Talk:Planet/Archive 1

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Archive 1 Archive 2 →

Contents

Pruning the Introduction

I understand that being brief is desired, but in this instance and at this time, it would be prudent to include information about the hiatus on the Pluto decision. Various people keep deleting the date and place of this decision and removing references to the controversy surrounding the decision. Given that ~90% of the delegates had already left the conference when this vote was taken, it is reasonable to suppose that this is not the end of the story.

By keep a brief "tombstone" introduction, this implies a definitive certainty ... which is lacking here. I would suggest that it is appropriate to recognise this by alluding to these things in the introduction. Specifically, at this time, I suggest that it is both relevant and appropriate to show the date and place that this decision (vote) took place and to allude to the fact that many who had been at the conference earlier are not happy with the decision. It will be interesting to see how this develops in the coming months and years.

Pluto decision.

You know, I think that some of these astronomers who voted against Pluto, arebeing a little too foolish...Pluto is by far an orbiting, round, over 1000 miles across, does not have fusion of any kind occuring in it's core, and formed from the standard sun-planet formation. Just because Pluto is smaller and orbits at an over 12 degree plane does Not mean that it is a measly, ugly, malformed asteroid, one of thousands in the unseemly Kuiper Belt. Pluto Should Be A Planet, whether a few proffesional astronomers like it or not...Omarionozone 20:51 25 August 2006 (Central Time...America)

I did not see any mention in the article of WHY having some precise definition of "planet" that either includes or doesn't include Pluto is important. 207.69.137.22 18:17, 9 July 2006 (UTC)

Hasn't the issue of whether Pluto should be counted among the planets been decided a couple of years ago? [Egil 2003-01-23t15:20:04z]

Nope, expect an announcement from the IAU's working body about the definition of the planet by November. TJM
The IAU did issue a press release on the status of Pluto on 1999-02-03 along with a comment in their FAQ that "The IAU considers the discussion closed with this statement and does not intend to reopen it in the foreseeable future." There is also an IAU FAQ article on TNO 2003 UB313 (Xena) which mentions the working group on definition of a planet, but only in the context of whether Xena should be considered a planet or not. Despite the comment in the main Wikipedia article that Pluto might lose its status as a planet, one certainly doesn't get that impression from reading the IAU web site. Is there any source to support this? Stephen.frede 06:33, 7 January 2006 (UTC)
Plenty. Just Google "Brian Marsden" and "Pluto". He's on the IAU team deciding the planet issue, and is very much in the "demote Pluto" camp. Serendipodous 12:11, 7 January 2006 (UTC)

Actually Pluto already has lost its status as a planet, it just hasnt been made widely known. I havent put it in the article because at this moment I cant remember the source well enough, but I can give you a vague idea of where to look if your interested. On an episode of The Colbert Report, Stephen Colbert interviewed an astronomer from the IAU who stated that pluto has officialy been removed from the list of planets. I cant remember the astronemers name which is why I havent put it up yet, but i'll look into it.--Mloren 23:35, 14 July 2006 (UTC)


Until today, I thought highly of the IAU. But today, they just lost their status in my books. MagnumSerpentine 8-24-06

Pluto did not change. Those people at IAU with nothing better to do changed the definition. What difference did it make? What next? Change the definition of satellite?

Keep in mind that the IAU executive committee proposed defining Pluto as a planet. It was the vote of 2400+ astronomers that (wisely, I think) demoted it. --Aelffin 04:19, 25 August 2006 (UTC)

Pluto is still a planet. Who is the IAU to determine which planets deserve to be "real" planets. I think the public should take a vote on this and not leave it up to some scientists who don't care what other people think.

It's got nothing to do with what people think. The IAU is a huge group of astronomers. Astronomers need to use the term planet consistently so that they can understand each other. Astronomers have not thought of Pluto as a planet for a long time, and astronomers decided together that they would no longer use the term planet because it's confusing. The only reason it was called a planet for 76 years is that the IAU said it should be. They have a right to change their mind. --Aelffin 09:07, 26 August 2006 (UTC)

Planet candidates

Considering the recent debate over what constitutes a planet since the discovery of "Xena", are all the other possible planets listed? I read somewhere that if a planet was classified as something "spherical that orbited a star" (which may well happen) there would be more than a dozen new planets. At the moment only Sedna, Varuna, Quaoar, Orcus and the recent three discoveries are listed. Could anyone that knows a little more suggest a few more names? TJM

  • Not to worry, Ive done it myself. Now all objects with a diameter above 750km are listed, which is the approximate size needed for icy bodies to become spherical with self-gravity.
    • As a side point, can anyone provide pages for those TNOs listed with dead links?

