Talk:Charon (moon)

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Contents 1 Pronunciation 2 Comments 3 Barycenter; inclination 4 Inclinations apparent discrepancy 5 Discovery image 6 Charon, the planet? 7 Article name change 8 Satellite 9 IAU Streaming Video 10 symbol?? 11 Newly added section 12 dwarf planet now 13 Popular culture 14 Moon? Or Dwarf Planet? section 15 Terrible Illustration 16 Surface Area may need to be Updated 17 New evidence of active geology on Charon 18 Charon: Pluto's Moon... or Pluto's Twin? 19 Non-displaying comment on Charon's name 20 Minor planet number

[edit] Pronunciation

I've heard all kinds of pronunciations for this - even chair'-un. Would be good to know if Christy pronounced the first syllable as Charlene (shar'-un), or if he pronounced it like Sharon (shair'-un), which is easier to say. It would be nice to reduce the pronunciation to just two variants, Christy's and classical. Dont know if I'll be able to contact him, however, so if anyone knows for sure, please comment here and make the correction. kwami 08:48, 2005 May 5 (UTC)

The OED lists the adj. form Charonic (kair-on'-ik), so Charonian (shair/kair-oe'-nee-un) should do for the demonym. kwami 2005 June 30 06:27 (UTC)

Going with shar'-un, based on this comment:

The word Charon is pronounced "KAIR en." Alternatively, some pronounce it "SHAHR en." [1]

That makes sense, given the pronunciation of Char(lene), but really needs to be confirmed with one of the Pluto teams. kwami 22:50, 4 November 2005 (UTC)

The Science channel (cable TV) just aired a special on the New Horizons mission (it's two days to launch). Three people mentioned Charon, and all pronounced it [ˈʃɛɹ.ən]. This includes Hal Weaver, co-discoverer of the outer moons, who said it three times. Given that print sources are often ambiguous as to whether the vowel is [ɛ] or [ɑ], and that even if they're explicit, they may be trying to interpret ambiguous material, I'm switching over to Weaver et al's pronunciation. (It's also the easier to reconcile with the print sources.) I'm also going to make the assumption that it's identical except for the initial consonant to the classical pronunciation, which the OED has as [ˈkɛərən] in RP, so that people who distinguish marry and merry would still pronounce it as air. kwami 10:29, 16 January 2006 (UTC)

Heard a story on NPR on 19 Jan 06 specifically discussing pronunciation of Charon the planet. Seems that Christy, in addition to pronouncing the Ch as "Sh" also gave equal weight to both syllables, rather than an accent on the first syllable. I don't know if this matters, but here is the link. [2] Isoxyl 14:06, 20 January 2006 (UTC)

Thank you for that. Not equal weight, but full vowels, at least while illustrating the classical and astronomical pronunciations. The astronomer at Christy's institution pronounced these both with exaggerated vowels, [ˈkɛːɹɑːn] and [ˈʃɛːɹɑːn], but when assimilated into normal speech [ˈʃɛɹən] with a reduced vowel (like the name Sharon) still seems to be the form used. Very clear account though from Christy's colleague that Charon does not have the [ɑ] vowel of Charlene in its first syllable, as he clearly distinguishes them. kwami 19:13, 20 January 2006 (UTC)

Just to confuse matters further, classicists do not always pronounce classical names consistently, and the pronunciations normally used by classicists may not always be the historic pronunciations (which may also have varied during the classical period). However, I believe that the historic pronunciation of Charon have a hard "ch" as in "loch" (that shook you). PatGallacher 17:30, 30 January 2006 (UTC)

There's a standardised literary English pronunciation of Greek words, but of course some people will try to be more authentic than that. We really don't need to give the [k] pronunciation of Charon at all - after all, Io is commonly pronounced ['i:ou], but we don't list that because it can be understood from the Greek, which we do give. There's just more debate in the case of Charon, and we'd get in an edit war if we only listed the Sharon pronunciation alongside the Greek. kwami 19:15, 30 January 2006 (UTC)

