1f70:95d6:6193:3465:be7 (talk) 20:43, 29 August 2021 (UTC)

S/2003 J 24 announced

Just a heads-up: This article (the list, count, and lead section, as well as S/2003 J 24 itself) needs an update. The new moon has been officially announced yesterday.[4] Official discoverer is S. Sheppard, if I am not mistaken. K. Ly is mentioned in the MPEC; given the news coverage involving them, I think the mention can stay, regardless of how far official recognition goes. Also tagging @Nrco0e: to let them know. Renerpho (talk) 12:40, 16 November 2021 (UTC)

80th moon of Jupiter

A new moon has been discovered, the first known by an amateur astronomer. [5] Nussun05 (talk) 09:31, 1 July 2021 (UTC)

I've added the astrometry to the list in preparation for its verification. 108.160.120.108 (talk) 12:25, 1 July 2021 (UTC)

@Nussun05: @108.160.120.108: I would advise you to hold off editing this article and wait until the Minor Planet Center actually publishes the discovery MPEC for that object. Nrco0e (talk · contribs) 16:19, 1 July 2021 (UTC)

Alright, should I revert the changes already present? Nussun05 (talk) 16:22, 1 July 2021 (UTC)

@Nussun05: Please do; at the moment there are no reliable sources that cover this discovery. Nrco0e (talk · contribs) 16:24, 1 July 2021 (UTC)

It is done. Nussun05 (talk) 17:17, 1 July 2021 (UTC)

The article now begins, stating that there are 80 known moons, while elsewhere, it says there are currently 79 known. May I suggest that the statements are changed to include a date, so that if another moon or moons is/are discovered, the article doesn't become wrong (in the sense that "Jupiter currently has 79" is wrong). Nick Barnett (talk) 08:47, 18 November 2021 (UTC)

Galileo, not Galilei

I changed the name in the table for discoverers from "Galilei" to "Galileo", which is the accepted way to refer to him. His name is like that of Leonardo da Vinci, in which the accepted way to refer to the person is through the given name, Galileo or Leonardo, respectively.Interlingua 18:36, 8 February 2022 (UTC)

Should we stop creating articles for newly-discovered irregular moons?

Notifying @Double sharp, Exoplanetaryscience, Kwamikagami, Renerpho, and Ruslik0:

At this point, the irregular moons of Jupiter and Saturn are being discovered and announced so frequently that it is difficult to consistently keep track of in Wikipedia. Every single moon that has been announced in the last 10 years is too faint (mag >22) and unremarkable (with the exception of outliers like Valetudo and S/2004 S 36) to warrant any further study individually, so why bother creating articles for all of them if they'll stay as one- or two-paragraph stubs for decades? There isn't much to say about them other than their orbit, discovery story, and in rare cases, their name. Their known characteristics are so bare-bones that you can pretty much copy-and-paste their contents to other similar irregular moon articles and still be factually accurate. For these reasons, they clearly fail the WP:NASTRO notability guideline for articles. Plus, Jupiter is expected to have over 600 retrograde irregular moons larger than 0.8 km in diameter, while Saturn is expected to have more than 3 times as many at that size range! Obviously we do not need that many stub articles.

Now that I've made my arguments, I believe that we should limit article creation only to irregular moons that are either significantly large/bright (i.e. >10 km?), have outlier orbits (i.e. Carpo, Valetudo, S/2004 S 24), or have additional properties measured beyond basic orbital information and size (i.e. known rotation period, color indices, and shape like Kiviuq and Bestla). I prefer that existing articles that fail these criteria be deleted, but I'd rather not get too ahead of myself yet. I would like to hear your thoughts about this matter. Nrco0e (talk) 22:59, 5 January 2023 (UTC)

I don't object to redirecting them to a list of moons where we keep all the relevant information. Maintenance is easier that way if nothing else. We might have a notes section at the end of the table for the odd fact that isn't worth an article but shouldn't be omitted, or perhaps we can put two rows in one of the cells.

For the other (dwarf) planets, I think it's still worth having articles for every moon. We don't though for the moons of many asteroids and large TNOs, redirecting to a section in the primary article instead. I think 10km is probably a reasonable cut-off; also any moon that has enough info that it cannot be easily packed in the table.