---

Planet redirects

  • Planet Uranus and other unecessary Planet redirection pages Planet XXXX etc.
    • This is an unecessary extra redirection page, and really adds only clutter, not value. A search for Uranus already produces Uranus (planet), and a search for Planet would show Uranus (planet) on the first search results page, if that first page was not cluttered with all these extra, useless references to Planet Uranus, Planet Krypton, Planet Jupiter etc. Other such unecessary extra references I can find are
    • I would keep them just because people will still write them into articles. If you really want to delete useless redirects hunt down the CamelCase ones. SimonP 16:00, Jul 31, 2003 (UTC)
    • I've just done all the work of cleaning up, changing outdated references, and you want to keep the rubbish there in case someone messes up again in the future. Pleeeese ! That is not the way to achieve a decent clean structure. The extra entries add no value, and cause the search results to be over populated with a load of useless redirects. RB-Ex-MrPolo 16:55, 31 Jul 2003 (UTC)
      • It's wikipedia policy not to delete redirects which are likely to be used in the future. - Efghij 17:06, 31 Jul 2003 (UTC).
      • Firstly, if there is such a policy, please point me to it. If. Secondly, the whole Wikipedia:Disambiguation example is based on Mercury, and it doesn't mention it there as far as I can see. That seems pretty much to support what I am doing in cleaning up.And thirdly, just why do we need to preserve the future right to use the link <<Planet Mercury>> instead of just <<Mercury>>, or <<Mercury (planet)|Mercury>>. The search results for Planet are just a mess. That is the problem I'm trying to get rid of. And I'm not asking anyone else to do the work. You want to preserve useless redirects just in case someone might use a non-standard link in the future ??? Do we expect to have redirects for <<City of Rome>> as well as for <<Rome>> ? For "State of Dakota", "Country of France" etc ? Why does "Planet Mercury" have any more validity than those examples ? Why not encourage people to use the "standards" , encourage those enthusiasts amongst us who are willing to clean up ?RB-Ex-MrPolo 17:49, 31 Jul 2003 (UTC)
      • Agreed - the Planet ... links are no better than your "Country of France" example, let's clear up that search! Tompagenet 18:04, 31 Jul 2003 (UTC)
      • Planet XXXX is a very natural construction that people will type in. For instance "The book 2001 discusses a voyage to the planet Jupiter." Redirects are just as much for easy linking as they are for searching. Also in the long run the search function will probably be able to exclude these sorts of redirects. SimonP 19:05, Jul 31, 2003 (UTC)
        • Just what is so compellingly natural about putting square brackets around the two words, like <<planet Jupiter>>, instead of like planet <<Jupiter>>. You give your argument away in your own example, as you did not use a capital P for planet, because it is not part of the name. By your argument we would also end up with the search cluttered with links to the <<god Jupiter>>, to the <<<Jupiter space program>> etc etc etc.
          Anyway, if we delete them now, the search is improved, and nothing lost. If later, someone puts them back again, then some enthusiast like me can clean them up again, or someone can fix the search mechanism. But, meanwhile, I've done the work of cleaning up all the links. I'm just asking for the dead and useless redirect pages to be cleaned up also. I am not asking for deletion of ANY content. RB-Ex-MrPolo 17:09, 1 Aug 2003 (UTC)
          • planet <<Jupiter>> takes you to the wrong place. The correct link would be planet <<Jupiter (planet)|Jupiter>>, which some find unnatural. Martin 03:05, 3 Aug 2003 (UTC)
      • I'm beginning to think I've hit a raw nerve here which the administrators might want to take off into a separate discussion page ?? An argument between the natural organisers and the "do what comes naturally" people.RB-Ex-MrPolo 17:09, 1 Aug 2003 (UTC)
      • Please see Wikipedia:Redirect#How do I delete a redirect?. We have hundreds of redirects from natural constructions to wikipedia standard titles (eg New York City, State of Georgia, Mary Queen of Scots). This is no different. If someone is writing an article and they want to link to the page about the planet Jupiter, they won't type ... voyage to Jupiter ... if they think Jupiter is likely to be about the Roman god; insted they might write ... voyage to the planet Jupiter ... One of the ideas behind having redirects is that someone doesn't acidentally create a duplicate article. That's why we have a policy against deleating useful ones. - Efghij 21:50, 1 Aug 2003 (UTC)
  • RTM please - They are valid redirects, keep. Furthermore the articles used to be at the /Panet names and that is where the old article history is. See [1] If you delete that page then you violate the GNU FDL by removing author attribution. The other page title redirects (such as Planet Mars) were linked to at least some external sites and exist in at least some bookmark files. Thus they stay as well. --mav 07:01, 3 Aug 2003 (UTC)
  • Leave the redirects. They can be usefull and do no harm. -- Infrogmation 18:37, 3 Aug 2003 (UTC)


From the article:

  • Sedna—a world orbiting the sun 2 billion miles beyond Pluto. Sedna, after the Inuit goddess ot the sea, is the provisional name given to this object by NASA[2]

No cite provided: removed until this can be corroborated. -- The Anome 13:35, 14 Mar 2004 (UTC)

