Talk:Jupiter/Archive 4

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Maximal diameter?

Section Mass:

As a result, Jupiter is thought to have about as large a diameter as a planet of its composition and evolutionary history can achieve.

which is true unless the planet compared is a epistellar jovian, in which case it might be inflated by high temperature... ... said: Rursus (mbork³) 22:16, 16 December 2009 (UTC)

Ehmm, I change my mind: it is of course always true according to the maxim:

Jupiter is the only planet that has its own composition and evolutionary history.

... said: Rursus (mbork³) 22:18, 16 December 2009 (UTC)
Well, what was really said was "Jupiter is about the largest a 5 billion year old formed in-situ planet can be without having less helium", but then it wouldn't be a quote anymore.
Strangely enough, using the narrower view of "object", nothing can be larger than Jupiter without being younger, warmer, or having less helium.. Sagittarian Milky Way (talk) 01:13, 17 December 2009 (UTC)

Gas giant or Ice giant

Dr. Richard Pogge from Ohio State mentions in 2007 in one of his Astronomy 161 lectures that Neptune is, in fact, an ICE giant ( ref. Lecture 38, Astronomy 161, iTunes podcast).

Perhaps this part of the article should be changed: Jupiter is classified as a gas giant along with Saturn, Uranus and Neptune —Preceding unsigned comment added by 122.57.13.252 (talk) 02:02, 9 February 2010 (UTC)

This has been discussed before. Ice giants are a subset of gas giants - after all, Neptune is still by far mostly gas. The sentence is fine as is. -RadicalOne•Contact Me•Chase My Tail 02:13, 9 February 2010 (UTC)

Why are cgs units used in this article?

Why are cgs units used in the article, e.g. "1.326 g/cm³", when they have been supplanted by SI units?

Shouldn't it be e.g. "1.326 kg/m³" instead?

--Mortense (talk) 21:35, 20 February 2010 (UTC)

Go for it. TJRC (talk) 23:15, 20 February 2010 (UTC)
Wrong. It would be 1,326 kg/m³. And all of the planets and asteroids are currently using the g/cm³ format since that is often what the quoted source is using. -- Kheider (talk) 23:26, 20 February 2010 (UTC)
I agree. Use of cgs units for densities is a common scientific convention.—RJH (talk) 01:27, 21 February 2010 (UTC)
Yes, cgs is nice for densities because it makes various substances easy to compare with liquid water (1 g/cm³). CosineKitty (talk) 02:06, 13 March 2010 (UTC)

Interior update

There is a ton of new information out in the world on Jupiter's interior based on recent simulations.[1] [anon.]

How did ancient astronomers estimate the diameter of Jupiter?

Some recent edits to this article and the Mars article have added claims that ancient astronomers estimated the diameter of these planets. I find this very surprising and interesting. What is missing is any explanation of how they did this. Was it based on some rational, logical method, or was it based on some primitive superstition like reading tea leaves? (There are references cited, but they don't appear to be available online.) Some explanation of how anyone without a telescope could do this scientifically would be fascinating. But if it is just a lucky guess based on superstition, I would find it a bit off-topic for this article. CosineKitty (talk) 02:14, 13 March 2010 (UTC)

