Talk:Pluto

Pluto is a planet like other planets are and not a dwarf planet

pluto is not a dwarf planet from the kuiper Belt its the 9th planet from the sun and the farthest and Neptune is not the farthest 46.217.64.77 (talk) 18:24, 16 November 2024 (UTC)

Source, please! _ZZ^Z'S 18:28, 16 November 2024 (UTC)

They are not the only ones saying this. I don't know what their source is, but see https://edition.cnn.com/2018/09/10/world/pluto-planet-status-trnd/index.html which says in part Pluto is most definitely a planet – and should never have been downgraded, say some scientists.

Actually, the problem is the other way round: Pluto should never have been classified as a planet in the first place. Skeptic2 (talk) 07:07, 12 June 2025 (UTC)

Save the Planet Pluto. I think someone should sell merch such as T shirts etc saying that. I'm sure they will sell. Maybe they already do? Andrewa (talk) 20:06, 2 March 2025 (UTC)

It's a non-argument and the headline is misleading. The IAU definition is not ambiguous: there is no alternative definition that returns us to those nine planets, and ones that include Pluto would not bring us to nine, but dozens of planets. Remsense ‥ 论 20:30, 2 March 2025 (UTC)

True. But the IAU is not the only reliable source, and sources do not agree on this. So, we should not in Wikipedia's voice support any one of these POVs, but rather report them all. Andrewa (talk) 00:08, 4 March 2025 (UTC)

WP:NOTFORUM, please. ArkHyena (it/its) 23:38, 2 March 2025 (UTC)

Good point. I was trying, in a humorous way, to point out that there are various POVs on this. And as is said above, we should not endorse any one of them, but rather we should report them all. Andrewa (talk) 00:10, 4 March 2025 (UTC)

Keep in mind that even though the IAU definition isn't "official" (insofar that Alan Stern can call Pluto a planet in all of his papers and nobody can stop him), it is still accepted by astronomers and broadly acknowledged by planetary scientists. Additionally, we cannot report every caveat lest each Wikipedia article be hopelessly lengthy, so we consolidate: the IAU definition of a planet and competing/alternative definitions are discussed on Definition of a planet, and we link there when appropriate. ArkHyena (it/its) 00:15, 4 March 2025 (UTC)

OK, I should have said every significant POV. Agree that we cannot report every caveat. I think that is obvious. But is it now clarified? Andrewa (talk) 01:13, 4 March 2025 (UTC)

Pluto is Planet Nine

Pluto is Planet Nine because it is round, it orbits the sun, its geologically active. Pluto is the ninth and outermost planet in our solar system! Gage3491 (talk) 23:52, 11 June 2025 (UTC)

It's not a planet under the IAU definition because if it is then Eris is too cause it's bigger and a lot more than 9 things are round Ceres is one of them. Planet Nine is about the possible planet in a specific area of the sky beyond Pluto if Pluto was a planet it'd be Planet Ten. Sagittarian Milky Way (talk) 01:17, 12 June 2025 (UTC)

^ user was blocked indefinitely 2603:6080:21F0:6C00:A1BF:6180:21F3:8B91 (talk) 10:04, 28 September 2025 (UTC)

Infobox color/minor planet number in the infobox

Is there a reason why the Pluto infobox has its own unique color-scheme, even though all other TNOs (including the consensus dwarf planets) have the blue TNO minor planet one? After all, isn't Pluto also a Kuiper Belt object?

When you look at the Asteroid minor planet infobox color-scheme, even Ceres (a dwarf planet) shares it.

Additionally, I noticed that a month ago an editor removed Pluto's minor planet number from the infobox name - should this edit be kept? And if so, only in Pluto's case or in the cases of other consensus dwarf planets beyond Neptune? IvarTheBoneless123 (talk) 18:52, 21 June 2025 (UTC)

I think your suggested change makes sense, so I made it.

With that said, perhaps somewhere there ought to be a codification of the colour palette being used... Double sharp (talk) 15:24, 5 July 2025 (UTC)

I see that you also edited the MP number back in the infobox - which is fine, but personally I think it might be better to only keep the name (no MP number) at the top of the infobox in regards to consensus dwarf planets in general: my reasoning being that it would add to their distinction to other minor planets since the infobox name is one of the first things a reader sees when looking at a page.