Is this the same as 2004 DW? -- The Anome 13:41, 14 Mar 2004 (UTC)
Sedna (planet) says its 1200 miles (1900 km) vs 1600 km. Same team to have discovered it. I dunno. Morwen 13:44, Mar 14, 2004 (UTC)
2004 DW was reported last month, along with 50000 Quaoar, which was disocvered in 2002, is about a billion miles beyond Pluto. 2004 DW is about 900 miles across and Quaoar about 800. Sedna is bigger and further away. By rights, perhaps 2004 DW and Quaoar deserve entries here as planets too. Source: today's sunday Times, p.3. 217.75.160.30 13:48, 14 Mar 2004 (UTC) (Ooops I got logged out User:Matthew Stannard)
Wikipedia doesn't set trends. If everyone starts referring to them and treating them as planets, we will follow. Morwen 13:50, Mar 14, 2004 (UTC)
Having read & edited many of the Solar System pages today, let me say 1) I agree with Morwen that the "Is Sedna planet or planetoid issue?" is far from settled (it will take years); 2) The controversy is covered in the Sedna page; 3) Sedna is mentioned in the Solar System article, which is the best written and most complete of the bunch. Joelwest 04:03, 21 Mar 2004 (UTC)

I think this page should have more about the history of planets, such as which were ancient (and naked eye visible) and which discovered in modern times. There should also be more discussion on how a planet is defined--this page makes it seem very clear cut, when in truth it isn't. See [3] for a discussion that describes the main points. --zandperl 18:27, 20 Mar 2004 (UTC)

youngest planet

How do we incorporate information about the youngest planet recently discovered? :) --Hemanshu 20:01, 29 May 2004 (UTC)

The great Vandal attractors

I deleted the cute sayings or mnemonics. Just a silly vandalism magnet. -Vsmith 03:45, 5 Dec 2004 (UTC)

Do laws of physics allow a Jupiter-sized solid planet?

If anyone with knowledge of astrophysics could answer, is it possible (not necessarily probable, just possible) that somewhere in the universe is a solid, non-gaseous planet with an atmosphere that's sized like one of the gas planets in our solar system? Do the laws of physics (which I know nothing about -- I'm a computer science type) allow such a thing to happen? Or would an object that large need a very specific amount of self-gravity to stay together without crushing itself too much? --I am not good at running 14:45, 20 Jan 2005 (UTC)

Sorry to spoil any sci-fi imagination but I'm afraid the answer is no. "Rocky", or "terrestrial" planets as they are known have a much greater density then gaseous planets, and hence would have a much greater gravitational pull towards the centre meaning a lesser volume. If you kept adding mass then deuterium would start to fuse in the centre, making the planet a "brown dwarf", and more mass further would then make it a star.
It might help you envision this better if you remember that Jupiter IS solid in the centre, but with such a dense centre that it has a captured an enormous atmosphere of gas. However, if you tried to walk on that dense centre the gravitational pull is such that you would become squashed with the gravity and form part of that core. Hope this helps. TJM
From what little I know, a pile of any kind of material above a certain size (1 Ceres is already well above that size) will have more than enough self-gravity to stay together. Also, no known material (when you have that much of it) is strong enough to resist its own self-gravity pulling it into a sphere -- that's why all the planets, moons, and the larger asteroids are almost perfect spheres.
If the pile of material is too large, it may collapse into a neutron star or a black hole -- but I think the limit of "too large" is the Chandrasekhar limit, about 1.4 times the mass of our sun.
Would such a large, solid planet be classified as a Brown dwarf, White dwarf, or Black dwarf, or something else entirely?
I'm not astrophysicist, but I play one on Wikipedia :-).
--DavidCary 18:00, 3 Feb 2005 (UTC)
I don't know, I'm not convinced by the above that you can't have a Jupiter-sized rocky planet. In fact a "back-of-the-envelope" calculation seems to indicate otherwise: Brown dwarfs need to be about 13 Jupiter masses to start fusing deuterium (if the WP article can be trusted, that is. I'm not an astrophysicist either.). Now rock + metal core will have a density similar to the Earth (solids aren't very compressible until you get into a white dwarf-type material, which requires stellar mass), which is 5.5 g/cm³. Jupiter, in comparison, has density 1.3 g/cm³, sooo, a Jupiter-sized rocky planet would have about 5.5/1.3=4.2 Jupiter masses. Not nearly enough to start fusing deuterium, apparently. So such a huge rocky planet does look possible.
Having said that, I don't think this is likely, just that it looks possible. The main problem is that I don't see how to accumulate that much rock without it attracting lots of gas - just like our giant planets. In fact, so much gas that you probably do reach the deuterium-burning mass well before you accumulate a Jupiter-sized rocky core in the middle. Gas is a lot more common than rock. Deuar 20:38, 19 May 2006 (UTC)
Well, saying that you'd start fusing deuterium presupposes the presence of deuterium. But, I think you could envision some exotic scenario where a jupiter-mass core accretes very close to a hot star such that the body's atmosphere "burns off" faster than it can accumulate. I don't see why it wouldn't be possible. Unless the mass is enough to cause the core to collapse into neutronium. --Aelffin 04:31, 25 August 2006 (UTC)
The key is probably likelihood, owing to the abundance of hydrogen and helium in the universe and the scarcity of everything else. The size of a giant terrestrial planet will be limited by the mass threshold for internal fusion reactions to take place. Small stars have been found at about 8% the mass of the sun, which is still 80-90 times more massive than Jupiter. For a terrestrial planet composed of heavier elements approaching Jupiter size, the internal pressure needs to generate enough heat to spark fusion in those elements; hydrogen requires the lowest amount of heat to burn, and more heat is necessary as to fuse the more massive elements up to the stopping point at iron. Close enough to its parent star, and the lighter elements could outgas and escape the gravity of the planet itself. Again, the probability is low owing to the scarcity of enough heavier elements to be present in large enough numbers, but given a universe of millions of quadrillions of stars, not a statistical impossibility.PJtP 02:48, 26 August 2006 (UTC)