I have not checked the reference yet, but it can be found at Planetary Diameters in the Surya-Siddhanta -- Kheider (talk) 06:56, 13 March 2010 (UTC)
What they did was really very simple:
  1. They estimated apparent angular diameters by eye observations. The diameters were, of course, significantly overestimated and were close to the angular resolution of the human eye (Table 1). They are close to the values obtained by other observers.
  2. Next they estimated the orbital radii based on the known radius of the moon's orbit and assuming that the radii are proportional to the orbital periods (Table 2). This is not unreasonable, because is based on the assumption that all planets move with the same speed.
  3. Finally they calculated physical diameters from the two above quantities. The results for three planets are close to the real values, but for two they are smaller by ~50%, while the diameter of the Sun obtained by this method is much smaller than the real one.
I, however, disagree with conclusions that the author made. The diameters were not random numbers, and his model (Appendix A) is wrong. The fact that the diameters appeared to be close to real ones is just a coincidence, in my opinion. Ruslik_Zero 12:12, 13 March 2010 (UTC)
I also think this may be given too much credit since sadly there is not enough evidence. Page 196 (paragraph 3) very clearly states, "Note that even though the angular diameters are too large, and the orbital radii are too small, the calculated diameters are close to modern values for Mercury, Mars, and Saturn." It sounds a lot like a lucky educated guess. Though it is worth noting that they only missed the general target with the two brightest planets Venus and Jupiter. This may also be based off of 15th century material (page 197) and not 5th century. Perhaps it should be re-phrased "It is possible that the 5th century Indian astronomical text Surya Siddhanta estimates that ... -- Kheider (talk) 16:39, 13 March 2010 (UTC)
Thank you, Kheider, for providing a link to an online version of this reference. I am having trouble with the existing wording, because there is too much speculation to factually state what their values would be in modern units, and the proximity to correct values appears to be pure luck, according to the source.
  • On page 195: "Several scholars have argued that the yojana ... is about 5 miles, ...". This undermines the credibility of the given estimates; we can no longer factually say something like "... from which the diameter of Jupiter is deduced to be 41,624 miles". (And giving 5 significant figures implies a precision level far beyond what is justified. Even saying "about 40,000 miles" would be pushing it.)
  • The source indicates that the estimated angular values is far too large, and the estimated distances of the planets from the Earth is far too small. Both tended to cancel out. To get close to the right answer based on two very wrong suppositions needs to be qualified as something other than an "estimate".
So these ancient astronomers did the best they could, using logic and reason instead of superstition, but the wording in this article would leave the layman reader with the impression that their abilities were more advanced than is actually supported by the source. I would like to recommend some rewording to reflect this. CosineKitty (talk) 17:51, 13 March 2010 (UTC)
I've tried to add some additional wording to reflect this discussion (as I have with other changes to astronomy articles made by the associated editor).—RJH (talk) 17:58, 13 March 2010 (UTC)
A good discussion of Ptolemy's estimates of planetary diameters is in Measuring the universe: cosmic dimensions from Aristarchus to Halley by Albert Van Helden, pp. 24–27, including English translations of appropriate paragraphs from his Planetary Hypotheses. I have not found a good discussion of Siddhanta (AD) planetary diameters yet (other than Thompson), but for Puranic (BC) estimates of planetary distances see The Speed of Light and Puranic Cosmology (p.9) by Subhash Kak. The main purpose of this paper was to justify Kak's opinion that the speed of light of about 186,000 miles per second possibly given by the medieval Indian scholar Sayana was "the most astonishing 'blind hit' in the history of science!" (p.12). — Joe Kress (talk) 19:50, 16 March 2010 (UTC) I thought it was liquid -gas though!!!!???

Gas giant or liquid giant?

According to this article, "liquid metallic hydrogen makes up the bulk of Jupiter's mass." I know that Jupiter has long been classified as a "gas giant," but perhaps this should be corrected to "liquid giant." 71.219.235.189 (talk) 01:50, 28 March 2010 (UTC)

Gan De

"The Chinese historian of astronomy, Xi Zezong, has claimed that Gan De, a Chinese astronomer, made the discovery of one of Jupiter's moons in 362 BCE with the unaided eye. If accurate, this would predate Galileo's discovery by nearly two millennia.[63][64]"

thats rubbish —Preceding unsigned comment added by 61.68.170.124 (talk) 13:40, 29 March 2010 (UTC)

What reference do you have to dispute the claim? -- Kheider (talk) 17:27, 29 March 2010 (UTC)
The anon has a point, actually. The issue is more the references used to back up the claim. This is an extraordinary claim, and extraordinary claims need excellent sources. What kind of source is this Acta Astrophysica Sinica? The second source "Dong, Paul (2002). China's Major Mysteries: Paranormal Phenomena and the Unexplained in the People's Republic. China Books." doesn't seem adequate. Athenean (talk) 18:59, 29 March 2010 (UTC)
amateurastronomy.org cites 'Sky and Telescope', February, 1982 for this claim; [2]. Surely one of our editors has a closetful of old issues of S&T. TJRC (talk) 19:09, 29 March 2010 (UTC)
See also [3](p. 131); [4] (p. 229); [5] (p. 279, n.10). TJRC (talk) 19:12, 29 March 2010 (UTC)
In Sept 2010 we will know if the human eye can see either Callisto (moon) or Ganymede (moon)... -- Kheider (talk) 17:08, 30 March 2010 (UTC)
I am shocked -- shocked! -- to see a suggestion that we resolve this with original research. TJRC (talk) 17:16, 30 March 2010 (UTC)
This link has some more details. It sounds like it may be plausible, but the statement about it being a red star makes the claim questionable. The moons don't appear reddish in a telescope.—RJH (talk) 18:11, 30 March 2010 (UTC)
Based on the ample citations here, I see no problem with the wording as given above: it is phrased as a "claim" and it attributed to a particular historian. If someone finds a citation to a skeptical interpretation, that would be good too. CosineKitty (talk) 01:33, 31 March 2010 (UTC)
Here's one:
"However, Gan De's reference to the reddish color continues to be mystifying, because Ganymede is too faint for its color to be perceived with the naked eye." —Huang Yi-Long
per:
Yi-Long, Huang (1997). "Gan De". Encyclopaedia of the history of science, technology, and medicine in non-western cultures. Springer. p. 342. ISBN 0792340663. {{cite encyclopedia}}: Unknown parameter |editors= ignored (|editor= suggested) (help)
—RJH (talk) 16:03, 31 March 2010 (UTC)