Should we use the same estimated 10km cut-off for TNO moons? Personally I'd rather have those instead of the small Jovians if I had to choose. — kwami (talk) 23:07, 5 January 2023 (UTC)

Honestly, I feel like a footnotes section below the table would be a hassle to look through especially when the list is long. Perhaps we could add extra columns for discovery/announcement dates, apparent magnitude, and notes, but that'll make the table exceed the page width and I'm not sure if people are okay with that.

Also, wouldn't it be more appropriate to set the TNO moon size cutoff to be higher at 100-200 km than 10 km? TNO moons 100-200 km in diameter are already quite common and I doubt that we'll be able to productively probe TNO moons down to 10 km in the near-future. Nrco0e (talk) 00:15, 6 January 2023 (UTC)

I think a number cutoff might be best - making articles for, say, only the 50 largest moons of any given planet. Recent research has shown that Saturn, Uranus, and Neptune all have even MORE moons of a given size than Jupiter does- with Neptune possibly having thousands of ~1-5km moons (see Graph at the top of this article). Doing a size cutoff would mean that Jupiter gets a couple dozen moon articles, while Neptune and company might be getting hundreds and hundreds. exoplanetaryscience (talk) 23:25, 5 January 2023 (UTC)

I feel that having just a number cutoff sounds too arbitrary. But if I were to suggest anything else, I'd end up reiterating my ideas above. Nrco0e (talk) 00:38, 6 January 2023 (UTC)

It would make sense to handle this like the list of minor planets, with less notable moons being redirects to their entries on this list (or moons of Saturn, etc). SevenSpheres (talk) 23:26, 5 January 2023 (UTC)

I've just added an anchor and redirect for the newest moon, S/2021 J 1. SevenSpheres (talk) 23:36, 5 January 2023 (UTC)

Thanks, I appreciate that. Nrco0e (talk) 00:38, 6 January 2023 (UTC)

I have initiated the first AfD for a moon at Wikipedia:Articles for deletion/Jupiter LI. We will likely be seeing a large number of similar AfD's shortly, if NASTRO-failing articles are not redirected unilaterally. –LaundryPizza03 (dc̄) 01:48, 6 January 2023 (UTC)

I don't object to this at all: I agree that the time has finally come that we treat them like asteroids. The one thing I'd suggest, though, is to add a "Naming" column to the main tables at "Moons of X", so that that information is also in one place (I think it is the only information that isn't already duplicated somewhere other than the individual moon articles).

Perhaps in most cases we could just redirect them to the respective groups, which should have more analysis and information available? Like, for example, all the Pasiphae group moons (except Pasiphae and Sinope) would become redirects to Pasiphae group. This doesn't really solve the problem for Uranus and Neptune (since small moons are not yet known for them), but at least in those cases the problem is only potential. Double sharp (talk) 02:03, 6 January 2023 (UTC)

Agreed; we would need a new column for that information, immediately after the pronunciation column. For all of the outer-planet moon lists, this would be the fifth column, between Pronunciation and Image. –LaundryPizza03 (dc̄) 03:34, 6 January 2023 (UTC)

That location sounds good to me. Double sharp (talk) 04:04, 6 January 2023 (UTC)

I've replaced the most-recently announced moons S/2018 J 2, S/2011 J 3, and S/2016 J 3 with redirects and created their respective anchors in the list. Nrco0e (talk) 05:19, 6 January 2023 (UTC)

Also added a "Year announced" column to this list. Nrco0e (talk) 06:00, 6 January 2023 (UTC)

Should we add this column at all the outer-planet moon tables? –LaundryPizza03 (dc̄) 06:07, 6 January 2023 (UTC)

Only for the four gas giants, yeah. The announcement year column would be redundant for Mars and Pluto which have few satellites. Nrco0e (talk) 06:25, 6 January 2023 (UTC)

Yes, similarly not needed for Haumea (the other DP with a "Moons of" list, since more than one is known). Double sharp (talk) 08:13, 6 January 2023 (UTC)

