Talk:Pluto/Archive 1

(Untitled discussions)
I think that it is well worth including an account of the discarded specular reflection theory as an illustration of the point that although scientists have many neat ideas, the neat ideas that actually work are a painfully small minority. -- Alan Peakall 12:45 Feb 21, 2003 (UTC)

This sentence is silly:


 * There is mounting evidence that Pluto may in fact be a member of the Kuiper Belt, only one of a large number of distant icy bodies.

...because the definition of the Kuiper belt, "an area of the solar system extending outwards from the orbit of Neptune (at 30 AU) to 50 AU," clearly inclueds Pluto.

Perhaps the sentence should read:


 * There is mounting demand among astronomers that Pluto should no longer be classified as a planet but only a member of the Kuiper Belt.

--Uncle Ed 18:22 Feb 26, 2003 (UTC)

Or maybe:


 * There is mounting evidence that Pluto should no longer be classified as a planet, but only a member of the Kuiper Belt.

otherwise these pesky astronomers seem to be demanding on a whim! -- Tarquin 19:10 Feb 26, 2003 (UTC)


 * However, there is no real reason not to also call Pluto a planet, since the definition of "planet" is "whatever IAU points to and calls a planet". The debate has never been over whether to "demote" Pluto, but rather whether to add a category which it falls into. I think that the existing wording is just fine. Bryan

"Pluto orbits in a 3/2 resonance with Neptune." -- what does that mean? resonance doesn't seem to be about orbits and planets. -- Tarquin 11:02 Mar 28, 2003 (UTC)


 * When Neptune approaches Pluto from behind, they start to pull on each other slightly, and you get one of those complicated interactions of the same sort that produce Trojan points, L4 & L5, etc. Since the orbits are eccentric, the 3/2 periodic ratio is favoured because this means Neptune always passes Pluto when they're almost furthest apart. On the other hand, half a Pluto orbit later, it seems like Neptune's about to catch up to Pluto, but Pluto speeds up with the acceleration from the Sun, stays ahead of Neptune, and pulls ahead, until they meet again on the other side of Pluto's orbit.
 * So while it isn't one of the more common uses of the term resonance, it is a resonance. -- John Owens 11:27 Mar 28, 2003 (UTC)

Thanks. I was asking more for the benefit of the Constant Reader than myself, so the above is best off in the article :-) -- Tarquin 15:59 Mar 28, 2003 (UTC)
 * ... ah, I see someone has linked to Orbital resonance. cool. :-) -- Tarquin 16:00 Mar 28, 2003 (UTC)

Would someone please shuffle around the paragraphs of Pluto (planet), so all the debate over "planet vs. Kuiper Belt object" is in one place? I think our readers are more interested in its location, orbit, and other characteristics; followed by how the heck those science johnnies found it in the first place; and also might be amused by the Great Status Debate -- but let's not scatter all the planet vs. object stuff all throughout the article. --Uncle Ed 20:22 Apr 4, 2003 (UTC)

Does anyone know why the picture of Pluto is all red and orangey? What kind of camera/imaging technique was used? --dave


 * I have no idea what the case is for this particular picture, it could be a false color image, but I recall reading in multiple sources that Pluto really does have a reddish color. The red comes from complex organic compounds formed when methane ice on the planet's surface is hit with ultraviolet light. Bryan

From what I've read Pluto doesn't reflect much light, and just shows up as grey/white. -- User:goatasaur

Yeh. I've read it's grey. -PY

According to http://webs.wichita.edu/lapo/o40.html it's red. Perhaps it's a matter of whether the atmosphere is frozen out or not. Bryan

You have got to be kidding.
The statistics on Pluto show:

Mean radius 5.91352×109 km

Divide that by one million and you at least have the right order of magnitude. Whether the figure is right in that case, I don't know, but the order of magnitude is majorly wrong.


 * That's the orbital radius (it's under the "Orbital characteristics" heading). The planet radius is correctly reported as ~2300 km. At18 12:09, 23 Nov 2003 (UTC)

Pluto's moon section
Had this in it:

(this is due to the fact that Charon's period of revolution about Pluto and the time it takes for Pluto to turn once on its axis are almost identical - though not exactly identical: At the time of Pluto's discovery in 1930, Charon happened to be positioned directly behind Pluto as seen from Earth, preventing it from being discovered; over the next 48 years, however, the infinitesimal difference between the periods of Charon's revolution and Pluto's rotation had sufficiently built up to allow Charon to "peek out" from behind Pluto from a terrestrial perspective, enabling Charon to be discovered then)

As far as I can tell, this entire parenthetical is inaccurate. Charon is completely tidally locked with Pluto, not just nearly so. It wasn't discovered initially because telescopes just weren't that good back then, not because it was hidden behind Pluto. Even if it was its orbital period is 6 days, so it wouldn't take anywhere near 48 years for it to "peek out" from behind Pluto. Bryan 08:44, 26 Mar 2004 (UTC)


 * Yeah, it seems that way. &mdash;Bkell 09:22, 26 Mar 2004 (UTC)

Not a "smoking gun", but...
This appears on page 662 of the 2004 World Almanac:

"At the U.S. Naval Observatory in Flagstaff (Arizona), in 1978, James Christy obtained a photograph of Pluto that was distinctly elongated. Repeated observations of this shape and its variation were convincing evidence of the discovery of a satellite of Pluto, now named Charon." (Presumably previous photos of Pluto taken between 1930 and 1978 did not show this "distinct elongation" - and if not, why not?).


 * Because telescopes weren't good enough before then. Look at the best photograph we have now in 2004&mdash;it's a blurry circle. I doubt telescopes in the 1940s were able to see Pluto as anything more than a dot.