Tm

What means 13 Tm (the paragraph about Sedna)? Tm is abbreviation for what?

It's supposed to mean "terameters" (SI units). I think this could be considered a bit confusing or unusual, would prefer meters with scientific notation (M × 10N m). -- Curps 18:46, 2 Feb 2005 (UTC)

added

i've added a few lines to this article. One on possible classes of exoplanets that do not exist in our solar system (ammonia giants and carbon planets) and one on a special class of hot Jupiters. My mother tongue is, however, not English so will please someone check my new lines to make sure they are in correct English?

definition

The definition at the beginning of the article (while beeing quite sensible) wouldn't be conseidered correct by many scientists. We won't find a better one, simply because the definition of what a planet actually is, is very much disputed.

Shouldn't that be mentioned and an additional definition be given as a possible example?

There's a seperate article on the ambiguities inherent in defining a planet; the link is at the bottom of the page. 157.140.6.143 11:20, 25 May 2005 (UTC)

Planet found with 3 stars : CNN tech who could write this into this article? Aleichem 14:25, 15 July 2005 (UTC)

Naming

Not sure if this is the right place for this, but I couldn't think of anywhere else, so I'll just put it here. I noticed that there's a schism among the naming of planetary articles. Uranus, Mars, Venus, and Jupiter are direct links to the planet pages, while Mercury, Saturn, Neptune and Pluto are all disambiguation pages (I'm not including Earth because it's kind of an exception). Can we standardize on one of these? If no one has any objections (like... if there's some Martian out there who thinks it will be a gauntlet to the cheek to make Mars a disambiguation page), we can set up a Wikipedia:Survey to get consensus on this. Any preliminary thoughts/ideas? --DropDeadGorgias (talk) 21:54, July 26, 2005 (UTC)

Two items: (1) Mercury is a special case because of the existence of a third important meaning, the chemical element; this makes it very different from the others; (2) Venus was recently on Requested Moves to "Venus (disambiguation)" and it was resoundingly defeated, so likely the choice should be to put the planets as primary meaning.
Let's put Saturn (planet), Neptune (planet), and Pluto (planet) on Requested Moves but leave Mercury where it is. —Wahoofive (talk) 01:39, 27 July 2005 (UTC)
(I saw the note you left on Wikipedia talk:Disambiguation.) I don't think you can really standardise this just because they're all planets. I mean, you could pick this out for any topic — say, for instance, that all Roman(?) gods have to be on primary topics (stupid poor useless example, but you get the idea). I think the rules for disambiguation must take precedence, even if it creates intra-category inconsistency, just because that's how the system goes. I don't really think saying they're all planets is grounds to change that. (If all the planets are actually primary topics because they're actually more common, and in my view they are, then that's a different story.) Neonumbers 12:36, 29 July 2005 (UTC)
My observation (by doing dab cleanup) is that the planet references outweigh the mythology references 10 to 1 on all the planets (but there are at least as many chemical references to Mercury).—Wahoofive (talk) 15:50, 29 July 2005 (UTC)
I have now put Saturn, Neptune, and Pluto on WP:RM. —Wahoofive (talk) 17:02, 4 August 2005 (UTC)

Planet count

Still holding at nine. See the IAU's [4] (August 16, 2004):

« Definition of a Planet

The IAU notes the very rapid pace of discovery of bodies within the Solar system over the last decade and so our understanding of the Trans-Neptunian Region is therefore still evolving very rapidly. This is in serious contrast to the situation when Pluto was discovered. As a consequence, The IAU has established a Working Group to consider the definition of a minimum size for a Planet. Until the report of this Working Group is received, all objects discovered at a distance from the Sun greater than 40 AU will continue to be regarded as part of the Trans-Neptunian population. »

Urhixidur 22:51, 2005 August 4 (UTC)

Someone rather annoyingly edited the opening paragraph to say that the IAU claimed there were ten planets. Just re-edited it, but keep an eye out if someone else makes that error again. Sometimes the media have a lot to answer for. Serendipitus 14:31, 25 August 2005 (UTC)14:26, 25 August 2005 (UTC)


Interstellar, brown dwarfs.

