Talk:Jupiter/Archive 2

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Contents

The absolute grand-daddy of diamonds?

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)

"Measurements?"

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)

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)
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)
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)
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)
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)

The first paragraph reads "Jupiter is two and a half times as large as the other planets combined." True if "large" is defined as "massive". However, in terms of volume (which is probably a more common intuitive interpretation), Jupiter is only about 1.5 times as large as the other seven (poor Pluto) planets. Jupiter's volume is 1321 Earths, the other seven if I added correctly are about 886 Earths. If surface area is the definition, then Jupiter is less than 5% larger than the other seven planets (120.5 Earths vs. 116 Earths). I suggest changing the line to: "Jupiter is one and a half times larger by volume, and is two and a half times as massive, than the other seven planets combined." 72.73.214.14 19:10, 28 April 2007 (UTC)

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)

"Earths"

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)rAS
Yes, I think so. --P3d0 19:10, 30 April 2007 (UTC)

g = gee?

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)

I've tried fixing that, but the table where it shows all the facts wasn't there! Kamope 12:40, 16 December 2006 (UTC)

  • It was an error in the infobox template we were using. That error had been there since the first version of that template. I have fixed it. --Dgies 22:17, 20 December 2006 (UTC)

There is an error in the section about accelerations at the surface of Jupiter. Whereas 'g' (gravity) is correctly given as (approximately) 24 m/s^2, the centripetal acceleration is incorrectly given as (approx) 23 m/s^2. Its a factor of 10 too large, which is easily verified by calculating the centripetal acceleration as v^2/R using the data given in the table. It should be about 2.3 m/s^2, and I made the appropriate correction in the text. If the centripetal acceleration really were 23 m/s^2, there would effectively be hardly any gravity at the surface of Jupiter (it would be about 1 m/s^2). This is actually how I spotted the error, because it seemed absurd that this would be the case. Erik Larsen, 9:56am, June 6 2007, EST.

Life on Jupiter

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)

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)

Movies

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)

I go with you. I have actually been thinking that too, before I even read this. Kamope 12:41, 16 December 2006 (UTC)

Pronunciation key

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)


Moons from the atmosphere???

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)

Looks like some crackpot theory.--84.10.180.181 (talk) 17:54, 8 March 2008 (UTC)

infobox

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)

Great Red Spot Images

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)

I was always taught that the diameter of the earth fits neatly three times into the diameter of the red spot. the image shown doesn't seem to indicate that at all. I think we need a more accurate image - danny

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)

We could put a picture of the earth to scale with the red spot?-MJRoberts

Expanded Task List (ACID)

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)

  • Exand the lead: it is currently only two sentences summarizing an extremely long article. Actually, the "Overview" section should be retooled into a proper lead (which is really THE overview) and something else (because it looks too long to be a lead by itself).
  • A serious copy edit: sentence that need help:
  1. In light of this, it is also interesting to note...
  2. Quite naturally, Jupiter's gravitational influence...
  3. Extrasolar planets have been discovered with much greater masses. does not seem to currently relate to the brown dwarf sentences in its paragraph.
  • Historical observations: needs expansion. Currently we have only its discovery and its 5th moon! (And the fifth moon paragraph doesn't actually seem to relate to Jupiter, but rather to Barnard.)
  • Exploration of Jupiter: I'm not sure that each mission sequence needs its own very bold header. How about just a new paragraph for each? Or perhaps "Pre-Galileo" missions could be combined?
  • References: Lots needed.
  1. Some easy references should be web-available for the "Future probes" section.
  • Galilean Moons: The list under classification needs to be converted to text format rather than a list.

GA on hold

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)

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)

Template vandalised?

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)

GA passed!