With that out of the way - the reason why I insisted on Pluto having the KBO color scheme is that, unlike the planet/moon infoboxes, the minor planet infobox (and its variant color schemes) are actually applied consistently across Wikipedia, so Pluto really was sticking out like a sore thumb in that context.

As for the planet/moon infobox color schemes: yes, these really are in desperate need for at least some kind of standardization. At first I thought that the moon infobox was only variant in regards to color scheme when applied to the 'big 7' (the 7 satellites larger than the largest dwarf planet) but than I realized that Triton has the same generic magenta color scheme as every other moon.

Also, Phobos and Deimos, the tiny captured moons of Mars also have their own infobox color scheme for some reason.

And then there's Charon, the (relatively) massive moon of Pluto itself - it also has its unique color scheme.

My thinking, in regards to what infobox color schemes should look like, would be:

1) a 'terrestrial planet' color scheme (including Mercury, Venus, Earth and Mars)

2) a 'gas giant' infobox (Jupiter and Saturn)

3) an 'ice giant' infobox (Uranus and Neptune)

4) the non-spheroidal moons having the generic moon infobox color scheme (in the absence of data, as is the case for most KBOs for example, the generic moon infobox color scheme would be appropriate IMO).

5) the spheroidal moons having their own new infobox color scheme (with possible color variations to indicate the planet/dwarf planet they are orbiting?) IvarTheBoneless123 (talk) 20:30, 5 July 2025 (UTC)

It seems that currently the 8 major planets have their own individual colour schemes matching somewhat their real colours. Rather clever; what was inexplicable was that Pluto was following it and not some other objects that had their real colours known, like Io. (But for some reason Titan has its actual colour. Go figure.)

I do like the idea of keeping the big 8 the way they are, but classifying spherical vs non-spherical moons after that certainly makes more sense with your scheme (at the very least it'd require much less work changing things). Because I guess logically if all 8 planets get their colours, then the moons logically should have their parent planet's colour, and that's a whole lot of work changing small irregulars' infoboxes. :P Double sharp (talk) 16:51, 6 July 2025 (UTC)

I like the idea of coupling moons' infobox colors to their parent planet's color, it's another useful cue for readers to tell at a glance which moon orbits which planet. I'm not sure how to deal with the dwarf planets. As Pluto shows, they're more than capable of hosting complex, "planetary-style" satellite systems, and as our ability to detect fainter objects improves we're only going to find more dwarf planet moons. But that also couples with the fact that there's a lot of dwarfs out there, so ambiguity is hard to avoid either way... ArkHyena (they/any) 23:25, 6 July 2025 (UTC)

Really I'm fine with whatever - as long as there's some measure of consistency.

I still (slightly) prefer the moon infobox color scheme being divided into two instead: spheroidal and non-spheroidal moons - it feels really odd lumping in some 1 km sized space junk with, say, Ganymede or Titan in terms of them having the same color scheme in the infobox. IvarTheBoneless123 (talk) 10:42, 7 July 2025 (UTC)

Though I suppose we're already doing that with the asteroids and KBOs when we're including the dwarf planets within their color schemes... IvarTheBoneless123 (talk) 10:44, 7 July 2025 (UTC)

Backstory for the 2006 reclassification

I just added a paragraph about Brian Marsden's original 1998 proposal to assign Pluto a minor planet number. Marsden had first suggested in 1980 to stop calling Pluto a planet and instead consider it a minor planet.[1] That background did not go unnoticed, and the public outcry following in late 1998 and early 1999 urged the IAU to issue a press release, to "clarify" Pluto's planet status.[2][3] I believe this episode played an important role in why the subsequent reclassification in 2006 was perceived as a demotion by so many.

I don't know if there's a reason why this was left out of the article so far. If so then please let me know. Renerpho (talk) 03:24, 27 June 2025 (UTC)

Let me paste the full text of the 1999 IAU press release here, because I think it is quite a remarkable document. It is in the public domain as a NASA publication. [4] Quote:

IAU Press Release 01/99
For immediate release
February 3, 1999
THE STATUS OF PLUTO: A CLARIFICATION

Recent news reports have given much attention to what was believed to be an initiative by the International Astronomical Union (IAU) to change the status of Pluto as the ninth planet in the solar system. Unfortunately, some of these reports have been based on incomplete or misleading information regarding the subject of the discussion and the decision making procedures of the Union.

