Talk:Solar System/Archive 3

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This article within the scope of the WikiProjects Systems

Hi, I have put this article under the scope of the WikiProject Systems because of the formal relation, but more because of the inspiring and motivating example this article can give our project and it's participants (to come). We are still a small and beginning group, and working to get our own toko going. In due time I hope we can also deliver a valuable contributions here from our point of view. In the mean time I wish all of you all te best. Best regards - Mdd 21:21, 4 May 2007 (UTC)

Definition of north and south

We should explain how north and south are defined for other objects than earth. I assume it is defined as the same direction as earths north pole. Are the rotational axes of all planets parallel? --Apoc2400 01:49, 8 May 2007 (UTC)

Kinda. The only planets that could be said to be upside down are Venus (which rotates from left to right instead of right to left) and Uranus (which, depending on your point of view, is either 82 degrees tilted and rotating right to left, or 98 degrees tilted and rotating left to right. Serendipodous 13:27, 12 May 2007 (UTC)
So, is north and south for a planet defined from the planets orbit around the sun, or as parallel to earth? Which was does north point for Venus? --Apoc2400 07:35, 15 May 2007 (UTC)
As I understand it (keep in mind that I'm not a scientist) "north" is based on what we call "north" on Earth. In space, there is no "up" or "down", so theoretically an alien visiting us could come at us from "below" and thus conclude that north was south and south was north. North and south are completely arbitrary concepts anyway, and are based more on the prejudices of cartographers than anything else. There's no real reason why maps can't be upside down; they just aren't. If, say, the Maori had been the culture to colonise the globe, then North and south could very well have been opposite. Serendipodous 12:31, 15 May 2007 (UTC)
The cartographers that have given us the reversed map ? --68.0.124.33 (talk) 21:48, 8 January 2008 (UTC)

There are varying definitions of "north"; see North_Pole#Defining_North_Poles_in_astronomy. --Doradus 13:31, 17 May 2007 (UTC)

This content has since been moved to Poles of astronomical bodies. -- Beland (talk) 22:12, 1 January 2008 (UTC)

Is there some way

to upload this video onto Wikipedia? I think it's better than the sequence of still images we now have. Serendipodous 15:28, 30 May 2007 (UTC)

"Future" section

This was added a short while ago:

The sun will stay in main sequence for about another 3 billion years. Eventually when it reach giant star it is expect to almost reach Earth's orbit. However the current research shows, the loss of the sun's gravity, mass, and probably atmosphere will cause all the planets to move further from the sun. Although Mercury is likely to escape to higher orbit, but it can definitely not escape from being engulfed by the sun because it can still expand large enough, the remaining gravity can still drag the planet down and still swallow it up in 5 billion year's time. In about 7 billion years from now the sun is expected to reach 110 times its current diameter. The Earth and even Venus will be able to escape to higher orbit to escape from being enveloped by sun. Venus is expected to reach 1.1 AU which will travel slightly beyond the current orbitof the Earth, while the Earth will escape to 1.4 AU which is almost as big as the current orbit of Mars. However all the oceans on Earth will boil up and its atmosphere will be stripped away.

... Anyone want to take a crack at reworking it, or is it too specific for this article? Thoughts? --Ckatzchatspy 23:55, 12 June 2007 (UTC)

Not necessary; the future of the Solar System was broken off this article over a year ago and is now at Formation and evolution of the Solar System#Future Serendipodous 17:14, 13 June 2007 (UTC)
  • Actually few informations is wring in 5.5 billion years sun will swell up to 100 times its current diameter. Earth will move out to 1.55 AU, and Venus will move out to 1.1 AU. sun suppose to stay in main sequence for about another 2.5 Gyrs. in 5.5 Gyrs sun will become RGB. Mercury will just stay in the same orbit the whole time and get destroyed, disintegrate, engulfed and destroy its magnetic field is too low for the planet to escape to higher orbit. Mercury will be swallowed up before the sun enters the RGB, almost after the Earth undergoes similar surface conditon as Venus. --Freewayguy--Comm 90 00:40, 10 November 2007 (UTC)
I came here looking for information on the future of the Solar system (including information about the stability of the planets' orbits), and when I couldn't find it, I came to the Talk page to ask someone to add it. We should at least have a brief summary section with a pointer to the main article. --Doradus (talk) 18:43, 27 January 2008 (UTC)
OK. Revised the formation section. Bit truncated and choppy, but I think all the absolutely necessary info is there. Serendipodous 20:13, 27 January 2008 (UTC)

Definition of a planet???

Here's some food for thought... According to the definition of a planet in this article, six of the existing planets should not be considered planets. Earth, Mars, Jupiter, Saturn, Uranus and Neptune have not cleared their path! There are still objects orbiting around them and, inadvertedly, block the way for such a body to clear through. Am I right? Shouldn't they be as Mercury and Venus with nothing in their way?

Of all the wacky things I have heard about the Solar Sytem, I have never heard such a thing that would disclude our own home as a planet. Until now, that is.

If anyone agrees with me, please note so.—Preceding unsigned comment added by Son of the right hand (talkcontribs) 21:13, 22 June 2007

Please read What is a Planet? by Steven Soter from the January 2007 issue of Scientific American. It's quite well done and made a believer out of me.  :) Oh, and please sign your posts with ~~~~ Thanks. --EarthPerson 21:16, 22 June 2007 (UTC)
I don't beleive that there is any objects in the way of any of the planets, exept for pluto, of course, my grade 8 science and technologies teacher told me so, if there were things in the way of our orbit, we would be considered a dwarf planet! androo123 16:56, 14 September 2007 (EDT)

About the planets?

I don't agree with this revert. Who says that section is only about the planets? I think we should reinstate the text. --Doradus 20:05, 18 July 2007 (UTC)

The section read (and currently reads) as follows:

"The five closest planets to Earth – Mercury, Venus, Mars, Jupiter, and Saturn – are amongst the brightest objects in the night sky and were called "πλανήτης" (planētēs, meaning "wanderer") by the Ancient Greeks. They were known to move across the fixed stars; this is the origin of the word "planet". Uranus is also visible without optical aid at its brightest, but it is at the very limit of naked-eye detectability and therefore evaded discovery until 1781."

The change added notes about Vesta, Saturn's moons, and the invention of the telescope - all interesting, but it bulks up what was a clear and succinct paragraph. --Ckatzchatspy 20:48, 18 July 2007 (UTC)

This page should be semi-protected

I'm not sure if this is a valid measure of vandal attraction, but once the first fifty edits in the history section consist entirely of reverted vandalism, I think it's time to put a lock on it. Serendipodous 07:20, 27 July 2007 (UTC)

Hmm, I don't know. The vandalism isn't overwhelming (~2 or 3 edits per day, all quickly reverted), and that "semi-protected" tag is kind of ugly. Gnixon 16:20, 31 July 2007 (UTC)

Definition of the Solar System

I find it irritating that the Solar System is defined in the opening sentence by its contents. It is given no context of location or significance; there are billions of other star systems in existance, why is this one special? If you look at the articles of the planets, they say 'this is a planet in the Solar System', and when you look at this article, it says 'the Solar System contains these planets'. It's like saying 'black is the opposite of white' and 'white is the opposite of black', it's a comparitive definition that makes no sense to people unfamiliar with the concepts referred to. --84.64.77.228 02:28, 30 July 2007 (UTC)

Our Solar System isn't special. It's just the star system we happen to be in. Is saying "Venus is a planet in the solar system" and "The solar system contains the planet Venus" any different from saying that "The lung is an organ in the vertebrate body" and "The vertebrate body contains lungs?" Serendipodous 07:25, 30 July 2007 (UTC)
Yes, that's different. The latter statements imply that the lung is an organ in every vertebrate body. The former implies that there is only one solar system. --Doradus 04:03, 31 July 2007 (UTC)
There is only one Solar System. The Solar System is the star Sol and its planetary system, hence the capital letters. Believe me I've gone through this many times in the past. The problem of definition arises because, oddly enough, there is no commonly accepted generic term for stars plus planetary systems. You'd think after ten years of extrasolar planet discovery they would have worked it out by now, but they haven't. Serendipodous 06:48, 31 July 2007 (UTC)
Well, that answers my question. Shouldn't this be explained in the article?
Not sure how. It's impossible to prove a negative, so I can't see how we could say that there is no official generic term for "solar system" unless we found a source explicitly saying so. Thing is, no source I've ever found has ever said that. Serendipodous 21:04, 8 October 2007 (UTC)
How better can one define the Solar System than to say that it is this collection of astronomical bodies orbiting that particular star? There is nothing special about the region of space we currently occupy (fringe theories about the aether, geocentrism etc. aside), nor about our coordinates relative to the galaxy or universe as a whole. Description (of our position or whatever) is not definition. Sheffield Steeltalkersstalkers 17:08, 31 July 2007 (UTC):
Isn't the generic term for a star plus planetary system "Star System?"

This article's main image is a bit out of date

It gives the impression that Pluto is a major planet. Perhaps someone could photoshop the Kuiper belt into the last orbit? Serendipodous 18:59, 11 August 2007 (UTC)

I seem to recall there being a version of that image where Pluto had been airbrushed out, which struck me as being somewhat reminiscent of Stalin-era photos of Kremlin staff (you know the sort of thing: Foobarov is out of favour, so we must remove him from the official history). Maybe that image is still on the servers? Sheffield Steeltalkersstalkers 17:27, 12 August 2007 (UTC)
Indeed. If the image should be planets only, then pluto should not be present. If dwarf planets are considered significant, then ceres, sedna, and all the other known ones should be included. As is, the image is self-contradictory. —Preceding unsigned comment added by 68.230.161.164 (talk) 04:14, 29 December 2007 (UTC)

Factual Errors

The picture of the Solar system on the bottom includes Eris, Pluto, and ceres, even though it shouldn't. They were designated as not planets, but dwarf plnaets and what happens to Wikipedia when later we find much more dwarf planets? Keep adding them? I mean, dwarf plnaets, I suppose, are much samller and thus easier to be made and thus there would be an abundance of them. The picture should take the dwarf plnaets out.—Preceding unsigned comment added by PRhyu (talkcontribs)

That image was provided by the IAU upon reaching their decision last year. Planets are listed on the top, dwarf planets on the bottom. Should they add new dwarf planets, which probably won't be until 2009, then doubtless they will release a new image to illustrate it. When they do, we'll swap it out. Serendipodous 07:33, 12 August 2007 (UTC)

converting metrics in scientific articles

I'm seeking consensus at MOSNUM talk for a change in the wording to allow contributors, by consensus only, to use unconverted metrics in scientific articles. Your opinions are invited. Tony 15:09, 25 August 2007 (UTC)

Renaming the article to Solar system

It seems to me that this article should be renamed from Solar System to Solar system. It seems common in all direct related articles like for example:

It seems that you only keep use capitals in a article title if it really an own name. But I'm not expert in Wikipedia rules & conventions. What do you think? - Mdd 22:18, 27 August 2007 (UTC)

I don't have an opinion, but I think perhaps the rationale is that a "solar system" is any system orbiting a star, while the "Solar System" is the proper name for the solar system that we inhabit. --Doradus 22:35, 27 August 2007 (UTC)

Thanks, I didn't think of that. - Mdd 22:51, 27 August 2007 (UTC)

Definition of solar system

It should be mentioned that solar system can also refer to all other star systems, and generally does, at least in American English. In American English, our solar system is almost always refered to as our solar system or the solar system. Notice the our and the.

Webster's definition of sun: "1. a) the self-luminous, gaseous sphere about which the earth and other planets revolve and which furnishes light, heat, and energy for the solar system: it is the star nearest the earth, whose mean distance from it is nearly 93,000,000 miles: its diameter is about 864,000 miles; its mass is about 333,400 times, and its volume more than 1,300,000 times, that of the earth  b) the heat or light of the sun [to lie in the sun]  2. any star that is the center of a planetary system  3. something like the sun, as in warmth, brilliance, splendor, etc.  4. [Poet.]  a) a day  b) a year  5. [Poet.] a clime; climate  6. [Archaic] sunrise or sunset."

