Talk:Pluto

"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)

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)

active image of Pluto's orbit

-Have been seeking answers on Gemini for Astronomical facts. NASA and Wikipedia are often cited as its sources. -Can't tell you how many times---and in how many completely absurd ways---A.I. has given me wrong answers.

But, for roughly a month, A.I. has claimed that Pluto's Perihelion is very close to Pluto's high point above the Invariable Plane. And---less consistently---that, were a clock superimposed over our Solar system, Pluto's Perihelion happened at ~2 minutes after 12:00: on the Minute-Hand. -In 1989, last. The moving graphic on the map shows both Pluto's Perihelion and Aphelion as being far from the highest- and lowest points of Pluto's orbit. -Which (OP) may actually be about 90° turned. -With Pluto's Aphelion (thus low point) being at ~0:32:00. -With the Aphelion distance being roughly 1.67 times Pluto's Perihelion's distance.

Is A.I. still feeding me inaccuracies? Or would it be nice if the image were to replicate the above paragraph's positions? ~2026-12034-19 (talk) 23:27, 3 March 2026 (UTC)

Sounds like AI is feeding you inaccuracies. I'm not telling you to get your info from Wikipedia, but it's a starting point (a much better one than any of the chat bots that are currently around). Renerpho (talk) 23:36, 3 March 2026 (UTC)

Wrong surface area

The surface area stated in the article is wrong, it is the result of a simple 4*pi*r^2 but is way off from the real result of 16,647,940km2, (source from NASA: https://solarsystem.nasa.gov/pluto-by-the-numbers/) ~2026-18317-68 (talk) 12:19, 26 March 2026 (UTC)

@~2026-18317-68 Feel free to change it! – LuniZunie_(talk) 12:21, 26 March 2026 (UTC)

LuniZunie Not so fast, please. The mean radius is defined as the radius of the sphere with the same volume as the object, so a "simple" calculation is okay for the volume. I'm not sure about the area, but that NASA source has values for the radius (1151 km), and equivalently for the volume, that are very far from what we give in the article (1188.3 km), and I think our value is better than theirs. Our numbers are based on published papers, whereas NASA's sources are... not specified... and I'm skeptical about what that NASA page is saying. NASA's public outreach sites are not necessarily a very reliable source for information of this kind. Renerpho (talk) 14:35, 26 March 2026 (UTC)

I should have clarified this, what I meant by this was to remind them that Wikipedia can be edited by anyone, yes it is good to go to the talk page of course, but it is also important to remind newcomers that they can edit in the first place, especially when the edits are good faith. Yes it may be reverted, but I would rather a newcomer be reverted (and hopefully sent a nice message) but have had a taste of editing to hopefully continue editing, than to go to the talk page and be told no and then never come back. – LuniZunie_(talk) 14:39, 26 March 2026 (UTC)

Fair.

@~2026-18317-68: Note that the NASA page warns that their numbers are approximations, and to refer to JPL for the actual numbers. https://ssd.jpl.nasa.gov/planets/phys_par.html#refs has the "real" value for planetary radii, at least per the last update to that page (2019). Renerpho (talk) 14:51, 26 March 2026 (UTC)

So, Pluto is bigger than Russia in surface area after all Homlos (Message me bro) 08:12, 27 March 2026 (UTC)

@My planet is Homlos: Yes. That's nothing new -- Pluto's actual size has been known since about a year before New Horizons flew by it on 15 July 2015 -- although Wikipedia for quite a while wasn't using the most recent sources (or, in some cases, was misinterpreting them).

Up until 2006 or so, our best estimate for Pluto's size was around 1150 km, and we said so for a long time. For some time before the flyby, there was conflicting information in the article without there actually being any real uncertainty in the up-to-date scientific literature. Compare the state of the article in 2010 (Special:Diff/396362264, adding a 2006 source), March 2014 (Special:Diff/600677187, adding a 2014 source but leaving the -- now outdated -- 2006 source standing), and 13 July 2015 (Special:Diff/671302077, finally removing the redundant number).

That the fact sheet in https://solarsystem.nasa.gov/pluto-by-the-numbers/ still uses a radius estimate that has been known to be false for over a decade is a bit sad, but expecting them to update those pages may be expecting too much. At least their numbers aren't nonsense; they've just been outdated for 20 years.

The question of what's bigger, Pluto or Russia, has been answered one way or the other, depending on what number (~1150 km or ~1185 km) has been used. The answer is now unambiguous (Pluto is bigger), regardless of whether you use the surface area given in Russia, or that given in Geography in Russia (the two Wikipedia articles famously cannot agree on how big Russia is). Renerpho (talk) 23:22, 27 March 2026 (UTC)

History of mass estimates

@Tioseafj: Thanks for removing the circular citation to a Wikipedia clone in this edit (10 March 2026). I have now removed the entire statement ("The mass is much less than thought before Charon was discovered") as factually wrong, or at least misleading.