 * Charon goes around Pluto in fewer than seven days. If you have a telescope that can resolve Charon, you would be able to observe a complete revolution in a week, not 48 years. Christy was able to observe the variation in the shape, after all; there would be no variation to observe if it took years and years. The reason Charon wasn't discovered until 1978 is that telescopes weren't good enough, not because Charon was hiding behind Pluto. &mdash;Bkell 10:44, 28 Mar 2004 (UTC)

This was not my contention at all; what I was trying to assert is the possibility that, say, Pluto's rotation period could be something like 6 days 9 hours 17 minutes and 36.2435 seconds while Charon's revolution period might be 6 days 9 hours 17 minutes and 36.2436 seconds or something like that. Over many (Earth) years, this difference would have eventually caused the apparent relationship between the two bodies to change ever so slightly - much like the difference between the Julian calendar and the actual solar year caused the seasons to change ten days too early by the 16th Century.


 * Erm, what? That would only change which face of Pluto faces Charon. How would it have anything to do with the "distinct elongation" that would be visible in the 1978 photograph? I don't follow your reasoning at all. &mdash;Bkell 12:22, 28 Mar 2004 (UTC)


 * The reasoning just isn't right. An astronomer can observe Pluto at any time (any phase) in its rotation period. We aren't forced to look only when one spot on Pluto is underneath the Sun. Thus, in the last 74 years, Pluto has been observed many times with Charon on one side, with Charon on the other side, with Charon hidden, with Charon in front. -- hike395 15:16, 28 Mar 2004 (UTC)

Possibility of rings
On page 409 of the 2004 TIME Almanac, there is a horizontal row in the table marked "(Number of) Rings." Under Pluto a "?" appears - in stark contrast to the definitive "0" entered for Mercury, Venus, Earth and Mars (the numbers for Jupiter Saturn, Uranus and Neptune being 3, 1,000, 11, and 4 respectively).

In addition, Pluto's density of 32% of Earth's is far closer to that of Jupiter, Saturn, Uranus and Neptune (the four known ringed planets, with density ratios of 24%, 12%, 23% and 30% of Earth's respectively) than to that of Mercury, Venus and Mars (at 98%, 95% and 71% respectively). Since Pluto seems to take after the other outer planets in this respect, shouldn't the possibility exist that it also takes after them as per other characteristics as well (the existence of rings)?


 * Pluto is not a planet. Are there any other planetoids (asteroids, KBOs etc.) with rings? &mdash; Jor (Talk) 12:35, 28 Mar 2004 (UTC)


 * Don't forget that Pluto is very different to the other outer planets - the four ringed planets are extremely massive compared to the five smaller planets, and Pluto is a midget compared to the latter five. I'm no expert on planetary rings but I would guess that there's a good reason why none of the smaller planets have rings - probably something to do with the smaller Roche limits of those worlds. It seems very improbable to my mind that Pluto has any rings, so I would guess that Time is playing safe: we know for sure that eight of the nine planets have rings but we don't know this for sure yet in Pluto's case. -- ChrisO 12:45, 28 Mar 2004 (UTC)


 * I agree with Jor and ChrisO. A question mark in the Time Almanac is not a definitive source for rings. How about a scientific paper? Rings only occur in the super massive planets. The density of the planet is irrelevant. Finally, scientists do have occultation data for Pluto... If there were a ring system, it would occlude the starlight in a special pattern. This is how the rings of Uranus were discovered. No such pattern has been discovered, hence there is no evidence of rings. --- hike395 15:09, 28 Mar 2004 (UTC)

The Image?
Well, the image that is there is a blatant lie. There is a far better image of Pluto (in color no less) over at some nasa site. However, being a n00b, I haven't the slightest clue how to not violate copyright. So someone either needs to get that image, or to change the caption on the current one. Ctachme 04:02, 8 Apr 2004 (UTC)


 * Nice! If it's a NASA image it is likely in the public domain. Anyone see any reasons why it might not be? Bryan 04:07, 8 Apr 2004 (UTC)

Pluto a KBO?
Who says what is a planet and whats not? some stupid astronomers that dont even know what planet means? There are also theories to classify as planets those objects that have more than 360km of diameter, the size enough when gravity pulls in the way that a planet gains round shape. And I strongly agree with this. Pluto can be a KBO, that is a new type of planet. Why pluto shouldnt be a planet and jupiter should? Jupiter is mostly just gas, pluto is rocky ice. Then why Earth is a planet when is much smaller than Jupiter? Why Ceres isnt? In these day everything is so mess up, that even rocks are classified has moons and with unpronunsable manes! Astronomy sucks these days. Where did the good managers of names and classification go? :( -Pedro 22:32, 16 Jun 2004 (UTC)


 * Calm down, and don't get too worked up about a classification issue like this. (And if you do want to get worked up, then it might be good to actually look into just *why* Pluto is considered a Kuiper belt object by some ^_~) -- Schnee 00:33, 17 Jun 2004 (UTC)

Exploration info
Some of the info is taken from a public domain text at.

http://www.vectorsite.net/taxpl_f.html

Distances in AU?
I think it would be very helpful if planetary distances were specified in AU units (in addition to the current metric distances, see the article on Earth). That way it would be much easier to relate facts about the Kuiper belt (30-50 AU) and the Oort cloud to the mean distance of planets like Pluto.

But maybe this suggestion should be made elsewhere?

I agree this would have helped me with my school project.

Help!
I am doing a project on Pluto and I have a question... How many seasons does Pluto have and what are they called/how long do they last? Please help!