Notice especially the definition of the sun under 2. The definition of sun is ambiguous, like a lot of the English language, and should be mentioned in the sun and solar system articles. Excluding that information is an example of Wikipedia's bias.

Also look at the Merriam-Webster Online definition for solar system: "the sun together with the group of celestial bodies that are held by its attraction and revolve around it; also : a similar system centered on another star." These sources are much more reliable than Wikipedia, an encyclopedia that anyone can contribute to.

Dictionaries don't employ official definitions; they draw citations from any and all printed works, not just scientific ones. The distinction between "the Solar System" and "a solar system" is one that is employed frequently in popular culture, but it is not one that has been officially accepted by astronomers. Yet. Serendipodous 05:35, 9 September 2007 (UTC)

Pluto

Pluto should still be a planet!! It is a dwarf planet and orbits around the sun! Why is it classified as an asteroid?! (and please please please dont delete this article!) --70.110.4.132 22:17, 8 October 2007 (UTC)Plutsave

It's not classified as an asteroid, but as a dwarf planet. Ben Hocking (talk|contribs) 22:24, 8 October 2007 (UTC)

Terminology

Could someone explain something to me that I have not been able to immediately figure out on my own after quick review of several articles. Is our solar system a galaxy? or are there several solar systems in a galaxy? Does the word "solar system" refer only to OUR solar system? If not, what is the name of our solar system? and what is the name of our galaxy? and what is the milky way? a series of galaxies that we can see from Earth?

Thanks. dearly 02:25, 17 October 2007 (UTC)

The solar system is not a galaxy. A galaxy is a gravitational union of a hundred billion stars. The Solar System is one star and the planets around it. Our Solar System is one star in the Milky Way galaxy, which probably contains a hundred billion other similar systems. The Solar System (with capital letters) is the name of the star system we live in. Some people use the term "solar system" (no capital letters) to describe other such systems, but that isn't official. Serendipodous 06:42, 17 October 2007 (UTC)

New Image

File:PIA03153.jpg
montage of planetary images taken by spacecraft managed by the Jet Propulsion Laboratory in Pasadena, CA. Included are (from top to bottom) images of Mercury, Venus, Earth (and Moon), Mars, Jupiter, Saturn, Uranus and Neptune. The spacecraft responsible for these images are as follows: * the Mercury image was taken by Mariner 10, * the Venus image by Magellan, * the Earth and Moon images by Galileo, * the Mars image by Mars Global Surveyor, * the Jupiter image by Cassini, and * the Saturn, Uranus and Neptune images by Voyager. * Pluto is not shown as no spacecraft has yet visited it.

This new Image might be useful.--Nemissimo 16:44, 8 November 2007 (UTC)

Planet Orbits

I was looking for an article or image that explains planet orbits. Preferably approximate scale image for inner planets, showing ellipses and sun position? is there one in wikipedia, or should there be one? -- 16:32, 11 November 2007

Well, there's this. Not sure what you want. Do you want distances? There's an old image from this page that I took down because it swamped the text. You can see it here Serendipodous 21:45, 11 November 2007 (UTC)
thanks. what i had in mind is the fact that planet orbits are not circular but more of the ellipse (as keppler told us), yet its hard to see on images of large scales. on all images they look very circular. for example in December Earth is closer to sun that in June. yet i couldn't find a wikipedia diagram that shows that. thanks -- 17:01, 12 November 2007 —Preceding unsigned comment added by 12.106.237.2 (talk)

Link to Hindi version

...would be nice if someone could add the link to the excellent Hindi version of the article - thanks? Watasenia (talk) 15:51, 24 November 2007 (UTC)

If you provide a URL, I'll provide the link. My Hindi is rather limited… Ben Hocking (talk|contribs) 16:11, 24 November 2007 (UTC)

Photos of the sun

As an earlier attempt at commenting was reverted (probably mistook as vandalism even though the comments were hidden from normal view), here's another go:

Is the shot (probably taken by a compact digital camera) in current form truly encyclopedical? Consider Image:The sun1.jpg (which is currently used) and the previous Image:The Sun.jpg. What do they show? A burnt out highlight, some blue sky and lens flare. In comparison, perhaps these do not quite fit in? As the article history only goes back to April 20 2007 I can't determine if they were included in the version that underwent the FA process. Cheers, 88.148.207.23 12:07, 1 December 2007 (UTC)

They were. Or at least earlier versions of them. Serendipodous 13:04, 1 December 2007 (UTC)

Sol System

Isn't that like the name most people use in fiction when we found other star systems i can try to find references but i doubt it --24.107.202.65 (talk) 22:12, 22 January 2008 (UTC)

Some scifi books have used it, most notably the Foundation series, but it's not used much in reality. Serendipodous 00:27, 23 January 2008 (UTC)

Header: Greco-Roman mythology references

Either referring to the Greco-Roman mythological origins of various planetary designations is inappropriate in the header, or including the Greco-Roman mythological names for Earth alongside the other planetary designations is necessary to fairly present information on the subject. I've tried both options to no avail. Discuss. Adraeus (talk) 22:40, 25 January 2008 (UTC)

I don't understand what your problem is. This is the English Wikipedia. In the English language, all the planets save Earth are named for Graeco-Roman mythic figures. English hardly ever uses "Terra", except in science fiction, and rarely even then (not to mention the fact that "Terra" isn't a god). Gaia is irrelevant save in reference to the Gaia hypothesis. Serendipodous 22:45, 25 January 2008 (UTC)
Gaia and Terra are both Greco-Roman mythological names for Earth, which only became the name for this planet in circa 1400. The Gaia in the Gaia hypothesis isn't a factor here. As for Terra not being a god, what are you, blind? Adraeus (talk) 23:00, 25 January 2008 (UTC)
I believe, mythologically speaking, Tellus is the more common term. I still don't understand what you're talking about. The Earth wasn't even recognised as a planet in 1400. This article states a simple fact; the planets are named after Greek and Roman gods, except Earth. Your claim that it is irrelevant is preposterous. The origins of the names of the planets are perfectly relevant to the article. Serendipodous 23:05, 25 January 2008 (UTC)

From the Oxford English Dictionary:

10. a. Considered as a sphere, orb, or planet.

  • c1400 Rom. Rose 5339 Erthe, that bitwixe is sett The sonne and hir [the moon].
  • 1555 EDEN Decades W. Ind. Cont. (Arb.) 45 A demonstration of the roundenesse of the earth.
  • 1658 CULPEPPER Astrol. Judgem. Dis. 18 The Earth is a great lump of dirt rolled up together, and hanged in the Air.
  • 1726 tr. Gregory's Astron. I. 403 The Place of the Aphelion or Perihelion of the Earth.
  • 1796 H. HUNTER tr. St. Pierre's Stud. Nat. (1799) I. Introd. 32 The Earth is lengthened out at the Poles.
  • 1854 BREWSTER More Worlds Introd. 2 The earth is a planet.

Nevermind the Online Etymology Dictionary. [1]

I also never said that the origins of the names of the planets are irrelevant to the article. I said that they were irrelevant to the header of the article unless their reference was made complete with a reference to Earth's Greco-Roman mythological names. Adraeus (talk) 23:15, 25 January 2008 (UTC)

I don't see how you can't possibly comprehend that identifying the Greco-Roman names for what is now called Earth alongside planetary designations, whose historical names were retained, does not complement the information and presentation of the information in the header. Adraeus (talk) 23:20, 25 January 2008 (UTC)

A planet is a wandering star. By definition, it moves. Even after 1543, when Copernicus first proposed the idea that the Earth might be moving, it was at least a century before the Earth was considered a planet. A sphere, yes. Not a planet. But again, what is the issue here? This is the English Wikipedia, not the Latin or Greek Wikipedia. That sentence describes the name origins of the planets in the English language. The other planets are named after Greek and Roman gods, and Earth isn't. "Terra" and "Gaia" are hardly ever used in English, and never were common (Greek didn't become widely understood in the English-speaking world until the 1500s) and therefore are not notable enough for inclusion. Serendipodous 23:25, 25 January 2008 (UTC)
People perceive reality in their language. Their "sphere" was our "planet." (By the way, stop telling me this is the English Wikipedia. I've been a major contributor to the English Wikipedia for years. I don't care for your insults.)
The issue is that Mercury, Mars, Uranus, etc., are Greco-Roman names for planets, once considered spheres, too. Gaia and Terra are Greco-Roman names for what we call Earth. They might not be commonly used anymore, but they remain a significant part of history and are relevant alongside other Greco-Roman names. Don't be a revisionist. Adraeus (talk) 23:32, 25 January 2008 (UTC)
Believe me, there is a big difference between "sphere" and "planet" in geocentric cosmology. Earth was a sphere, but it was not a planet. Early astronomers were very familiar with both words, and never once considered Earth a planet. And how is not including the fact that Earth was very occasionally referred to by its Greek/Roman name in English "revisionist"? Neither the Greeks nor the Romans ever considered Earth a planet. Why is it even relevant, let alone necessary? Serendipodous 23:49, 25 January 2008 (UTC)

(resetting indent)Adraeus, I think you're overlooking the fact that this article is intended to be an overview of the Solar System as a whole. The information you're adding is, in that context, not relevant here. Moreover, it is already mentioned in Earth (in the lead sentence), which is the more appropriate place for details. There are many, many, many details that have had to be trimmed simply to keep the article to a manageable length. --Ckatzchatspy 00:53, 26 January 2008 (UTC)

Table

The anonymously added table was a variant of one that existed as part of this article years ago, but was ultimately removed. It and its sister tables can now be found at the page Attributes of the largest solar system bodies. If the table is to be reinstated, I think it should be discussed first. Serendipodous 15:11, 29 February 2008 (UTC)

Thanks, Serendipodous, for that history. I almost reverted it, but just copyedited it instead. Thanks for the institutional memory. Cheers Geologyguy (talk) 15:14, 29 February 2008 (UTC)

Debate of planet classification

A comment was added to the article stating that the definition of a planet is hotly debated. Is this really the case? I know that some people didn't like the re-classification of Pluto - but it seems that the definition of a planet given in the article is pretty standard and accepted. Comments? PhySusie (talk) 05:15, 2 March 2008 (UTC)

I reverted it. This is not the place to discuss this. Wikipedia has three other articles devoted to this topic: Planet, Definition of planet and 2006 definition of planet. Serendipodous 07:57, 2 March 2008 (UTC)

New image

Overall, I like the new lead image (it's certainly more scientifically accurate than the last one) but it makes Mercury's orbital inclination out to be about 45 degrees, when in fact it's about 7 degrees. This exaggeration is misleading. Serendipodous 12:39, 10 March 2008 (UTC)

Can we swap the two - put the new one in "Terminology", and restore the other one to the lead? No offence to the creator, but the image quality is stronger in the original one (and may better suit the lead). --Ckatzchatspy 21:44, 10 March 2008 (UTC)

Declining Orbit?

Is the earth theorized to be in a declining orbit? Why is there no detected decline in orbit? What's the theory behind why the planets weren't aborbed into the sun a long time ago? Could we add something to this article the gravitational balance of the solar system, and a calculation as to how much mass would need to be vaporized before we would expect an upset in that balance? 68.75.88.171 (talk) 02:20, 26 March 2008 (UTC)

Sounds like it might be an interesting thing to cover, but it would probably be better placed in Formation and evolution of the Solar System. Serendipodous 08:13, 26 March 2008 (UTC)
Actually the orbits of the planets are expanding, due to the Solar mass loss. Saros136 (talk) 04:53, 8 April 2008 (UTC)

Image with orbits to scale?