What anchor format should I use for the moons that have been numbered? I am about to redirect Jupiter LIV and need to create a new anchor for it. Preferably, I will create anchors for all the moons in the table, even if their articles are ultimately kept. –LaundryPizza03 (dc̄) 20:48, 6 January 2023 (UTC)

I have redirected all the remaining unnumbered Jovian moons. I will be logging future removals of existing moon articles at User:LaundryPizza03/Moon AfDs. –LaundryPizza03 (dc̄) 21:19, 6 January 2023 (UTC)

@LaundryPizza03: Per discussion below, please keep the following:

• 10 Jovian irregulars (Themisto, Leda, Himalia, Lysithea, Elara, Ananke, Carme, Pasiphae, Sinope, Callirrhoe)
• 9 Saturnian irregulars (Phoebe, Albiorix, Erriapus, Ijiraq, Kiviuq, Paaliaq, Siarnaq, Tarvos, and Ymir)
• All Uranian and Neptunian irregulars (there's not that many, so a merge is not urgent).

Feel free to redirect all the other irregulars. :)

As for the anchors, I favour using the format the article title had. So the anchor for Jupiter LIV should be "Jupiter LIV". When you get to named moons, I'd suggest using just the name, e.g. "Eukelade". Double sharp (talk) 04:43, 7 January 2023 (UTC)

I added all the anchors for Jupiter, but haven't redirected anything yet. Double sharp (talk) 04:53, 7 January 2023 (UTC)

And I've added the anchors for Saturn. Double sharp (talk) 04:58, 7 January 2023 (UTC)

By the way, watch out for the plethora of double redirects that end up being created from our mass-redirection efforts (i.e. S/2003 J 20 → Carpo (moon)). That should be automatically fixed by bots in a few days according to WP:2R, but still do keep watch just in case the bots happen to miss any. Nrco0e (talk) 07:00, 7 January 2023 (UTC)

I began a new AfD about three candidate moons of Saturn identified by Cassini–Huygens which remain unconfirmed, as candidate objects are rarely notable: S/2004 S 3, S/2004 S 4, and S/2004 S 6. All three of these candidates are associated with Saturn's F ring.

In the meantime, about half of Jupiter's irregular satellite stubs are now gone — 37, as I counted, plus 6 more at AfD. Nontrivial information about these candidates' existence and discovery history should be merged at Moons of Saturn#Unconfirmed and possibly also Rings of Saturn#F Ring. –LaundryPizza03 (dc̄) 07:38, 7 January 2023 (UTC)

@LaundryPizza03 and Nrco0e: I finished redirecting all the Jovians (except the ones already at AfD). I also fixed the double redirects from the "S/20xx J x" and "Jupiter x" designations. Double sharp (talk) 09:45, 7 January 2023 (UTC)

Be sure to remove the stub templates when redirecting articles. This was not done at several moons that had a stub template, such as Template:Astronomy-stub at Jupiter LXI. –LaundryPizza03 (dc̄) 09:53, 7 January 2023 (UTC)

@LaundryPizza03: Thanks; I removed some that I'd forgotten.

I might get to Saturn later, but hopefully someone beats me to it. :D Double sharp (talk) 10:00, 7 January 2023 (UTC)

Done the Saturnians! :D Double sharp (talk) 13:25, 7 January 2023 (UTC)

@LaundryPizza03, Nrco0e, Exoplanetaryscience, Kwamikagami, Renerpho, and Ruslik0: Skathi (moon) was restored by Astrophobe, so I sent it to AfD. Double sharp (talk) 15:20, 7 January 2023 (UTC)

Etymology in tables

Users seem to agree with adding etymologies in all of the tables, and I did this first at Moons of Neptune, though we need more direct citations for namesakes of moons, especially where this is not already cited as it is at Hippocamp (moon). We can do the same for Saturn's and Jupiter's moons (with blanks for the moons that have not yet been named). At Moons of Uranus, this is already covered outside of the table at Moons_of_Uranus#Names; I'd recommend cutting this for redundancy in order to add more context, perhaps brief descriptions of the characters for which they are named. However, there would be far more redundancy at Moons of Mars with several places in the text, and as there are only two of them, the column may therefore be unnecessary for Mars's moons. At List of natural satellites, the quickest route would then be to copy-and-paste the etymology columns after all others have been completed, plus new etymology summaries for satellites not tabulated elsewhere. –LaundryPizza03 (dc̄) 04:54, 6 January 2023 (UTC)