 * Seasons would be named and defined the same way as here. Plutonian Spring would begin when the Sun goes through Pluto's equatorial plane into its northern celestial hemisphere, and so on. Each season would normally last 1/4 of an orbit, but since the orbit is quiet eccentric, this will lengthen some and shorten others. The Pluto article gives the co-ordinates of Pluto's pole and its complete orbital parametres, so you should be able to compute this for yourself...If you have the math for it, of course.  ;-)
 * I think you'll find this article on the phases of Charon quite interesting too.
 * Urhixidur 23:22, 2005 Jan 11 (UTC)


 * The seasons on Pluto will be a bit different from those on Earth in terms of climate due to the high eccentricity of the planet's orbit. When the planet is close to the Sun the temperature of both hemispheres rises and when it's farther away the temperature of both hemispheres drops - enough that the planet's whole atmosphere freezes out as snow when it's farther away. This is a change in the planet's average temperature, independant of the seasonal changes in temperature that each hemisphere experiences. Bryan 00:38, 12 Jan 2005 (UTC)


 * The expected temperature variation, given the albedo of 0.30, would be 66 K at perihelion and 51 K at aphelion. Not a large difference (29% energy difference), but then the atmosphere is so thin that the effects can be substantial.
 * Urhixidur 03:12, 2005 Jan 12 (UTC)

Diameter
I changed the diameter back to 2390 per the NASA factsheet that is linked at the bottom of the Pluto page. This also matches the given volume. If NASA doesn't have it right, who would? The "most sources" referred to by the previous poster cannot be relied on. If someone has other numbers from a major astonomical org. then please post here. I also checked the diameter in miles, corrected the diameter in Earths per the NASA factsheet, checked the volume against the NASA number, and verified the area by calulation from the NASA number. - --Enon 19:45, 24 September 2005 (UTC)
 * Changed the diameter from 2390 km to 2274 km. Most sources say around 2300 km, only Wikipedia had 2390 km, which seems wrong. [unsigned]

Orbital period?
I've seen Pluto's orbital period listed as 247.7 or as 248.54 Earth years. Converting from Julian to Gregorian won't account for this discrepancy, or with the value 248.09 Julian years in the article's table. Can somebody clarify?--192.35.35.35 20:52, 14 Feb 2005 (UTC)
 * Well, I checked out JPL Horizons, and it turns out that Pluto's orbital elements are considerably affected by perturbations. The instantaneous orbital elements (what they would be if no further perturbations were ever received) show the following orbital periods at different times:


 * 1920: 91438 d
 * 1980: 91828 d
 * 2005: 91115 d
 * 2040: 90210 d
 * 2100: 90065 d


 * The variation here is almost 3 1/2 years. So maybe the figures quoted represent some kind of average... but I wouldn't be surprised if that average also varies slowly over time. -- Curps 02:35, 15 Feb 2005 (UTC)
 * Then what is the value 90,613.3058 d in the table? Genuine result of a careful computation, or wildly unjustified precision? Do we really know the period down to the nearest 10 seconds, or only within ± 2 years?--192.35.35.34 18:00, 15 Feb 2005 (UTC)
 * At any given time, we know Pluto's orbit with extremely high accuracy, it's just that that orbit changes over time as a result of perturbations (but again, we can predict those perturbations with extremely high accuracy). So I'm sure this figure represents a valid result and the digits after the decimal point represent the actual precision... I'm just not sure what result it represents. -- Curps 19:36, 15 Feb 2005 (UTC)
 * Let's see. The JPL data tables give the semi-major axis with ten digits of precision, and we know the heliocentric gravitational constant and the value of the AU to twelve digits. Nine digits of precision on the period (more accurately, the instantaneous mean orbit for J2000) is what the error bars give.Urhixidur 01:32, 2005 Feb 16 (UTC)
 * The upshot I get, then, is that these superprecise results are not actual real world orbital periods, but extrapolations fraught with uncertainty over what the actual perturbations will be in the long long run. I, too, can apply Kepler's law and get 9 decimal places, but I'm ignorant of what 240-some years of perturbations do to the final orbital period or the accuracy with which it is known.--192.35.35.36 15:43, 2 Mar 2005 (UTC)
 * Not quite. The instantaneous orbit is very well known, and so is its future evolution over a fairly large time span, since we know the masses of all main objects quite well, down to the larger asteroids. Uncertainty creeps in, but before it can make a detectable difference probably takes on the order of a million years or more. Note that an orbit may also vary "chaotically" but within very well-defined bounds. Search the ADS, there may be some papers on the long-term orbit of Pluto already in there.
 * Urhixidur 23:04, 2005 Mar 2 (UTC)

On Pluto's Name
The article mentions that the grandfather sent the idea for Pluto's name to a former Astronomer Royal. Does this refer to Frank Dyson, as he was the only retired Astronomer Royal at the time? [unsigned]
 * Numerous sources say that it was Herbert Hall Turner who cabled his colleagues in America with Venetia Burney's suggestion (see, , ). He was not, however, a former Astronomer Royal.  I have edited the article accordingly. -- Curps 00:19, 7 August 2005 (UTC)

Also, and by the way, you've got to be kidding me when you state that an 11-year old by the name of Venetia Phair (nee Burney) knew all the deep facts about Roman and Greek mythology.

The real reason she suggested "Pluto" was because that was her favourite cartoon character. Yes, the lovable dog courtesy Disney.


 * Please allow me to kill this rumor once and for all. Pluto first appeared in The Chain Gang, released 18 August 1930, though he did not receive the name "Pluto" until a few cartoons later.  The name for the planet Pluto was announced 1 May 1930.  May comes before August.  (And in the future, sign your contributions with 4 ~s, which will turn into a signature and timestamp.) DenisMoskowitz 15:35, 23 February 2006 (UTC)


 * Right, the dog was named after the planet.--Jyril 17:02, 23 February 2006 (UTC)

Pluto's composition
Is there any more information available about Pluto's surface/interior composition? Right now it just mentions nitrogen and carbon monoxide ice. Surely there's more information than that. Kaldari 18:28, 23 May 2005 (UTC)
 * This page may be helpful if someone wants to write up a new section. Kaldari 18:46, 23 May 2005 (UTC)

Other symbols
See Symbols.com

Poorly written section
"there may *now* be many other such objects beyond Neptune -- the foremost of these being Fred L. Whipple"

Requested Move

 * Support strongly. Pluto the planet is by far the most important of the Pluto articles.--Jyril 12:54, August 5, 2005 (UTC)
 * Strongly support: Not only is Pluto the most important of the Pluto's, it isn't even a planet so calling it Pluto (planet) is incorrect. --Ctachme 14:20, 5 August 2005 (UTC)
 * Support. There is precedent, in that Venus, Mars, Jupiter, Uranus point directly to the planet. For the other planets, Mercury will undoubtedly have to stay at Mercury (planet) because of competition from the chemical element (and car), and Saturn (planet) also because of the car. On the other hand, Neptune (planet) could probably be moved to Neptune as well.  For most of the planets, the planets are a more common usage than the Roman gods. -- Curps 15:20, 5 August 2005 (UTC)
 * Support. Dragons flight 18:36, August 5, 2005 (UTC)
 * Support.Septentrionalis 19:12, 5 August 2005 (UTC)
 * Support. Even though the definition of planet is up in the air, Pluto shares the dubious honor of disambiguation with Mercury, Saturn (!), and Neptune; all other planets "own" their names, and are the obvious primary meaning for modern readers. Let's standardize. --Dhartung | Talk 06:55, 6 August 2005 (UTC)
 * Support. As with other planet names. – AxSkov ( T ) 07:10, 6 August 2005 (UTC)

This article has been renamed after the result of a move request.