Jupiter's Flyby Missions

Pioneer 10 Pioneer 11 Voyager 1 Voyager 2 Ulysses New Horizons

You missed Cassini. See Jupiter#Flyby missions.—RJH (talk) 21:56, 28 April 2010 (UTC)

Pic fail

The animation a quarter of the page down exceeds the upload limit, and cannot be seen. I speculate that some sort of taxonomic error has occurred, with the animation being mistakenly classified as a still.

213.120.17.163 (talk) 17:50, 7 April 2010 (UTC)

They have been making changes to the media download, discussed here: Wikipedia:Village pump (technical)#Re-enabled GIF scaling. Unfortunately it has had negative consequences.—RJH (talk) 18:44, 7 April 2010 (UTC)
I have just now replaced the two animated GIF images with equivalent Theora OGG videos. Before my edit this animated GIF image in the Cloud layers section was not animating, while now the reader will see a Theora OGG video thumbnail, with links to "Animation at larger widths". I chose 10 frames per second in my re-encoding rather than the original 30 because even my fast PC was not rendering the original GIF that fast. -84user (talk) 19:03, 29 May 2010 (UTC)

Lost Cloud Belt

Just thought I'd post this link here, if someone wants to add this in the article. Not entirely sure if it's all THAT notable, in the grand scheme of Jupiter, or exactly how to incorporate it, but for somone with more of a clue than I, here it is: Jupiter Has Lost a Cloud Stripe, New Photos Reveal. Jedikaiti (talk) 17:46, 14 May 2010 (UTC)

This is the SPACE.com page. And images. Oda Mari (talk) 18:21, 14 May 2010 (UTC)
It probably belongs on the Rings of Jupiter article.—RJH (talk) 18:24, 14 May 2010 (UTC)
Disagree - it's an atmospheric phenomenon, not anything to do with the ring system. Icalanise (talk) 18:31, 14 May 2010 (UTC)
Maybe Atmosphere of Jupiter then?
--Gyrobo (talk) 18:37, 14 May 2010 (UTC)
I already added it to Atmosphere of Jupiter. Serendipodous 19:07, 14 May 2010 (UTC)
Sorry.—RJH (talk) 19:43, 14 May 2010 (UTC)
It should be in both seeing as it makes the current picture of jupiter no longer even an accurate picture--69.146.108.94 (talk) 20:43, 21 May 2010 (UTC)
"Clouds" come and go on planets with active atmospheres. The Southern Belt is visible most of the time, so I would not go so far as to say pictures showing the belt are an inaccurate representation of Jupiter. -- Kheider (talk) 22:27, 21 May 2010 (UTC)
Not so much on Jupiter if they did just come and go it wouldnt have been a headline on websites or even have an article and it is an inaccurate in the sence that Jupiter looks very different where as if you looked at a picture of earth with different clouds it would look mostly the same--69.146.108.94 (talk) 17:35, 24 May 2010 (UTC)
"Jupiter's Southern Equatorial Belt tends to fade from view about every three to 15 years." -- Kheider (talk) 17:43, 24 May 2010 (UTC)
Wonder why the article I read read as though it was a suprise first time occurance haha well that should be mentioned if not in here the article about cloud layers--69.146.108.94 (talk) 19:55, 24 May 2010 (UTC)
If this has happened before, then it would probably be better to mention it here in the general sense, rather than as a singular event. I.e. it happened in years ???? and 2010, &c.—RJH (talk) 20:59, 24 May 2010 (UTC)
Agreed.. The website Kheider showed me wont work right on my computer probably either typed it wrong expired or my comp has issues doesnt really matter though no reason to doubt them but that is what I would have put if I found the information all the information I can find is articles about the currect incident--69.146.108.94 (talk) 15:34, 25 May 2010 (UTC)