I trimmed this paragraph down to a nub saying that the IAU had not yet defined the term "planet"

"Such objects are not considered "extrasolar planets", however, since the International Astronomical Union has ruled that "Objects with true masses below the limiting mass for thermonuclear fusion of deuterium (currently calculated to be 13 Jupiter masses for objects of solar metallicity) that orbit stars or stellar remnants are "planets" (no matter how they formed)." In other words, planets must orbit stars."

The problem with this was that the conclusion does not follow from the premise. The IAU was ruling that brown dwarfs are not planets and took no position on whether planets must orbit stars, only that if the mass is less than a brown dwarf but large enough to be detected over interstellar distances and the body DOES orbit a star, then it is an extrasolar planet. The IAU has not taken a position on the lower size limit for a planet nor, so far as I know, has it taken a position on whether planetary-mass objects not bound to a star system are to be called planets. Since no such bodies have yet been discovered I would expect the IAU has not yet ruled on the matter. Enon 21:11, 24 September 2005 (UTC)

Uranus' symbol

The symbol listed in the article for Uranus is the astrological symbol, not the astronomical one. See [5] for the astronomical one. I don't know the code for it so if someone else does, please change it. --zandperl 00:19, 27 September 2005 (UTC)

There are no Unicode slots for the astronomical symbols; the 263D-2647 set of symbols are astrological. Until this is fixed, we must do as in the Uranus article and just use an image.
Urhixidur 22:37, 27 September 2005 (UTC)
Actually, Unicode has the astrological symbol for Uranus but the astronomical symbol for Pluto. (The other planets use the same symbol for both.) DenisMoskowitz 20:23, 2 December 2005 (UTC)

New moons of Pluto.

I've added the two new moons of Pluto to the list in the article. I've added them in as just S/2005 P 1 and S/2005 P 2. Am I right to assume that they have been confimed now however? Bennity 23:04, 31 October 2005 (UTC)

Planetary candidates

I've just taken out some of the candidates as I don't think they qualify as rounded. These are Ixion, 2002 UX25, Varuna, 2002 TX300, 1996 TO66, 2002 AW197, 2002 TC302. Some of these are dead links and I can't even find any reliable source to show that (for example) 2002 TC302 actually exists. Debates? Questions? Suggestions?130.126.76.27 23:52, 28 November 2005 (UTC)

Number of moons?

Query: In this planets article, the number of moons listed adds up to 155. However, in solar system, the number mentioned is 158. And in natural satellite, it says only “at least 140.” Does anyone know which is more accurate? Or is the number changing so fast that we can't keep up?

It very much depends on our definition of "moons" both in the scientific and structural sense.

I would say that the number is just changing so fast we can't keep up. In the last decade, there's been dozens of new moons discovered. Tuvas 17:38, 19 May 2006 (UTC)

Double planets

Under Planet#further classification, a "reason" given why Earth+Moon is to be considered a double planet is that the Sun's gravitational influence is on the Moon is larger than the Earth's. This is a weird argument - it would exclude any closely-orbiting bodies from being "double". In fact, Pluto and Charon are a good example: Pluto's influence on Charon is about 600 times stronger than the Sun's, but these two are widely considered to be a "double planet". Deuar 22:42, 27 January 2006 (UTC)

I don't see it as necessarily being "weird". If the strongest pull on Luna is from the Sun it means Luna is more orbiting the Sun than it is orbiting the Earth, thus it is more a planet than a moon. If the strongest pull on Charon is by Pluto, then it means Charon is orbiting Pluto more than it is orbiting the Sun and is more a moon than a planet. 130.126.76.27 02:59, 2 February 2006 (UTC)
As far as I remember (please disproof me if I am wrong) The Earth and its "the Moon" have their "shared center of mass/rotation point" outside of the Earth and/because "the Moon" is velatively big compared to its "planet" Earth and many scientists see Earth and "the Moon" as "double planets". Wouldn't this make "the Moon" a "13th planet" by the most actual definition(s) that define 12 planets? Or doesnt that matter at all by current definitions because suns influence on "the Moon" is far superior? --Ollj 18:55, 16 August 2006 (UTC)
You are mistaken. The Earth-Moon Center of mass#Barycenter is about 3/4ths of the way up from the core, but still below the surface. Frankie

Explicitly Exclude Moons?