Atmosphere
I removed the following sentence from the article:


 * It is thought by some that Pluto shares its atmosphere with its moon.

It struck me as misleading. I think the intention of the author (and the closest thing I found to the sense of this) is that some of the atmosphere escapes when it is at its hottest and somehow interacts with Charon. The sentence as it was implies that that an extremely thin atmosphere could be shared across 20000km, or that it's believed Charon has an atmosphere. Both of these seem unlikely to me, but if anyone knows what this is about, please put it back. Moogsi 13:18, 16 September 2005 (UTC)
 * Besides, it's clearly a disco ball. lysdexia 00:52, 9 October 2005 (UTC)
 * There is contradictory information about the atmosphere. In the box area, atmosphere of Pluto is nitrogen and methane. In the written section, the atmosphere is nitrogen and carbon monoxide. Which is it? [unsigned]

Camelot 30K
As this review shows, Camelot 30K occurs on "1999 ZX", "a celestial body between comet and planet, out in the Kuiper belt at 35 AU from the Sun". It turns out that designation is "safe", since no minor planet can have Z as it first letter (see Provisional designation of asteroids or New- And Old-Style Minor Planet Designations) &mdash;Z would be the half-month after December 31... Urhixidur 23:03, 4 October 2005 (UTC)

article introduction
''Pluto is a small celestial body in the outer solar system. ''Discovered in 1930 and originally classified as a planet, its status is currently under dispute.

Someone added this "small celestial body". It is in dispute by some, but its status is that it is a planet. It seems that wikipedia as taken a position, against what is the common sence and the official designation by the IAU.
 * The problem is that "common sense" is _opposed_ to the official designation by the IAU, which was approved a long time ago based on data which turned out to be wrong. Common sense says Kuiper belt objects orbiting in resonance with Neptune aren't planets.  If Pluto is a planet, then so are all the rest of them.  Either way the "nine planet story" we remember from grade school is bullshit. 216.99.217.92 05:42, 16 November 2005 (UTC)

THE STATUS OF PLUTO: A CLARIFICATION IAU Press release.

Besides, what size is small? what is celestial body a star? I've said previously this article focus little on the planet, but is foccus to much on controversy over what humans on Earth call it.

surely, It needs a POV tag. -Pedro 21:52, 9 November 2005 (UTC)


 * "what is celestial body a star?" What the hell are you talking about? 216.99.217.92 05:42, 16 November 2005 (UTC)


 * Dropped small. Not small compared to its neighbourhood. Does not need a POV tag unless we claim A not B. Come up with a sentence briefly explaining the debate. Marskell 22:32, 9 November 2005 (UTC)
 * I changed 'originally classified as a planet' to 'officially classified as a planet', to stress that it hasn't changed (yet). The Singing Badger 22:36, 9 November 2005 (UTC)

Pluto's albedo is wrong in the article.
This article lists Pluto's albedo a 0.30. It is considerably more reflective than that; the estimate used by Mike Brown at Caltech in his article on the "New Planet",:

http://www.gps.caltech.edu/~mbrown/planetlila/index.html#hack

lists the ablbedo at 0.60. That's actually at the low range of albedo estimates that I have read over the years. Similarly, the albedo of Triton is listed at 0.76. The last I heard, which was around the time of the Voyager flyby, was 0.90.

No absolute magnitude is listed for Pluto, Triton, Charon, or several other objects. I stumbled onto this error because I wanted the absolute magnitude to compare to other absolute magnitudes listed by the Minor Planet Center. Also, there is some dispute about the diameter. As a result, I am calling for help on this rather than editing it directly. Thank you. Mike Emmert 19:41, 21 December 2005 (UTC)Michael C. Emmert
 * Yeah, albedo of 0.3 is way too low for Pluto. I replaced it with a value of 0.5 – 0.7 from NSSDC's Pluto fact sheet. I wonder if this wide range represents uncertainty or albedo differences, because Pluto's surface has highly contrasting lighter and darker regions.--Jyril 01:35, 30 December 2005 (UTC)

Dark King Star - Kanji
Can someone insert the Kanji characters into the article for Pluto like we have for the other planets? WilliamKF 03:23, 15 January 2006 (UTC)
 * Okay I found on wiktionary: 冥王星 WilliamKF 03:34, 15 January 2006 (UTC)

Retrograde rotation
I believe Pluto rotates retrogradely? At least my physics books and a couple of google's says so. Anyway, I don't know how to edit those Infoboxes - can't find any button for it. -josteinaj 20/01/06 20:15
 * Pluto's axial tilt is over 90° (122.54°), which means its rotation is indeed retrograde. However, the difference is small enough that it is better to say Pluto orbits on its side than it orbits backwards. Uranus has similar situation, whereas Venus rotates clearly in retrograde motion.
 * Fixed; the minus sign denoting the retrograde motion was missing before the rotation period.
 * You can't edit infoboxes directly, instead you must edit the infobox template, which in the case of Pluto is Template:Planet_Infobox/Pluto.--Jyril 20:09, 20 January 2006 (UTC)