I noticed that while there's a lot of nice images here, the article lacks an image of the solar system showing the relative distances to the sun and the relative sizes of the planets at the same time. That would obviously be a bonus. --Strappado (talk) 17:57, 26 March 2008 (UTC)

The article does have such an image; in the layout and structure section, there is an image captioned, "orbits of the objects in the Solar System to scale." Serendipodous 18:01, 26 March 2008 (UTC)
The problem is that the size of the planets and the size of their orbits are on completely different scales - you can't show them usefully on the same diagram. If you can see the orbits, the sizes of the planets are too small. If you can see the size of the planets, the orbits are way (way way) off the page. The compromise is in the article - one diagram shows the relative sizes of the planets, another shows the relative sizes of the orbits. PhySusie (talk) 18:48, 26 March 2008 (UTC)
Oops. Sorry, misread the OP. Yeah, that would be hard to do. I wonder what the scales would be like if we set Mercury at one pixel? Serendipodous 18:55, 26 March 2008 (UTC)

opening paragraph

Could we include the vast number of man-made objects which currently orbit the sun in the opening paragraph? —Preceding unsigned comment added by Oddzag (talkcontribs) 22:27, 27 April 2008 (UTC)

The number of man-made objects orbiting the Sun isn't all that vast; certainly not when compared to the number of man-made objects orbiting the Earth. Serendipodous 05:07, 28 April 2008 (UTC)

Transit of Mercury image

This is a very odd image to use for the "Sun" subsection. The title makes no explanation of the fact that the image is of the Sun, with one of the blurred dots being Mercury, so the uninformed reader (which is who the article is for - someone who is looking up "Solar System" can't be expected to know what a "transit of Mercury" is) might assume that the image was of Mercury. Also as previously mentioned the transit of Mercury is not discussed in the article. Rachel Pearce (talk) 09:49, 2 May 2008 (UTC)

  • Instead of assuming something one just may hit the link,or to go to the image caption and hopefully to learn something new and interesting of course assuming one wants to learn.--Mbz1 (talk) 15:44, 2 May 2008 (UTC)
That isn't how Wikipedia is supposed to work. Articles aren't supposed to introduce material without explaining it. It's unfair and confusing. Serendipodous 16:55, 2 May 2008 (UTC)
Agreed. But the editor who placed it there seems insistent that it is more informative, though of what I'm not certain. I'll revert it again and direct the editor to the talk page. Serendipodous 09:51, 2 May 2008 (UTC)
  • IMO The image The sun1.jpg not only has no encyclopedic value whatsoever, it has a negative value. What one could possibly learn from that image? The only thing that could be learned from this image is how not to take a similar image in order do not damage both your camera and your eyes. The image quality is horrible. It is full of camera artifacts.On the other hand the image Mercury transit 2.jpg is highly encyclopedic. It shows not only the sun, sunspots and Mercury, but also Limb darkening. The image is a great illustration of the size of the Sun compare to Mercury. It is easy to correct the caption under the image and provide the link to the Transit of Mercury article. Then maybe somebody would go there and learn something new.--Mbz1 (talk) 12:51, 2 May 2008 (UTC)

This article isn't about sunspots, limb darkening, or transits of Mercury. It's about the Solar System. Such material is better covered in the Sun article itself. We can't assume that any reader, staring at this picture, would have a clue what sunspots, transits, or limb darkening are. If that picture were to be included, it would have to have some relevance to the article, which means that this already-gargantuan article would have to be expanded to discuss sunspots, limb-darkening, and transits of Mercury. I have no interest in doing so, and I doubt you do either. This article's section on the Sun is little more than a brief explanation of what the Sun is, which is all it needs to be, so a simple picture of the Sun is really all that's required. Serendipodous 16:49, 2 May 2008 (UTC)

The article talks about sunspots, about Mercury and about the Sun. The Sun has sunspots and limbs darkening. If a reader is interested in learning solar system, he would hit the links and learn something new. My image is of the Sun. Do you call that The sun1.jpg an image of the sun? It is not what the sun is about. This image looks like a picture made by a 2-years old. No encyclopedia that respects itself would put such an image in the Solar System article. As I said earlier IMO that image is not only bad, but might be also harmful.BTW you've never answered what one supposed to learn from the current image of the sun?--Mbz1 (talk) 19:12, 2 May 2008 (UTC)
The article doesn't go into any detail about what the Sun is "about". Why introduce new ideas not covered in the article? It's not the reader's responsibility to compensate for our lack of explanation. Serendipodous 21:18, 2 May 2008 (UTC)
I've told you that introducing new ideas could make some readers to want to learn more and it is what education is about. You've never responded what ideas and values the current image of the sun has.--Mbz1 (talk) 22:35, 2 May 2008 (UTC)
It's a picture of the Sun. It isn't filtered; it isn't altered. It requires no further explanation. I would have preferred such a picture of the Sun from space, but there aren't any in the Commons. Serendipodous 08:09, 3 May 2008 (UTC)
  • You've never answered my question What one suppose to learn from that so-called picture? Why to look at the article and not just at the sky? Wikipedia is encyclopedia and not a children picture book. BTW the only pictures of the sun taken from the space are taken with filtered telescopes. There are no other way to take the image of the sun.--Mbz1 (talk) 14:26, 3 May 2008 (UTC)

No other picture could be as encyclopedic. All other pictures of the Sun are taken with filters, so you can't see the Sun doing it's most important job: shining. An image of the Sun that looks like a star is better than an image of the Sun that looks like a beach ball. Serendipodous 17:01, 3 May 2008 (UTC)

  • The sun at the image is not shining - the camera artifacts do.--Mbz1 (talk) 17:20, 3 May 2008 (UTC)

Directions of spin of each planet

I would love to see the directions of spin of each planet listed in a table somewhere, ideally along with as much other information as possible, including year length, day length, obliquity, eccentricity, and direction of spin of moons (if applicable). This information is currently scattered and I am not quite knowledgeable enough to consolidate it.

Directions of spin could be given as "North" or "Up" for Earth's rotation around itself each day, and "North" or "Up" for Earth's rotation around the sun. North/up is a nice way to use the right-hand rule, and I find it less ambiguous that clock/counterclockwise. North/up could also be called "counterclockwise when viewed from above/looking down at the Northern hemisphere."

Specific questions: What direction does Earth's rotational axis precess in? I assume from the difference in sidereal and tropical years that it must precess "down/South." And what direction does the anomalistic precession (the precession of the apsides) go? I also assume that is "up/North" from available, albeit indirect data. I could answer these questions myself, but not as fast as most of you. Plus, I want the table for the good of the world, not just the answers in a talk page for me. Thanks.Fluoborate (talk) 07:37, 6 May 2008 (UTC)

Sounds like you want this article. Serendipodous 10:30, 6 May 2008 (UTC)

Ice Giants

Isn't it that Uranus and Neptune are no longer called Gas Giants (Jovian Planets), but now called Ice Giants? From what I know, it's because they were found to be made of frozen gases like the KBOs rather than gaseous gases like the Jovians. —Preceding unsigned comment added by 222.127.219.236 (talk) 13:00, 9 June 2008 (UTC)

Uranus and Neptune are referred to as ice giants, yes. Some consider ice giant to be a different classification than gas giant, others consider it a subclass of gas giant. They are called ice giants because their atmospheres contain far less hydrogen and helium than Jupiter and Saturn and a far higher proportion of volatile compounds such as water, ammonia and methane. Astronomers refer to these compounds as "ices" whether they are actually ice or not. Uranus and Neptune are also far smaller than Jupiter and Saturn; their combined mass is barely a third that of Saturn and barely a tenth that of Jupiter. Serendipodous 19:31, 9 June 2008 (UTC)

Dwarf Planets

This page says that our solar system has exactly three dwarf planets. It is missing entries such as Xena [2]. National Geographic says that there are 44 dwarf planets [3].

MassimoH (talk) 17:36, 26 June 2008 (UTC)

"Xena" is the informal nickname given to the dwarf planet Eris before it was officially named. The issue of the number of dwarf planets is contentious. The defining characteristic of a dwarf planet (as opposed to a mere Kuiper belt object or asteroid) is that it is large enough to be round. But how can you tell whether or not a tiny lump of ice three billion miles away is round or not? Telescopes aren't really up to the job. The simplest solution would be to do what Mike Brown does and say that any object beyond a certain diameter, which would then be large enough to be round, should be called round. This would mean there were, as NatGeo says, about 44 dwarf planets. Unfortunately, there's a problem with this method: gravity alone cannot determine whether or not an object is round. Neptune's moon Proteus is larger than Saturn's moon Mimas, yet Mimas is round and Proteus is not. The reason is that Proteus is a lot colder than Mimas, and colder materials resist gravitational collapse more strongly than warmer ones. Also, icy objects like KBOs become spherical more easily than rocky objects like asteroids. Simply fixing a diameter, then, is not enough to qualify. So the IAU came up with a rather stupid solution. Any object with an absolute magnitude less than than H=1 (which meant it was exceptionally bright) would be called a dwarf planet. This would mean that there are unlikely to be more than four official dwarf planets in the outer Solar System: Pluto, Eris, 2003 EL61 and 2005 FY9. Neither of the last two have been officially classified as dwarf planets yet, and probably won't be until they get names. Serendipodous 17:49, 26 June 2008 (UTC)
Wow, what a knowledgeable response. Thanks! Maybe the main article can contain an extra sentence or so that clarifies the issue a little better?

MassimoH (talk) 02:43, 27 June 2008 (UTC)

The issue's a bit too complex to be explained in a few sentences. The articles dwarf planet and plutoid cover the issue fairly well. Serendipodous 06:45, 27 June 2008 (UTC)
This honestly makes me think that decisions are being made only to keep the number of entities with 'planet' in their name to a minimum and not for any scientific reason. This was the main argument for the whole dwarf planet thing in first place, that it would be awful for schoolkids to have to memorize several dozen planet names. Zazaban (talk) 19:48, 16 July 2008 (UTC)

Unsourced sections

There are a lot of unsourced sections in this article, particularly towards the end. Are any specific editors maintaining it?-Wafulz (talk) 19:32, 8 July 2008 (UTC)

What unsourced sections? Serendipodous 20:09, 8 July 2008 (UTC)
Sorry, should've clarified. A lot of subsections are unsourced.-Wafulz (talk) 00:41, 9 July 2008 (UTC)
Aside from "Discovery and exploration", which sections do you think need more sources?

EDIT: Could you, to make my job easier, tag each uncited fact with [citation needed]{{cn}} ), so I can get an idea of how many are needed?Serendipodous 05:54, 9 July 2008 (UTC)

Map

The map does not show Makemake, this should be fixed. Zazaban (talk) 19:49, 16 July 2008 (UTC)

the largest...

i propose to eliminate the tags from the list of dwarf planets at the beginning of the article that say "the largest..." to make it similar to the above list of planets --SquallLeonhart_ITA (talk) 16:17, 24 July 2008 (UTC)

Well, there's really no reason to do so, and it is relevant information. I'd support leaving it as is. --Ckatzchatspy 22:08, 24 July 2008 (UTC)
As do I. Serendipodous 05:47, 25 July 2008 (UTC)

Sun's expansion

This site say by 6 to 7 billion years from now sun's expansion can be between 200 and 700 times the size of now (between 1.0 and 3.5 AU). This means sun's expansion have a possiblity to encompass Mars orbit and it may give it a chance to swallow the planet up. When the sun evolve into a white dwarf star and if Mars still exists; then Mars is likely to be the innermost planet.--Freewayguy Call? Fish 21:59, 24 July 2008 (UTC)

FG, you've already gone through this over at Formation and evolution of the Solar System, which is the article to discuss this issue in anyway (this article contains a summary of the information in that article, so there isn't any point in adding any more information). Serendipodous 05:49, 25 July 2008 (UTC)

List In Order From Sun

Novices reading this article may very well think that all the dwarf planets are beyond Neptune, because the first list is the three-categories lists (terrestrial, gas-giant & dwarf) which is described as "In order of their distance from the Sun".

I think the primary list must be the order from the Sun of all the planets, dwarf planets and gas giants.

The list of three categories of objects I don't think can be thought of as the primary one.