Yes, there is a standardized literary pronunciation (since this article is in English, let's not confuse the question further by going to Greek; if we did, the Classical Greek pronunciation of the Ch- is just like initial English k, not as in loch and in Modern Greek). In the case of Charon, the standardized literary pronunciation is the one represented on the current page ˈkɛərən. Both Classics scholars and astronomers (and we could add mathematicians, doctors, etc., etc.) are, taken as whole groups, very sloppy about observing any principles, rules, or traditions to pronouncing names derived from Greek and Latin. In graduate school, I heard a Macarthur-genius-grant-winning Greek professor pronounce the Hellenized version of the Egyptian pharaoh's name--Cheops--with the same initial consonant as "chopstick." So we can't use the "scholar on the street" as the authority. What are the advantages of sticking with the traditional literary pronuciation? There are two big ones. First, these names are chosen by astronomers because of their resonance with mythological stories familiar to English-speakers; for example, there is absolutely no doubt that, in Byron's Don Juan II.ci.803 [3], or in Walter Savage Landor's "Dirce" [4], we are to pronounce ˈkɛərən. Second, astronomers have by and large traditionally gone with those same pronunciations familiar from English literature and every generation of cultivated English speakers up until things got anarchic in the last 50 years; I'd like to cite some decisive proof for this, but I can't--however, have a look at the article Pronunciation of asteroid names, since this article, not infected by any controvesy that I can tell, lists remarkably conservative and traditional-literary pronunciations. Check out the recommended pronunciation of Protogeneia, for example; this would make Byron or an Oxbridge snob of 1940 very happy. I think the traditional literary pronunciations (these are always easily checked by looking in a slightly older dictionary, like say the 2nd Webster's or the OED) are a fairly clearly established norm of English-language usage, both literary and astronomical. Wareh 03:46, 29 August 2006 (UTC)

Let me add a brief clarification. Christy may have enjoyed fancifully connecting the name to his wife's, etc. But the IAU has pretty strict principles about what makes a valid name. A satellite in our solar system must be the name from Classical mythology. Moreover, if "Charon" did not have a mythological connection to Pluto (via the underworld), it would never have won acceptance. This is an article about the celestial object known to astronomers throughout the world. We should use the name that conforms with the international principles of naming astronomical objects. To anyone who thinks English speakers ought to say "sh," I ask one simple question: why does not a single German-speaking astronomer attempt to honor Christy's pronunciation, but rather they all use the standard pronunciation known to Germans as the ferryman's name? Wareh 04:03, 29 August 2006 (UTC)

You're missing the central point.

(And BTW, I wrote the Pronunciation of asteroid names article, as I wanted to provide a ref for the Oxbridge snob types. Most of these names cannot be found in Webster's 2nd or similar dictionaries, they're too obscure. Also, if you can contribute further to that list, I'd be obliged!)

That point is this: The pronunciation of a word is how it is pronounced. Among astronomers, and even on astro documentaries on television, shair'ən is the dominant pronunciation. The IAU is completely irrelevant, as they have nothing to say about pronunciation. There are no official guidelines for the pronunciation of astronomical bodies in English. As for German, that again is irrelevant: German orthography is reasonably phonemic, English is not. The sh pronunciation is an English convention. kwami 09:26, 29 August 2006 (UTC)

Well, my intention was to improve the information provided by the article. I certainly think it should include information about the mispronunciation current among astronomers. Mathematicians misspell and mispronounce parallelepiped in scholarly journals, but quality works of reference (dictionaries, encyclopedias, etc.) do not stop providing the more authoritative guidance. So I will respectfully disagree with the principle here and leave the editing of this article to others. Before I got to the article, however, there was a lot of bad misinformation by anyone's standards: that there exists a "Classical" pronunciation with the sound of "loch," etc. I hope the article will, in its eventual form, inform the curious reader as to the only widely accepted pronunciation of the name of the Stygian ferryman in English. This is where the IAU is not irrelevant, because it has in fact enforced the principle that satellites in our solar system are to be referred to by the names of such mythological beings. And those who want to follow the IAU's principles & enjoy connecting the satellite to the ferryman, may wish to know the standard pronunciation by which he's usually known in all other contexts. Wareh 18:16, 29 August 2006 (UTC)

The pronunciation of the name Charon in Dutch is not commonly pronounced with the classical 'k' sound, as suggested by the author. The sound of the first syllable in Dutch is not common in the English language and sounds a bit like a gentle clearing of the throat.

Presumably as in "loch" and "Bach"? I notice that "The Sky at Night" (long-running UK astonomy TV programme) tends to pronounce it as in "church". Bluap 19:27, 29 October 2006 (UTC)

The reason for my recent edit was that Italian, Spanish, and Portuguese pronounce the first consonant of the mythological figure's name as /k/. It seemed an oversimplification to have "which is the ch sound" there. The sentence without that final clause was still accurate: "In European languages other than English, speakers generally follow the pronunciation established for the mythological figure." (I don't have a strong opinion about what the correct English pronunciation is.) --Cam 23:40, 31 October 2006 (UTC)

On second thought, I do have a strong opinion about it, but it's not relevant here. :-)

I think if the clause stays it should probably have a little more detail (some say [x], some say [k], or whatever). --Cam 23:48, 31 October 2006 (UTC)

