Talk:Jupiter/Archive 2

message: Seems rather an informal phrase to describe the postulated core of a planet. 
- Dr S.
That was probably vandalism (I'll check if it's still there). Thank you for pointing it out. Please add new comments at the bottom by the way. · AndonicO Talk 11:43, 6 June 2007 (UTC)
thread_title:  The absolute grand-daddy of diamonds? 

message: What do people mean by radius or circumference of these solar system objects, especially if they have atmospheres, giant atmospheres at that?  Are the measurements dependent on some well-defined extent of the atmospheres of the objects?  Does the atmosphere count?192.91.147.34 19:48, 16 February 2007 (UTC)
replies: text: Good question. I'm going to speculate that, for ease of measurement purposes, it's probably based on an opacity level in the atmosphere. That is, you could plot the light curve of a background star as it is occulted by Jupiter. When the star reaches some fraction of its normal intensity, perhaps half... or else 1/e, that'd be the interception point of an effective "surface". Alternatively it could be based on a particular gas pressure, but that'd be harder to measure. A radius measurement of a solid body is based on some standard level; such as the sea level for the Earth. But even there it's not an exact measurement. — RJH (talk) 23:03, 16 February 2007 (UTC)
replies: text: P.S. I read that fly-by mission occultations have been used for the same purpose. I.e. tracking the point at which the radio transmission is occulted was used to refine the measurements of the radius and polar flattening. — RJH (talk) 15:50, 19 February 2007 (UTC)

text: You are correct.  For Jupiter, the atmospheric profiles are good down to the ~10 atmosphere level and the fiducial for radius is above that (of course, the thickness of the atmosphere is much less than the radius of the planet). Michaelbusch 15:58, 19 February 2007 (UTC)
replies: text: If the Jovian equatorial radius is ~5.6 Earth diameters, what fraction of that radius is ~solid?  The article mentions metallic hydrogen to 78% of that radius...  22% is much less?  22% is absolutely gigantic compared to the Earth, whose atmosphere's thickness is genuinely just a higher order term compared to the overall radius.  Where does solid end and the atmosphere begin?  Thanks.  192.91.171.42 23:24, 19 February 2007 (UTC)

text: There is no solid surface, unless you count a core, which may not exist.  The distinction between atmosphere and the bulk of the planet is fairly simple: what do you see when you look at the planet?  That defines the radius.  This is somewhat dependent on wavelength, but only weakly so for Jupiter (Venus is a much different case).  The fiducial radius is where the planet's optical depth is ~1 in the optical.  That atmosphere is very thin compared to the size of the planet.  The same applies to the Sun. Michaelbusch 23:36, 19 February 2007 (UTC)

text: Good suggestion. I took the libery of just changing "large" to "massive", since mass is this planet's primary influence on the system. Thanks. — RJH (talk) 18:33, 29 April 2007 (UTC)
thread_title:  "Measurements?" 

message: I edited "polar_radius = 66854.5 km (5.2585 Earths)" to read "polar_radius = 66854.5 km (5.2585 Earth diameters)".
Old version was misleading (one may think that "Jup polar radius is 5.2585 x Earth polar RADIUS" by analogy. It is still somewhat bad (I think that precision of "5.2585" is bogus - Earth's polar/equatorial diameter difference is probably larger than this precision...).
: I've noticed that, for all the gas giants, the radii are compared to Earth diameters. Wouldn't it make more sense to compare radii to radii? I.e., "Equatorial radius: 71,492 km (11.2 Earth radii)" 192.75.95.127 09:46, 11 February 2007 (UTC)
replies: text:  Yes, I think so.  --Doradus 19:10, 30 April 2007 (UTC)
thread_title:  "Earths" 

message: Someone incorrectly put the abbreviation of "acceleration due to gravity" (in relation to Earth) as "gee" instead of "g". I have attempted to edit it and have even cut and pasted the entire article into my word processor to search for "gee" but have been unable to find it. Can someone please fix this? SteveSims 02:32, 30 November 2006 (UTC)
thread_title:  g = gee? 