CJKV name
In Vietnamese, Pluto is called Diêm Vương Tinh or Sao Diêm Vương, named after Yama (閻王), not Minh Vương Tinh (冥王星) as in the CJK languages. At the time of Pluto's discovery, the Chinese grip on Vietnamese culture isn't as strong as before and Vietnamese had already started to be written in quoc ngu. Writing 冥 in quoc ngu would become Minh, which is easily misinterpreted as "bright" (since that is the much more common meaning of minh), and I suspect that's the reason it wasn't named that. DHN 18:04, 9 March 2006 (UTC)
 * Actually, like in Vietnamese, 冥 and bright (明) share the same pronunciation in Chinese, too. — Yaohua2000 09:06, 11 March 2006 (UTC)

NPOV concerns
Some editors are getting caught up on the amount of controversy surrounding the classification of pluto as a planet. I find that the addition of qualifiers, such as "some controversy" and "sometimes under controversy" marginalize debate over pluto's classification, and so violate the standards at WP:NPOV. Ihe amount of controversy isn't as important as the fact that there is controversy. shaggy 02:57, 14 March 2006 (UTC)

First Photograph?
On the front page today, it is said that Pluto was photographed for the first time on March 19, 1915. The article indicates the same thing with no additional information. It this a reference to photos taken at Lowell Observatory on March 19 and April 17, 1915 with the 9-inch camera from Swarthmore College, or to some other photograph(s)?

In any case, does anyone have information about when these prediscovery images were discovered, and when the positions derived from them were incorporated into a determination of Pluto's orbit? As most hanging around here will know, prediscovery observations of minor planets have been of great significance to orbit determination in the past, and I'm curious whether this was the case with Pluto. A fifteen-year prediscovery arc in the first years of Pluto's observation could have been significant.

I've done some checking in the references I have, and am turning up empty-handed on both questions. --Jeff Medkeff | Talk 01:06, 19 March 2006 (UTC)
 * Most of the prediscovery observations were found within a year or so of the discovery in 1930, although I don't recall about those specific ones (I'll check my source tonight). I have a list of them if people are interested in it being posted. CFLeon 21:47, 5 April 2006 (UTC)

Second Largest
I reverted a edit that said that Pluto was the second largest. I assume in reference to 2003 UB313, which is already mentiond in the article, This link http://www.gps.caltech.edu/~mbrown/planetlila/ says 2003 UB313 is a Kuiper belt object, is there some doubt about this? Should we change it back to Second largest object? Orangutan 18:33, 30 March 2006 (UTC)
 * It's a scattered KBO, like Chiron. It has an inclination of 39°, compared to Pluto's 12°. The Scattered disc is usually considered apart from the Kuiper Belt, just as with the Main Belt, but that's a matter of definition. kwami 19:29, 30 March 2006 (UTC)
 * Thanks Kwami, That's what I love about Wikipedia, I'm always learning new stuff.Orangutan 14:35, 31 March 2006 (UTC)

100 Planets?
The problem with classifying Pluto as a planet is that: suppose we find a hundred objects that size out beyond Neptune? Or 200? or 1000? Do we WANT a hundred planetary bodies to memorize? It's basically the same problem that the 19th Centurians faced with the bodies between Mars and Jupiter, except their's was easier- it was quickly apparent that none of the objects was even the size of Luna, let alone Mercury. So they came up with 'minor planets', and that worked fine. Our problem is rather more complicated by Pluto being the only one known for over 60 years. We need to consider what is the MOST USEFUL definition. It certainly is useful to have names for the type of movement: primary vs secondary revolution around a star ('planet' vs 'moon')in rather low eccentric orbits to distinguish from comets (but aren't there some comets with lower eccentricies than Pluto?). So, using that, Pluto is a planet (but so is Ceres, Juno, Eros, Chiron, etc.). However, that can be carried TOO far, with all the tens of thousands of bodies just over a km!!! So, there NEEDS to be a size limit, 'major planets' vs 'minor planets' ('planets' vs 'planetoids'?; although I propose 'planetoid' as being very fitting for the loose interstellar bodies not orbiting a star). The POOREST choice is probably what the entertainment industry and some PR people for NASA do already and letting size ALONE being the factor and upgrading the major moons to 'planets'. There's ALREADY a word for large spherical bodies with atmospheres, no matter if they're revolving around a star or a planet: 'worlds'. As I see it, our BEST solution is to keep it at 8 planets (I know, what if we find an Earth-sized body out there? or even another Jupiter or larger?), and 2 'minor planet belts' (we can work on the exact term) typified by Ceres and Pluto. Perhaps a new term: I like 'plutinos', but it's become restricted to a particular type of orbit; and I think 'cubinos' and such, while useful for destinguishing between different types is too restricting to use as a general term. How about a contest like they did with picking Pluto's name? For a dollar (or equivalent currency), you can make an entry to pick the generic name of the trans-neptunians? Set up some basic rules (limited to 3 syllables, NO living people, no businees intests represented, that sort of thing), run the contest for a year or two, and have the winner picked by the IAU? All proceeds go to fund research on TNOs. Just give me credit for the idea! CFLeon 21:47, 5 April 2006 (UTC)
 * I'm not sure what kind of a response you're looking for, but this page is meant for discussing the Wikipedia article on Pluto, not the IAU policies on Pluto, so your idea won't get much exposure here. This same debate has been going on for decades, and is also occurring on Talk:Planet if you're interested.  --Doradus 20:12, 27 April 2006 (UTC)

Barycenter; Inclination
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 16:26, 27 April 2006 (UTC)

P1 and P2 Names
Any idea when the names for P1 and 2 will be out? Aeon 18:31, 30 April 2006 (UTC)
 * Badstronomer said that... Science Now said that... Friday. =) *shrug* don't ask me... --wwwwolf (barks/growls) 00:49, 22 June 2006 (UTC)

New Moon Names
Per http://sciencenow.sciencemag.org/cgi/content/full/2006/620/1, the moons are Nyx and Hydra. Thank you for your attention to this matter. 206.53.16.78 04:33, 22 June 2006 (UTC)