As I noted in the edit summaries to my most recent edits, some context about the history of mass estimates for Pluto had been missing in the §Planet X disproved section. For the decades following Pluto's discovery, its mass was overestimated; the last such estimate I could find dates to 1971. However, the true mass was essentially known by 1976, at least to much better than an order of magnitude, two years before Charon was discovered. One source for the confusion seems to be that we were citing a book from 1997 that itself quoted and commented on the relevant 1976 paper; and some important nuance was lost there.

The way we phrased this, we were giving the wrong impression that the 1976 paper's mass estimate was a lot larger than what the authors were actually saying, which I hope becomes clearer by citing the actual paper. The exact phrasing had been added in Special:Diff/670667005 (9 July 2015), likely intended to be synonymous with what was there before, but actually saying something quite different. The Wikipedia mirror was added as a source in 2022, but of course they got that information from us. Renerpho (talk) 00:57, 28 March 2026 (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)

@Anonymsiy What is your take on the current Pluto infobox image? True color or not? IvarTheBoneless123 (talk) 19:45, 14 May 2026 (UTC)

The question depends on what you mean by "true color". Unfortunately, those wavelengths don't correspond to the range of wavelengths that the human eye can detect, so there is no way in principle to combine them into what you'd see with your own eyes, or even into an image that looks like what you'd get with a well-calibrated camera that captures an RGB image.

This image is an approximation that tries to use the available data to mimick what the human eye would see, and it's probably somewhat close. Jason Perry's comment at Talk:Io_(moon)#c-Volcanopele-20240125221100-Nrco0e-20240123220900 applies to this, just like to every other photo ever taken by a spacecraft. There is no actual "true color", but there are approximations that maybe deserve being called "true color".

And in that latter sense, yes, the photo used here is "true color". Renerpho (talk) 22:15, 14 May 2026 (UTC)

From the file description (which is quoting pluto.jhuapl.edu):

These natural-color images result from refined calibration of data gathered by New Horizons' color Multispectral Visible Imaging Camera (MVIC). The processing creates images that would approximate the colors that the human eye would perceive, bringing them closer to “true color” than the images released near the encounter.

Closer to true color than anything else we have. Renerpho (talk) 22:27, 14 May 2026 (UTC)

honestly, unless the image departs significantly from approx. true color and there is a more accurate alternative of at least similar quality—to where maintaining the older image is clearly detrimental for the reader's understanding of the object—these types of discussions really tread towards WP:BIKESHEDding territory ArkHyena_woop! (she/they/it) 22:39, 14 May 2026 (UTC)

+1 on that. Renerpho (talk) 00:03, 15 May 2026 (UTC)

@ArkHyena: The question may be related to this comment from yesterday. Renerpho (talk) 00:06, 15 May 2026 (UTC)

Yeah, I'm probably getting unhealthily obsessed and I will let it go. But what prompted my follow up comment was the simple frustration of not getting any reply to my original post from 6 months ago and a desire for some clarification (which I got now, thank you Renerpho). IvarTheBoneless123 (talk) 10:47, 16 May 2026 (UTC)

Semi-protected edit request on 19 May 2026

Change the Sidereal rotation period from −6.387230 d to -6.387222 d

Explanation: The sidereal day duration is - 6 days, 9 hr, 17.6 min according to the source 9 of this article i.e https://cseligman.com/text/sky/rotationvsday.htm this is accuratelly displayed as −6 d, 9 h, 17 m, 36 s within the table.

But the conversion to days seems to be wrong: −6 d, 9 h, 17 m, 36 s is 551856 s or 6.387222 d

The corrected value will also be consistent with https://ssd.jpl.nasa.gov/planets/phys_par.html Artriant (talk) 01:54, 19 May 2026 (UTC)

 Not done: according to the page's protection level, you should be able to edit the page yourself. If you seem to be unable to, please reopen the request with further details. Day Creature (talk) 03:06, 19 May 2026 (UTC)

Ok thanks im eligible to edit now. Done. When i did the request i had 9 edits :] Artriant (talk) 23:14, 19 May 2026 (UTC)

Why is Mercury nowhere mentioned?

For some time in the past, Mercury and (then-considered-a-planet) Pluto were thought to be similar in size. So why wasn't this mentioned anywhere in the History section? ~2026-33827-66 (talk) 03:11, 8 June 2026 (UTC)

The history of downward revisions of the mass estimate are documented in Pluto#Planet X disproved. The earliest estimates were close to Earth-size. –LaundryPizza03 (dc̄) 03:24, 8 June 2026 (UTC)

But one of those estimates considered it to be similar to Mercury in size. Mercury explicitly was used as a point of reference for size comparison. So... why isn't this mentioned? (The dwarf planet article currently says this with a citation that mentions Mercury.) ~2026-33827-66 (talk) 03:42, 8 June 2026 (UTC)

The source also describes early estimates of Pluto's diameter, so I will be working that in as well. –LaundryPizza03 (dc̄) 03:56, 8 June 2026 (UTC)

The 1976 estimate of its size is reported to be smaller than the Moon; Mercury is intermediate in size and mass between the Moon and Mars. Is that good enough? –LaundryPizza03 (dc̄) 04:19, 8 June 2026 (UTC)

Semi-protected edit request on 24 June 2026

please change the following text to the text afterwards. I dont know how to change the referencing but a new one needs to be added.