Size in solar radii

I'd like to suggest that somewhere in this article it mention the radius of Jupiter in terms of the Sun's radius: RJ ~ 0.1 solar radii.—RJH (talk) 18:16, 28 May 2010 (UTC)

Done.—RJH (talk) 19:09, 3 June 2010 (UTC)

Rain of impact related postings

Looks like the trend to report every Jovian impact is continuing. These are almost starting to look like annual events, so I don't think they all need to be mentioned. I'd like to suggest moving them to an article on Jupiter impacts and just having a brief summary here.—RJH (talk) 21:41, 4 June 2010 (UTC)

I am only aware of 3 known recent impacts: Comet Shoemaker-Levy 9, the 2009 Jupiter impact, and this 2010 impact. I would say it is only in the last 2 years with the power of the modern CCD and image stacking that amateurs have become powerful enough to detect such phenomena. Anthony Wesley discovered both the 2009 and 2010 impacts, quite impressive. But yes a small 2011 Jupiter impact would be somewhat less notable. I suspect Jupiter is always accreting debris. -- Kheider (talk) 23:26, 4 June 2010 (UTC)

help

Talk:Hot europa--Demomoer (talk) 05:37, 5 June 2010 (UTC)

Infobox image change proposed

I deeply respect the work and effort put into the current image, an 840x840 resolution USGS processed color image of Jupiter was produced in 1990 by the U.S. Geological Survey from a Voyager image captured in 1979. The colors have been enhanced to bring out detail. However it's not nearly as good as the 2,260×3,207 composite of images taken by Cassini buried at the bottom of the article. This is currently the best picture available of Jupiter, period, according to its NASA caption and on close inspection I tend to believe them. Anynobody(?) 05:10, 9 June 2010 (UTC)

Current image, readers who click on it are treated to a slightly larger version of the thumbnail
Proposed is a featured image and when a reader clicks on the thumbnail for high resolution view they will be able to see fine details not visible in the thumb nail alone
It's a great picture, but the main image should have the whole sphere, not just half of it. Serendipodous 07:02, 9 June 2010 (UTC)
We've discussed the infobox image before, but never really came to a consensus. I do like the Cassini image, but it clearly won't satisfy everybody. :-) —RJH (talk) 22:32, 9 June 2010 (UTC)
Being that Jupiter is my favorite planet to look at in a telescope, I do admit that a half-Jupiter looks weird to me. As we all know, you will never see a half-Jupiter from Earth. Not really an answer, just my 2 cents. -- Kheider (talk) 17:01, 10 June 2010 (UTC)

There are two full disc images of a better quality. Ruslik_Zero 18:16, 10 June 2010 (UTC)

The one to the left looks good, and it shows the red spot. But I know some people will balk because it is a composite image.—RJH (talk) 18:49, 10 June 2010 (UTC)
I like the Cassini image (on the left) showing the GRS and Europa's shadow. -- Kheider (talk) 20:38, 10 June 2010 (UTC)
I made the change. Ruslik_Zero 12:24, 11 June 2010 (UTC)

Jupiter the third-brightest object in the night sky after the Moon and Venus

Jupiter is the third-brightest object in the night sky after the Moon and Venus because the brightest apparent magnitude(m) of Mars is -2.91 and Jupiter -2.94.—Preceding unsigned comment added by Hevron1998 (talk • contribs) 10:39, 24 June 2010 (UTC)

Two things I don't understand, editor Hevron1998... 1) If the Sun is number one, the Moon is number two, and Venus is number three, how can Jupiter ever be the third brightest object in the sky? and 2) When Jupiter gets dimmer as it goes to the other side of the Sun from Earth, are these not times when Mars can get brighter than Jupiter?
 —  Paine (Ellsworth's Climax)  11:20, 24 June 2010 (UTC)
Jupiter the third-brightest object in the night sky after the Moon and Venus because Mars in 27.08.2003 apparent magnitude -2.88 (http://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=mb&sstr=499), Jupiter in 03.10.1951 apparent magnitude -2.94 (http://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=mb&sstr=599).

Mars Maximum apparent visual magnitude -2.91 Jupiter Maximum apparent visual magnitude -2.94 Mars never is brightest than Jupiter in opposition. — Hevron1998 12:23, 24 June 2010 (UTC)

For the record, Mars 2003 opposition was brighter than Jupiter's 2003 opposition. -- Kheider (talk) 04:42, 25 June 2010 (UTC)
And what is Jupiter's minimum value of magnitude? If Mars' maximum magnitude is brighter than Jupiter's minimum value, then Mars does appear brighter than Jupiter at those times, yes?
 —  Paine (Ellsworth's Climax)  13:48, 24 June 2010 (UTC)
Then sometimes Saturn and Mercury is brightest of the Mars?