The IAU regrets that inaccurate reports appear to have caused widespread public concern, and issues the following corrections and clarifications:

1. No proposal to change the status of Pluto as the ninth planet in the solar system has been made by any Division, Commission or Working Group of the IAU responsible for solar system science. Accordingly, no such initiative has been considered by the Officers or Executive Committee, who set the policy of the IAU itself.
2. Lately, a substantial number of smaller objects have been discovered in the outer solar system, beyond Neptune, with orbits and possibly other properties similar to those of Pluto. It has been proposed to assign Pluto a number in a technical catalogue or list of such Trans-Neptunian Objects (TNOs) so that observations and computations concerning these objects can be conveniently collated. This process was explicitly designed to not change Pluto's status as a planet.
   A Working Group under the IAU Division of Planetary Systems Sciences is conducting a technical debate on a possible numbering system for TNOs. Ways to classify planets by physical characteristics are also under consideration. These discussions are continuing and will take some time. The Small Bodies Names Committee of the Division has, however, decided against assigning any Minor Planet number to Pluto.
3. From time to time, the IAU takes decisions and makes recommendations on issues concerning astronomical matters affecting other sciences or the public. Such decisions and recommendations are not enforceable by national or international law, but are accepted because they are rational and effective when applied in practice. It is therefore the policy of the IAU that its recommendations should rest on well-established scientific facts and be backed by a broad consensus in the community concerned. A decision on the status of Pluto that did not conform to this policy would have been ineffective and therefore meaningless. Suggestions that this was about to happen are based on incomplete understanding of the above.

The mission of the IAU is to promote scientific progress in astronomy. An important part of this mission is to provide a forum for debate of scientific issues with an international dimension. This should not be interpreted to imply that the outcome of such discussions may become official IAU policy without due verification that the above criteria are met: The policy and decisions of the IAU are formulated by its responsible bodies after full deliberation in the international scientific community.

Johannes Andersen
General Secretary, IAU

(End quote) Renerpho (talk) 03:35, 27 June 2025 (UTC)

"1930 BD" listed at Redirects for discussion

The redirect 1930 BD has been listed at redirects for discussion to determine whether its use and function meets the redirect guidelines. Readers of this page are welcome to comment on this redirect at Wikipedia:Redirects for discussion/Log/2025 July 8 § 1930 BD until a consensus is reached. -insert valid name here- (talk) 02:32, 8 July 2025 (UTC)

@-insert valid name here-: Curious... I think there's more to this than what came out in the deletion discussion. That designation isn't correct, so I agree the redirect should have been deleted, but it's not a simple mistake. The Wikipedia article for some time said:

Because Pluto was nowhere near the asteroid belt (trans-Neptunian objects would not be discovered until much later), it never got an asteroidal provisional designation; had it obtained one, it would probably have been "1930 BD".

This was added in November 2005, and was removed about 3 months later. Luckily, User:Urhixidur who wrote this has been an active admin at the time, and still is, so maybe they remember where they got this from? Does anyone know when the designation "1930 BM" was actually assigned? Did this happen in 2006 when Pluto was reclassified? Renerpho (talk) 10:59, 23 February 2026 (UTC)

Equatorial rotation velocity

I made an edit to the Equatorial rotation velocity and I'm having second thoughts on whether I did the conversion correctly. I will check it in the morning. S Philbrick(Talk) 00:01, 2 October 2025 (UTC)

I did make an error, now corrected.

Here's the values I picked up from the citation:

Pluto Equatorial Radius 1188.3(km) Sidereal Rotation Period -6.3872 (d)

Calculation: Equatorial Radius*2*PI/Sidereal Rotation Period/24=-48.71

Then use built in converter to convert to m/s so it displays 13.53 S Philbrick(Talk) 01:58, 2 October 2025 (UTC)

Discussion at Wikipedia talk:Featured topics/Dwarf planets

A discussion involving this object is taking place at Wikipedia talk:Featured topics/Dwarf planets#Unhelpful short descriptions. Everybody is welcome to comment there. Renerpho (talk) 17:44, 20 October 2025 (UTC)

True color?

Is this really Pluto's true color?

From New Horizons specifications - "MVIC Bands: There are six channels that use Time Delay Integration and another that takes a frame and is for navigation."