I think all the pronunciation references should be kept on the page, as long as they are accurate. Keep all the information about the various pronunciations and the reasons behind them. This kind of thing is good, informative, and accurate. Why do we need to minimize the data? People use the planet/planetoid pages for different reasons. I use the pages for a-good half-dozen reasons myself -- for astronomical, historical, and literary research. The naming tie-in with the discovery, any historical conflict, and references to their associated ancient mythological counterparts is important to me. Other folks may use other data elements that I have no use for. So, it is important to continue incorporating the many sides of the subject matter. That is what encyclopedias do. Please keep the pronunciation data. One man's soup is another man's dessert. Tesseract501 8 March 2007

[edit] Comments

Charon is a moon? I thought it was determined to be another planet? Capt.Nero

You might be thinking about theories that it's been captured, and therefore had an independent orbit about Sol at one point - or that it and Pluto are sometimes called a "double planet". As for the former, it's currently a moon, and in any case there are alternate theories; and as for the latter, even the planetary status of Pluto has been called into question. If you want to define a "planet" as a body large enough to pull itself into a sphere, as some do, then yes, Charon is a planet, but then so is our moon. kwami 19:44, 2005 July 29 (UTC)

Within the next couple of days the International Astronomical Union will have declared Charon a planet, part of a "double planet" configuration with Pluto in our 12-planet solar system. Better get to revising. Bustter 13:50, 16 August 2006 (UTC)

... or not. Jimp 13:21, 31 August 2006 (UTC)

I noticed that near the bottom of the page, there is mention of Charon "occulting." Having little to no experience with Astonomy, I haven't the faintest idea what that verb means. Perhaps someone could make it a link? Canaen 2005 July 29

Charon page notes that surface is thought to be frozen water unlike Pluto which is said to have a surface largely composed of frozen nitrogen. However New Scientist reports (10:35 30 July 2005 Jeff Hecht)that Pluto is covered in frozen methane (like newly discovered planet [2003 UB313]). Anyone have recent actual knowledge of this? Pluto's surface composition should be well known by spectrographic analysis. Charon may not reflect sufficient light to do this analysis.Sidney2 19:20, 30 July 2005 (UTC)

[edit] Barycenter; inclination

copy of the entry in Talk:Pluto

• Could someone trace the source of the statement that the barycenter lies above the planet's surface, please? New data from (Bluie, Grundy et al. 2006 do not seem to support that (mass ratio: 0.1165±0.0055)
• Does someone know the source of the inclination data for the moons (Charon's infobox)? Again, they are at odds with the source quoted above (~96 degrees to the ecliptic). Thank you. Eurocommuter 16:30, 27 April 2006 (UTC)

Question

"Charon and Pluto revolve about each other every 6.387 days"

is this meaning 6.387 Earth days or Plutonian days?

Earth days. Since they're tidally locked, they revolve around one another once each Plutonian day. ;) --Stlemur 23:56, 15 June 2006 (UTC)

[edit] Inclinations apparent discrepancy

Note the apparent discrepancy between the (ecliptic) inclination value for Charon's orbit given by http://arxiv.org/abs/astro-ph/0512491 vs. the one shown here. The explanation resides in their Table 3, which gives an inclination of 96.145±0.014° for epoch JD 2452600.5. The calculation used here takes their Fig. 2 orbital/rotation pole coordinates, for epoch J2000 (JD 2451545.0), and reduces it to the J2000 ecliptic. --Urhixidur 18:46, 3 August 2006 (UTC)

I'm very puzzled by the 96.145 value in that Buie et al paper. I get practically the same values as you (112.79° to ecliptic & 119.60° to solar orbit), using only the following: RA (133.05°)& declination (-6.15°) of the Charon orbit from Fig2 in the paper; known inclination and longitude of ascending node of Pluto's orbit; and Earth's axial tilt (for the ecliptic->equatorial coordinate transformtaion). Surely none of these quantities change much over those ≈3 years between the epochs you mention above. So what's this weird inclination of 96.145° with respect to? I can't seem to track down an explanation in the paper. Deuar 20:04, 4 August 2006 (UTC)