Planet X
The following statement appearing under Pluto is somewhat inaccurate: "When Pluto was discovered in 1930, H.P. Lovecraft wrote a short story ('The Whisperer in Darkness') which proposed that Pluto was a base of invading extraterrestrials known as the Mi-go, who called it Yuggoth."According to S. T. Joshi and David E. Schultz (An H. P. Lovecraft Encyclopedia ISBN 0-3133-1578-7) this is not true: "It cannot be said that the discovery of Pluto inspired the writing of ['The Whisperer in Darkness']" (p. 298). Lovecraft began writing the story February 24, 1930, but the discovery of Pluto was not officially announced until March 14. Lovecraft was already aware that a trans-Neptunian planet might exist and had alluded to such a possibility in previous writings. Thus, the discovery of Pluto and the writing of the tale are simply coincidences. _,-~ R 'lyeh R isin g  ~-,_  02:58, 2 June 2006 (UTC)

non-sequitur
'Constance Lowell, Percival's widow who had delayed the search through her lawsuit,...' what lawsuit? Has something been removed here or have I missed something?Badgerpatrol 22:37, 5 February 2006 (UTC)

Research
If anyone is needing info on Pluto, I wrote a paper about it last year. User:The_stuart/Is_Pluto_a_Planet --The_stuart 01:36, 9 May 2006 (UTC)
 * I think you meant nuclear fusion in your article. --Doradus 20:04, 9 May 2006 (UTC)

orbit
i came here wanted to know how many years it takes for pluto to complete its orbit. this should be in the orbit section. thanks. --MateoP 20:47, 27 May 2006 (UTC)

Front page now?
Right now, there is an astronomical congress in Pague in Czechslovakia, where 3000 sci people from all over the world get to decide whether to demote Pluto into a mere space pebble. I heard on radio a small group of amateurs is already protesting in the street against "Pluto-theft"... Maybe the event could bring Pluto onto wikipedia (wikinews) front page. 195.70.32.136 12:08, 14 August 2006 (UTC)


 * I suspect we'll be there in a few days (is it this week or next?) when they make the final announcement. However, early sources suggest that it's decided already - it'll remain a planet, possibly by creating a new category of "dwarf planets" to include it and some others. Shimgray | talk | 12:31, 14 August 2006 (UTC)


 * They decided but are not releasing until Wednesday, 2 am Eastern time. A member of IAU said the new definition of a planet with not be what anyone expects (to build suspense maybe?) Zeusnoos 23:24, 14 August 2006 (UTC)
 * Dwarf planets already exist: those are asteroids. --Pedro 23:37, 14 August 2006 (UTC)
 * Asteroids are formally "minor planets", not "dwarf planets". Shimgray | talk | 00:03, 15 August 2006 (UTC)
 * I know, but those have very similar meanings, and it is just used in the English-speaking world - and it doesnt say much about these objects. I would be happy with an official "telluric planets" "terrestrial" for English speakers, "gaseous planets" and "ice planets" (that would include Pluto and UB313) and I hope they dont forget the planet-like moons - which today are the most remarkable planets around and space rocks around the sun and planets: like 1221 Amor should be considered just rocks and their best names used by real planets. --Pedro 11:35, 15 August 2006 (UTC)


 * Eh, they haven't said what the new category will be - "dwarf" was just an attempt to find a word that wasn't "minor", I suspect. The intriguing possibility is that if Pluto is reclassed along with UB313, we may also end up reclassing Ceres and Mercury (now that would be interesting). Shimgray | talk | 12:43, 15 August 2006 (UTC)
 * Hm?! Mercury is similar to Earth. Ceres is possibly also similar to these two. You must be talking of size issues. Ceres and Mercury are way bigger than most rocks in space. And Jupiter is far bigger than Earth. Maybe they will end up with a mass differentiation in order to consider Ceres a planet and some KBO's and asteroids as rocks, I don't know. I just hope they clean this mess. --Pedro 15:40, 15 August 2006 (UTC)


 * See this.--JyriL talk 17:23, 15 August 2006 (UTC)


 * Off-topic nitpick: Czechoslovakia was dismantled 13 years ago. Prague, where the IAU is holding its conference, is the capital of the Czech Republic.--JyriL talk 00:56, 15 August 2006 (UTC)

Picture
What the hell is that thing used for a pictur of pluto at the top of the page?That doesnt even look like pluto.--Killswitch Engage 16:17, 25 May 2006 (UTC)Killswitch Engage
 * That is an image taken with I believe the Hubble. As of now no images other tahn a few low res pics have been taken.  Other images are drawn or created by people. Aeon 22:17, 25 May 2006 (UTC)
 * If you know what Pluto looks like, feel free to tell us. Otherwise we have to wait until 2015 when New Horizons gets there. The title image is created from data collected from the mutual eclipses of Pluto and Charon which occurred between 1985 and 1990. Maps created from Hubble data are less detailed, but unlike this they cover whole Pluto except for the south polar region.--JyriL talk 05:44, 26 May 2006 (UTC)


 * Even that picture of Pluto has been enhanced from the Hubble's original image. I'm looking forward to 2015. User:mustang6172

Planetoid Pluto
I'm just another guy who is clueless when it comes to Astronomy, but there are scientists who believe that since Pluto is smaller than half of Saturn’s or Jupiter’s moons that it's not a planet at all. The Astronomers who support objects smaller than moons aren't planets apply here. They suggest that there is only 8 planets in the Sol planetary system and 1 enormous planetoid.