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


Atmosphere

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)

Under the heading "Composition....being still too warm to hold all of its nebular neon (this requires temperatures below 17 Kelvins)." This clause has an unknown meaning which can be corrected by deletion or rewrite as a complete sentence. The 17 Kelvins is likely the temperature where the vapor pressure of frozen neon becomes negligible, as the melting point of neon is about 24.33 k, and the boiling point at one atmosphere pressure is 27 k. Neil

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)

Core model

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:

Lodders, Katharina (2004-08-10). "Jupiter Formed with More Tar than Ice". The Astrophysical Journal 611: 587-597. doi:10.1086/421970. 

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)

Error

There is no such thing as "metallic hydrogen" - could someone check that please. --Zureks 08:38, 6 March 2007 (UTC) (moved from top of page)

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)
I believe that metallic hydrogen has been demonstrated in a laboratory.[1] — RJH (talk) 16:27, 17 March 2007 (UTC)

Another error: the composite photos of the Galilean moons incorrectly show Callisto appearing to be larger than Ganymede.

Observation section comments

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)

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)
Thanks for confirming - and, rechecking that section, it seems much clearer now! Excellent work... human 22:24, 19 March 2007 (UTC)

Formation

Would there be enough information to include a section on Jupiter's formation? Sancho (talk) 14:06, 26 March 2007 (UTC)

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)
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)
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. --P3d0 14:01, 9 May 2007 (UTC)
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)

Infobox Photo

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)

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)

Great Red Spot

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)

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)

Too Big?

Ok, it appears to be getting a little big. Is there info that can be shifted out? Harvestdancer 18:38, 20 April 2007 (UTC)

I think it's fine. The other FA'd planet articles are pretty meaty as well. — RJH (talk) 22:08, 20 April 2007 (UTC)
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)
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)
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)

GRS

"Before the Voyager missions, astronomers were uncertain of the nature of Jupiter's Great Red Spot. [Historically] Many believed it to be either a solid or a liquid feature on the planet's surface as this appears consistent with the observable turbulence patterns.[1] " I have removed this since it is not in the source cited, and I'm certain we knew it was a storm long before voyager. Rich Farmbrough, 12:26 22 April 2007 (GMT).

...and then the deluge

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)

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)
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)

Note that this was originally published well before the article appeared on the front page. It is not a comment on the main page featured article protection policy. — RJH (talk) 14:49, 6 June 2007 (UTC)

What would happen

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)

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)
Is there any way to transport enough oxygen there to maintain combustion? --NEMT 12:21, 9 May 2007 (UTC)
Folks, this is not a place to talk about Jupiter. It's a place to talk about the Wikipedia article on Jupiter. --P3d0 13:56, 9 May 2007 (UTC)
Oh it's relevant, since I was considering adding a section on this subject. --NEMT 15:07, 9 May 2007 (UTC)
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)
Yes, I suppose Jupiter can be troublesome that way. --NEMT 15:07, 9 May 2007 (UTC)

well dont shut the guy down so hard! ya know, just cuz ya know all this stuff doesnt mean ya gotta be pricks to each other! —Preceding unsigned comment added by 72.84.246.18 (talk) 09:21, 16 January 2008 (UTC)

Planetary evolution

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)

"Gas Giant"?

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)
  • First, in the planetary science the word 'gas' means hidrogen and helium. So since Jupiter is primarily made of these gases it is rightly called a gas giant. Second, temperature in the interior of Jupiter is much higher than the critical temperatures of all gases, so it's meaningless to speak about the liquid phase — it simply doesn't exist. In other words the transition between high and low densities is continues if the temperature is higher than critical. So interior of Jupiter is made of a dense, hot hydrogen-helium mixture, but not from any liquid. Jupiter is sometimes called gas-liquid planet. However, I should repeat again, it is scientifically wrong to call the interior of Jupiter liquid. Ruslik 10:05, 6 June 2007 (UTC)
  • The term works for me because it is indicative of a planet that does not have a well-defined, solid surface. Otherwise I'm not sure how you could characterize Earth as a solid planet since significant portions of the interior are liquid and/or viscous. The plastic mantle does form 84% of the Earth. — RJH (talk) 15:00, 6 June 2007 (UTC)