Are you using the RA of the pole to get the inclination angle? The Pluto page seems to do the same thing. Isn't that different way to define "Inclination" and "Obliquty" from how all the other planet pages (and other source data, such as NASA's planet pages, etc.)? I could be mistaken, but I think its a simple angular calculation in 2D (not 3D). Orbital Inclination (unless the page specifically indicates something different) is supposed to be the body's orbital plane to the Earth's ecliptic (orbital plane). Or, in the case of satellites and secondaries in binary systems (such as Charon), in relation to their principal's orbital plane. Pluto's orbital plane (around the Sun) is about 17.16º (not 112.78º) -- per sources like NASA (www.spds.nasa.gov/planetary/factsheet/plutofact.html). Since the 112.78 value matches the Pluto page, I assume the intent is to give them the same reference point (i.e, the orbit of the Pluto-Charon-Nix-Hydra System around the Sun - such orbits inclination to the Earth's ecliptic. Why does the page indicate 112.78, when other source documents indicate 17-degrees? If you are adding additional parameters (RA of the poles, etc., to come up with a concise value for a 3D model, then maybe the value should be given a different lable (instead of Inclination)? Or, am I way off base here? Regardless, the labeling and use should be consistent on all the planet and planetoid pages, because the general reader (i.e., me among many) is easily confused). Tesseract501 8 March 2007

Seems like you've definitely sniffed out something fishy here. Here's what i've been able to pin down:

1. The inclination of Charon's orbit to the ecliptic is ≈96.1° (this Nasa datasheet gives 96.16° and explcitly says that it is with respect to the ecliptic, while Buie at al gives 96.145 ± 0.014° for what they call "inclination").
2. The orientation of Charon's orbit is given by Buie et al as Ω = 223.046 ± 0.014°. Nix and Hydra get extremely similar numbers, so this must be in standard ecliptic coords.
3. There's no reason to doubt Pluto's orbital parameters in its article I think (i=17.14175°, Ω=110.30347°).
4. It's known that Pluto's pole is in the same direction as the axis of Charon's orbit.

So, clearly Charon's inclination and Pluto's axial tilt to the ecliptic must currently be wrong. Deuar 17:50, 9 March 2007 (UTC)

As for the inclination of this plane to Pluto's orbit, the angle between the normal vectors can be calculated. For a plane characterised by i and Ω, the unit normal vector is going to be ( sin i sin Ω, – sin i cos Ω, cos i ), where (1,0,0) is the direction of the vernal equinox, and (0,0,1) is perpendicular to the ecliptic. The angle that I get between Pluto's and Charon's orbital planes is 102.45° Deuar 18:41, 9 March 2007 (UTC)

No, sorry, something is still not right.

5. NASA gives 119.61° for Pluto's equatorial inclination to its orbit.

Perhaps my point 4. above was way wrong? Deuar 18:52, 9 March 2007 (UTC)

6. Now in This forum discussion with Marc Buie, he Sanjay Limaye gives Pluto pole coordinates as RA=311.63°, δ=4.18°.

Calculating away as per the formulas in ecliptic coordinate system, this gives β=21.31° and λ=315.33°. The angle between this and the normal to Pluto's orbital plane turns out to be 117.61°. Almost the same as the NASA data, but differs by exactly 2°. The fact that the two most significant digits are the same makes it look suspiciously like one of the above sources made a typo. But which one? Deuar 19:51, 9 March 2007 (UTC)

Ah, NOW I get it. The coordinates in Buie et al (http://arxiv.org/abs/astro-ph/0512491), and in particular the inclination, were given in J2000 coordinates, which are practically the same as equatorial coordinates. Hence, the Charon orbit pole (as well as the Pluto spin pole since they're tidally locked) is pointing at RA=133.046±0.014°, declination=-6.145±0.014°. This finds confirmation at the JPL ephemeris, where the inclination of 96.151° of Charon's orbit is referred to the ICRF. Having this, then the inclination of the orbit to the ecliptic can be worked out as 112.78° and to Pluto's heliocentric orbit as 119.59°, agreeing with some but not all of the previous values. Deuar 17:32, 20 March 2007 (UTC)

[edit] Discovery image

I've substituted the initial uploaded image (seen on the right)

for a cropped version that does not contain the blue border and caption (to avoid a messy look to the page, while keeping the discovery image, which I agree is a good idea to have). The caption appears in text on the description page of the newer cropped image.

[edit] Charon, the planet?

Charon is soon to be redefined as a planet, not a moon. This will mean a huge reconstruction of the article and renaming. -- 86.13.152.237 12:28, 16 August 2006 (UTC)

Those who have argued against Pluto as a planet consider the two as the first discovered trans-Neptunian objects.