message: I feel that the thing about carl sagan's "hypothesis" about a hypothetical life on jupiter do not really belong in the article. Or atleast should have its section tile renamed and maybe added to a "Jupiter in Science Fiction" section because that level of hypothesis is basically science fiction. Any ideas? Ergzay 03:15, 3 October 2006 (UTC)
replies: text: Europa, maybe. On Jupiter itself, no. Europa is suspected of having some kind of ocean and the suspected lifeforms may be chemosynthetic in nature, thus it does not need sunlight.
It may have "thermal vents" similar to what is found here on Earth, and these have chemosynthetic life forms. Three other satellites may have oceans, w/ heat supplied by the tidal forces present in the jovian system. Martial Law 02:16, 12 October 2006 (UTC)
thread_title:  Life on Jupiter 

message: I suggest removing the black & white movie of the Great Red Spot as it's basically just taken from the larger color one above it and cropped up. It's pretty redundant and it takes a serious bandwidth toll plus it kind of clutters the article with images. Does anyone agree with me? Ugo 08:07, 20 October 2006 (UTC)
thread_title:  Movies 

message: I have just changed the IPA pronunciation back to the original one I put in for this article. I understand that there are different IPA symbols relating to different codes, but I use the one standard in the Oxford English Dictionary, in my opinion (and more-or-less accepted worldwide as) the most authoritative reference for English, and have done the same for all the planets. If a different pronunciation key is preferred (i.e. the American one that a lot of my IPA edits get changed to) do you think we should introduce consistency across all planets' articles? Kris 15:18, 23 October 2006 (UTC)
thread_title:  Pronunciation key 

message: This paragraph was added by an anonymous user:
:Over forty new satellites have been discovered in the vicinity of Jupiter between 2000 and 2006 and it is suggested that many, in particular those of icy composition were originally comets and other objects captured by the large gravitational field. It is possible however, that considering the Jovian atmospheric composition and activity, some of these objects are being formed by materials coalescing within the extremely hot, high pressure conditions then lifting into higher, visible orbits above the cloud tops as their mass increases. Based on this argument a logical extrapolation might suggest that the accumulation of matter on a point fixed to the surface, in much the same fashion as crystals are formed, may provide an explanation for the stationary Red Spot phenomena. It is therefore conceivable that as more data becomes available from subsequent Hubble observations and probes like New Horizons, scheduled to arrive in February 2007, that if regular growth patterns are discovered, the Red Storms may be evidence of the early gestation of additional major moons.
How would such an object get the energy to achieve orbit?? Jupiter's rotational period is 35.7 ks (kilo-seconds), an object above Jupiter's equator would have an orbital period of 10.8 ks. In velocities, this is 12.6 km/s vs. 41.7 km/s. Due to this consideration, I would call the added paragraph nonsense - I'll remove it now. Icek 12:02, 3 December 2006 (UTC)
thread_title:  Moons from the atmosphere??? 

message: There is a discussion at Wikipedia_talk:WikiProject_Astronomical_objects#Planet_infobox_conventions_.28km_vs._AU_vs._miles.29 on standardizing the planet infoboxes, as well as the possibility of changing the planet diameter to radius. If you care about these things, let your opinion be heard there. Lunokhod 10:10, 4 December 2006 (UTC)
thread_title:  infobox 

message: I was bold and removed 3 images from The Great Red Spot section.  As much as I love images, it really was not illustrative to see 5 pictures of the same thing and push the other images in this article around.  Please put them back in (or even better, just switch them) if you don't like the ones I chose to keep.--Will.i.am 14:53, 29 December 2006 (UTC)
replies: text: The north-south dimension of the GRS is 12-14,000 km, while the Earth's diameter is 12,744 km. So I think the image is correct. — RJH (talk) 16:28, 3 April 2007 (UTC)
thread_title:  Great Red Spot Images 

message: Please add the things that you feel need to be done to improve this article to this list (be as specific as possible).  If you have the time, then fix one and cross it off (don't erase it!), of if you don't like the improvment, please discuss.--Will.i.am 15:22, 29 December 2006 (UTC)
thread_title:  Expanded Task List (ACID) 

message: The "Great Red Spot" section has a needs-references tag. This needs to be fixed with the addition of references before it can become a Good Article. - Aerobird Target locked - Fox One! 03:36, 17 January 2007 (UTC)
replies: text: I've added enough references to the section for it to be verifiable, and removed the now redundant tag. Cheers. SeanMack 10:41, 17 January 2007 (UTC)
thread_title:  GA on hold 

message: There's a line of text at the top of the page, right below the "for..." disambig line, that reads:
" {{#if: | }re} "
I assume this is in the see-also template, as I can't find it in the edit thing for the page itself. - Aerobird Target locked - Fox One! 15:59, 17 January 2007 (UTC)
thread_title:  Template vandalised? 