NASA is on the verge of confirming this too. It's about people excepting the truth it's not a planet that's a problem. There is a lot of denial here. —Preceding unsigned comment added by Renegadeviking (talk • contribs)
 * It isn't up to NASA, but a decision by the International Astronomical Union (IAU) which is currently studying the situation to determine a precise definition of a planet. Currently, the IAU considers Pluto to be a planet.Shsilver 19:51, 21 September 2005 (UTC)
 * The planetology articles in En. wikipedia are in the verge of useless and disinformative articles, full of POV on this subject about planethood. This article about Pluto is dreadful, and it focuses on useless things about planets, namely theories that some wikipedians like a lot, like that planetoid or asteroid thing. It is really sad. In every article where Pluto comes along comes this theory that Pluto is not a planet. What a stupid idea to define a planet by the size of the moons of Saturn, what kinds of scientists are those, some wikipedians? I don't believe that real scientists said that. Very nice scientific definition! A planet is an object bigger than the moons of Saturn. OMG. "An enormous planetoid"?! Oh jesus... -Pedro 23:22, 28 October 2005 (UTC)
 * Don't worry, it's just a matter of time and the IAU will sort it all out. Frankly, any object orbiting the Sun, that isn't in resonance with a larger object with an overlap in the range (q ,Q ), is >95% of the mass orbiting near that semimajor axis, and is rendered spherical due to its mass, will someday be the "official definition".  Due to Pluto being locked in a 3:2 dance with the more massive Neptune, that is what will sink Pluto.  Resonance also will sink Xena, Orcus, and many other TNO's.  And the mass fraction will sink Quaoar.  Sedna might skate by: but as soon as a second Sedna-class object of similar mass is found (and it will be, surely) it loses planethood, too.  As for Pluto not being a planet: not a problem, although minor planet number 10000 is gone (as is 100000 as of October 2005), the elegant solution is to use 0.  0 Pluto does have quite a ring to it.  --Sturmde 02:43, 29 October 2005 (UTC)
 * I agree with this point of view. Currently it would seem to me at least that Sedna has a greater claim on planethood than Pluto, given the uniqueness of its orbital location. I particularly agree with your last point there on classifying Pluto with Minor Planet number 0. I actually suggested that to Brian Marsden of the Minor Planet Centre about 7 years ago when the whole debate about classifying it as 10000 was floating about, and he indicated he had a favourable view of that solution.
 * You make a claim about what will "someday be the 'official definition'" of a planet. One, Wikipedia is not a crystal ball, so claims about what will be are out-of-place here.  On the assumption that some currently argue those criteria should be the official definition of a planet, can you please cite your source?  Thanks. --DragonHawk 14:49, 2 January 2006 (UTC)
 * Excuse me, but you're confusing articles, with discussion about articles. I haven't edited the article to reflect my comments above.  THAT would be what you're bogusly claiming has been done.  It is not an assumption that there is currently debate.  There IS current debate.  See the IAU page at, and you'll note that the final determination will be in September 2006.  What I have provided above is the shared opinion of a number of actual astronomers and physicists (such as me) who have interests in Solar System dynamics.  Pluto is in "trouble" because it's in a 3:2 lock with Neptune; and it isn't the preponderance of matter contained in the range (qPluto,QPluto).  Its only argument is that it is rendered spherical by its gravity.  Providing an informed scientific observation in the DISCUSSION about an article is entirely appropriate.  You may of course choose to ignore anything in discussions at your own leisure.  Were these observations expressed in the article, then that would be different. --Sturmde 20:57, 15 March 2006 (UTC)
 * This is just a comment I will add at the bottom of this topic. If the "planet" Pluto should be found to be on the inside of the orbit of the exterior asteroid belt Kupor Belt (I believe thats how its spelled) then as long as the orbit is a respectible distance from the belt wouldn't it make sense to classify it as a planet. Given that it could be an asteroid from the Kupor Belt that was somehow pulled into orbit, but the fact that it does indeed have another object that orbits it as a moon and the fact it is profoundly more rounded then an asteroid would classify it as a planet. As we further leave the forces of gravity induced by the sun we have to take such things into consideration, don't we? As we go out of the suns influence obviously certain conditions would change and therefore the orbits and appearance of such planets that can be found there. -Comment by Just another guy on November 1 2005
 * (It's 'Kuiper Belt'.) CFLeon 01:43, 4 August 2006 (UTC)
 * I think we all have different perpectives of what's a planet, on a common view and a planetologist view it is a planet. But to those people who looks at the orbit it isnt. But Lets see... Titan is a moon of Saturn and it has a denser atmosphere than Earth. So, Earth is not a planet, but a planetoid. And, what if we discover something bigger than Earth in the Kuiper Belt? Certainling we will also question Earth position as a planet in the future, the same for the other planets. It is acceptable too see the smaller KBO's and Ceres as planetoids, but something bigger than Pluto should be named a planet, and the limit is already big anough cause a planet should be every round object that "doesnt shine by itself" (in a simplist view). We can have terrestial planet, gas planets, ice planets and planets that dont orbit any star. -Pedro 19:25, 3 November 2005 (UTC)
 * If Pluto is considered a planet for "planetologist" reasons, then so are dozens of other objects. Pluto would never be called a planet if it were discovered today.  "The planet Pluto" is a mistake and an embarrassment.  I am mystified by people who are emotionally attached to a nine-member planet list that happens to be wrong. 216.99.217.92 05:36, 16 November 2005 (UTC)
 * I'm checking out this article and this talk section for the first time. While it's clear that there is some question on Pluto's status, we need to keep in mind the Wikipedia policy of verifiability.  Regardless of what any of us believe is the right classification for Pluto, we need to keep in mind that Wikipedia's purpose is not to establish correctness, but to summarize the work of others.  So, when making claims about Pluto's status one way or the other, please cite your sources.  This is not a place for unverified claims. --DragonHawk 14:29, 2 January 2006 (UTC)

Exploration of Pluto
Regarding the recent addition ("In 1989, NASA also considered sending Voyager 2 to Pluto using a gravitational assist from Neptune, but this would not permit an optimal science flyby of Titan. It was eventually decided to calculate the Neptune and Titan flybys for maximum science regardless of the consequences to the craft's final trajectory."), please pardon my ignorance, but what are 'optimal science flyby' and 'maximum science?' Aquirata 14:03, 30 June 2006 (UTC)


 * My interpretation would be that the 'optimal science flyby' is one that allows the best observations to be made, and 'maximum science' is a calculation based on the trade-off (would we learn more by observing Titan, or Pluto?). However, the terms are overly jargon-y and strike me as being very NASA-y (possibly direct from JPL's pages?) and they could do with being rewritten; I've made an attempt at doing so. blech 11:19, 6 July 2006 (UTC)
 * Thanks, that's a good rewrite. Aquirata 12:56, 6 July 2006 (UTC)