This needs a citation

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)

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)

"burn deuterium"? (in Mass)

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)

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)
The term "thermonuclear burning" is frequently used in scientific papers.[2] I don't think it is incorrect usage, so it shouldn't need to be changed. — RJH (talk) 21:26, 6 June 2007 (UTC)
You learn something every day. Jlaramee 17:10, 7 June 2007 (UTC)

Reference needed

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)

Low-mass black holes & heat generation

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)

Studies of Jupiter

Should the "Studies of Jupiter" section be renamed? It seems to be about Jupiter's name rather than "studies". Would it count as an etymology section? Thanks! Vsst 14:38, 6 July 2007 (UTC)

The name is meant to encompass the sub-sections, including the ground-based observation and spacecraft exploration of the planet. It is primarily a scientific topic, with the first two paragraphs being pre-telescopic history. I don't think it would count as an etymology section (although flogging the name definition has been creating a non-stop churn on this page).
Per some of the other planet articles, I moved the etymology-like content down into a section on "Human culture" and added in some of the out-of-place material from the lead section. "Studies on Jupiter" has been renamed to "Research and exploration". I hope that helps — RJH (talk) 16:46, 7 July 2007 (UTC)

That does indeed help, congrats! Vsst 01:15, 8 July 2007 (UTC)

Why is this Jupiter and not Jupiter (planet)?

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)

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)

This line seems odd

"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)

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)
The presence of lithium does not distinguish a brown dwarf from a giant planet, but rather distinguishes a brown dwarf from a fusing star. [3] 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, [4] both gas giants and brown dwarfs possess lithium chemistry. Serendipodous 14:18, 30 July 2007 (UTC)
Yes, lithium apparently only indicates a minimum mass.[5] But there's also deuterium[6] and (in some brown dwarfs) iron hydride.[7] There's probably more if you search around a bit. — RJH (talk) 15:12, 30 July 2007 (UTC)
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)
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)
I've removed it. - ∅ (∅), 16:12, 1 August 2007 (UTC)

about Voyager 1's Animated Picture

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)

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)
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)
The images collide in my browser. I took the liberty of moving it down. — RJH (talk) 15:27, 1 August 2007 (UTC)

For the record

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)

Issue with modified orbital elements

The orbital elements have been revised, but they do not appear to match the associated elements. Drilling down into the http://ssd.jpl.nasa.gov/?horizons reference, I find the following from http://ssd.jpl.nasa.gov/txt/p_elem_t1.txt:

Parameter Current WP Reference
a 5.20433612 AU 5.20288700 AU
e 0.048787597 0.04838624
I 1.304631° 1.30439695°

So something appears amiss with the recent revisions. I checked the remainder of the HORIZONS site but it does not display the data that has been modified in the info box. I slapped a dubious tag on it and I hope this can be clarified. — RJH (talk) 14:57, 8 August 2007 (UTC)

