Talk:Pluto

Pluto-Charon, the largest binary system in the solar system? Not Sun-Jupiter?

In this page's section, Charon, it states the follwing:

The Pluto–Charon system is noteworthy for being the largest of the Solar System's few binary systems, defined as those whose barycentre lies above the primary's surface (617 Patroclus is a smaller example).

At the Mass section at Jupiter it states:

Jupiter's mass is 2.5 times that of all the other planets in our Solar System combined—this is so massive that its barycenter with the Sun lies above the Sun's surface at 1.068 solar radii from the Sun's center.

The Sun-Jupiter system clearly meets the definition of "binary system" given in this article, so unless I am misunderstanding or overlooking something, these statements are contradictory. Any thoughts?--Racerx11 (talk) 06:18, 5 December 2011 (UTC)

I don't know if I trust the Jupiter article. The statement isn't sourced and simply doesn't sound right. The rotation of the sun would be highly irregular if that were true. --68.39.25.109 (talk) 00:27, 16 January 2012 (UTC)

I withdraw my argument above. I had a short discussion on the Jupiter talk page and the issue I had was clarified. --68.39.25.109 (talk) 01:01, 16 January 2012 (UTC)

I had a really good explanation for you, but ditched it at the edit conflict. There is no doubt the Jupiter article statement is correct. The question really comes down to if Sun-Jupiter meets the definition of binary system. This article's definition is "those whose barycentre lies above the primary's surface", which Sun-Jupiter meets. But is this the correct definition? Does the system need to contain two and only two bodies to be binary as the name suggests? If so, Pluto-Charon isn't binary either.--Racerx11 (talk) 01:28, 16 January 2012 (UTC)

The article Binary system (astronomy) states: "Some definitions (e.g. that of double planet, but not that of binary star) require that this center of mass is not located within the interior of either object. A multiple system is like a binary system but consists of three or more objects."

I am ssuming the multiple system here is one where three or more objects orbit a point not located in any of the three objects, otherwise virtually every binary system would also be a multiple system.--Racerx11 (talk) 01:48, 16 January 2012 (UTC)

I think it's a good idea to point out that Sol–Jupiter is the largest, but there's another point to 'binary': the implication that the two objects are comparable. Pluto–Charon are (both DPs if not in the Plutonian system, both planemos regardless), but Sol–Jupiter are not so directly comparable. They're neither a binary star nor a binary planet. Not that that really matters. — kwami (talk) 02:25, 16 January 2012 (UTC)

I'm unsure how to fix it though. Any suggestions on the wording? We would have to explain why Sol-Jupiter is considered binary, since that fact would be unexpected by most readers. If we say...

The Pluto–Charon system is noteworthy for being one of the largest of the Solar System's few binary systems, defined as those whose barycentre lies above the primary's surface. The largest binary system in the solar system, Sun-Jupiter, is also considered binary because their barycentre lies just above the Sun's surface.

...would that be fine?--Racerx11 (talk) 03:03, 16 January 2012 (UTC)

How about, instead, the sentence be deleted. We should ask ourselves is the Pluto-Charon system really so noteworthy after all? How is "noteworthy" defined? If you have to go about making all sorts of extra disclaimers then I question the noteworthy-ness of the original claim. HumphreyW (talk) 03:25, 16 January 2012 (UTC)

Good idea. Personally I am all for simply deleting it.--Racerx11 (talk) 03:33, 16 January 2012 (UTC)

I edited the sentence so it reads: The Pluto–Charon system is noteworthy for being one of the Solar System's few binary systems, defined as those whose barycentre lies above the primary's surface (617 Patroclus is a smaller example).

Another editor added mention of the larger Sun-Jupiter system. I was hesitant in adding this because I thought it would require to much additional explanation as discussed above. Instead of removing it, I linked "Sun and Jupiter" to Jupiter#Mass thinking that this would be a satisfactory explanantion. Hope this will lay the issue to rest.--Racerx11 (talk) 00:10, 18 January 2012 (UTC)

I hope so. People will hear that Pluto–Charon is the largest binary system, so we should address it. It is, of course, if we're thinking of planemos and SSSBs; people just forget about Jupiter, so that should be mentioned too. — kwami (talk) 00:31, 18 January 2012 (UTC)

Classification as a planet

So I'm really disappointed that I was taught in school that pluto was the smallest planet, and now I'm being told it's not, because it's too light. How can a planet one day just disappear (from a scientific perspective)? I'm just saying, for me, it was worse than saying Santa is here, then no he's not, because nobody believed in Santa anyway. Are there any more references that could be added, because even the article seems to indicate that this is a contentious point. My thought is that if Pluto is far enough out, then it's considered a planet. Twigfan (talk) 16:16, 9 December 2011 (UTC)

It is still there, its category has merely been changed. See IAU_definition_of_planet. Your opinion on how a planet should be defined has no bearing. --Daniel 17:24, 9 December 2011 (UTC)

I think he's just asking for clearer support for the classification. Twigfan, the issues are discussed at definition of planet and at IAU definition of planet. — kwami (talk) 20:36, 9 December 2011 (UTC)

Twigfan, it's a matter of definition. Everyone agrees that Pluto is a dwarf planet; the difference in opinion comes in when deciding whether a dwarf planet is a planet (per Stern and a significant minority of astronomers) or a sub-planet (per the IAU and a majority of astronomers). Since this isn't a matter of fact, but only of convention, there is no right answer. Brown at least thinks that the Solar system is more easily understood with 8 planets than with 200; Stern disagrees. — kwami (talk) 00:35, 18 January 2012 (UTC)

I understand why the main article has to be the way it is but also I think the talk page is a good place where all should be free to present arguments pro and con including personal opinions. I think it's a mean and shortsighted decision by astro bureaucrats that stripped Pluto of being a planet. For example, two Americas are one continent and Eurasia two so obviously convention surpasses nature. Second, those competitors of Pluto, basically only one that is "bigger" (is it all about size!!!), are not round, are not rocky, don't have moons or atmosphere. Pluto , albeit small, is a real little world, a miniature planet, round, rocky with moons. In other words so cute and that's why we love it so much! I am sure when in 2015 new photos come in they will be ashamed of that injustice and humiliation. Go Pluto, go! — Preceding unsigned comment added by 31.147.24.201 (talk) 08:53, 30 January 2012 (UTC)

The talk page is not a forum, so it is not a place where one is free to post personal opinions. As for those "competitors", many are expected to be round (only which ones are round is still uncertain, really), some are quite rocky, much more so than Pluto, the largest have transient atmospheres, just like Pluto, and most have moons (but note that the planets Mercury and Venus don't have moons). As for Pluto being a miniature world, so are all the other dwarf planets (whether already identified as such or not). There is no justifiable way to not lump Pluto with all the other dwarf planets. --JorisvS (talk) 10:50, 30 January 2012 (UTC)

The moons' spectral similarity to Charon

May I ask, where does this paper describe the minor moons' spectral similarity to Charon? Thank you very much. Jan.Kamenicek (talk) 17:56, 4 January 2012 (UTC)

Missing sources

I added some citation requests into the article, because I failed to find the information in the given sources and did not see it anywhere else either. They are [1], [2] and [3]. Since this is a featured article, I believe that the information has to be referenced. Jan.Kamenicek (talk) 12:15, 11 January 2012 (UTC)

I agree this needs a reference. I recall reading years ago that the albedos were basically best-fit estimates (as is generally the case). -- Kheider (talk) 14:23, 11 January 2012 (UTC)