The WGPSN's Satellite Nomenclature page includes all name citations for planetary satellites. You can just use that reference for the entire etymology column. Nrco0e (talk) 04:58, 6 January 2023 (UTC)

I note that some of their etymologies for Saturn's irregular satellite do not have enough nuance. –LaundryPizza03 (dc̄) 06:03, 7 January 2023 (UTC)

Moons of Uranus is now fully documented. –LaundryPizza03 (dc̄) 05:35, 6 January 2023 (UTC)

Moons of Pluto is now fully documented. –LaundryPizza03 (dc̄) 05:54, 6 January 2023 (UTC)

I do agree that it's starting to become a bit of a hassle to keep track of every single known moon. Not too long ago, it was reasonable to memorize every known moon. But now it's becoming challenging, so this seems like a reasonable step. I would appreciate a reference to more detailed orbital elements/ephemerides where possible and also a reference to their naming and correct pronunciation (not all of these names are intuitively easy to pronounce — Bebhionn, anyone?). Other than that, no objections. The irregular outer moons are a good starting point. The inner moons may come with time depending on how boring they are. There's more to say about say, Epimetheus than Adrastea, Despina or Bianca. Should such moons be treated similarly to the outers? 108.160.120.214 (talk) 12:47, 6 January 2023 (UTC)

I remember them only up to Caliban and Sycorax. :)

The inner moons of Jupiter and Saturn surely have been more studied by orbiters, haven't they? (Perhaps S/2009 S 1 is one step too far.) Just for proximity reasons they are easier to get to, whereas the one close flyby of an irregular we have is Phoebe on Cassini approach – Triton doesn't count as a normal irregular, and we only had one flyby of that too. The problem is also not so acute because there aren't as many: I imagine we must've found all the persistent satellites around J and S by now, no? (Although there's probably some moonlets shed from Jupiter's inner moons.) I'd be happy to be corrected if that's not the case, though I think it would not change my opinion on any of them.

(I wonder if there's any mission concept to study the irregulars around Jupiter. I speculated about such a thing at Kwamikagami's talk page in 2021.) Double sharp (talk) 15:18, 6 January 2023 (UTC)

Asking for specifics

@Nrco0e: Some AfD's have already started (thanks LaundryPizza03), but since there are so many (and the intent is not deletion but redirection), I feel like I should ask here first: which Jovian and Saturnians are we keeping?

Judging by size alone, most of them should probably become redirects: Eggther and Alvaldi are large (6 km diameter), but there's nothing to say. Going to the slightly larger ones, Kiviuq, Ijiraq, and Paaliaq have spectral data, but the precise text is repeated across articles and perhaps it might make sense to cover them all in the Inuit group subsection only (despite a much longer article, I could see the same being done with Siarnaq; the section about naming applies to all of them). Same goes for Albiorix and Tarvos for the Gallic group. In fact I am unconvinced that even having spectral data is enough to hang an article on (e.g. Praxidike) because that's literally one sentence of unique information still. I'd rather merge such things into a section on spectrometry on the "Moons of X" article.

But once one goes that far, there's literally no reason to keep anything but the up-to-1975 irregulars around Jupiter (VI-XIII) and Saturn IX Phoebe.

P.S. Skathi is a GA, but much of the text comes from re-explaining stuff common to all satellites like orbital elements and the origin of irregulars as a whole. So I'm not really convinced about that one either. Double sharp (talk) 15:31, 6 January 2023 (UTC)

Also notifying @Exoplanetaryscience, Kwamikagami, Renerpho, and Ruslik0: (previously pinged when the discussion as a whole started). Double sharp (talk) 15:33, 6 January 2023 (UTC)