Yes, let's sort this out. The way I obtained the orbital elements was to go to the HORIZONS site, choose "web-interface", and fill in appropriate data on the search form as follows:
Ephemeris Type: ELEMENTS
Target Body: Jupiter [599]
Center: Sun (body center) [500@10]
Time Span: Start=JD 2451545.0, Stop=JD 2451546.0, Step=1 d
Table Settings:         defaults
Display/Output:         default (formatted HTML)
This should give orbital elements at J2000 when submitted. Among the data on the output form that is generated one has:
2451545.000000000 = A.D. 2000-Jan-01 12:00:00.0000 (CT)
 EC= 4.878759658155463E-02 QR= 4.950429070291162E+00 IN= 1.304630997751757E+00
 OM= 1.004911094561275E+02 W = 2.750691069128022E+02 Tp=  2451318.454454166815
 N = 8.305451682727923E-02 MA= 1.881563084855639E+01 TA= 2.072856035575974E+01
 A = 5.204336121459753E+00 AD= 5.458243172628345E+00 PR= 4.334502369674350E+03
with legend:
   JDCT     Epoch Julian Date, Coordinate Time
     EC     Eccentricity, e                                                   
     QR     Periapsis distance, q (AU)                                        
     IN     Inclination w.r.t xy-plane, i (degrees)                           
     OM     Longitude of Ascending Node, OMEGA, (degrees)                     
     W      Argument of Perifocus, w (degrees)                                
     Tp     Time of periapsis (Julian day number)                             
     N      Mean motion, n (degrees/day)                                      
     MA     Mean anomaly, M (degrees)                                         
     TA     True anomaly, nu (degrees)                                        
     A      Semi-major axis, a (AU)                                           
     AD     Apoapsis distance (AU)                                            
     PR     Orbital period (day)
These indeed differ (quite substantially) with the values given in the link you found (deep drilling there! :) ). However, I notice the following somewhat vague statements in the new reference you provide:
 These data are to be used as described in the related document
 titled "Keplerian Elements for Approximate Positions of the
 Major Planets" by E.M. Standish (JPL/Caltech) available from
 the JPL Solar System Dynamics web site (http://ssd.jpl.nasa.gov/).
and
Keplerian elements and their rates, with respect to the mean ecliptic
and equinox of J2000, valid for the time-interval 1800 AD - 2050 AD.
The statements "valid for the time-interval 1800 AD - 2050 AD." and "for Approximate Positions" suggest to me that the values given there are some sort of mean orbital elements, averaged over the above long time period, with shorter-time perturbations averaged out. In that case, I believe that if we want to give full elements at a particular epoch, the current ones in the infobox are the correct ones. Deuar 11:26, 9 August 2007 (UTC)
Thanks for the clarification. — RJH (talk) 15:07, 9 August 2007 (UTC)

Orbital elements issues generally

The above discussion of orbital elements spurs me to bring up several related issues which have been bugging me:

  1. Just what elements do we want to give in these infoboxes? - exact elements at a particular epoch, or some averaged values? If averaged, then over what period? averaged elements are more "long-lasting", while elements at exactly J2000 are useful for trying to visualize where planets are relative to each other at a given moment, since they include things like mean anomaly, which makes no sense for long-time-averaged values. For example, I found such details useful just recently to determine what exactly is shown in the diagram Image:Outersolarsystem_objectpositions_labels_comp.png.
    Probably a good topic for discussion at Wikipedia:WikiProject Astronomical objects. — RJH (talk) 15:13, 9 August 2007 (UTC)
  2. What precision do we want to go to? For example, we see that for example for a, instantaneous and mean elements disagree by about 1 part in 5000. Remarkably, on a smaller scale, on the Horizons form that I specified above, the day-to-day variation is of similar magnitude! This is real big, and begs the question of what exactly is going on there. Ths brings up the third question:
    That sounds too variable to be perturbation. Perhaps it's rounding errors in the software; as if they're not carrying enough digits? I dunno. Sometimes contacting the web site owner can be beneficial. — RJH (talk) 15:13, 9 August 2007 (UTC)
    It's the moons, I believe (see the numbers in point 3). E.g. Ganymede is about 10,000 times less massive than J (similar magnitude to the changes), and has orbital period of about a week (similar timescale). Deuar 17:27, 9 August 2007 (UTC)
  3. Orbital elements of what, exactly? Consider the dates 2000-Jan-01 12:00:00 (J2000) and 2000-Jan-02 12:00:00. If we choose orbital elements of Jupiter around the Sun, get a = 5.204336121459753 and 5.205144641797600, respectively (big difference!). However, choosing to calculate for the [Jupiter Barycenter (5)], obtain 5.204266578934183 and 5.204266590197608 for the consecutive days, which differ only by 1 part in 500 million. So, apparently the main changes must be due to the motion of Jupiter's moons. Another possibility is to choose the orbital elements around the Solar System barycenter, not the Sun. Then the day-to-day changes are similar as in the last case, but the actual value of a is different to 1 part in 300, since Jupiter is pretty big itself: a=5.191133362015722 and 5.191948561649226, respectively. For smaller planets, choosing to use elements around the SS barycenter would mostly eliminate Jupiter perturbations, but it involves more conceptual gymnastics.