message: Congrats, Jupiter is now a Good Article. :-) - Aerobird Target locked - Fox One! 16:01, 17 January 2007 (UTC)
thread_title:  GA passed! 

message: *
*
*
These three references give a good overview of the atmospheric chemistry and the unknown particles or chromophores resposible for the color of the jovian atmosphere.--Stone 10:29, 19 January 2007 (UTC)
replies: text: Yes you're right. A Galileo Mission web page lists precipitation of neon itself through the metallic hydrogen as a likely explanation. So the sentence appears erroneous. The article also doesn't discuss the depletion of atmospheric helium through a similar mechanism, instead stating that it is close to the primordial abundances. — RJH (talk) 16:28, 29 March 2007 (UTC)
thread_title:  Atmosphere 

message: The following was posted about the internal structure:
:Or, according to another model, the core may be a ball of tar studded with rocks.
Based on the following reference: 
:
Unfortunately I'm not seeing anything in the reference that suggests such a model. Only that carbonaceous material aided in accretion during the planetary formation. Could somebody clarify why the above is an appropriate addition? Thanks. — RJH (talk) 15:30, 20 February 2007 (UTC)
thread_title:  Core model 

message: There is no such thing as "metallic hydrogen" - could someone check that please. --Zureks 08:38, 6 March 2007 (UTC)
replies: text: Indeed there is such a things as metallic hydrogen, at least in theory, and I direct you to the wikipedia article on the subject for more information. siafu 16:23, 6 March 2007 (UTC)
replies: text: I believe that metallic hydrogen has been demonstrated in a laboratory. — RJH (talk) 16:27, 17 March 2007 (UTC)
thread_title:  Error 

message: I just changed two-thirds to two-fifths Under "Observation" (relative periods of J. and Saturn), not sure how an error like that could happen, since moments later they are referred to as a 5:2 resonance.  Also, I'd fix it but I'm not fully sure what it means (!), in the last paragraph of "Observation", "the phase angle of Jupiter as viewed from the Earth never exceeds 11.5°, and is almost always close to 100%" just seems unclear to me, even though I can sort of see what it means.  It is explaining why we don't see a "crescent" Jupiter from Earth (although that 11.5 degree thing would imply that we could see a slightly less than round version), but I think it just muddies the waters with the mixed terminology - degrees vs. percent - can someone who really knows what it should say try cleaning up the sentence/paragraph?  thanks all (PS feel free to move this comment to another section if it's appropriate) human 02:02, 14 March 2007 (UTC)
replies: text: Yes you're right, it should be 2/5; I thought I'd corrected that already. Phase angle is the angle subtended by the Earth and the Sun at Jupiter. Thanks. — RJH (talk) 16:27, 17 March 2007 (UTC)
replies: text:  Thanks for confirming - and, rechecking that section, it seems much clearer now!  Excellent work... human 22:24, 19 March 2007 (UTC)
thread_title:  Observation section comments 

message: Would there be enough information to include a section on Jupiter's formation? Sancho (talk) 14:06, 26 March 2007 (UTC)
replies: text: Do you mean in more detail than information on the "formation and evolution of the Solar System" page? If there is more information that could be presented, perhaps a separate article is needed on the formation and evolution of Jupiter? That could always be included summary-style in this article. — RJH (talk) 16:24, 26 March 2007 (UTC)
replies: text: Oh, no, I didn't mean in more detail that that link. I didn't know it was already in an article. Thanks! Sancho (talk) 18:42, 26 March 2007 (UTC)
replies: text: But Sancho has a point.  Someone interested in Jupiter's formation wouldn't be able to find out about it from this page.  I think we ought to have a quick summary and a link to the "formation" page RJH gave above.  --Doradus 14:01, 9 May 2007 (UTC)
replies: text: If you are interested in developing the topic, that'd be great. But it would need to meet the FA criteria or else this page may be demoted. (Which I'm trying to avoid.) So a helpful approach may be to fully developing the topic on its own page (with refs. and a peer review) and then adding in a summary here. That way we would already have the necessary references and information. — RJH (talk) 17:17, 4 June 2007 (UTC)
thread_title:  Formation 