Actually, if these two are reclassified as plutons, it wouldn't change their status as trans-Neptunian objects (and Kuiper belt objects).--JyriL ^talk 12:33, 16 August 2006 (UTC)

Plutons, according to the proposal before the IAU, are planets. We have a 12-planet system. It's all here. Bustter 13:53, 16 August 2006 (UTC)

Pluto is currently officially planet. But it doesn't stop it from being a Kuiper belt object. Nobody is denying that. The debate is about can Pluto and other similar object be also planets. (BTW: Here's the original release: [5]).--JyriL ^talk 14:06, 16 August 2006 (UTC)

My point is, there is no longer a debate. The certain ratification of the proposed definition of "planet" makes Pluto and Charon a binary planet, part of our 12-planet system. This becomes scientific consensus August 24, between 14:00 and 17:30 CEST Bustter 14:22, 16 August 2006 (UTC)

It is still only a draft. Nothing has been voted yet. It is possible that they don't accept the draft and the current status remains.--JyriL ^talk 14:41, 16 August 2006 (UTC)

Why does this proposed definition include Charon but not the Earth's moon? Is it because the gravitational centre of the Pluto-Charon system is outside Pluto? That could be a rather fine distinction. PatGallacher 16:02, 16 August 2006 (UTC)

Yes: the IAU has a nice Q and A page, which says:

" Q: What is a “double planet”?

A: A pair of objects, which each independently satisfy the definition of “planet” are considered a “double planet” if they orbit each other around a common point in space that is technically known as the “barycentre”. In addition, the definition of “double planet” requires that this “barycentre” point must not be located within the interior of either body." [6]

Henry^Flower 16:38, 16 August 2006 (UTC)

[edit] Article name change

Ok. Assuming that the propopsal passes on the 24th, this page will need a name change. So let's see if we can get a good name agreed to in advance. Let me stress that this is assuming the thing passes. If the proposal fails, this whole discussion becomes moot.

Charon itself is already a disambiguation page. The other two possibilities that occur to me are Charon (planet) and Charon (pluton). The second seems a bit more specific to me, but the first seems more basic and logical. More intuitive. I lean towards the first. Whichever is chosen (or something else someone else comes up with), the other likely should be created as a redirect, IMHO. - TexasAndroid 17:01, 16 August 2006 (UTC)

I'd favor Charon (planet) as it is more general; more likely to be found, and not conflicting with any other Charon in the solar system. --Stlemur 17:20, 16 August 2006 (UTC)

I'd also go for Charon (planet). However, let's wait until the IAU decision is ratified before making the move. Bluap 17:49, 16 August 2006 (UTC)

100% agree. Nothing is official until the IAU votes. - TexasAndroid 18:21, 16 August 2006 (UTC)

While nothing is "official," the proposed definition for planet represents the closest thing to a "scientific consensus" on these long-debated matters that we have, as it was derived by an international, official body of the IAU. Areas of debate remain open prior to the vote, but at present the information presented here could be argued to be contrary to the scientific consensus. I don't think the proposed changes should be applied prior to the vote, but the essentials of the matter (12 planet system, status of Charon and Ceres), including the date and time of the vote, should be incorporated into the affected articles now, perhaps through a template that could be applied to all affected articles (Charon, Pluto, 2003 UB313, 1 Ceres, Solar System, planet, perhaps others). People will be looking up these matters in the next few days, a template would allow up-to-date information to be easily included. There's an [interesting NY Times piece] that indicates a bumpy road to ratification. If ratification fails, a template would provide a useful means to delineate an extended disagreement.

addendum I find that Wikipedia policy recommends against including article information in a template. Therefore it may be best for any such template to include a link to a separate article on IAU Draft Resolution 5, which in my opinion merits an article of its own anyway, owing to its ambitious goal of debate resolution, whether it is ratified or not. - Bustter 21:55, 16 August 2006 (UTC)

It does have its own article: 2006_redefinition_of_planet --Volcanopele 21:59, 16 August 2006 (UTC)

So I see. I'm happy with what's been done at the top of the article. Bustter 01:53, 17 August 2006 (UTC)

I have nominated Charon (planet) for a speedy deletion since Charon (by definition) is NOT a planet.
-- Kheider 14:51, 9 November 2007 (UTC)

I redirected the only link to it from Main article space. Go ahead and delete. (Or I will if you like.) kwami 01:43, 10 November 2007 (UTC)

I would like to see it deleted, but it looks like we need more time to see what the outcome will be.
See: Wikipedia:Redirects_for_discussion#Charon_.28planet.29_.E2.86.92_Charon_.28moon.29 -- Kheider 01:50, 10 November 2007 (UTC)

[edit] Satellite

Reading this article for the first time, trying to understand the IAU proposal, I baulked at the first sentence, which states that Charon is a "satellite" of Pluto. This is contrary to the following Q&A from the IAU site.

Q: What is a “satellite” of a planet?

A: For a body that is large enough (massive enough) to satisfy the definition of “planet”, an object in orbit around the planet is called a “satellite” of the planet if the point that represents their common centre of gravity (called the “barycentre”) is located inside the surface of the planet.