I would suggest to use J2000 exact elements of the Jupiter barycenter around the Sun, with precision up to whatever digits are unchanged over the timescale of a day, but I am very interestd what others think. Deuar 11:26, 9 August 2007 (UTC)

Okay. I can't imagine why anybody reading wikipedia would need such accuracy. Personally I'd be fine with 3-5 decimal places, but then somebody is bound to come along and add back in longer values. — RJH (talk) 19:42, 9 August 2007 (UTC)
exactly. Deuar 09:49, 10 August 2007 (UTC)
I'm in the process of trying to standardize all the infoboxes of the planets and this question I think is important. Certainly to be useful we need the same baseline. Personally I like J2000.0 - then we can compare with other planets. However there is no real need to go to 15 decimal places. And anyone who does need to go to that level definitely won't be consulting wikipedia for the values! One could also argue that they're not useful at all - I mean who is going to use the value of longitude of the ascending node? Although on the other hand, inclination is something that everyone can grasp and I'd definitely argue for its inclusion. Just my 0.02. Jim77742 05:56, 10 September 2007 (UTC)
I'm not sure whether longitude of the ascending node is all that useful for planets, but it is appropriate for inclusion with double star elements. — RJH (talk) 16:09, 10 September 2007 (UTC)
Hey, I've used the longitude of ascending node from WP a few times, remaining a complete amateur. :) The angular elements (also argument of perihelion and mean anomaly) are essential if you want to compare the locations of several planets, or e.g. is it above or below the ecliptic at a certain time, etc. I strongly suggest that we should keep the full orbital elements there. For the interested amateurs who might want to use them, although they won't be making use of them professionally, obviously.
On the other hand, the current number of decimal places is indeed pretty silly. The rationale we had recently was that if they're left out someone else will try to put them in again. However, you're right, this is probably excessive second-guessing. A possible place to cut them off is for example at 5 significant digits for a and e, and say 2 points after the decimal place for angles (also giving 5 sig dig for most angles). Deuar 07:42, 11 September 2007 (UTC)
Or maybe rather some analogous number of places after the decimal point for a and e, otherwise it will be irritating to compare Pluto to Mercury if true significant digits are used. e.g. 5 places after the decimal for e and for a in AU, so multiples of 1000 km for a in km. Deuar 08:21, 11 September 2007 (UTC)
Some type of consensus via WP:MoS would been useful for this issue. There are obviously cases where it is worthwhile to maintain extended decimals, such as for precisely measured physical constants. So in that case it would make sense to keep an extended range of the measured value of an AU in km, for example. Likewise extended mathematical constants make sense. On the other hand, if a table is going to show a parameter in more than one type of units, it makes little sense to me to retain more digits in one form than in the other. Likewise, for example, having different numbers of digits for similar measurements makes little sense. (See, for example, the semi-major and semi-minor axis on the Earth page.) — RJH (talk) 22:02, 11 September 2007 (UTC)
The MoS does cover this. Avoid over-precise values where they are unlikely to be stable or accurate, or where the precision is unnecessary in the context. (The speed of light in a vacuum is 299,792,458 metres per second is probably appropriate, but The distance from the Earth to the Sun is 149,014,769 kilometres and The population of Cape Town is 2,968,790 would usually not be, because both values are unstable at that level of precision, and readers are unlikely to care in the context.) —Preceding unsigned comment added by Saros136 (talk • contribs) 11:49, 31 January 2008 (UTC)

OT discussion on other planets

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.[2] 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.[3] 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.[who?]