message: The photo used in the infobox (Jupiter.jpg) seems to be having some problems.  It is showing up as a broken image on my browser.  Does anyone else see this?  I've checked other articles using the same image and apparently any article that uses a scaled image (e.g. |240px|) is showing a broken image.  However, any article using the |thumb| tag shows the image properly.  Any idea what's going on and how to fix it? -Sarfa 21:03, 29 March 2007 (UTC)
replies: text: It displays fine for me in both Firefox and IE browsers. Perhaps the image in your cache is corrupted? Sorry. — RJH (talk) 21:43, 29 March 2007 (UTC)
thread_title:  Infobox Photo 

message: The Great Red Spot section says that the Great Red Spot is an "oval" shape. According to the oval wikipedia article, "Unlike other curves, the term 'oval' is not well-defined and many distinct curves are commonly called ovals." Since 'oval' is not a very specific term, wouldn't it be more informative to call the Great Red Spot 'elliptical,' since the term 'ellipse' is more specific? Jolb 15:33, 9 April 2007 (UTC)
replies: text: Since Oval BA is an official name for a storm on Jupiter, I don't think the word Oval is inappropriate. I'm not even sure that the GRS forms a precise ellipse, so perhaps a little vagueness is appropriate. — RJH (talk) 16:53, 9 April 2007 (UTC)
thread_title:  Great Red Spot 

message: Ok, it appears to be getting a little big.  Is there info that can be shifted out? Harvestdancer 18:38, 20 April 2007 (UTC)
replies: text: I think it's fine. The other FA'd planet articles are pretty meaty as well. — RJH (talk) 22:08, 20 April 2007 (UTC)
replies: text: I think I was premature anyway.  I didn't know Wiki was going to list bytes as a mater of course, I thought the listing was to warn us about size.  It's not too big.. Harvestdancer 15:31, 25 April 2007 (UTC)
replies: text:  Part of the problem is that Wiki also includes the size of the images when it lists the length. The text component can actually be less when there are a lot of images. — RJH (talk) 18:35, 26 April 2007 (UTC)

text: The warning was added because some browsers can't handle large texts within the edit box, which can lead to clipping of text. The problem can be avoided by editing only sections of the article.— JyriL talk 16:56, 25 April 2007 (UTC)
thread_title:  Too Big? 

message: It looks like the vandals are back to sack the article, now that the protection have been removed. The history is replete with their sorry little grafitto. — RJH (talk) 22:30, 2 May 2007 (UTC)
replies: text: If you want Wikipedia's policy on main page featured article protection to change, you'll have to make your voice heard at Wikipedia:Main Page featured article protection. Current practice is to protect only during heavy vandalism. For an active debate about whether semi-protection should be left for the whole day in the case of heavy vandalism see Wikipedia talk:Main Page featured article protection#Alison's revert: Period of protection. For some developing guidelines on what 'heavy' actually is supposed to mean, see WP:ROUGH. Richard001 10:39, 6 June 2007 (UTC)
replies: text: Actually the policy is sort of in a transition - it currently states pages should be protected for the whole day in the case of heavy vandalism. The data we have collected (see WP:WPVS) seems to indicate vandalism will just return after unprotecting (why wouldn't it?), though the policy has literally been changed a few minutes ago. Administrators are of course at liberty to make their own decisions about protection, though they should take note of recent changes in policy and observe the very strong support of these changes in those who have made their position known thus far. Richard001 10:52, 6 June 2007 (UTC)
thread_title:  ...and then the deluge 

message: What would happen if a probe were sent to Jupiter emitting sparks - would the planet ignite?  How would this affect other planets in the solar system, particularly Earth? --NEMT 04:32, 5 May 2007 (UTC)
replies: text: Lightning storms on Jupiter are not uncommon. In fact they can be much more powerful than on Earth. I don't think we need to be concerned about a spark, as there is virtually no free molecular oxygen in the Jovian atmosphere to create a combustion reaction. — RJH (talk) 17:15, 7 May 2007 (UTC)
replies: text: Is there any way to transport enough oxygen there to maintain combustion? --NEMT 12:21, 9 May 2007 (UTC)
replies: text: Folks, this is not a place to talk about Jupiter.  It's a place to talk about the Wikipedia article on Jupiter.  --Doradus 13:56, 9 May 2007 (UTC)
replies: text: Oh it's relevant, since I was considering adding a section on this subject. --NEMT 15:07, 9 May 2007 (UTC)