This article implies but does not directly state that moons of planets may not be called planets themselves. Perhaps it should? Frankie

Suggested wide definitions

If the definition of a planet is that it shall be an object that is round from self-gravity (but not having nuclear fusion), how it that determined ? Assuming you have a principle how to determine roundness and are able measure it also for objects beyond Neptune. You have to have a limit that is not scientifically decided but quite arbitrary. Furthermore, how do you determine the roundness of an object beyond Neptune. It is hard enough to determine the diameter of 2003 UB313. How round is it ? /BIL 14:13, 5 February 2006 (UTC)

The difficulty of determining the roundness of UB313 at present, is only a technical issue. Just like it was difficult to say anything about Jupiter's Galilean moons in Galileo's time. The shape is a completely scientific criterion -- once you make instruments that can determine it, it is verifiable.
Also, we know that 2003 UB 313 is almost certainly round due to its calculated mass. However, the definition of "roundness" comes into question with smaller sized objects. Whether something is round or not depends on the mass of the object, the composition of it, and how far it is from the sun (I believe a colder temperature means the structure is more solid and less likely to 'round' itself). 130.126.76.27 22:20, 11 February 2006 (UTC)

There is a more subtle question of exactly how close to spherical (or spheroidal) does it have to be to be considered "round"... Deuar 20:34, 6 February 2006 (UTC)

The 'roundness' is actually not a measure of it's true roundness, but rather it's ability to become so. Otherwise, if someone tossed a marble into space we would be forced to call it a planet. Different masses of different bodies create different shapes. Once they go over a critical mass, which is typical of objects over about 550km in radius (Don't quote me on that...), then the gravitational force is enough that the object will tend to be more of a sphere rather than any kind of object. Take a look at the moons of Mars. They are potato-shaped. That's because they aren't big enough to collapse gravitationally upon themselves. Hope this helps a bit. Tuvas 17:37, 19 May 2006 (UTC)

Extrasolar description names

This section is poorly written and uncited, looks more like a list of definitions rather than a discussion - also, have the terms "phoenix planet" and "zombie planet" actually been used? Chaos syndrome 11:22, 10 July 2006 (UTC)

Merging with "Definition of Planet"

Just a headsup; when the IAU announces its final definition in September, I'm planning to merge this article with Definition of planet. Just wanted to make sure everyone's OK with that.Serendipodous 19:22, 23 July 2006 (UTC)

Nope, sorry but I don't think I agree with that idea. Both articles are quite long already, so this would greatly exceed the standard article length and produce issues with some browsers. Also I think the two subjects stand by themselves, with only partial overlap.
What I would like to see is the "Definition and classification of planets" section of the Planet page thinned down to the bare essentials. It's by far the largest section on this page. I'd like to see room freed up for discussions of planets as physical objects, rather than the symantics of the word. Does that seem reasonable? — RJH (talk) 17:45, 28 July 2006 (UTC)
That still leaves me with the unenviable task of deciding what to do with "Definition of planet" once the definition is finally announced. For now, the "Definition and classification of planets" section of this article is necessary, as it needs to be made plain that there is no one accepted definition of planet (the reason I began the "Definition of Planet" article in the first place was to counter a definition listed here). That said, a lot of the "suggested definitions" particularly Gibor Basri's work, are really just the suggestions of single individuals and are unlikely to have any impact on whatever definition is finally decided. And unless you can come up with a citation for "zombie planet" or "phoenix planet," I'd ditch em. Serendipodous 17:57, 28 July 2006 (UTC)
So how sure are we all that the IAU will give a widely usable definition of a planet? Will it be readily applicable to e.g. extra-solar planets? My point being that it's quite plausible that definition of a planet may still be able to stand on its own after any announcements the IAU makes. For example, whatever they decide may only apply to the bottom range of the planet scale. As for zombie planets, phoenix planets, and similar obsolete stuff it can (and probably should) get the chop. Deuar 19:15, 28 July 2006 (UTC)
  • Once it's announced the Definition of planet could become a history page that explains the definition and the reasoning behind the IAU's decision. That can also include rejected definitions and such. I don't really see any reason to just dump that page, as the history can definitely be of interest to students of astronomy. :-) As for the whole "Extrasolar Description Names" section, I have no idea where that came from. Maybe the original poster needs to be contacted to obtain citations? — RJH (talk) 19:47, 28 July 2006 (UTC)
    • I ran down the user's name: Marasama added the entry 2006-06-01. I left a message, so hopefully a reference will be forthcoming. — RJH (talk) 20:49, 28 July 2006 (UTC)
      • It's odd but I got a message back from CarpD in reference to the message left for Marasama. Possibly it's a multi-aliased user. Anyway they said they had no reference for the "Extrasolar Description Names", and possibly those names were just aliases. I'm going to go ahead and delete that short section, since there's a pretty clear consensus. :-) — RJH (talk) 15:41, 30 July 2006 (UTC)


A tenth planet

It was my understanding that the IAU had confirmed the veritable existence of a tenth planet. The press went public with this story earlier this year proclaiming that there are now ten planets. 14:54, 12 August 2006 (UTC)

And that's why you should never pay attention to the news :-). Yes, a lot of organizations, including JPL, rather oddly, proclaimed immediately that there was a tenth planet. In fact what really happenned was that the IAU was thrown into a tailspin. They've been shoving this issue under the carpet since 1992, and now it's finally caught up with them. They haven't officially released a statement yet, but they will in September. They've remained tight-lipped but from the rumours going round it looks like there are going to be dozens of planets in the solar system, not ten. Serendipodous 14:54, 12 August 2006 (UTC)

Definition of a planet

I think Nasa is working on the definition of a planet right now. So maybe put that thing on the article that says it's a current event and may change rapidly as time etc.....