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)

Size relative to extrasolar bodies

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)

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)
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)
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)
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)
Looks good to me. Thanks. — RJH (talk) 17:34, 6 October 2007 (UTC)

Possible vandalism.

Can anyone confirm this edit? · AndonicO Talk 23:54, 5 October 2007 (UTC)

No homogeneous model

I removed this sentence:

One model shows a homogeneous interior with no solid surface, with density increasing gradually toward the core.

There is a consensus that there is no solid surface, but also that it is not homogeneous. The liquid metallic hydrogen layer is generally accepted because of the physics of hydrogen, and the presence of more heavy elements in the core is supported by measurements of Jupiter's gravity. I will try to clarify the areas of uncertainty based on a recent survey article. Mark Foskey 02:55, 13 October 2007 (UTC)

Your changes appear to contradict the abstract for the Guillot et al citation. Do you have a more recent citation to back it up? Thanks. — RJH (talk) 05:11, 13 October 2007 (UTC)
Yeah, I did a poor job of summarizing that work. The authors seem to consider the presence of the core very likely but not certain. But there is certainly a layer of molecular hydrogen above the level of metallic hydrogen, even if there's no sharp phase transition at the boundary, so saying that one model proposes a homogeneous interior isn't right. See if the current version doesn't seem more correct.
I also put in the assertion that there is known to be a smooth transition from gaseous to liquid hydrogen. Mark Foskey 03:43, 23 October 2007 (UTC)

Angular Size, Angular diameter, Apparent Size

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)

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)

Not a problem. But even your quoted ephemeris shows a maximum of 49.7 (1999-Oct-23) so I thought it would be good to quote a source that would bump the 47.1 to at least 49.0. Even the NASA Fact Sheet says: "Note that the values listed on the factsheets are not "official" values, there is no single set of agreed upon values. They are based on ongoing research and as such are under study and subject to change at any time. Every effort has been made to present the most up-to-date information, but care should be exercised when using these values." I have sent them an e-mail about how even their JPL Horizons is generating numbers up to 49.9. We'll see if I get a reply. Since Jupiter is the largest planet and has a 12 year orbit, it should experience a favorable perihelic opposition roughly every 12 years depending on the dates of Earth's aphelion and Jupiter's perihelion.

Actually the NASA fact sheet bothers me more with Saturn since their listed maximum magnitude does not account for the bright rings, so I quoted a professional source that does include the rings since they do effect the brightness of the "star" Saturn. So unfortunately, the answers will vary a little based on the methods used.
-- Kheider 16:33, 29 October 2007 (UTC)

What happened to the article?

Why and how it became so poor? 84.94.169.192 14:43, 29 October 2007 (UTC)

Probably just the usual plebish vandalism. I may have to request another lock on the page. — RJH (talk) 15:00, 29 October 2007 (UTC)

Gradual transition between gas and liquid

In its current state, the article says "there is probably a smooth gradation from gas to liquid" between upper and lower levels. I don't think there is any question about this. You can only have a liquid surface below the critical temperature for that liquid. The critical temperature for hydrogen is 33 K. What sources I can find indicate that the atmospheric temperature bottoms out at around 110 K in the stratosphere, and gets steadily warmer as one goes deeper. These temperatures have been measured by the Galileo probe, so one can be fairly confident of them.

Many sources, such as [8], talk about an "ocean" of hydrogen, but they are making the point that the hydrogen is compressed enough that it is reasonable to think of it as a liquid. At those pressures the distinction is unclear anyway.