"2 panchromatic channels (observing light wavelengths from 400 to 975 nm): - Blue (400–550 nm) - Red (540–700 nm) - Near infrared (from 780 up to 975 nm light wavelengths) - methane band (860–910 nm)"

Do all these above frequencies combine to the infobox image of Pluto, and is such an image in true color? And if not, what would be? IvarTheBoneless123 (talk) 12:01, 21 November 2025 (UTC)

Uncertainty?

Guys what is the uncertainty of Pluto's radius, I saw 2 sources being 1188.3±1.6 km which means its diameter is 2376.6±3.2 km but there's one saying it's 1188.3±0.8 km the uncertainty accidentally decreased then it would make diameter 2376.6±1.6 km and the sources are like all published in 2015/2016 I believe? Which ref is right guys My planet is Homlos (talk) 03:13, 21 February 2026 (UTC)

@My planet is Homlos: Quote from the abstract for Nimmo et al. 2017: The resulting mean radii of Pluto and Charon are 1188.3 +/- 1.6 km and 606.0 +/- 1.0 km, respectively (2-sigma). The 2-sigma uncertainty for the radius is 1.6 km. We generally give 1-sigma uncertainties (compare 68–95–99.7 rule), which would be 0.8 km. The same is true for Charon (moon), which correctly gives the uncertainty as 0.5 km. Reverting your edit from 30 January 2026. Renerpho (talk) 11:23, 22 February 2026 (UTC)

Links to water and water ice

As noted by User:My planet is Homlos on 20000 Varuna, water was never linked in that article. In an attempt to determine if it should be linked, I looked at our articles about Dwarf planets, and found that none of them (including Pluto) have such a link. Haumea, Sedna, Gonggong and Orcus are the only ones with a link to water ice, even though all of those articles mention it, sometimes very heavily as in Quaoar. Haumea has had such a link since c.2008, Sedna only since my own edit from 25 September 2025.

I wonder why that is? If there has been any prior discussion about this then I cannot find it. The only reason I can think of to omit these links is that water is rather common, but I don't think that argument should be applied here, where the water is generally in an unfamiliar state.

Shouldn't water (or possibly Water#Distribution in nature, or Extraterrestrial liquid water when we're talking about liquid water), water ice, and subsurface ocean all be linked from the articles that mention them? I believe all three should be consequently linked at first instance of the term. Renerpho (talk) 11:13, 22 February 2026 (UTC)

Ok I guess I'll look for some TNO articles that mentioned them, and I'll link them My planet is Homlos (talk) 01:20, 23 February 2026 (UTC)

My comment wasn't meant as an assignment. I genuinely wonder if others think they should be linked or not! Renerpho (talk) 07:59, 23 February 2026 (UTC)

Oh sorry I misunderstood My planet is Homlos (talk) 09:19, 23 February 2026 (UTC)

I think generally we avoid linking common terms, like years and countries, per WP:Not a dictionary, because they seldom add any relevant information. (If you're reading about a particular language in Nigeria, then a link to the country isn't likely to illuminate anything about the language, and if you don't know where Nigeria is, you can look it up yourself, confident that we'll have an article on it. But a link to 'languages of Nigeria' might be helpful, as it could take you some time to find it yourself, if you even know to look for it.)

If it's just 'water' or 'ice', then the reader is unlikely to get anything from the links. If however the usage is more specific -- phases of ice, or density of ice under pressure, or distribution of water in the outer SS -- then a link to an article or section on that specific topic might be beneficial. 'Subsurface ocean' might too, as that's not a routine concept for most readers. Readers might not realize we have such articles. But water and ice are something they can look up for themselves, and probably not because they're reading this article.

Too many links and we end up with a WP:Sea of blue, which not only isn't useful, but obscures links that would be useful. — kwami (talk) 03:58, 24 February 2026 (UTC)

Oh ok I'll remove my edits in Pluto and Varuna now My planet is Homlos (talk) 04:02, 24 February 2026 (UTC)

I reverted them already kwami (except water ice in Pluto) My planet is Homlos (talk) 04:12, 24 February 2026 (UTC)

WP:Sea of blue is a fitting argument to get rid of some water. :) I'll see if I find some more links like that, and remove them accordingly. As you said, kwami, 'Subsurface ocean' is likely a good article to link from the TNO articles that discuss that possibility (which I believe are quite a few by now). Renerpho (talk) 10:05, 24 February 2026 (UTC)