text: What would be the point? There is already oxygen in Jupiter's atmosphere, but it's locked up in various molecules. — RJH (talk) 14:59, 9 May 2007 (UTC)
replies: text: Yes, I suppose Jupiter can be troublesome that way. --NEMT 15:07, 9 May 2007 (UTC)
thread_title:  What would happen 

message: I removed the following edit because it is not supported by the cited source (which does not, for example, treat subsequent evolution.)
:When it was first formed, Jupiter was much hotter (glowing red hot) and was about 1.2 to 1.6 times its current diameter. It was about 1.1 times its current radius 2 Billion Years ago and might have been more white in appearence due to the increased heat. By the time the Sun becomes a Red Giant, Jupiter would roughly be 95% its current Radius.
I think additional references is needed to substantiate this change. Otherwise it is unclear whether this is just subtle vandalism. Sorry. — RJH (talk) 16:43, 3 June 2007 (UTC)
thread_title:  Planetary evolution 

message: I was under the impression that "gas giant" is really a misnomer, as the majority of Jupiter's mass (and other "gas giants'" masses) is liquid.  Only a small portion is gas.  Shouldn't we omit, or at least address the misleading nature of this term in the introductory paragraph?
: I've never heard that. Do you have a source? thx1138 08:21, 6 June 2007 (UTC)
thread_title:  "Gas Giant"? 

message: I removed this statement because it needed a citation and was uglifying an otherwise great article:
While at Jupiter, New Horizon's instruments refined the orbital elements of Jupiter's inner moons, particularly Amalthea.--Wafulz 14:06, 6 June 2007 (UTC)
replies: text: That works for me, as it is probably too minor a detail to be listed at this level. The goal of refining the elements is mentioned on the New Horizons page, but I'm not sure that anything specific has been published yet. Thanks! — RJH (talk) 14:46, 6 June 2007 (UTC)
thread_title:  This needs a citation 

message: I was under the impression that the term "burn", from a specific scientific standpoint, would refer to combustion, i.e. a substance undergoing a rapid oxidation reaction. I'm pretty sure that the reaction referred to here is not that? Or perhaps "burn" has no precise scientific meaning. Either way, should this phrase be changed to something else? Jlaramee 18:54, 6 June 2007 (UTC)
replies: text: Burn is also loose term for thermonuclear fusion, as in the sun "burns" hydrogen to make helium. But I'll change it. SBHarris 21:04, 6 June 2007 (UTC)
replies: text: The term "thermonuclear burning" is frequently used in scientific papers. I don't think it is incorrect usage, so it shouldn't need to be changed. — RJH (talk) 21:26, 6 June 2007 (UTC)
replies: text: You learn something every day. Jlaramee 17:10, 7 June 2007 (UTC)
thread_title:  "burn deuterium"? (in Mass) 

message: The following assertion was lacking a solid reference, and so was temporarily extracted from the text:
:In Hindi, Thursday is referred to as Guruvaar (day of Jupiter).
Does anybody know of a good source? Thank you. — RJH (talk) 15:59, 17 June 2007 (UTC)
thread_title:  Reference needed 

message: This reference:
* 
has a novel proposal concerning primordial low-mass black holes, including possible heat generation on Jupiter and Saturn. It'll be interesting to see if this idea gathers any credence. — RJH (talk) 14:53, 20 June 2007 (UTC)
thread_title:  Low-mass black holes & heat generation 

message: Was there a policy or discussion about this or other form of justification or consensus? It doesn't seem appropriate to me, as the planet's name is taken from the Roman god Jupiter (mythology), which is just as notable and just as likely to be searched for. I think "Jupiter" as an article should either be the disambig page or the mythology page. Ham Pastrami 17:02, 9 July 2007 (UTC)
replies: text: Actually, I find it very dubious that Jupiter as god is "just as notable" and even more so that it is "just as likely to be searched for".  Just check google with Jupiter -"god" vs. Jupiter +"god"; 31 million vs. 2.2 million, and the second search even includes pages about the planet that are explaining its name.  Previous discussions on this topic for other planets have also born this out, with the exception of Mercury, which is disambiguated-- not because of the Roman god, however, but because of the element Hg. siafu 17:13, 9 July 2007 (UTC)
thread_title:  Why is this Jupiter and not Jupiter (planet)? 