Can somebody say why doubt should be expressed about the transition from gas to liquid? Mark Foskey 03:02, 6 November 2007 (UTC)

You need an equation of state for high-pressure hydrogen to decide this question. There is no easy answer, since we can't measure it directly. Michaelbusch 05:11, 6 November 2007 (UTC)
I'm still confused. The critical temperature and pressure for molecular hydrogen are about 33 K and 13 bars, right? Is there some possibility of a phase transition reappearing between gaseous and liquid molecular hydrogen at high pressures? I've never seen a phase diagram like that, but I haven't seen that many. I realize that there is uncertainty about the existence of a plasma phase transition between the molecular and metallic levels (although the article right now acts as if that is known). Mark Foskey 03:32, 8 November 2007 (UTC)

Gravity

Could someone please tell me what Jupiters average gravitational field strength is. I don't think it actually states it in the article. It says the field strength at the equator is ~2.4 times greater than Earth because of centripetal forces, but if its mass is 300 odd times greater, then shouldn't the average field strength be ~300 times greater? Thanks. ArdClose (talk) 14:01, 19 December 2007 (UTC)

But its radius is 11 times greater, so the average gravity acceleration is 318/11^2\approx 2.5 earth's. Ruslik (talk) 14:39, 19 December 2007 (UTC)
The "Orbit and rotation" section discusses the equatorial acceleration in a little more detail. I'm not sure that it makes sense to list the "average" gravitational strength for a planet as oblate as Jupiter.—RJH (talk) 16:41, 19 December 2007 (UTC)
Ah ok, thanks for clearing that up. ArdClose (talk) 17:26, 19 December 2007 (UTC)

The values shown in the infobox for the "Equatorial surface gravity" are 24.79 m/s^2 (which is 2.52787649 g, being g=9.80665 m/s^2) and 2.358 g, so they differ in ~0.17 g. In my opinion if they express different facts, as the account of the centripetal acceleration, it should be made clear with an additional footnote. Otherwise the reader will assume they are equivalent. —Preceding unsigned comment added by 79.147.39.120 (talk) 11:54, 31 December 2007 (UTC)

I went ahead and removed the 2.358 g value as it lists no source for the conversion. The 24.79 is from the Jupiter Fact Sheet ref. Thank you for pointing it out.—RJH (talk) 18:16, 1 January 2008 (UTC)
It seems that the removed 2.358 g value came also from the Jupiter Fact Sheet, where it is stated as: "Acceleration (eq., 1 bar) (m/s2) 23.12" (we have to divide it by 9.80665).
In that Fact Sheet, "Gravity" tells about the strength of the gravity field at the equator, while the lower "Acceleration" value is given for a point fixed to the rotating equatorial surface or atmosphere. Actually both values were correct and the consequences of being different are shown in the "Orbit and rotation" section of this article.
However, according to http://en.wikipedia.org/wiki/Surface_gravity , the surface gravity is "the gravitational acceleration experienced at its surface"; therefore there's no account for other accelerations experienced -such as the one derived from rotation- and I think that the infobox's gravity is correct after the removal. The equatorial acceleration is an interesting data to include as well, but it would require an additional footnote or its own label.
Thank you all for your wikiwork. —Preceding unsigned comment added by 81.34.102.93 (talk) 17:52, 3 January 2008 (UTC)

Reduce precision of elements in infoboxes?

I reduced the precision in the table, but I wonder if we could reach a consensus here on these infoboxes in general. (Or should I revert?) The MoS says Avoid over-precise values where they are unlikely to be stable or accurate, or where the precision is unnecessary in the context. (The speed of light in a vacuum is 299,792,458 metres per second is probably appropriate, but The distance from the Earth to the Sun is 149,014,769 kilometres and The population of Cape Town is 2,968,790 would usually not be, because both values are unstable at that level of precision, and readers are unlikely to care in the context.) I'm guessing that this consensus was reached after the template was created, and the template now conflicts with wiki policy. Saros136 (talk) 19:21, 31 January 2008 (UTC)

I think that 7-8 digits, as you have it, is plenty for most measurement purposes. Eight will allow you to convert years to seconds, for example. Rounding an orbital distance on the order of 108 kilometers to the nearest hundreds will still put you inside the radius of the planet.—RJH (talk) 18:21, 1 February 2008 (UTC)