  • NASA doesn't have the authority to define what a planet is or is not. The IAU is responsible for that. Tachyon01 23:41, 15 August 2006 (UTC)
Looks like Ceres, Xena, and Charon get upgraded to planets! Added a CURRENT marker to this article. Hopquick 05:08, 16 August 2006 (UTC)
The part of "IAU Resolution 5 for GA-XXVI" that describes the planet definition, states "A planet is a celestial body that (a) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (b) is in orbit around a star, and is neither a star nor a satellite of a planet." Member of the Planet Definition Committee, Richard Binzel says: "Our goal was to find a scientific basis for a new definition of planet and we chose gravity as the determining factor. Nature decides whether or not an object is a planet."Hopquick 05:10, 16 August 2006 (UTC)
But according to that defintion, there should be at least 25 planets, possibly more, not 12! Even our own Moon would qualify, and certainly if Charon does. Serendipodous 06:31, 16 August 2006 (UTC)
The article I'm reading right now [[6]] says that the new ruling "suggests retaining Pluto and immediately adding" the above three, with "perhaps dozens" more to follow, pending further study/discussion/debate I assume... It should be noted though, that this isn't an IAE ruling, it's the suggestion of an "international panel formed to devise a scientific definition of a planet," and that "a vote of the union's general assembly is scheduled for Aug. 24 at a conference underway in Prague." So I guess we have a few days till it's official. -- MyrddinEmrys 09:42, 16 August 2006 (UTC)
The Moon won't qualify, as it orbits a planet, not a star. The same goes for the gas planet moons (some of which are larger than Mercurius). The proposed number of 12 is certainly a low number... I can easily think of three more asteroids which would qualify for re-admission to planethood, and then there are a lot more round large rocks beyond Uranus... or plutons. -- Jordi·✆ 13:06, 16 August 2006 (UTC)
There are reports that as many as 40 more objects would be added as "planets".
- Loadmaster 14:18, 16 August 2006 (UTC)
Charon is being considered because it is the only "moon" who's baricenter is "above" the surface of the planet. Ergo, the statement "Pluto orbits Charon" is as true as saying "Charon orbits Pluto", thus making it a binary planet. This is not true of the Earth-Luna system, even though other methods of classifying binaries would imply that it could be. Hopquick 15:13, 16 August 2006 (UTC)
I think that technically, one shouldn't say that body A orbits body B. Rather bodies A and B orbit their common barycenter. This is true of all bodies, but in many systems one body is so much more massive that the barycenter is only a miniscule distance from the center of the larger body. We tend to say one body orbits another for the sake of convenience, but it's not exactly correct. --Aelffin 04:17, 25 August 2006 (UTC)

I think a more viable and worth while discussion is wether or not this means they will make characters Sailor Ceres and Sailor Charon and Sailor 2003 UB313 (rolls right off the tongue). ..... okay .... so many that's not a worthwhile discussion. At least it's easy to change that familiar line to "My Very Excellent Mother Can Just Serve Us Nine Pizzas and Calzones" for the time being. I wonder though if this isn't going to be the end of the discussion. Sedna, Quaoar, and others look (note LOOK) like they're round ... and since the definition seems to be key on "roundness" as the factor then will they be upgraded to Planet once there is confirmation that they can hold their gravity? SargeAbernathy 15:28, 16 August 2006 (UTC)

I've started a new article on this topic, see 2006 redefinition of planet. Please help to expand that article. Thank you. --Cyde Weys 18:05, 16 August 2006 (UTC)

Titius-Bode

I've deleted a paragraph referring to the "Titius-Bode" law because it seems to violate the prohibition against original research (or at least NPOV). The IAU is the widely-recognized authority on definitions of planets, etc., and neither their traditional definition of the planets nor their proposed new definition of 12 planets makes any reference to Titius-Bode. Perhaps a brief reference would be appropriate later in the article. Gnixon 04:13, 18 August 2006 (UTC)

Please be aware that PlanetCeres is trolling multiple articles and talk pages with his periodicity theory. Check his contributions and those of anonymous IP 71.215.54.11 for details. Nick Mks 09:02, 18 August 2006 (UTC)

Does not violate original work. Verified publicly accessible for four years. IAU definition, although competes with the definition is not mutually exclusive. Please see the Titius-Bode discussion for the actual derivative.