message: "A large planet such as Jupiter is distinguished from a brown dwarf star by the rather specific spectral lines of the latter."
It is unsourced, and contradicts the rest of its paragraph. Still, if a source could be found for it, it would be really useful. Serendipodous 08:06, 29 July 2007 (UTC)
replies: text: That edit was made way back in September 13, 2003 by user Jerryb1961, so it's been around for a while. The brown dwarf page mentions the presence of Lithium lines, so that may be what he meant. Perhaps one of the external links on the brown dwarf page could serve as a suitable reference? — RJH (talk) 17:28, 29 July 2007 (UTC)
replies: text: The presence of lithium does not distinguish a brown dwarf from a giant planet, but rather distinguishes a brown dwarf from a fusing star.  The distinction is therefore irrellevant in Jupiter's case. If  Jerryb1961 wished to make a claim that the presence of lithium absorbtion lines separated a brown dwarf from Jupiter, then he was mistaken. As this article shows,  both gas giants and brown dwarfs possess lithium chemistry. Serendipodous 14:18, 30 July 2007 (UTC)
replies: text: Yes, lithium apparently only indicates a minimum mass. But there's also deuterium and (in some brown dwarfs) iron hydride. There's probably more if you search around a bit. — RJH (talk) 15:12, 30 July 2007 (UTC)
replies: text: Yes, but none of those sources imply that those compounds are distinguishing characteristics that mark them out as different from giant planets, so I don't see what connection they have with Jupiter.Serendipodous 09:41, 31 July 2007 (UTC)
replies: text: Well personally I would suffer no remorse if both paragraphs dealing with extra-solar planets (from "Extrasolar planets have..." down to "...basic physical difference") were completely expunged. The only relevant fact they seem to add is that the amount of mass needed to fuse Deuterium is much larger than Jupiter. Otherwise they're relatively OT. — RJH (talk) 21:25, 31 July 2007 (UTC)

text: I've removed it. - ∅ (∅), 16:12, 1 August 2007 (UTC)
thread_title:  This line seems odd 

message: Hi, I wonder if it would be proper to add the Jupiter's animation taken by Voyager 1 probe. thanks --Andersmusician VOTE 01:38, 30 July 2007 (UTC)
replies: text: I suspect the page is fairly saturated with pictures already. Does it add something that is not already present? — RJH (talk) 15:14, 30 July 2007 (UTC)
replies: text: Yes, there is only one other motion picture in the article, and it's a loop which isn't nearly as neat and doesn't shows the circulation of the spot and bands as well. So I'm gunna stick this new one in the "spot" section. SBHarris 23:46, 31 July 2007 (UTC)
replies: text: The images collide in my browser. I took the liberty of moving it down. — RJH (talk) 15:27, 1 August 2007 (UTC)
thread_title:  about Voyager 1's Animated Picture 

message: I just read this article, and, umm, well... it's wonderfully well-written, so refreshing to read... yeah, let's just say it deserves its featured status. Matt Yeager ♫ (Talk?) 07:11, 7 August 2007 (UTC)
thread_title:  For the record 

message: The following discussion in the section on Mass appears off-topic, and it had been slapped with a citation needed tag:
:Extrasolar planets have been discovered with much greater masses than Jupiter. Some of these planets may be gas giants similar to Jupiter, but because some of these planets are extremely close to their primaries, they may be a class of planet known as hot Jupiters which are not present in our solar system.
:Currently, if an object of solar metallicity is 13 Jupiter masses or above, large enough to fuse deuterium by thermonuclear fusion, it is categorized as a brown dwarf; below that mass (and orbiting a star or stellar remnant), it is a planet. Whether this definition has any fundamental physical significance is unclear; many astronomers argue that large planets and brown dwarfs are essentially the same type of object, and that the distinction between the two does not reflect any basic physical difference.
To me this page doesn't appear to be the appropriate place for a discussion of this nature. So I was "bold" and removed these two paragraphs from the text. But perhaps others disagree with this. If so could you perhaps explain why this is needed in the article? Thank you. — RJH (talk) 15:40, 17 September 2007 (UTC)
thread_title:  OT discussion on other planets 