I'd say keep Jupiter's irregulars from 1905 to 1999. Although Jupiter's irregulars are very poorly characterized, I consider the pre-2000s irregulars to hold some historical significance. There is some scientific relevancy since there has been recent attention to occultations by Jupiter's large irregulars (Gomes-Junior et al.), for which there have been numerous attempts by amateurs to observe them during 2020 and prior. The occultations by Himalia and Lysithea have been successfully detected during these observation efforts. Callirrhoe is large enough to have its colors, spectrum, size, and albedo directly measured. Plus, it holds some significance for having a pretty unique discovery history (in my opinion) and being an imaging target of New Horizons. I've decided to not keep the outliers Carpo and Valetudo since there's no extensive scientific commentary on their orbit and history. Valetudo only appears as a brief mention in Sheppard's short-enough research note, while Carpo is seldom focused on in irregular moon orbital dynamics papers, which only remark on its Lidov-Kozai resonant orbit.[6][7]

For Saturn, keep only its 8 largest members out of the 12 from 2000: Albiorix, Erriapus, Ijiraq, Kiviuq, Paaliaq, Siarnaq, Tarvos, and Ymir (they all have diameters ≥10 km, see Denk's Saturnian irregulars page). Besides their historical significance of being the first Saturnian irregulars discovered since Phoebe, these moons have been subjects of multiple studies on their physical properties (Grav - size & albedos, Denk - rotations & shapes, Bauer & Verbiscer - opposition effect). Denk et al. are currently working on determining spin poles and shapes for individual Saturnian irregulars, while Rogoszinski et al. made preliminary inferences on their collisional histories from their rotation states. With that amount of ongoing work dedicated to these moons, they're scientifically relevant enough to keep here.

It'd be a shame to lose the multitude of discovery, loss, and recovery histories of these moons, but they can be summarized in the relevant pages anyway. I'm not sure whether to copy-and-paste the irregulars' discovery histories to main lists like Moons of Saturn, or the specific group pages like Carme group, so I'd appreciate any ideas for that. Nrco0e (talk) 18:50, 6 January 2023 (UTC)

Specific moons can be mentioned in the overall discovery page of "Moons of Jupiter/Saturn/etc." articles. I don't think there's enough info on specific groups to warrant mention, other than perhaps notably unusual cases like Perdita or Themisto. Of course, such cases may be more common with time. 108.160.120.214 (talk) 22:29, 6 January 2023 (UTC)

The Alkyonides are interesting because they're perfectly round despite being only a few km across, and we have good photos of two of them that are worth seeing at a large size, so I think it's worth keeping all the confirmed regular moons. — kwami (talk) 00:22, 7 January 2023 (UTC)

Thanks all for the responses. I'm convinced by Nrco0e, so we'll keep 10 Jovian irregulars (Themisto, Leda, Himalia, Lysithea, Elara, Ananke, Carme, Pasiphae, Sinope, Callirrhoe) and 9 Saturnian irregulars (Phoebe, Albiorix, Erriapus, Ijiraq, Kiviuq, Paaliaq, Siarnaq, Tarvos, and Ymir). Uranian and Neptunian irregulars won't be touched for now.

P.S. This also compares well with 9 known Uranian irregulars and 5 known normal Neptunian irregulars (i.e. excluding Triton and Nereid). Double sharp (talk) 13:51, 7 January 2023 (UTC)

As for discovery history, I think the group article makes sense (the next article in the hierarchy to merge up to). Double sharp (talk) 03:39, 7 January 2023 (UTC)

I'm working on revamping this list's Discovery section (focusing on irregulars specifically) right now. Nrco0e (talk) 06:41, 7 January 2023 (UTC)

Thanks! I guess some material will go back in, e.g. the rotation periods known for some outer Saturnians. Double sharp (talk) 12:45, 7 January 2023 (UTC)

• No, of course not, this is the world's major encyclopedia and articles on moons in the Solar System, especially Good articles, should of course be kept and created. Please refrain from removing any, thanks. Randy Kryn (talk) 16:46, 7 January 2023 (UTC)
  • By this logic we would have articles on all 600,000+ asteroids (many of which are larger than these sub-10-km moons). WP:NASTRO begs to differ. Double sharp (talk) 16:50, 7 January 2023 (UTC)
    • You nominated (in good faith) a Good article. That should tell you that there's a problem with decisions about pages going on here. Randy Kryn (talk) 16:57, 7 January 2023 (UTC)
      • @Randy Kryn: Would you mind to comment on the other moon AfDs Wikipedia:Articles for deletion/Jupiter LI, Wikipedia:Articles for deletion/Eirene (moon), and Wikipedia:Articles for deletion/S/2004 S 3? Nrco0e (talk) 19:24, 7 January 2023 (UTC)