Removing The List of Dwarf Planets

Removing this list has helped stop novices becoming confused that ALL dwarf planets orbit beyond Neptune, and it looks a lot "cleaner". HarryAlffa (talk) 14:48, 31 July 2008 (UTC)

What I'd Like After First Paragraph

In order of their distance from the Sun, those named celestial objects bound to it by gravity (excluding moons) are:

Good Idea?

I thought it a reasonable (if not a good idea) to list the order of these objects in distance from the Sun, it is quite a major feature of the Solar System after all!

Then could come the paragraph: "In broad terms, the charted regions of the Solar System consist ...", then the lists of the categories.

HarryAlffa (talk) 21:41, 30 July 2008 (UTC) and HarryAlffa (talk) 23:00, 30 July 2008 (UTC)

That would work if dwarf planets were planets, but they aren't, so including the dwarf planets among the planets is incorrect. Serendipodous 21:43, 30 July 2008 (UTC)
Yes. I did write "major named bodies" at first, but you undid me! I was then inaccurate in my rewrite for this page (which I've now changed above). Just to be clear - I am trying to improve the article! Not just change for change's sake. I hope you are not feeling proprietorial about the page. HarryAlffa (talk) 22:22, 30 July 2008 (UTC)
I'm not being proprietorial. All I care about is factual accuracy. "major named bodies" doesn't mean anything. What is "major"? There are seven moons in the Solar System larger than all the dwarf planets, and they all have names. Serendipodous 22:26, 30 July 2008 (UTC)
Ok. Good point. I've changed it above using the language from the first paragraph. HarryAlffa (talk) 22:44, 30 July 2008 (UTC).

The proposed list just makes clear and complete the hard to read list of objects in the image. HarryAlffa (talk) 23:18, 30 July 2008 (UTC)

This needs fixing - as is, it isn't appropriate for a FA-class article. The image description should not be in the main body. I'll try to repair it later tonight. --Ckatzchatspy 00:11, 31 July 2008 (UTC)

I think that including a list of the dwarf planets at all in the lead is cumbersome, particularly since the number of known dwarf planets will likely continue to rise over the next few years. The lead should describe the major orbits: all the planets (by definition), as well as the asteroid belt, scattered disk, etc.; that is, essentially as it was.

Both the lead image and the image in the "Terminology" section make the order of the bodies in the Solar System amply clear. I agree that the long list intermixing dwarf planets with planets is not an improvement. —Alex (ASHill | talk | contribs) 00:28, 31 July 2008 (UTC)

The lead image is incomplete, and the names of the objects are difficult to read. The incompleteness of the image supports your view that a list of dwarf planets would be cumbersome to maintain. So why has this image been included for so long? I think a list of objects, including dwarf planets, in order from the Sun is a primary motive for novices to astronomy looking at the article. It would be helpful to them to have a simple list of these at the start of the article - which must be part of the reason to have had the image there all this time. It is unlikely that there will be many more dwarf planets found in the asteroid belt, so including Ceres would not be an editorial burden. For the Kuiper Belt perhaps saying "Pluto and other dwarf planets ..." would be a satisfactory solution to maintainance. - HarryAlffa (talk) 14:40, 31 July 2008 (UTC)
Any list that combines dwarf planets and planets instills in the novice the false assumption that dwarf planets are planets. They are not planets and should not be included with the planets. Yes, they're called dwarf planets, but, I repeat, they are not planets. Serendipodous 14:50, 31 July 2008 (UTC)
But you don't object to the list in the lead image using this reasoning?
The list I have above makes clear which are planets, dwarf planets, or gas giants. So not all combining lists behave as you describe them. Again I say that a list of the named celestial objects in their order from the Sun is a pretty good idea for the introduction to this subject. -HarryAlffa (talk) 19:15, 31 July 2008 (UTC)

New List

Can we combine both a category list & a named object list? I would propose to replace the current list with this;

{===============

In broad terms, the charted regions of the Solar System and their constituents, in order of their distance from the Sun are:

===============} -HarryAlffa (talk) 20:38, 31 July 2008 (UTC)

Makemake Pluto and Eris are KBOs. Your list {list now edited} implies they're not. And the image doesn't use the same reasoning. It separates the planets and the dwarf planets.Serendipodous 20:56, 31 July 2008 (UTC)

I offered this combined list in the spirit of compromise and cooperation. I thank you for your previous objections because I think this new list is better than my original or the current list. Like the image, it clearly identifies, and gives the relative positions of the dwarf planets, and it also includes the relative positions of the Asteroid and Kuiper belts, something the image and neither list did before - well done us! I have further amended the list as per your objection to imply that those dwarf planets in the Kuiper belt are KPO's, and added the Scattered Disk containing Eris. -HarryAlffa (talk) 21:42, 31 July 2008 (UTC)
I personally like the current list; though if we were to use this one it should be made into a table so that the information wouldn't take up as much room (i.e. vertical vs. horizontal) -- Phoenix (talk) 05:45, 1 August 2008 (UTC)
The description of the current list as, "in order of their distance from the Sun are", does lead an Astronomy novice (surely the target audience, at least for the introduction) to think that ALL the dwarf planets orbit beyond Neptune.
Web designers will tell you that having a lot of white-space helps a human to absorb the information better - it's not as if screen space costs anything. The linear arrangement of the list intuitively informs the reader of an ever increasing distance from the Sun while progressing through the list.
In fact now you've got me thinking of "detail density" and detail level. I think the second paragraph is too densely packed and goes in to too much detail. It lies about itself when it says "In broad terms ...", and then gives details of composition of the regions!
I would replace the second paragraph with, "In broad terms, the charted regions of the Solar System and their constituents, in order of their distance from the Sun are:", and follow this with the list of regions and their constituents; I've now changed the list above to reflect this. -HarryAlffa (talk) 13:31, 1 August 2008 (UTC)
(Jumping into this discussion a bit late; I've had limited time the last few days but have been following the discussion.)
We need to remember that this is the lead and should follow the style guideline WP:LEAD. Particularly: "The lead should be able to stand alone as a concise overview of the article. It should establish context, explain why the subject is interesting or notable, and summarize the most important points." (emphasis added) In the lead, a list is rarely appropriate at all, and I really don't think it's needed here. As I mentioned above, the names of dwarf planets are definitely not needed; in the grand scheme of things, the dwarf planets aren't terribly important.
I think a pargraph something like "In order of their distances from the Sun, the terrestrial planets are Mercury, Venus, Earth, and Mars. The outer gas giants (or Jovians) are Jupiter, Saturn, Uranus, and Neptune. Some of the largest objects in the asteroid belt, Kuiper belt, and scattered disc are classified as dwarf planets." I think this sentence effectively summarizes the presence of the dwarf planets and their role in the Solar System without excessive detail; the information is covered and organized quite logically in the body of the article. —Alex (ASHill | talk | contribs) 14:28, 1 August 2008 (UTC)

I think the most important fact about the solar system is the eight planets, and they should be clearly listed by themselves in the intro, with no breakdown by type. Many readers will come to this article looking for just that list and they should get it up front in its most simple form. The types of planets and the wide variety of other objects should then be introduced. Minor planets should come next simply because of the interest in Pluto. We should then begin to present the whole picture, perhaps beginning with a better diagram.--agr (talk) 14:12, 1 August 2008 (UTC)

I generally agree. However, I think we have to be careful about choosing the content of the lead based on popular interest. It's best if we stick to what our sources say and present the facts; we should trust our readers to read what the article says. Wikipedia is not here to bust common misconceptions. If we focus on popular misconceptions, we may wind up inadvertently strengthening them, particularly among readers who didn't have those misconceptions before reading the article.
(Note: this comment is partially in reply to other threads in this discussion.) —Alex (ASHill | talk | contribs) 14:37, 1 August 2008 (UTC)
Alex, you said lists where rarely inappropriate, then your suggested replacement text contained 2 lists! You've proven that you cannot write about the Solar System without a list of planets!
The proposed bullet point list is clear, consise and gives up more information the more a novice studies it, rather than a comma seperated list which is rather indigestable!
Arnold, I agree with you about the planets, that was my initial "improvement", but debate on this page has forced the evolution of the list above.
I think the proposed bullet point list gives the order of the regions, planets, gas giants, dwarf planets, asteroids, KPO's and scattered disc objects. It does it all, and it does it more concisely than the current second paragraph + the three current bulleted lists! -HarryAlffa (talk) 15:13, 1 August 2008 (UTC)
I'm sorry I wasn't more clear. I think the bulleted list is inappropriate and unnecessary: there are only four items in each list, which I don't think is hard to ingest at all in prose. I also think that the current second paragraph clearly and concisely summarizes the major components of the Solar System.
I agree that listing the eight planets (in some form) in the lead is entirely a good idea. (I don't think there's any disagreement on that point.) I think that the gas giants and terrestrial planets are fundamentally different objects and ought to be separated; I don't think that adds to confusion. However, I feel less strongly about that last point. —Alex (ASHill | talk | contribs) 15:23, 1 August 2008 (UTC)
(I said lists are "rarely appropriate in the lead", not "rarely inappropriate".) —Alex (ASHill | talk | contribs) 15:25, 1 August 2008 (UTC)
Apologies for the "inappropriate" typo.
The three current bulleted lists mislead the novice reader to think that all the dwarf planets orbit beyond Neptune. The dwarf planet list is also too detailed.
The second paragraph lists seven regions and descripes the composition of three of them, giving a list stretching to fifteen data items! Then you seem to be suggesting that eight more items are "condensed" (at least in screen-space if not in kilobytes) into prose?
The Open University course I've done, which included theories on Human Compter Interaction and Interaction Design, tell me that a bulleted list is far better here.

-HarryAlffa (talk) 16:57, 1 August 2008 (UTC)

I think the current version tries to do too much in the intro. We have the rest of the article to explain these concepts. I also think we should avoid editorializing comments like "Dwarf planets are unlike other categories of named celestial objects in that they populate more than one region of the solar system..." which is also just plain wrong (e.g. comets and asteroids). All we have to say is the the dwarf planets are in several regions. As for terrestrial vs gas giants, the scientific community calls them all planets and that should be our starting point. --agr (talk) 22:59, 1 August 2008 (UTC)

I agree that the intro tries to do way to much; the current version is not at all concise (as the lead is supposed to be). The lead does not need to stand alone as a full description of the topic, only a concise summary (re this edit summary). I think it is fairly clear that there is a strong consensus amongst all but one of the editors here that the verbose version is not a good starting point, so I am reverting. —Alex (ASHill | talk | contribs) 20:05, 2 August 2008 (UTC)
You cannot say that my version was verbose! Are you confusing the amount of screen-space it occupied with verbosity? It contained the same or a lesser amount of text! Almost all of the current second paragraph was subsumed into the new list and in a great deal less text. -HarryAlffa (talk) 17:43, 3 August 2008 (UTC)

I agree with agr that saying "the dwarf planets populate several regions" is far more consise! Although in my own defence I would say that my description became somewhat inflated to accommodate criticism!