 * This must be a misquote or misinterpretation- no trajectories with both Pluto and Neptune were feasible, since Pluto was in the opposite direction from Saturn and required an inclination change also. Early planning considered one craft to do the four Jovian planets and the other to go to Jupiter-Saturn and then Pluto. As it was, none of the good trajectories for Io or Titan led to an encounter with Neptune, so it was decided that Voyager 1 would be sacrified for this purpose, letting V2 with a not-as-good Titan encounter, but able to make Neptune. CFLeon 20:39, 27 July 2006 (UTC)

Hubble
Should we add a pic from hubble on Pluto? That would show some more detail that the real color one does not: Nitrogen ice patches. Just a thought... --Galaxy001 04:29, 3 July 2006 (UTC)

Pluto: American planet, European Kuiper belt object?
Sorry, but in the light of recent discoveries it appears more than obvious that Pluto is nothing but a (huge) object belonging to the Kuiper belt. Its status as a planet, therefore, has to be considered a whimsical anachronism, and it's rather funny to read through the (more or less) scientific debate on both sides of the Atlantic. In the 1930s, Pluto's classification as a planet was based on insufficient knowledge about the outer Solar System (being understood as its outer edge, rather than the inner edge of the - then unknown - Kuiper Belt). Fair enough, but what is it based on today? American patriotism? 80.145.233.192 00:47, 11 February 2006 (UTC)-
 * Historical precedence. I don't see any patriotism or nationalism in the debate at all...--Stephan Schulz 12:34, 14 August 2006 (UTC)


 * The key appears to be that the IAU considered it a planet for historical reasons, and pending their reclassification of it as either "still a planet" or "not a planet any more", it'll still be called a planet in general texts for the time being. Shimgray | talk | 12:38, 14 August 2006 (UTC)


 * I really don't think people wanting to keep Pluto as a planet is a result of OMG evil American patriotism but rather that the idea of it being a planet is stuck in the minds of the public (not so much for the scientists). I'm an American and I always thought it was discovered by a British guy O_o.PhoenixSeraph 13:43, 24 August 2006 (UTC)


 * Now we just need to drop the rest of our historical anachronisms and recognize that everything else in the so-called "solar system" is nothing more than debris floating around a giant reactor. Perhaps we should just call the "solar system" the galactic "dust bin" for now until we can come up with a better name. SHED HISTORY! PLUTO IS DEAD, LONG LIVE THE IAU!!! &mdash;Two-Bit Sprite 20:27, 24 August 2006 (UTC)


 * Who cares what a bunch of unelected bureaucrats have to say about anything? Pluto is a planet (and will remain a planet in many minds) because of CULTURAL DEMANDS, if we Demote Pluto as a planet then we need to strip Europe of it's Continent status. In fact we need to get rid of Africa and Asia while we are at it and make it Eurafasia and sorry North and South America, your just America now. Why? Because the geology bureaucrat on the left says you are. The Fading Light 22:42, 24 August 2006 (UTC)


 * Precisely. &mdash;Two-Bit Sprite 22:54, 24 August 2006 (UTC)


 * Eurafasia is a continent. The word "continent" can refer to political continents (where Europe is included) and scientific continents (where it is not).  Talk to a geologist or biologist, and they will not see Europe as seperate from Asia.  Just because Europe is historically and politically important, and just because people are use to calling it a continent doesn't make it true.  The same goes for Pluto.  Just because we have been calling Pluto a planet rather than a Kuiper Belt object doesn’t make it so.  As much as it upsets some people, democracy doesn’t trump science.  --Arctic Gnome 23:07, 24 August 2006 (UTC)


 * I really hate to burst your bubble but there are some things that are more important than science. The Fading Light 23:19, 24 August 2006 (UTC)


 * Of course there are, but importance does not decide scientific truth. If everyone really wanted to categorise elephants as a type of fish, that would not make it true, regardless of the importance of public opinion.  --Arctic Gnome 23:39, 24 August 2006 (UTC)


 * You say "democracy does not trump science", so oligarchy does? Firstly, whether or not Pluto is a Planet is merely a matter of definition and/or convention, nothing scientific about it. So, your statement should read "convention does not trump oligarchy". &mdash;Two-Bit Sprite 14:03, 25 August 2006 (UTC)


 * They aren't an oligarchy because they cannot tell you what to do. You can keep calling it a planet, but the scientists got together and decided that they will not call it a planet.  Personally, I choose to use the wording of the people who work in this field rather than the wording of some people who are fans of a cartoon dog from the 1930s.  --Arctic Gnome 18:56, 26 August 2006 (UTC)


 * I totally agree with Arctic Gnome. Yes, this is a matter of ceonvention, and everything is. In that case and the elephant/fish example, it makes more scientific sense not to call Pluto a planet. Free to you to call it so and to call an elephant a type of fish, but I'd stick to the definition of those who work on it. Oh and "CULTURAL DEMANDS" is no argument to keep Pluto a planet: by "cultural demand", the Earth was flat several hundred years ago. It made quite a fuss at the time, but I'm glad it turned round after all. 221.249.13.22 00:44, 28 August 2006 (UTC)


 * You make it sound as though consensus was reached on the definition, which is far from the case at this point. Even the leader of the New Horizons mission at NASA is upset about the redefinition.  I also find it interesting that people seem to suggest that the decision was reached unanimously, when the vote was 40:60.  --Xaliqen


 * Well, New Horizons leader Alan Stern has a huge incentive to be against this. Imagine that you spent years working on something as historic as the first probe launched to a planet, and then hear a few months after launch that your craft isn't going to a planet after all.  Ouch!  On the other hand, "Xena's" discoverer Michael E. Brown seems to agree that it shouldn't be called a planet, despite being larger than Pluto. Ubermonkey 14:48, 27 August 2006 (UTC)