      I seem to agree here. In particular, the decision-making for Saturnian moons was criticized by several participants at the Skathi AfD, including myself, for applying a too strong standard of notability. In particular, about half of the named irregulars may need to be revisited through AfD, based on the Denk source alone. At the moment, I am using this to expand Ymir (moon) and identify possible SIGCOV among the other irregulars that are considered. –LaundryPizza03 (dc̄) 03:39, 9 January 2023 (UTC)

      I think we should restore all the Jovian and Saturnian irregulars with known rotation periods or colors. We've definitely jumped the gun with this one.

      If NASA has pages on some of the individual irregular moons on their Solar System Exploration website, then it should be reasonable to have pages about them on Wikipedia too. Nrco0e (talk) 05:00, 9 January 2023 (UTC)

      Thanks, I restored Tarqeq first because it has an unusually slow rotation, which according to Denk et al. is close to mean-motion resonance with Titan. –LaundryPizza03 (dc̄) 05:41, 9 January 2023 (UTC)

      (edit conflict × 1) NASA has pages on most of the Jovians, including some like Philophrosyne that were actually nominated for AfD per the above. If that's going to be the line, then we may as well undo all the redirects and embrace having stubs on everybody, even S/2021 J 1, since presumably the main reason it doesn't yet have a NASA page (as opposed to Philophrosyne with a similar lack of information) is because updates do not happen instantaneously. Note however that this would entail a total reversal of everything done after the initial consensus. Since the irregulars are not my main interest, I'll leave you to decide. I would be happy to revert any to all the redirects back to articles if I get a clear request to do so based on a general consensus, but considering the back-and-forth that just happened after I acted on what seemed to be a clear line supported by consensus, perhaps it would be better if I stayed out of it. If any of you restore whatever you feel is notable enough, I won't object. Double sharp (talk) 05:44, 9 January 2023 (UTC)

      Just to be safe, I would like to restore only Jupiter and Saturn's moons with measured colors, sizes, and rotations. The ones with completely unknown physical characteristics (i.e. Philophrosyne and S/2003 J 23) will remain in limbo for now. Here's my proposed list of moons to restore (don't take this for granted, please do feel free to suggest any more things to add/remove):

      • Jupiter: all named moons from 2000–2003 announced before 2012, plus Valetudo. WISE measured diameters for Praxidike and Kalyke. Harpalyke, Iocaste, Megaclite, and Taygete and the two aforementioned have measured colors.
        • Jovian objects of interest (need opinions on these ones): unnamed 2003 moons, S/2010 J 1, S/2010 J 2, S/2011 J 1, S/2011 J 2, S/2011 J 2, 2017-2018 moons announced in 2018, S/2003 J 24. Basically anything that had news coverage.
      • Saturn: Every named moon announced before 2019. Nearly all named ones have colors recently measured by Pena et al. (2022).
        • Saturnian objects of interest (need opinions on these ones): S/2004 S 7, S/2004 S 12, S/2004 S 13, S/2004 S 17, S/2006 S 1, S/2007 S 2, S/2007 S 3, S/2004 S 24, S/2004 S 24, Saturn LVIII, S/2004 S 36.

      If you're going to restore any of these pages, please check the "What Links Here" pages for Jupiter and Saturn to restore the directs as well. Nrco0e (talk) 07:57, 9 January 2023 (UTC)

      As of writing, Bestla and Narvi have been restored by Nrco0e and Thrymr by myself. Be sure to fix any redirects that may have pointed to these moons. but were auto-corrected by the bot to the table anchor. –LaundryPizza03 (dc̄) 10:58, 9 January 2023 (UTC)

      I've made up my mind--let's be more lenient with interpreting notability. The moons announced before before 2010 have been around for a very long time and nobody objects to their existence. NASA has individual pages for Jovian and Saturnian moons announced before 2010, and objects like Jupiter LII (S/2010 J 2), Valetudo, and S/2004 S 24 have either made headlines or have unusual/superlative characteristics (i.e. smallest size, farthest orbit) that are of interest to a reader. Therefore, I believe everything announced before 2010 shall be definitively kept.