message: In the Mass section, there is a number of statements which are mutually contradictory as they stand and need some clarification:
*Theoretical models indicate that if Jupiter had more mass than it does at present, the planet would shrink. ... As a result, Jupiter is thought to have about as large a diameter as a planet of its composition and evolutionary history can achieve. The process of further shrinkage with increasing mass would continue until stellar ignition is achieved.
*Although Jupiter would need to be about seventy-five times as massive to fuse hydrogen and become a star, the smallest red dwarf is only about 30% larger in radius than Jupiter.
So what's going on here? - as they get more massive than Jupiter they shrink, and in fact it is said that Jupiter has as large a diameter as a planet can achieve, but then the smallest star is actually larger. There must be a gradual transition back to larger bodies somewhere as mass increases. Deuar 16:32, 25 September 2007 (UTC)
replies: text: A red dwarf is not a planet. Different equilibrium conditions apply for a fusing star. Fig. 3. of Guillot (1999) shows a nice illustration of the mass versus radii relationship. (It also shows that the peak radii occurs at 4-5 RJ, although it's not significantly larger. So the first bullet is not quite accurate.) — RJH (talk) 17:59, 25 September 2007 (UTC)
replies: text: 4-5 MJ, I assume you meant? Anyway, so presumably Jupiter size is again reached by large enough brown dwarfs that burn deuterium, right? Deuar 15:54, 26 September 2007 (UTC)
replies: text: Yes MJ. Per the paper, "A local maximum of the radius at a mass of ~4 MJ for isolated planets is due to the competition between additional volume and increased gravity." If I am reading the scale correctly, it looks like the radius hits a local minimum at ~50 MJ. But that's well above the wikipedia's value of 13 MJ for burning deuterium, so perhaps there is a critical burn rate where the radius starts to increase. — RJH (talk) 16:43, 26 September 2007 (UTC)
replies: text: Thanks for the clear explanation. I've tried to incorporate some of this in the article. If it's ended up too lengthy, feel free to chop. Deuar 18:20, 26 September 2007 (UTC)
replies: text: Looks good to me. Thanks. — RJH (talk) 17:34, 6 October 2007 (UTC)
thread_title:  Size relative to extrasolar bodies 

message: Can anyone confirm this edit? · AndonicO Talk 23:54, 5 October 2007 (UTC)
thread_title:  Possible vandalism. 

message: On 12 February 2007 RJHall put in a useful 1995-2006 ephemeris reference of (47.1 to 30.6) 
On 20 October 2007 kheider replaced it with the "Jupiter Fact Sheet" reference (49.0 to 29.8) (Dave Williams of NASA updated to 50.1" on 2007-11-02)
On 27 October 2007 RJHall restored the dated reference without comparing the contents of the two references.  :-)
The "Jupiter Fact Sheet" (ref name="fact"/) does mention apparent diameters and I assume uses more than a 10 year range.
Between 1995 and 2006, Horizons shows Jupiters closest approach as 1999-Oct-23: "-2.78APmag  49.748"  3.9629AU in Psc" which agrees perfectly with Publication 1349!
I think the Jupiter Fact Sheet makes a better long term reference.
Horizons also shows Jupiter as 49.861" @ 3.953AU on 2010-Sep-21 and
1951-Oct-02 -2.79APmag   5.37surfbright   49.926" 3.94872AU
The real question is, "Why does the NASA Fact Sheet only show a maximum of 49.0 and not show 49.9 to cover the points generated by their own Horizons program?  Perhaps they used a smaller diameter when they created the original fact sheet."
-- Kheider 06:45, 28 October 2007 (UTC)
replies: text: Sorry, I must have missed the entry in the NASA fact sheet the first time I checked it. Whether it's correct or not, I don't know. The ephemeris appeared more up to date and gave a realistic range. — RJH (talk) 14:56, 29 October 2007 (UTC)
thread_title:  [[Angular Size]], [[Angular diameter]], Apparent Size 

message: Why and how it became so poor? 84.94.169.192 14:43, 29 October 2007 (UTC)
replies: text: Probably just the usual plebish vandalism. I may have to request another lock on the page. — RJH (talk) 15:00, 29 October 2007 (UTC)
thread_title:  What happened to the article?