For clarity; I meant individually named objects like Makemake or Ceres; perturbed objects, like comets, can't be said to populate the other regions they are passing through; asteroids only populate the Asteroid belt. -HarryAlffa (talk) 18:46, 3 August 2008 (UTC)

@HarryAlffa: I think the current list, separating planets and dwarf planets, is slightly better than your suggested "new list" since it is more readable (not a "list of lists") and somehow "catchier". I put the planets in a single list and added the "smaller" attribute in the sentence leading to the dwarf planet list, so that it becomes (hopefully) clearer that planets and dwarf planets are two different categories, and each category's list is ordered for itself. Also, the total order is already provided by the picture given. --Roentgenium111 (talk) 22:06, 3 August 2008 (UTC)

Since there are likely hundreds or even thousands of dwarf planets waiting to be discovered and then waiting some more to be classified, I think the template should be:

In broad terms, the charted regions of the Solar System and their constituents, in order of their distance from the Sun are:

Delaszk (talk) 15:01, 7 August 2008 (UTC)

Heliopause

The second paragraph should be clear about the heliopause being "a named ovoid region of space where the solar wind meets the interstellar medium and not known to contain objects". All the other regions named are known to contain objects. The Oort Cloud is still theoretical, but the theory includes objects. HarryAlffa (talk) 22:32, 30 July 2008 (UTC)

The heliopause is not a region, it's a thing; it's the edge of the bubble created in the interstellar medium by the action of the Sun. And it does contain objects. Quite a few billion solar particles, in fact. Serendipodous 10:08, 31 July 2008 (UTC)
It's more accurately described as an interaction rather than a thing, you cannot assert that interaction is an inaccurate descriptor! I suppose you might say it is a thing, like the asteroid belt, but I think this would be wrong. The asteroid belt occupies a region of space obviously, but the Heliopause is the region of space where the interaction happens - and this region changes depending on the solar wind.
I don't believe your assertion that "a few billion solar particles" are objects, is a useful one in the context of describing the Solar System. HarryAlffa (talk) 13:59, 31 July 2008 (UTC)
And what? Are you going to argue that an interaction would contain objects? By definition it wouldn't. There's no point in bringing it up, any more then there is in saying, "The atmosphere contains no continents." Serendipodous 14:52, 31 July 2008 (UTC)
I agree with you that the Heliopause contains no objects. My opening proposal was {now with minor edit} to describe the Heliopause as "a named ovoid region of space where the solar wind meets the interstellar medium and not known to contain objects".
So we are now in agreement that the region contains no objects.
"The first sentence on the Heliopause in the Solar System article says, "The heliosphere is divided into two separate regions." Then names the Heliopause as the outermost region.
So unless you want to rewrite the Heliopause section, or main Heliosphere article, and change the description of it as a region, and you want to include celestial objects, then you are in agreement that the Heliopause can be described as:
"a named ovoid region of space where the solar wind meets the interstellar medium, and is not known to contain objects". - HarryAlffa (talk) 19:05, 31 July 2008 (UTC)
Plenty of objects have orbits which take them through the heliopause. Sedna for one. Eris's orbit probably takes it into the termination shock. There are probably thousands of objects crossing the heliopause right now. But the heliopause is not a population, like the asteroid or Kuiper belts. You're trying to compare apples and oranges. Or maybe apples and machine guns. Serendipodous 19:16, 31 July 2008 (UTC)
So we agree that the Heliopause is a region?
Yes, these object cross the Heliopause. I agree. The Heliopause does not contain them. Comets cross the inner region of the Solar System, but you would not say that it contains comets.
You said the the Heliopause is unlike the Asteroid or Kuiper belts. Yes. I agree. The Asteroid and Kuiper belts contain objects.
However, I would amend my proposal to "the Heliopause is an ovoid region of space named for the interaction of the solar wind with the interstellar medium, and not for any population of celestial objects." -HarryAlffa (talk) 19:59, 31 July 2008 (UTC)
Why? It's cumbersome and unnecessary. The article already explains what the heliopause is. Why add a line essentially saying that an apple is not a machine gun? Serendipodous 20:03, 31 July 2008 (UTC)
So you have no objections to the meaning?
If people do not know the difference between apples and machine guns then a line explaining that difference would be useful. I expect a number of people will not have heard of the Heliopause, and the context of the paragraph concentrates on the objects constituting the regions of the Solar System, so pointing out that the Heliopause is named for reasons other than for a population of objects seems pertinent and contrasting. Such contrast creates interest.
So that explains why it is necessary.
Cumbersome. No, it contains the data, reasons and interesting contrast. Any shortening would go beyond succinct into loss of either data, reasons, or contrast. -HarryAlffa (talk) 21:06, 31 July 2008 (UTC)

(outdent) Like the various collections of objects, the heliopause is an important part of the Solar System, so it's worth mentioning in the lead, but we shouldn't explain it beyond a mention. All these terms are both wikilinked and discussed in detail in the body of the article. —Alex (ASHill | talk | contribs) 15:06, 1 August 2008 (UTC)

It sounds like you are suggesting that the Heliopause is a collection of objects, but that could just be the way you've phrased it. It is surely a point of interest that it is NOT named for any population of celestial objects, therefore worth explaining for that reason alone, and for any assumptions the reader might make given the inner regions are named for their populations of objects. -HarryAlffa (talk) 15:45, 3 August 2008 (UTC)
No, I was contrasting the heliopause to the various collections of objects. Perhaps it is a point of interest, but this is the lead! It's not a place to include every point of interest. We can't spend our space in the lead trying to anticipate every possible assumption some reader might make.
The heliopause section of the body of the article (Solar System#Heliopause) perhaps could take a little bit of expansion; I think it's a bit short on context. —Alex (ASHill | talk | contribs) 17:13, 3 August 2008 (UTC)
"The readers assumption", thing I could have put better. The article leads the reader to believe that the Heliopause is another collection of objects. Surely you can see this is obvious; a long list of regions stated to contain objects, then the last two items (Heliopause and Oort cloud) listed without explanation; how is the novice meant to know what these last two items are? He must assume, due to the lack of contradiction, that they are both collections like the previous items in the list - and he'd be half right.
You quoted (for a different section of this talk page) that the lead should include, "why the subject is interesting or notable", from wiki recommendations for the lead.
You said you were contrasting the Heliopause; exactly my point! Contrast creates interest; "it's the only ..." is always memorable!
You said:
  • "not a place to include every point of interest"
  • "I was contrasting the heliopause to"
  • "perhaps it's a point of interest" {because of the contrast?}
  • and intimated that the lead should include points of interest
There are only two points of interest I want to include:
  • "The dwarf planets are the only ... "
  • "The Heliopause is the only ... "
Can't you see that the very points you make arguing against including these points logically support putting them in? -HarryAlffa (talk) 18:27, 3 August 2008 (UTC)

Heliosphere

On further thought, I think using the word "heliopause" in the introduction at all may be causing us to talk past one another. It's not so much the heliopause that's interesting; it's the heliosphere/interplanetary medium. Perhaps this wording of the second paragraph is better:

In broad terms, the charted regions of the Solar System consist of the Sun; four terrestrial inner planets; an asteroid belt composed of small rocky bodies; four gas giant outer planets; a second belt, the Kuiper belt, composed of icy bodies; the scattered disc; and ultimately the hypothetical Oort cloud. The stream of charged particles from the Sun, called the solar wind, creates the heliosphere which permeates the Solar System.

Thoughts? —Alex (ASHill | talk | contribs) 19:49, 3 August 2008 (UTC)

Works for me. Serendipodous 19:58, 3 August 2008 (UTC)
It misleads the novice into thinking that the Heliosphere stretches all the way out to the Oort cloud, see Unresolved Problems With The Lead below. -HarryAlffa (talk) 21:12, 3 August 2008 (UTC)

Unresolved Problems With The Lead

A lead is supposed "... to stand alone as a concise overview of the article. It should establish context, explain why the subject is interesting or notable, and summarize the most important points."; from Wikipedia:LEAD

The lead has problems with to deep a level of detail for a lead and with consistency of level of detail.

  1. The second paragraph is self inconsistent when it says "In broad terms ...", and then gives to much detail of the composition of some of the regions
  2. The second paragraph misses out the dwarf planet(s) which are part of the composition of the Asteroid Belt, Kuiper Belt and Scattered Disk
  3. The second paragraph is inconsistent as it lists the composition of all the regions it names apart from the Oort cloud.
  4. The second paragraph misleads the novice into thinking that the Heliosphere stretches all the way out to the Oort cloud
  5. The bullet list misleads the novice to think that ALL dwarf planets orbit beyond Neptune
  6. The qualifying text for each dwarf planet in the bullet list is too detailed for a lead
  7. The qualifying text for Pluto and Makemake is to complicated for a lead and would seem contradictory and confusing to a novice.

(any contradictions of one point with another emphasises the inconsistency of the lead) -HarryAlffa (talk) 20:55, 3 August 2008 (UTC)

Thank you for providing a concise summary of your concerns; it makes it much easier to make improvements to the article! I think you do have legitimate concerns, although I don't view inconsistency in the level of detail given to different things mentioned in the lead is necessarily a problem.
Re 1: I have reworded the paragraph a bit; I agree that "in broad terms" doesn't have much meaning.
Re 2: I reworded the first paragraph to (hopefully) make it clear that dwarf planets aren't anything special. The terminology is a bit awkward, as Small Solar System Body is (stupidly, I think) defined as any body that's not a dwarf planet; hopefully "small bodies" won't be equated with "Small Solar System Body".
Re 3: I added "of comets".
Re 4: I disagree that it's misleading, and I don't think it's a big deal anyway. There aren't rigid boundaries between these things (except between the solar wind and the interstellar medium). This doesn't say anything untrue (that I see), and the interested novice can read the article for the details! (The fact that the Oort Cloud is probably mostly outside the heliosphere is very much a detail.)
Re 5–7: As I've said above, I don't think the dwarf planets should be named at all in the lead; they're not particularly important. —Alex (ASHill | talk | contribs) 21:43, 3 August 2008 (UTC)

For the most part I think that the introduction to the article (lead) reads fairly well right now. I think that dwarf planets should still be mentioned; everyone has heard of Pluto. However,

  • "The largest of the small bodies are classified as four dwarf planets" - does not read well. The "four" should be moved or removed. The reference to their moons should also be removed - the fact that some dwarf planets have moons is explained more clearly later on anyway.
  • "the hypothetical Oort cloud of comets" - does not read well. I would argue that it is not only comets that make up the Oort cloud, but even ignoring that, this sentence should be re-written. As far as consistency goes, the scattered disc does not describe what it is composed of, and it's debatable that any of the planetary groups do either.
  • "the solar wind, creates the heliosphere which permeates the Solar System" - the word "creates" is definitely wrong here. Perhaps "defines" the heliosphere.
  • I definitely agree that the qualifying text for the dwarf planets is too complicated - the list would read just as well without any qualifying text. It is purely incidental anyway.

Feyrauth (talk) 07:16, 4 August 2008 (UTC)


Remember; a lead is supposed "... to stand alone as a concise overview of the article. It should establish context, explain why the subject is interesting or notable, and summarize the most important points."; from Wikipedia:LEAD

The lead has problems with to deep a level of detail for a lead and with consistency of level of detail.

  1. NOT SOLVED. (I thought the phrase "in broad terms" was exactly right for the lead). The second paragraph is inconsistent with Wikipedia:LEAD aims; it gives to much detail of the composition of some of the regions.
  2. NOT SOLVED. (Of course there will be confusion for the novice between "small bodies" and "Small Solar System Body"!). The second paragraph misses out the dwarf planet(s) which are part of the composition of the Asteroid Belt, Kuiper Belt and Scattered Disk.
  3. NOT SOLVED. The second paragraph is inconsistent as it lists the composition, or numbers their population, of all the regions it names apart from the Oort cloud.
  4. SOLVED. (I added "out to around the scattered disk". The heliosphere has a definite border, rigidly defined by fluid dynamics, not rigidly fixed in space). The second paragraph misleads the novice into thinking that the Heliosphere stretches all the way out to the Oort cloud
  5. The bullet list still misleads the novice to think that ALL dwarf planets orbit beyond Neptune
  6. SOLVED. (Text removed). The qualifying text for each dwarf planet in the bullet list is too detailed for a lead
  7. SOLVED. (Text removed). The qualifying text for Pluto and Makemake is to complicated for a lead and would seem contradictory and confusing to a novice.
  8. NEW. The second paragraph is tautological with itself and with the first paragraph

(any contradictions of one point with another emphasises the inconsistency of the lead)

I had resolved all of these problems by my previous (see my talk page) bold edit, which is what wikipedia encourages, but my changes were reverted. -HarryAlffa (talk) 13:13, 4 August 2008 (UTC)

...and so the next step is to discuss them. It's not a problem. SHEFFIELDSTEELTALK 17:34, 4 August 2008 (UTC)