      For moons that were recently announced without fanfare (S/2011 J 3, S/2016 J 3 S/2018 J 2, S/2021 J 1), we shall leave them as redirects since it's WP:TOOSOON to say anything else about them until there is follow-up or some future news announcement, like what happened with the preliminary 2017 publications of S/2016 J 1 and S/2017 J 1 before Sheppard's big announcement of 10 moons in 2018.

      As of writing, I've restored all moons of Jupiter before 2001, including outliers Carpo and Valetudo, and all named moons of Saturn announced before 2010. I'll eventually restore Jupiter's 2001-2003 moons and the rest of Saturn's pre-2010 moons, both named and unnamed. I'll give consideration to keeping some moons announced after 2010, particularly S/2010 J 2, Ersa, Pandia, S/2004 S 24, S/2004 S 26, S/2004 S 36, S/2003 J 24, S/2019 S 1, and the named 2004 Saturnian moons announced in 2019, but again I need some input on these since I shouldn't be the one deciding here.

      I'm very busy right now, so I won't be able to spend as much time dealing with this moon business. I plan on further renovation of the irregular moons, particularly: changing from osculating to proper (mean) elements from JPL, adding more infobox parameters, updating graphics (plus uploading real images, though that's a whole can of worms regarding copyright unfortunately), as well as expanding and standardizing the prose and infoboxes with up-to-date characteristics and references.

      Lastly, thank you everyone else for the feedback and hard work. Nrco0e (talk) 06:05, 10 January 2023 (UTC)

      @Nrco0e and LaundryPizza03: In that case, would you like to withdraw the AFDs? Double sharp (talk) 09:23, 10 January 2023 (UTC)

      No, this seems to be approaching a no-consensus result for most of the moons, and the AfD outcomes shoud reflect that. –LaundryPizza03 (dc̄) 10:27, 10 January 2023 (UTC)

It seems that some people here being unable to write anything useful themselves prefer simply to delete everything they can. Ruslik_Zero 20:40, 9 January 2023 (UTC)

Perhaps I may point out here that Nrco0e has written several GAs and I have written several FAs. Naturally, opinions differ, but I think we are acting in good faith, and I haven't objected to any of the restorations. Double sharp (talk) 07:39, 10 January 2023 (UTC)

I'd still thik they could have done the work to add nontrivial content to the articles such as the color and shape data, as I have done to all of my restorations. –LaundryPizza03 (dc̄) 08:19, 10 January 2023 (UTC)

Restorations of all the Jovians and Saturnians

Based on Nrco0e's comments above, I have restored all the Jovians, even the ones just announced. The reason is that all the ones up to 2018 got big announcements, and once one takes that line, there is literally no longer any reason other than recency why the latest four should not be included. The moons from 2003 to 2018 form a really ancient precedent on Wikipedia (e.g. the 2003 moons have been on since 2004!) that was until now never objected to, and what initially seemed like a consensus has evaporated.

So, I have restored the status quo ante: every irregular satellite of the major planets gets an article, per the existence of news coverage up till 2018, and extrapolating for the four last ones. (If we can have articles for 80 of 84 of them, why not just have all 84? Judging by the precedents of Jupiter LIV and LIX, they may well have coverage in a few years, and no less is known about them.)