Means not absolute values in the article.Then I understood. —Preceding unsigned comment added by Hevron1998 (talk • contribs) 14:08, 24 June 2010 (UTC)

Not sure about Mercury, because it's always so close to the Sun and difficult to see when it's really dark. But yes, Saturn is probably bright enough sometimes to exceed the minimum brightness of Mars. And it's powerful and wonderful that you are now able to understand that there are times when Jupiter is near its dimmest, and when Mars is near its brightest, that planet Mars' brightness can sometimes exceed planet Jupiter's brightness. Thank you very much for discussing this with me, and best of everything to you and yours!
 —  Paine (Ellsworth's Climax)  18:02, 24 June 2010 (UTC)
Mars will have a dimmest vmag of +1.84 on 2021-Jul-11 and Jupiter has a dimmest vmag of -1.66 on 2028-Sep-16. It seems JPL has updated Horizons data since I last run my Jupiter simulation in 2007. I now show Jupiter hitting vmag -2.94 on 1951-Sep-27, 1963-Oct-04, 1975-Oct-11, 2010-Sep-20, 2022-Sep-24, 2034-Sep-29, 2046-Oct-04. -- Kheider (talk) 19:21, 24 June 2010 (UTC)

Daytime visibility of Jupiter

Discussed here. You can actually see Jupiter with the naked eye during daytime but unlike Venus, only if the Sun is low in the sky. Count Iblis (talk) 23:42, 7 July 2010 (UTC)

Also see Table V (page 240) of The Visibility of Stars without Optical Aid that claims apmag -2.1 is possible from 10,000 feet. -- Kheider (talk) 05:40, 8 July 2010 (UTC)

He3 vs He4

Taking the atmospheric information in this article: 10.2±2.0% Helium And the Wiki Article on Helium-3 http://en.wikipedia.org/wiki/Helium-3 This ratio is about 1:10,000 [27], or 100 parts of 3He per million parts of 4He.

Referenced here (abstract) http://adsabs.harvard.edu/abs/1996Sci...272..846N The Galileo Probe Mass Spectrometer: Composition of Jupiter's Atmosphere ^3He/^4He ratio of (1.1 ± 0.2) x 10-4

Multiplying the values together, one gets:

10.2% He4

~.0011% He3

Not that much, but it comes out to be more He3 than HD, Ethane, or water.

Helium-3 (and Deuterium) may both be important for future Fusion Power Generation (see the Wikipedia article referenced above).--Keelec (talk) 22:21, 11 August 2010 (UTC)

I think there's more potential energy in Jupiter's deuterium (assuming we never figure out how to fuse light hydrogen), but nevertheless you're onto a basic fact. Most of the mass in the solar system is in Jupiter, and most of the energy in that is in He-3 and D in Jupiter. You can disassemble Jupiter with only a few hundred years of solar energy output, but the "fusables" in it (not counting the light hydrogen) are worth 50 or 100 times that. So you can get 10,000 years of solar energy from Jupiter without having to wait 10,000 years.

Morever, you can go to nearby stars, mine their gas giants of D and He-3 and send it back at 1% of the speed of light, and it's still energetically worth doing (especially if you use the power of the target mining star to launch the fusables back-- it's sort of like using them as energy currency). This is the ultimate energy resource in the nearby star cluster after we reach a Kardashev scale type II civilization, able to use all the power of the sun and needing more (and no point in traveling, because we have speed of light delays that make anybody we send, "not us.") I've put some of these thoughts into my essay in the book YEAR MILLION, and there are other essays on such things, as well.SBHarris 01:08, 12 August 2010 (UTC)

Density

The article includes this line:

Likewise, Jupiter has a radius equal to 0.10 times the radius of the Sun, but is only 0.001 times the mass of the Sun.

If that's true, doesn't it imply that Jupiter and the Sun have the same density? Since radius is a one dimensional quantity, the volume must be 0.001 (0.1 to the power of 3) times that of the sun, matching the reduction in mass! Or am I being dumb? David (talk) 21:21, 18 August 2010 (UTC)


Okay, nevermind, I was sort of being dumb, because they are roughly the same density. I'm going to try to reword that sentence, because it's a bit of a non-sequitur where it is. David (talk) 21:24, 18 August 2010 (UTC)

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