The following keeps being deleted in different forms. Should this information be included in the subject Planet? ____________________________________________________________________

The Titus-Bode Law was used in the early 1800's to predict planetary orbits. This "law" was disavowed when 1Ceres was found to be quite small and Neptune was too far out. A recent derivation of this "law" accurately predicted the orbital distance of 2003 UB313 from the Sun.

___________________________________________________________________ Your chance to put your word in. —Preceding unsigned comment added by PlanetCeres (talk • contribs)

  • Please be aware that PlanetCeres is trolling multiple articles and talk pages with his periodicity theory. Check his contributions and those of anonymous IP 71.215.54.11 for details. Nick Mks 09:02, 18 August 2006 (UTC)

Attributes table

Here's my recommendation for the new table. —Joseph/N328KF (Talk) 14:01, 22 August 2006 (UTC)

*Measured relative to the Earth.
**See Earth article for absolute values.
*** Pluto and Charon orbit the same point in space and so are considered a binary planet system. As such, they share many attributes, including their two moons and orbital data.
Planetary attributes
Planet Equator*
diam.		 Mass* Orbital
radius* (AU)		 Orbital period*
(years)		 Orbital
inclination (°)		 Orbital
eccentricity		 Day*
(days)		 Moons
Terrestrials Mercury 0.382 0.06 0.387 0.241  7.00    0.206 58.6 none
Venus 0.949 0.82 0.72 0.615  3.39    0.0068 -243 none
Earth** 1.00 1.00 1.00 1.00  0.00    0.0167 1.00 1
Mars 0.53 0.11 1.52 1.88  1.85    0.0934 1.03 2
Dwarf planets Ceres 0.15 2.5-2.9 4.6  10.587    0.080 0
Gas giants Jupiter 11.2 318 5.20 11.86  1.31    0.0484 0.414 63
Saturn 9.41 95 9.54 29.46  2.48    0.0542 0.426 56
Uranus 3.98 14.6 19.22 84.01  0.77    0.0472 -0.718 27
Neptune 3.81 17.2 30.06 164.8  1.77    0.0086 0.671 13
Plutons Pluto*** 0.18 0.002 39.5 248.5  17.1    0.249 -6.5 2
Charon*** 0.0095 39.5 248.5  17.1    0.249 -6.5 2
2003 UB313 0.38 37.77-97.56 557  44.187    0.44177 1
  • Looks good. It makes no sense for the current chart to only include Pluto as a dwarf planet, it's kinda misleading. Make sure you or somebody else can fill in the missing data on there. --...::: DietCoke119 :::... 19:09, 24 August 2006 (UTC)
    • I have to disagree. After Resolution 5B was voted down "dwarf planets" do *not* qualify as planets and thus should be absent from the table. This table would be best on either the solar system page or the dwarf planet page. I'm going to give it half an hour and then amend this.
  • "Pluto and Charon orbit the same point in space and so are considered a binary planet system." This is true of any moon and its planet. The distinction here is that the point in space is not within either Pluto or Charon. -JustSayin 18:05, 24 August 2006 (UTC)
  • Why is "pluton" on here? That term was dropped (thankfully) in the second revision. --Aelffin 18:46, 24 August 2006 (UTC)
    • Actually, Pluto and Charon orbit each other, rather than just the sattelite orbiting the planet. There is still debate about whether or not this makes it it's own dwarf planet or if it still should be considered a planet. I think maybe the whole dwarf planet part of the table should be removed and added to the Dwarf Planet article. --...::: DietCoke119 :::... 19:09, 24 August 2006 (UTC)
      • If I'm not mistaken, Pluto and Charon would just be considered plutinoids. Maybe co-orbital plutinoids or something, but there's precedence for small bodies orbiting each other within the asteroid belt, so I imagine the terminology would follow whatever model they used in those situations. --Aelffin 04:12, 25 August 2006 (UTC)

8 Planets

Hurrah! I see someone has already updated the intro and fixed the title of a table. More work needs to be done later in the article for it to conform with the new definition. Gnixon 15:01, 24 August 2006 (UTC)

ugh.

Why did this happen? it's stupid. Pluto is a planet and so are many others. I don't care what the whatever says they are wrong. 154.20.174.31 18:21, 24 August 2006 (UTC)

You're free to call it a planet if you like, but astronomers do not and have not for a long time. The "new" IAU definition just enshrines the current thinking among astronomers. Anyway, the new definition clarifies the relationship among the bodies of the solar system, grouping Pluto with the Kuiper Belt Objects since it has much more in common with them than it does with the real planets. That being said...I'll miss Pluto too. But life goes on. --Aelffin 18:44, 24 August 2006 (UTC)
Pluto has been erased althogether from the article. Surely the article should mention that from 1930 (or whatever it's discovery year was) until today it was considered a planet? Alexj2002 22:15, 24 August 2006 (UTC)
It's here: Planet#Historical planets. └ OzLawyer / talk ┐ 22:16, 24 August 2006 (UTC)