But I'm not clear on whether this a proposed new definition of satellite, or the existing one. --KJBracey 19:01, 16 August 2006 (UTC)

This article does not reflect the IAU proposal, since that proposal has not been approved yet. Once it is, we'll change those sentences. DenisMoskowitz 19:04, 16 August 2006 (UTC)

Well, that was kind of my question. If that is a propsed new definition of satellite, is there a formal existing one, or does it suffer same ambiguity as "planet"? The IAU press release totally glosses over the fact that they're redefining "satellite" too, leading to my uncertainty. I note that the Natural satellite article doesn't reference this IAU proposal - it could do with the same Current Event tag. --KJBracey 19:12, 16 August 2006 (UTC)

Hmm. I haven't heard that they are redefining satellite, just that they are redefining "planet" to include more objects. And Charon would now be considered a planet ofit's own, not a satellite. But the issue is more one of timing than of what the new definittions are.

There are a number of things in the article that will need to change, assuming that the proposal passes in a little over a week. Until the vote is taken on the 24th, nothing in the proposal is official, and Charon is still officially considered a moon. It's possible that the proposal will even be defeated, though I have no idea how likely that is. But until it passes, it's still a moon and a satellite. - TexasAndroid 19:18, 16 August 2006 (UTC)

Interesting definition. Wonder who invented it. Unfortunately it has no "official" or scientific basis (i.e. it sounds more or less original research).--JyriL ^talk 19:37, 16 August 2006 (UTC)

Ah, sorry for not reading your question carefully. I don't know what the IAU definition is, but our Satellite page says, under "Definition of a Satellite", "The general criterion for an object to be a satellite is that the center of mass of the two objects is inside the primary object." DenisMoskowitz 19:23, 16 August 2006 (UTC)

So it does, but "citation needed" I see. I didn't get there; I only read Natural satellite, which doesn't include that definition. So this article's first sentence is contradictory to the Wikipedia's definition of Satellite. I'll leave it to you experts to resolve it.

I also note there's no link from Satellite to Natural satellite; I think the relative structure of those two articles need a little work. The two articles don't seem to be able to decide whether they're a primary and satellite or a binary pair :) --KJBracey 23:52, 16 August 2006 (UTC)

This may be covered above, but if so I didn't see it. Our article first of all says Charon is a satellite of Pluto. Then later it says that Pluto and Charon are circling each other. Completely aside from the upcoming vote about the definition of planet, doesn't the binary nature of this system mean that either (a) they are satellites of each other or (b) neither is a satellite of the other. In other words, if Charon is a satellite of Pluto, then isn't Pluto also a satellite of Charon? JackofOz 06:54, 17 August 2006 (UTC)

[edit] IAU Streaming Video

The 2nd Session, at which the vote will take place, can be streamed here at 5 AM Pacific Time Thursday the 24th. Bustter 20:45, 16 August 2006 (UTC)

[edit] symbol??

Does Charon have a special symbol like the other planets have? If so, please add it to the article!--Sonjaaa 16:03, 17 August 2006 (UTC)

None of the moons in our solar system (other than our own Moon) have official astronomical symbols, as far as I know (and I've looked for them). There's one person out there using the planetary symbol plus the roman numeral of the moon, but I can't tell how official that is. I came up with symbols of my own for the major moons last year, so my symbols are what you'll find on a google search for "charon symbol". However, these symbols are completely unofficial. I imagine the IAU will come up with symbols for Charon and (once it is named) 2003UB313 if the proposal passes. (Ceres already has a symbol from its first stint as a planet.) DenisMoskowitz 20:45, 17 August 2006 (UTC)

Bonege! Dankon pro viaj simboloj!! Mi ne scias, kiun simbolon uzi por Urano, nek kial estas du... Hmmm. --Sonjaaa 22:17, 17 August 2006 (UTC)

We should stick to English on a general talk page, but this is off topic anyway - I'll reply on your talk page. DenisMoskowitz 22:24, 17 August 2006 (UTC)

[edit] Newly added section

The newly added section called "Pluto Flyby", is quite strange, firstly it seems to be mostly about Pluto, so I'm not sure what relevance it has to this article. Secondly it is often badly written in that it doesn't explain many of the things it's talking about, like what is "LORRI plus Ralph"? The section later mentions that it is talking about the New Horizons mission, but this is very unclear. It looks like this whole section has been copied verbatim from some other source, which would explain why it gives no context. Lastly the user who added this stuff, S035593, has only existed here for 1 day, and has only uploaded material ostensibly written by one Gopi Ravindran, whoever that is. In short I'm not sure this section belongs here, perhaps it would be better to be part of the New Horizons article, or something. What do the rest of you think? --Hibernian 13:53, 21 August 2006 (UTC)