I plan on doing the same thing for the Saturnians later. Hopefully, this settles the matter. Double sharp (talk) 09:23, 10 January 2023 (UTC)

And created a stub for S/2021 J 1: if Jupiter LII can get an article on the grounds of being Jupiter's smallest known moon, then so can this one (they are tied). Double sharp (talk) 09:41, 10 January 2023 (UTC)

I restored all the Saturnians. Double sharp (talk) 12:56, 10 January 2023 (UTC)

Eccentricity of Themisto

Nasa say it's 0.2424

Scott S. Sheppard from Carnegie Institution for Science say it's 0.242

Wikipedia say it's 0.2522112 (close but not quite the same value as the 2 others) : Themisto (moon)

But the table on this page say 0.340 which seems completely off Lebesnec (talk) 15:24, 8 March 2023 (UTC)

this diagram also seems to use a wrong eccentricity, if you compare it with https://lebesnec.github.io/solar-system/?goto=themisto Lebesnec (talk) 15:33, 8 March 2023 (UTC)

@Lebesnec: This list uses mean orbital elements provided by JPL's satellite orbits list. NASA's webpage and Sheppard's list are not reliable sources for irregular moon orbits because they use osculating orbits that do not account for gravitational perturbations by the Sun and other planets. In this Wikipedia list, there is a disclaimer that says that irregular moons' orbits are highly variable over time. For example, this 2017 paper by Brozovic et al. shows that Themisto's orbital eccentricity can vary between 0.075 and 0.463 in a 1,000-year period (note that this paper says Themisto has a mean eccentricity of 0.254 whereas JPL's list says 0.340, but I prefer going with the more recent source that is JPL). Nrco0e (talk) 03:26, 9 March 2023 (UTC)

By the way, this 2021 orbit diagram uses osculating orbits from JPL Horizons using a reference epoch of JD 2459200.5 (17 Dec 2020), meaning that it shows what the orbits of the irregular moons looked like on that date. Of course, they don't look like that now because their orbits have changed since then. I do need to update that orbit diagram however, as it's been outdated for 2 years now... Nrco0e (talk) 03:34, 9 March 2023 (UTC)

@Nrco0e ah thanks for the clarification! Lebesnec (talk) 18:07, 10 March 2023 (UTC)

12 new moons of jupiter

numerous sources say that a total of 12 new moons of Jupiter were discovered between 2021 and 2022, bringing the total to 92. I am very confused about this, as Wikipedia appears to say that nine moons were discovered in that period, for a total of 95. I haven't been able to figure out which sources are correct. Serendi^podous 18:51, 22 March 2023 (UTC)

@Serendipodous: These sources are outdated. Three more moons of Jupiter, S/2022 J 1, S/2022 J 2, and S/2022 J 3, were announced after these news reports. So 92 + 3 = 95. Scott Sheppard and JPL have not yet updated their lists to include these new moons—I assume they're waiting until they get recovered in follow-up observations, as their observation arcs right now are less than 2 months and are therefore at risk of becoming lost to orbital uncertainties. I've already included a footnote explaining all of this in the very beginning lead sentence of this list. Nrco0e (talk) 05:52, 23 March 2023 (UTC)

EDIT: Where did you get 'nine' from? Nrco0e (talk) 06:02, 23 March 2023 (UTC)

@Nrco0e: Arranging the list by year and counting from 2021. Serendi^podous 08:24, 23 March 2023 (UTC)

@Serendipodous: I see you counted the S/2021 J1-6 and S/2022 J1-3 moons. The 12 moons announced by Sheppard back in January 2023 were S/2011 J3, S/2016 J3-4, S/2018 J2-4, and S/2021 J1-6; that adds up to 1+2+3+6 = 12. Note that discovery dates do not correspond with their announcement dates from December 2021-January 2022; the moons discovered from 2011-2018 took several years to confirm since these were initially lost and were only recently rediscovered in Sheppard's 2021-2022 observations. To avoid confusion for this reason, I've added an "Announcement year" column next to the "Discovery year" for this list here. Nrco0e (talk) 15:55, 23 March 2023 (UTC)

@Nrco0e: Thanks. The sources claimed that all of the announced discoveries were made betweem 2021 and 2022. Is there a more reliable source I could use that would not fall prey to this problem? Serendi^podous 16:23, 23 March 2023 (UTC)

@Serendipodous: JPL's Planetary Satellites Discovery Circumstances and Sheppard's website lists all the new satellites' proper discovery years. If you want more specific discovery and announcement dates for each individual moon, you'd have to check the MPECs referenced from their respective Wikipedia articles. Nrco0e (talk) 16:45, 23 March 2023 (UTC)