I've reworded a bit. The first paragraph is mostly about the objects themselves, while the second paragraph is about the regions/groups of objects. There certainly is overlap, but I don't think it's tautological and I do think the two paragraphs are helpful. Hopefully this wording makes the paragraphs feel less redundant.
Note that I put this sentence at the end of the first paragraph: "The small bodies which are massive enough to be rounded by their own gravity are called dwarf planets." That material might better belong in the introduction to the list of dwarf planets (if that stays). —Alex (ASHill | talk | contribs) 19:28, 4 August 2008 (UTC)
Fraid I changed it. The wording made it seem like dwarf planets were small bodies when they aren't. This situation is complicated. Any attempt to make it clearer in the lead will probably just end up being wrong. Serendipodous 19:31, 4 August 2008 (UTC)
I would argue that the dwarf planets are "small bodies", just not Small Solar System Bodies. The terminology is really stupid, but because it's the lead, I don't think it's a big deal to not worry about the "small Solar System body" term. Again, dwarf planets aren't a distinct class of objects at all, which I think is the basis of Harry's concern. We could say "The small bodies which are massive enough to be rounded by their own gravity are called dwarf planets, while smaller bodies are called small Solar System bodies.", but that may be getting verbose (which is why I didn't put it that way). Another option might be to say "The smallER bodies which are massive enough...." —Alex (ASHill | talk | contribs) 19:41, 4 August 2008 (UTC)
If it's difficult to be precise enough without getting too wordy, that might be a sign that the sentence should be moved into the main body of the article. In other words, the lead can mention dwarf planets, without attempting to define them. SHEFFIELDSTEELTALK 23:00, 4 August 2008 (UTC)

1. & 3. are essentially the same problem. 2. the second paragraph relates to regions of the solar system. Dwarf Planets is not a region; the asteroid belt, the kuiper belt and the scattered disc are. This also affects your new point #8. 5. perhaps there should be qualifiers, but simpler than before. Eg. Ceres (located in the asteroid belt)

Feyrauth (talk) 07:25, 5 August 2008 (UTC)

You are mis-understanding the text, and possibly not reading all of it! 1. & 3. are different aspects of the same problem. Which is why a catch-all (any contradictions of one point with another emphasises the inconsistency of the lead) ended the list to try to prevent people from making that kind of point. 2. Again - read & analyse! It in no way says or implies that dwarf planets are a region! 5. Yes. You could add that qualifier to the dwarf planet list.

The changes made so far solve little of the problems, and they cumulatively make the lead an ever more better fit for the description May Contain Nuts.

Again, my version of the lead solves all the problems I've raised, it is consise (due to using nested, bulleted lists) and adds some interesting factoids at the end for the novice or casual reader.

It seems to me that no one else is empathising with the novice astronomer. Who else is likely to be seeking knowledge from the lead of this article? -HarryAlffa (talk) 15:48, 5 August 2008 (UTC)

As someone who teaches astronomy to non-science majors, I think the lead paragraph as it stands now is great. It gives the information they would be looking for in a clear and concise way without misleading them. I definitely do not feel that the editors here are doing an injustice to the novice astronomer.PhySusie (talk) 16:43, 5 August 2008 (UTC)
No one critisised the lead paragraph. It's the second paragraph onwards (of the lead) which contain problems.
The text of the image is very unclear, unless you have a good monitor. The image itself is an unusual construction, even with the image the two bullet lists make it seem as if ALL the dwarf planets orbit beyond Neptune, (how many times have I said that?!). -HarryAlffa (talk) 10:13, 6 August 2008 (UTC)

  1. SOLVED. (details removed). The second paragraph is inconsistent with Wikipedia:LEAD aims; it gives to much detail of the composition of some of the regions.
  2. SOLVED. (details removed). The second paragraph misses out the dwarf planet(s) which are part of the composition of the Asteroid Belt, Kuiper Belt and Scattered Disk.
  3. SOLVED. (details removed). The second paragraph is inconsistent as it lists the composition, or numbers their population, of all the regions it names apart from the Oort cloud.
  4. SOLVED. (I added "out to around the scattered disk". The heliosphere has a definite border, rigidly defined by fluid dynamics, not rigidly fixed in space). The second paragraph misleads the novice into thinking that the Heliosphere stretches all the way out to the Oort cloud
  5. NOT SOLVED. Even with the image the two bullet lists still misleads the novice to think that ALL dwarf planets orbit beyond Neptune
  6. SOLVED. (Text removed). The qualifying text for each dwarf planet in the bullet list is too detailed for a lead
  7. SOLVED. (Text removed). The qualifying text for Pluto and Makemake is to complicated for a lead and would seem contradictory and confusing to a novice.
  8. NOT SOLVED? tautological? The second paragraph's first sentence seems a bit redundant with the first paragraph and with the rest of the second.

(any contradictions of one point with another emphasises the inconsistency of the lead) -HarryAlffa (talk) 10:32, 6 August 2008 (UTC)

SOLVED 5. Replaced dwarf planet bullet list with; "Four smaller objects are classified as dwarf planets. Ceres in the Asteroid Belt, the other three (as of mid-2008, though the list is expected to grow) are all beyond Neptune - Pluto; Makemake; Eris." -HarryAlffa (talk) 12:33, 8 August 2008 (UTC)

Terminology

  • I think this section should read more like a dictionary, it's purpose is surely to act as a reference for the rest of the article?
  • It's not a novel, readers don't want to have to read through everything to get to stuff that's new to them.
  • It needs sub-sectioning, even if it makes the TOC a bit longer:
  • Terminology
  • Object Classification
  • Planets
  • Dwarf Planets
  • Ice
  • Distance Measurements

Is it worth explaining more about a year and a day being individual to the planet you're on, and contrast that with Earth-years?

What about the same for a day? Mars rover guys use Sol as the name of a Mars-day. Will other terms evolve with other planets? -HarryAlffa (talk) 12:28, 9 August 2008 (UTC)

Wikipedia is not a dictionary, and I think prose is preferable. Explaining years and days on individual planets is appropriate for their respective articles, not the Solar System article: the length of the day on the planets depends on their individual rotation rates, which is not really a function of the Solar System itself. —Alex (ASHill | talk | contribs) 13:28, 9 August 2008 (UTC)

Do you agree that the terminology section acts as a reference section for the rest of the article?

I think it does.

I did NOT say that Wikipedia was a dictionary, this is a fundamentally dishonest tactic, implying in your reply that I asserted something by nay-saying something I did not actually say, or imply.

I was suggesting that the Terminology section should be closer to a dictionary than a normal, complete article. A good idea in terms of conciseness. Straight to the point. Full prose can be saved for the main articles of which the Terminology section is a useful précis.

I did not suggest that we explain the lengths of the days and years for each planet.

I was suggesting exactly what you said "the length of the day on the planets depends on their individual rotation rates". I might edit what you said to "ALL the planets". If something about ALL the planets doesn't fit in the Solar System, where else do ALL the planets fit? -HarryAlffa (talk) 20:35, 10 August 2008 (UTC)

Wording of lead. The saga continues...

Two further disputes regarding the lead:

  1. Should the solar wind sentence begin "An incessant hail of charged particles from the Sun (the solar wind)..." or "A steady flow of charged particles from the Sun (the solar wind)..."? I strongly prefer the latter. For one thing, I'm not sure an inanimate object can be incessant. The solar wind is not constant in intensity/velocity/whatever, but it is steady in that it flows essentially continuously. Also, "flow" is the appropriate word to describe the motion, as it is a fluid, whereas "hail" evokes misleading images of a hailstorm (at least for me).
  2. There is a dispute between two versions of the dwarf planet paragraph:
As of mid-2008 four smaller objects are classified as dwarf planets. One (Ceres) is in the asteroid belt, while the other three (Pluto, Makemake and Eris) are all beyond Neptune.
and
As of mid-2008 four smaller objects are classified as dwarf planets, Ceres is in the Asteroid Belt, while the others are all beyond Neptune, and are: Pluto; Makemake; Eris.

I believe the first option reads better. I have refrained from reverting pending the thoughts of others. —Alex (ASHill | talk | contribs) 13:35, 9 August 2008 (UTC)

Well I wrote the first version, so I think it reads better. And I reverted it back. Call me territorial. Serendipodous 13:47, 9 August 2008 (UTC)

Ashill, it sounds like, from your use of the word Saga, that you are levelling some criticism at me for raising any questions?

1. The solar wind fluctuates, therefore "steady flow" is simply incorrect. Ashil, get a dictionary, if your not sure about the application of a word, don't try to use the fact of your ignorance as an argument. Incessant can be applied this way. You have said both that "the solar wind is NOT constant in intensity/velocity", AND that it is "steady! Do you actually read what you write? Arterial blood flows "essentially continuously", but it is NOT steady (it is pulsatile). The solar wind is continuous, incessant you might say, but it cannot be described as steady.

As I said on my edit note, I was trying to capture the dynamism (look it up) and the high speed of the solar wind, "steady flow" might describe pus seeping from a wound, but it is far to tame to describe a 400 km/s - 750 km/s storm of protons and electrons at temperatures of thousands of Kelvin. Incessant hail is much more dynamic.

2. Sod, you're territorial. Your "first" sentence is actually a rewrite of my "original" sentence - solving the problem of the bullet list misleading novices - which I pointed out and was met with resistance from you, but no logic.

Sod, on the dwarf planet sentence you've gone from insisting on a bullet list, to embedding the names in parenthesis in the middle of a sentence, plus you've introduced a higher level of maintainance by enumerating the dwarfs in two places.

My original solution to a problem only I spotted is easier to maintain as it enumerates the dwarfs once, and I think wiki convention allows my version precedence when it comes to matters of taste. My version is easier for the novice to absorb, it is closer to a bullet list than your re-write of my solution. Even going down to "in order from the Sun", yours mixes them all up, mine doesn't. -HarryAlffa (talk) 18:04, 10 August 2008 (UTC)

  • I apologize for giving the impression that I object to any editor raising questions; that was certainly not my intent. I must admit to being a bit frustrated by elements of this protracted discussion, but I could have chosen a better word than "saga".
  • I'll let other editors worry about who's territorial here, but my feelings about the clarity of the two options for the dwarf planet section should be as clear as yours.
  • Re dynamism: The solar wind does have high velocities and temperatures (by terrestrial standards), but it is so low density that "incessant hail" seems to me like an inappropriate description. How about just "flow"? In thinking about it, I'm not sure any adjective is necessary.
  • Editors' opinions evolve as we edit and discuss—that's the whole idea!
  • It is completely irrelevant who wrote what sentence or who first noticed which problem. New dwarf planets will undoubtedly be identified, but not exactly every few days; I think the burden of changing the number of dwarf planets in three places in one paragraph is not a convincing argument. We're here to write the clearest prose, not make our editing job easiest if and when a new dwarf planet is identified.
  • I see no evidence on the talk page that there is a consensus in favor of the "incessant hail" wording or the second dwarf planet wording (above), so I am reverting. If further opinions indicate a new consensus, then revert me (or I'll self-revert) and we'll go from there.
  • There is no policy that gives any editor's version of an article precedence over any others except consensus and verifiability. The only exception is trivial matters like choice of U. K./U. S. English (WP:ENGVAR). —Alex (ASHill | talk | contribs) 18:50, 10 August 2008 (UTC)


  • Your frustration showed in your use of the word Saga. You must have been frustrated by pointless objections, or ones without reason.
  • Sod invited himself to be called territorial.
  • You might say that "incessant hail" is colourful prose, but it can it really be inappropriate when the solar wind can be fatal to astronauts doing space-walks, or on the moon's surface? If flow it be, then it never stops and it is not steady.
  • I don't mind editors opinions coming closer to what I've been trying to tell them, but rewriting something just because of who the author is is irksome, particularly when they make such a mess of it.
  • I agree on clear prose, my version is clearer, no on likes tripping over multiple parenthesise.
  • Again my dwarf planet sentence is clearer.
  • Ashill you again show lack of cognitive ability, this article Wikipedia:The Truth is about idiots who believe "facts" without evidence, a bit like my May Contain Nuts is about idiots who don't get visual layout, among other things.