It was a cut-and-paste job from New Horizons. I've removed the text: the article refers to the flyby mission in the opening sentence - any interested in the details can go to the relevant page. Bluap 14:03, 21 August 2006 (UTC)

Ok then, I knew there was something not right about that section. --Hibernian 14:42, 21 August 2006 (UTC)

[edit] dwarf planet now

It's a dwarf planet now. Let's update the article and move it to Charon (dwarf planet).--Sonjaaa 19:26, 24 August 2006 (UTC)

Can you provide a cited source which says Charon is a dwarf planet? The IAU has officially announced only 3 dwarf planets, and Charon is not on that list. Derek Balsam 19:34, 24 August 2006 (UTC)

I should clarify that the IAU may yet decide Charon is a dwarf planet. But they have not done so. Until they do, wikipedia needs to remain accurate.Derek Balsam 19:38, 24 August 2006 (UTC)

http://news.bbc.co.uk/2/hi/science/nature/5282440.stm says " 2003 UB313 will now join Pluto in the dwarf category, along with Pluto's major moon, Charon, and the biggest asteroid in the Solar System, Ceres." and has a diagram where it lists Charon as a dwarf planet alongside Pluto and the others. --Sonjaaa 19:42, 24 August 2006 (UTC)

Egad. I think we need to wait for a primary scientific source. The BBC is neither primary nor scientific. Derek Balsam 19:45, 24 August 2006 (UTC)

There's nothing about Charon being a dwarf planet on the IAU website yet. This is their article on the vote results. Dancter 19:50, 24 August 2006 (UTC)

Key quote from the official vote results:The first members of the "dwarf planet" category are Ceres, Pluto and 2003 UB313 (temporary name). More "dwarf planets" are expected to be announced by the IAU in the coming months and years. Currently a dozen candidate "dwarf planets" are listed on IAU's "dwarf planet" watchlist, which keeps changing as new objects are found and the physics of the existing candidates becomes better known.Derek Balsam 19:53, 24 August 2006 (UTC)

Earlier today, the BBC had a pretty much identical image which didn't include Charon and which was attributed to the IAU ('International Astronomical Union' or whatever was written in the image itself). This current image which now includes Charon as a dwarf is just a modified version of that earlier image. The question is whether the IAU supplied a new one, or the BBC edited the earlier one after making the decision itself. Aaron McDaid (talk - contribs) 19:56, 24 August 2006 (UTC)

(Replying to self) The article has had some edits recently arguing over whether Charon is a moon or a dwarf planet. The section on the 2006 controversy is a bit vague and might seem to be saying that Charon is definitely not a dwarf planet, but that can't be referenced to an authoritative decision. Would anyone object to it being updated to say some or all of the following:

1. That while Charon was not explicitly named today (2006-08-24) as a dwarf planet, nor was an explicit decision made today that Charon was not a dwarf planet.
2. Charon might be a dwarf planet under the new definition, but there has been no formal ruling either way on it yet.
3. Charon will probably continue to be referred to as a moon by default until such a formal ruling.
4. And that the final decision would be expected to be based on whether or not Charon fits a formal definition of 'satellite'.

If there are any problems with this list, could you explicitly name which of the above are acceptable/unacceptable because I believe some of these could be put into the article without much dissent, but I'm just testing the waters here. Of course, somebody else might have a better list of outstanding issues. I'm off now, apologies in advance for not replying promptly. Aaron McDaid (talk - contribs) 22:08, 24 August 2006 (UTC)

1 and 2 seem perfectly fine to me. I'll have to defer to those more familiar with the situation for 3 and 4, at least until I have the time to read up on everything. The latter two seem a little like original research, though if you can cite sources for those, even that's not a problem. Dancter 22:23, 24 August 2006 (UTC)

I updated the subsection on "moon or planet" to include the IAU satellite definition, and a link to it, and I included a summarized version of 1 and 2.--mclauss 5:02, 25 August 2006 (UTC)

That IAU link which you just added seems to be out of date [7] - it describes Ceres as a planet. And it doesn't mention dwarves at all. The discussion of Pluto and Charon in it seems to be correct and it has the definition of satellite that I would expect, but some mightn't like it because it's out of date.

I think the article is pretty much correct as it is now as there's no doubt in my mind Charon is a dwarf planet, but it would be nice to get something more obviously up to date with the satellite definition. Also, I might just now add some more on the location of the barycentre. Aaron McDaid (talk - contribs) 10:55, 25 August 2006 (UTC)

The German article has it as de:Charon (Zwergplanet)--Sonjaaa 20:52, 25 August 2006 (UTC)

[edit] Popular culture

Do you thing that it is worth mentioning that Charon was the setting of the Marine training in the novel 'The Forever war'? There are some great descriptions of the moon being a very dangerous place to train on and taking many of the Marines lives.