Pluto's surface is quite varied, with large differences in both brightness and color.[115]

Pluto is one of the most contrastive bodies in the Solar System, with as much contrast as Saturn's moon Iapetus.[116] The color varies from charcoal black, to dark orange and white.[117] Pluto's color is more similar to that of Io with slightly more orange and significantly less red than Mars.[118] Notable geographical features include Tombaugh Regio, or the "Heart" (a large bright area on the side opposite Charon), Belton Regio,[6] or the "Whale" (a large dark area on the trailing hemisphere), and the "Brass Knuckles" (a series of equatorial dark areas on the leading hemisphere).

Sputnik Planitia, the western lobe of the "Heart", is a 1,000 km-wide basin of frozen nitrogen and carbon monoxide ices, divided into polygonal cells,

to....

Pluto's surface is quite varied, with large differences in topography[xxx], brightness, and color.[115, xxx].

Pluto is one of the most contrastive bodies in the Solar System, with as much contrast as Saturn's moon Iapetus.[116] The color varies from charcoal black, to dark orange and white.[117] Pluto's color is more similar to that of Io with slightly more orange and significantly less red than Mars.[118] Notable geographical features include Tombaugh Regio, or the "Heart" (a large bright area on the side opposite Charon), Belton Regio,[6] or the "Whale" (a large dark area on the trailing hemisphere), and the "Brass Knuckles" (a series of equatorial dark areas on the leading hemisphere).

Sputnik Planitia, the western lobe of the "Heart", is a 1,000 km-wide 3-km-deep [xxx] impact basin partially flooded with frozen nitrogen and carbon monoxide ices,

[xxx] Schenk, P., and others, Basins, fractures and volcanoes: Global cartography and topography of Pluto from New Horizons, 2018, Icarus, 314, 400-433.

File:Figure1 pmap cyl KH301-4x.jpg

Global 3-color map of Pluto, from New Horizons imaging acquired in 2015 [xxx reference].

File:Figure2 pdem Z cyl-corr-r-4x

Global topographic map of Pluto, derived from stereo images acquired in 2015 by New Horizons. Displayed range is -6 to +6 km. [reference xxx].

Diverpawl (talk) 22:03, 24 June 2026 (UTC)

@Diverpawl: I've done part of it. I'm not sure what you mean to do with the two non-existent files mentioned in your edit request. Renerpho (talk) 00:47, 25 June 2026 (UTC)

thanks. I wanted to insert them next to the new text but could not figure out how. how do I send or post the images? Diverpawl (talk) 01:18, 25 June 2026 (UTC)

@Diverpawl: After making sure that the images you want to use aren't restricted by copyright, you upload them to https://commons.wikimedia.org. Renerpho (talk) 02:11, 25 June 2026 (UTC)

You will need to wait until you are autoconfirmed before you can upload files to Wikipedia (Or you can go through the Files for upload process, which is recommended for new users), or if the images are available under a permissive license, you can upload them to Wikimedia Commons. Umby 🌕🐶 (talk) 02:14, 25 June 2026 (UTC)

If (as I suspect) those images are two of the figures from the Schenk et al. paper, then those are copyrighted, and I see no evidence that they come with a suitable license. Which means there's no way to add them to the article. Renerpho (talk) 02:17, 25 June 2026 (UTC)

I made them personally. I will modify them to have lat-lon labels. they are available publicly at:

https://astrogeology.usgs.gov/search/map/pluto_new_horizons_lorri_mvic_global_dem_300m

https://astrogeology.usgs.gov/search/map/new-horizon-global-mosaics

https://science.nasa.gov/photojournal/pluto-color-map/

thanks for the assistance. love WP. Diverpawl (talk) 06:42, 25 June 2026 (UTC)

@Diverpawl: Thanks! The last one already exists: File:Pluto color mapmosaic.jpg. The other two should actually be fine, per PD-USGov-NASA. I'm not sure if we really need the b/w-map (we already have this one, which may actually be the same image). The height map looks like a good addition though! We also have File:Burney Topology.png, which seems to be an excerpt from the global map.

Feel free to upload the height map to Commons, and then post a link to it here. You can use the same license as used in the Burnley image. Then we can look where to add it to the article. If you need help along the way, just ask here again. Renerpho (talk) 21:01, 25 June 2026 (UTC)