-HarryAlffa (talk) 19:40, 10 August 2008 (UTC)


Terminology section

The description of the definitions of the terms planet, dwarf planet, and small Solar System body was deleted from Solar System#Terminology. I restored it because that terminology is used extensively in the rest of the article and really ought to be explained in some detail on the Solar System page itself, rather than consigned exclusively to sub-pages. —Alex (ASHill | talk | contribs) 19:38, 10 August 2008 (UTC)

The description of the definitions of the term ice was deleted from Solar System#Terminology. I restored it because that terminology is used extensively in the rest of the article and really ought to be explained in some detail on the Solar System page itself, rather than consigned exclusively to sub-pages. -HarryAlffa (talk) 19:40, 10 August 2008 (UTC)

Well, I deleted the definition of the term "ice" per a user's suggestion; in response to that discussion, I added a definition. Should be defined in both places?
I think the terminology section is focused on the somewhat arcane uses of the "planet"-related terms, not every Solar System-related term, and I think that focus works well.
I'll refrain from reverting; I've done enough reverting on this page today. —Alex (ASHill | talk | contribs) 19:51, 10 August 2008 (UTC)

Can you see that the reasons you have given for restoring the description of the definitions of the terms planet, dwarf planet, and small Solar System body, must also result in restoring the "ice" section. Even Sod edited this section to improve it.

There are numerous references to "ice" & "icy" throughout the article (I searched), such a common word (intrinsically bound to water on Earth) MUST be explicitly explained for it's astronomical use. There is just no escaping this logic no matter what your emotional response is.

If the Terminology section is to focus exclusively on planet-related terms, then it must be renamed. But this is why I suggested earlier (where I answered your points there) that some sub-sectioning is required. And are you saying that ice is not a planet related term, but light-year is? That is the implication of what you are saying. -HarryAlffa (talk) 20:19, 10 August 2008 (UTC)

If that's the case, why did you remove my references to gas and rock? Both of those terms are also in the article, and both are equally misleading. Focusing on ice in a section that is meant to apply to the entire Solar System is confusing to the novice, as you say. Interesting nickname you have for me. Serendipodous 06:33, 11 August 2008 (UTC)
If I remember rightly, you obliterated my ice contribution with a poorly put together cut & paste job, I restored my paragraph and re-edited to included gas (rock is not misleading). -HarryAlffa (talk) 19:15, 16 August 2008 (UTC)

Having not been contradicted, in the wikialerts, in my count of active editors of the Ice paragraph - I'm restoring it. I make it two active talkers to one in favour of having some sort of version on Ice. -HarryAlffa (talk) 12:35, 22 August 2008 (UTC)

Have started a new Rock, ice and gas section below. -HarryAlffa (talk) 17:53, 24 August 2008 (UTC)

Planets, dwarf planets, and SSSBs

I think this combined heading, rather than separate headings, is fine. To help the readers eye maybe some bold 'pick-outs' of the three terms, and start each of their respective paragraphs with those terms?

  • Planet is any body in orbit around the Sun that has enough mass to form itself into a spherical shape and ...
  • Dwarf planet is a celestial body orbiting the Sun that is massive enough to be rounded by its own gravity but which has not ...
  • SSSBs are small Solar System bodies and are the remaining objects in orbit around the Sun

-HarryAlffa (talk) 18:46, 24 August 2008 (UTC)

Lead/Heliosphere

The lead reads pretty well right now, and most of HarryAlffa's initial points seem to have been addressed. Two brief comments:

  • "eight planets and their 166 known moons, four dwarf planets" - eight known planets, and four known dwarf planets. But using the word known three times would make the sentence awkward. Can somebody suggest an improvement?
  • the article has been reverted to "creates the heliosphere" - I would suggest rewriting the whole sentence, perhaps "A flow of charged particles from the Sun (the solar wind) permeates the Solar System. Roughly at the outer edge of the scattered disc this flow is interrupted by the interstellar medium. This region is known as the heliopause, and is widely acknowledged as the boundary of the Solar System." —Preceding unsigned comment added by Feyrauth (talkcontribs) 06:59, 12 August 2008 (UTC)
It's not quite right to describe the heliopause as the boundary of the solar system. It is the boundary of the solar wind, but the Sun's gravity holds out for several thousand times that distance. Serendipodous 07:24, 12 August 2008 (UTC)
That's a good sentence, but the article itself says there's a couple of different ways of looking at the boundary, speaking simplistically; the Oort cloud is thought to be the last region of orbiting objects; and the Sun's gravitational influence stretches out to 2ly.
The heliosphere is "a bubble in the interstellar medium", it's hard to argue against "the solar wind creates the bubble in the interstellar medium", but it's still good.
I would still like something a bit more exciting than "flow of charged particles". That seems to sedate for a 400 - 700 km/s hail of protons and electrons which could kill a man!
I would suggest the rewrite: "A low mass, but unceasing blast of charged particles from the Sun (the solar wind) permeates the Solar System. Roughly at the outer edge of the scattered disc this flow is halted by the interstellar medium. This boundary region is known as the heliopause." -HarryAlffa (talk) 22:15, 13 August 2008 (UTC)
I don't think "unceasing" or "blast" are really encyclopedic, or even accurate in this context. A supernova or the stellar wind from a massive star or an asymptotic giant branch star is a blast, while the solar wind is small potatoes, astrophysically. The solar wind does not have an impact on any significant volume of the interstellar medium or the Galaxy, very much unlike other astrophysical winds. Can the 400—700 km/s wind kill a man? If so, I don't think it would be because of the speed of the particles, although I haven't thought about it.
I do like saying that the heliosphere is a "bubble in the ISM"; that helps with context. (I'm biased, though, being an ISM scientist.) ;) I prefer something similar to the current wording like
A flow of charged particles from the Sun (the solar wind) creates the heliosphere, a bubble in the interstellar medium which permeates the Solar System. The heliosphere terminates in the heliopause, roughly at the outer edge of the scattered disc.
I think the "bubble in the ISM" part isn't controversial, so I'll make that change. It really is the wind that creates the heliosphere, so I think that word is good, although "defines" might work equally well. —Alex (ASHill | talk | contribs) 22:51, 13 August 2008 (UTC)
My initial choice was hail instead of blast, in an earlier edit. For someone who claims to be an ISM scientist, you say "unceasing" is an inaccurate way to describe the solar wind? Are you drunk? The solar wind does occasionally cease? - No. It doesn't. From what you have written then, if you really are a scientist, it has to be concluded that you are not a very good one. I won't even comment on a single word not being a compendium of knowledge. No! Really? Oh! Pardon me, you meant that "unceasing" and "blast" were unsuitable for use in an encyclopaedia? You want to remove these two words from all of wikipedia? No? You didn't mean that either? Are you drunk?
A blast from a car-bomb is small potatoes compared to the blast from an atom bomb. It doesn't mean you can only apply it to the latter. A blast from a fire-fighter hose is small potatoes compared to the blast from a ship's steam hose. It doesn't mean you can only apply it to the latter.
The volume of the interstellar medium virtually equates to the volume of the galaxy itself. Are you drunk? Of course it's not going to impact much of that volume, nothing will! Yes, the solar wind could kill an astronaut without specific shielding, for example, on the surface of the moon. You don't think it would be the speed of the particles that would do it? Are you drunk? It's a hail of free protons, and electrons! The faster they're travelling the more deeply they'll penetrate matter. So yeah, sure, the speed doesn't matter, yeah, yeah. Sure.
C'mon, you're a computer technician at an observatory aren't you! Confess all! -HarryAlffa (talk) 20:55, 14 August 2008 (UTC)
Harry, Ashill has been more than patient with you, regardless of your behaviour so far. Now you have crossed the line into personal attacks, and I have made a complaint at Wikipedia:Wikiquette alerts. Serendipodous 21:40, 14 August 2008 (UTC)

My objection to the word "bubble" is overruled; it seems that it is official terminology. I will put in a link to stellar wind bubble. But it's the solar wind, not the bubble, that permeates the solar system. How about: "A flow of charged particles from the Sun (the solar wind) permeates the Solar System. This creates a bubble in the interstellar medium known as the heliosphere, which terminates at the heliopause, near the scattered disc." Feyrauth (talk) 06:01, 15 August 2008 (UTC)

Looks good to me. Serendipodous 06:32, 15 August 2008 (UTC)
I like that wording. Done. (I didn't wikilink heliopause because it redirects to a sub-heading on the heliosphere page.) —Alex (ASHill | talk | contribs) 12:36, 15 August 2008 (UTC)
"A flow of plasma from the Sun" is better in my opinion. Solar wind carries magnetic field, and neutrals can be present as well. Or possibly "magnetized plasma". Ruslik (talk) 17:04, 17 August 2008 (UTC)
Plasma is good, particles suggest dust rather than free protons & electrons.
Terminates at the heliopause is bad! Could read like the heliopause is separate something which just happens to mark the end. Room for confusion with "termination shock". I think it has to read like the heliopause is an integral part of the heliosphere.
Near the scattered disk? The outer area of the scattered disk crosses through the heliopause.
I would suggest, "A flow of plasma from the Sun (the solar wind) permeates the Solar System. This creates a bubble in the interstellar medium known as the heliosphere, which ends in the heliopause, around the outer edge of the scattered disc." -HarryAlffa (talk) 13:29, 22 August 2008 (UTC)

I think there has to be a certain subtlety to describing the interaction between the stellar wind and the interstellar medium, while "using" the heliosphere and heliopause. I think what should be kept in mind is;

  • the heliopause is NOT separate from the heliosphere
  • the heliopause is still part of the heliosphere
  • the heliopause does NOT have a location like a planet does

This is why I changed "...the heliosphere, which is separated from the interstellar medium by the heliopause located around the outer edge of the scattered disc"

Separated

Of course there is a separation between the heliosphere and the interstellar medium, or else they wouldn't have separate names! But we have to be careful to leave no room for doubt that the heliopause is not actually separate from the heliosphere. It is an integral part of it. The 'helio' part of the names will indicate they are related, but care has to be taken so it reads like they are parts of the same thing, if possible - I haven't come up with a way of making this explicit AND short enough for the opening paragraphs. But I hope I've done enough to rule out the reader mis-reading the intended meaning.

Located

The "bubble" is dynamic. It depends on the interaction of the solar wind on the interstellar medium. The heliopause does not have a "location" like a planet. The heliopause's current location MUST be continually changing (even if not by much) with the fluctuation of the solar wind.