Nah, not really. Doesn't need that section. The description of the moon in Forever War is science fiction as the novellist has never been to Charon. Also, we have to mention in each of other planets of when they were used in popular culture. Earth will have a huge list as well as Mars. :) Azn Clayjar 20:04, 9 July 2007 (UTC)

[edit] Moon? Or Dwarf Planet? section

The newly named and rewritten section has the weasel words "it has been argued" a couple times, a phrasing which was not there before the rewrite. We need to clearly state who is doing the arguing, not simply that it has been argued. I'll try to rewrite later to make this explicit. Also, the new title does not conform to heading naming conventions (Wikipedia:Manual of Style (headings)) for Wording and Capitalization.Derek Balsam 22:23, 30 August 2006 (UTC)

I also think that the pictures of Pluto and Charon will not be changed until the space probe sent to Pluto arrives there. Until then, we will have to guess what the two look like.

[edit] Terrible Illustration

That diagram of the formation of charon looks hideous. Is there any way it could be replaced? Joelholdsworth 10:07, 12 February 2007 (UTC)

Probably not until the probe (currently traveling at 52,000 mph) reaches the Pluto system in 2015. At present, I think the image on the page may be the best representaional images available. Same with the Pluto page. I believe that the best actual resolution is something like less than one pixel -- the Pluto family is way, way out there. The imgaging probably shows a best-bet interpretation of the plantary surface variiations. I guess the grid could be blended, but then the image resolution would be more blurred. Unless an artist's interpretation is used, the image on the page may be the best we have available to us at present. Tesseract501 8 March 2007

[edit] Surface Area may need to be Updated

The page indicates the surface area at 4.5 x 10(power 7). Given the radius indicated (603.5), I belive that the surface area would be about 4.58 x 10(power 6). To the power of 6, not 7. Tesseract501 8 March 2007

Thanks for catching that! Deuar 12:43, 8 March 2007 (UTC)

[edit] New evidence of active geology on Charon

Evidence found for active geysers on Charon Serendipodous 16:51, 30 July 2007 (UTC)

[edit] Charon: Pluto's Moon... or Pluto's Twin?

Pluto, the ninth planet from the sun. Okay, now. I do know all of you think that Pluto is a dwarf planet. I understand. NASA, BrainPop, even Wikipedia has switched to beleiving it is a dwarf planet. I, however, remain as stubborn as a rock.

Pluto's first identifed moon is Charon. Charon might of formed the same ways most people think Earth's moon formed. A body might of crashed into Pluto, throwing material into orbit. Pluto and Charon look very similar, so I am guessing that the crash theory is accurate for Charon's formation.

Charon is playing an impact on Pluto's spin, although Charon is only half of Pluto's size. This impact causes the two to orbit around each other about every six-and-a-half days. So you could think sometimes Pluto becomes Charon's moon! Sadly, that is wrong.

Because of Charon's impact on Pluto's spin, I think Pluto and Charon should be considered a double planet. I ask anyone else with a say in this discussion put their comments below the line below.

---

—Preceding unsigned comment added by 163.153.103.166 (talk) 17:51, 21 September 2007 (UTC)

I agree with the previous commenter, as do many others. However, it is pointless to discuss the matter here - this article simply reflects the IAU's position (as the near-authoritative body on such matters). It is likely that the IAU will change Charon's classification in the near future (they have almost said as much http://www.iau.org/Q_A2.415.0.html). Md84419 08:41, 24 September 2007 (UTC)

Right now Charon is the closest thing we have to a double (dwarf) planet. It's a much bigger issue with asteroids with moons vs. binary asteroids, but we don't know enough about them for this to be a problem -- yet. At some point the IAU might come up with a definition of "moon", as they did for "planet", but in the end it really is all just semantics. kwami 01:26, 10 November 2007 (UTC)

[edit] Non-displaying comment on Charon's name

While making an edit, I came across the following non-displaying comment embedded in the text:

"Charon" first appears in print in March 1978: http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1978IrAJ...13..198O&db_key=AST&link_type=ABSTRACT&high=45eb6e10af25715

There is something wrong with the reference, as March 1978 is 3 months before the discovery, and when bringing up the journal article, it makes a reference to "last August." Otherwise, the article may have some research value. — Eoghanacht ^talk 13:03, 6 May 2008 (UTC)

[edit] Minor planet number

Does Charon have a minor planet number assigned, like Pluto has? --SJK (talk) 08:03, 4 June 2008 (UTC)

Since Charon is currently considered only a moon of Pluto, the closest thing to a MPC number it has would be (134340) 1. -- Kheider (talk) 15:43, 4 June 2008 (UTC)