The location therefore must be described in "vague" terms, or at least non-precise terms, unless we want to try to include the information I've put in the parqagraph above. -HarryAlffa (talk) 17:03, 24 August 2008 (UTC)

I agree that we should not be precise about the location of the heliopause; I think "the outer edge of the scattered disc" is far too precise and implies that the scattered disc and heliopause are related, which they're not. I reworded the lead paragraph to say "This creates a bubble in the interstellar medium known as the heliosphere, which extends out to around the scattered disc." I also added a better discussion of the relevant distances and the asymmetry of the heliosphere to the heliosphere section. —Alex (ASHill | talk | contribs) 21:59, 24 August 2008 (UTC)
I think simply not mentioning the heliopause is a good idea, and one I think you suggested before. It is now a simple statement about the heliosphere and subtler information is left to the body of the article. Now that the heliopause is not mentioned, and the scattered disk is quite wide, you could amend the sentence to "... around the outer edge of the scattered disk", but it is a minor point. -HarryAlffa (talk) 20:48, 25 August 2008 (UTC)

Rock, ice, gas

"used regardless of the state the substance" is a little inaccurate I think. It's really the three 'classical' states of solid, liquid or gas we are talking about here. Can you think of a pithy way of putting this? -HarryAlffa (talk) 17:58, 24 August 2008 (UTC)

"Planetary scientist & astronomers use ...", I wonder if we are tripping over ourselves needlessly trying to say who uses the terms (both obviously). Is the context of the solar system enough, without listing professions? "Planetary scientists, astronomers etc use ...", would be accurate, but ... -HarryAlffa (talk) 18:03, 24 August 2008 (UTC)

Gas Giants & Ice Giants. I think we should avoid trying to explain what these are here, the Mid Solar System section of the article does that. -HarryAlffa (talk) 18:14, 24 August 2008 (UTC)

Of ices, "... although they are still usually extremely cold", 'usually' is not perhaps very accurate. Maybe in the mid solar system on the surface of rocky bodies, but what about deep inside Uranus or Neptune? Ok, that's only two places, so maybe 'usually' is Ok? -HarryAlffa (talk) 18:33, 24 August 2008 (UTC)

Ckatz apparently just beat me to undoing HarryAlffa's latest edit (I had made the exact same reversion as him). For the record, I concur with Ckatz, in case there's any doubt about the consensus. I don't like the wording "intrinsically bound" and the unreferenced mention of "industrial processes on Earth". Most substantively, the claim that the terms are "as shorthand for substances depending on their boiling points" is false; boiling points are not the only (or even primary) factor distinguishing amongst the terms.
HarryAllffa's ice addition is not encyclopedic and reads like a mini-essay. Despite his claims on the edit list, I never agreed to have that bit reinstated. I want to keep this already overlong article focused on the Solar System, not on chemical industrial processes. Serendipodous 10:10, 26 August 2008 (UTC)
Serendipodus's implication that I claimed he agreed to anything is false. To further imply that my contribution focused on industrial processes is also false. I have no need to attach any adjectives to him, appropriate ones will spring to the mind of any intelligent reader. From these adjectives you can then judge his comment that my contribution was "not encyclopedic and reads like a mini-essay". -HarryAlffa (talk) 12:13, 26 August 2008 (UTC)
There you go, with the insulting again. You won't win by doing that, you do realise that right? Serendipodous 14:31, 28 August 2008 (UTC)
In fact, nearly the entire Terminology section is unreferenced; I'll work on improving the situation, but I'd appreciate help. —Alex (ASHill | talk | contribs) 21:55, 25 August 2008 (UTC)
Alright; I've largely rewritten the terminology section (with an actual source!). I deleted the mention of gas and ice giants; I agree that that's best left in the Mid Solar System section.
I remain unconvinced that the "Gas, rock, and ice" terms need to be defined in the Terminology section at all; if someone wants to delete the whole paragraph, I wouldn't mind. —Alex (ASHill | talk | contribs) 23:14, 25 August 2008 (UTC)
I completely disagree with deleting this.
You have to ask yourself what the name "Terminolgy" actually means, and from that what a reasonable reader would expect of a section thus named.
If you want the Terminology section to exclude all terminology except that related to the definition of a planet, then fine. But you would have to also get rid of the Distance paragraph, and rename the Terminology section.
If you want to keep the name Terminology then it must include those terms a reasonable reader would expect, and find useful, there. -HarryAlffa (talk) 11:28, 26 August 2008 (UTC)
Consensus

Ckatz did not have any evidence of concensus when he made this edit

  • 19:21, 24 August 2008 Ckatz (Talk | contribs) m (96,394 bytes) (Reverted to revision 233951406 by HarryAlffa; rv. to better version; S. has worked to accomodate you, please do the same.)

The version he obliterated was a merging of what I had done on Ice plus what Serendipodus had done on Rock and Gas.

At that time the talk page had only my four questioning points about the resulting merge. So any talk about consensus is blatantly false. It was one on one, and the other one wanted to delete the entry entirely.

Ckatz and Ashill's rv was emotionally motivated, not logically.

Unreferenced Industrial Processes

I revised what Sorendipodus said;

  • Planetary scientists use the terms rock, ice, and gas as shorthand for substances depending on their boiling points. These terms are used regardless of the state the substance happens to currently be in.

It is now obvious that "depending on boiling points" is very far from false! Quite the contrary!

I said;

  • Ice on Earth is a word intrinsically bound with the substance water; the only common exception is the term dry ice, which describes frozen carbon dioxide. Excepting hydrogen and helium, the terms ice, ices or volatiles also refer to other materials with low boiling points[1] which could only be liquefied or frozen by industrial processes on Earth. These ices, such as ammonia or methane, water or carbon dioxide need not, due to other conditions, actually be liquefied or frozen for the term to apply to them, although they are still usually extremely cold.

Common sense and general knowledge is enough to understand industrial processes are required to make dry ice, or liquefy methane!

I can only shake my head in pity at Ashill 'not liking the wording' of "intrinsically bound". That was a sentence with beauty and truth. Only a philistine would fail to appreciate it. -HarryAlffa (talk) 13:32, 28 August 2008 (UTC)

From a purely semantic standpoint, your addition, aside from being unsourced, was vague and unnecessarily absolutist. "Intrinsically bound" in what sense? Linguistically? Psychologically? Physically? Also, there is nothing "intrinsic" about linking the word "ice" only to water. Just because the wider usage of ice is not common, doesn't mean that it is only used by planetary scientists. To prove that the term ice is "intrinsically bound" to frozen water by the general public would require showing that absolutely no one outside the scientific community employs the term in its broader sense, which is impossible. "Beauty" and "truth" are irrelevant; we are writing an encyclopedia here, not poetry. Accuracy is required over metaphor. The "industrial processes" comment is also irrelevant. Suffice to say that these substances only freeze at very cold temperatures. Serendipodous 14:31, 28 August 2008 (UTC)

If you cannot see the answers to your questions are actually contained in the "ice" sentence, then there is no point in engaging with you on this.
Ok, "beauty" IS irrelevant, but it nice if it's there, it's better than ugly. No? At least you recognised that it was poetic, good, you are right, it was poetic and correct.
But "truth" is irrelevant in an encyclopedia? :)
If you cannot recognise that, "only frozen by industrial processes on Earth" says exactly the same as "only freeze at very cold temperatures", then there is little hope for you. -HarryAlffa (talk) 12:17, 30 August 2008 (UTC)
The recent edit to the Terminology section added a mention of refractory elements. I cleaned it up, but why mention that term at all? It's not used again in the article. A glossary of planetary science terms is not appropriate for the Solar System article.
A mention of refractory was a point of interest, not a glossary. -HarryAlffa (talk) 12:17, 30 August 2008 (UTC)
As for deleting the entire paragraph on rock, ice, and gas, if it is appropriate to change the section name from "Terminology" to "Definition of planet" or something similar, I'm all for it. The paragraph on regions could be more logically moved to the "Layout and Structure" section, and the AU explanation could do fine in a footnote. —Alex (ASHill | talk | contribs) 16:16, 28 August 2008 (UTC)
Agreed. Moved the ref to volatiles. There's no point in mentioning it here, since it isn't mentioned again in the article, and the point of the Terminology section is to define those terms within the article which might confuse the reader. I'm a but wary of splitting up more of the terminology section, since moving the zones section would mean moving the image, and I'm not sure it would fit in the new layout section.Serendipodous 16:30, 28 August 2008 (UTC)
OK, done. Actually, I think it works. Serendipodous 18:57, 28 August 2008 (UTC)
Yes. A logical move. However I think it would fit even better logically as the second paragraph: first about the Sun, second about the Regions, then get a bit more complicated about Keplars Law etc. I'll rejig it as bit and see what you think.
Also, the rock, ice and gas paragraph doesn't fit logically in the Layout and Structure, and is now simply hidden there. "the point of the Terminology section is to define those terms within the article which might confuse the reader". This is still required for ice, gas, AU and light-year. This could be done by moving the Notes section from the end, where it is completely useless, to the very begining, and calling it Terminology.-HarryAlffa (talk) 12:17, 30 August 2008 (UTC)

Known mass

A recent edit removed the word "known" from the statement that "the Sun ... contains 99.86 percent of the system's known mass". Can anyone explain how it is known that there's no extra mass lying undiscovered out there orbiting the Sun? I don't see how we can possibly rule out, say, an enormously massive Oort Cloud, spherically symmetric about the sun, composed of massive black holes. The referenced paper is a dead link, so if we can't find some explanation for this, I think we should put the word "known" back in there. --Doradus (talk) 14:28, 25 August 2008 (UTC)

I've put the word "known" back in there. --Doradus (talk) 12:58, 26 August 2008 (UTC)
Sorry I didn't reply more quickly; it took me a while to track down the Woolfson article (DOI:10.1046/j.1468-4004.2000.00012.x) which is the source for the statement. The relevant sentence is "The Sun with 99.86% of the mass of the system has only 0.5% of the total angular momentum contained in its spin; the remainder is in the planetary orbits." No mention of "known", but also no mention of how that number was derived. If there's a better source (particularly a more readily-available one), that would be fabulous, but I had a surprising amount of trouble tracking one down. —Alex (ASHill | talk | contribs) 16:25, 26 August 2008 (UTC)
Even if your hypothetical enormously massive Oort cloud was exactly spherically symmetric, its effects would be noticeable on other bodies in the solar system (due to assymetrical forces over an eccentric orbit). So the 99.86% is fairly certain. But we should definitely get a reference for this. Feyrauth (talk) 01:03, 1 September 2008 (UTC)
No, it wouldn't. A spherical shell exerts no net force on anything inside it.[4] --Doradus (talk) 18:15, 1 September 2008 (UTC)
It would affect the motions of Voyager 1 and probably some other spacecraft, though. Looie496 (talk) 20:56, 1 September 2008 (UTC)
Not until a spacecraft gets outside it, which hasn't happened yet. But that's a good point: when v'ger gets far enough away, we should be able to make definite statements about the total amount of mass in the Solar System. --Doradus (talk) 23:11, 1 September 2008 (UTC)
The fact is still that we have a source for the 99.86% figure, but not for the word "known". FWIW, estimates of the total Oort cloud mass are of order a few Earth masses (e. g. 1983 A&A 118: 90 and the Oort cloud article, which is well cited). —Alex (ASHill | talk | contribs) 23:34, 1 September 2008 (UTC)
@ spherical gravitational shell - I never heard that the net force is zero before! But it would have some pretty crazy effects over time as the solar system encounters interstellar bodies. I imagine a spherically symmetric shell of black holes would not be very stable. For that matter, although the net force on the bodies within the sphere may be zero the net force on the individual black holes would not be, so any mass within the sphere would pull the black holes inwards... with pretty nasty consequences for us if we *are* inside one... Feyrauth (talk) 08:56, 2 September 2008 (UTC)
I agree with all of the above. I'm just playing devil's advocate really, but I think Alex hit the nail on the head by focusing on sources we can cite. --Doradus (talk) 18:06, 6 September 2008 (UTC)

logarithmic image

I think that image works well in heliosphere, because it shows the various components of the heliopause in detail, but I don't think it works well in a general article about the Solar System because, for some odd reason, Mercury and Venus aren't in it. Serendipodous 06:55, 26 August 2008 (UTC)

Uranus is also missing, and the Sun is in the wrong place. (It seems to be at 0.1 AU, but the Sun's surface is actually at 0.00465 AU.) --Doradus (talk) 13:10, 26 August 2008 (UTC)
I think it's nice because it's the only image in the Solar System article that shows many of the constituents with distances to scale. It certainly could be moved down to the Heliosheath, Outer Solar System, or Neighbourhood sections, although when I looked through, the place I put it seemed the most logical at the time. (I could also see an argument to make it the lead image, as the article is about the Solar System, not the planets.) I think it's visually very nice and worth including on the more prominent Solar System article. I agree that it's odd that it lacks three planets, but it shows enough for a reader to easily infer their location. As for the Sun, there is no zero on a logarithmic scale, so you have to make a compromise, and I don't question the artist's decision on that point. —Alex (ASHill | talk | contribs) 16:09, 26 August 2008 (UTC)
For the record, the image right below it was supposed to provide an idea of the orbits to scale. Serendipodous 16:13, 26 August 2008 (UTC)
Ah; I had missed that because the image was too small to be legible. I made it larger and removed the logarithmic image, although I still really like it and think it would be good elsewhere in this article. —Alex (ASHill | talk | contribs) 16:33, 26 August 2008 (UTC)
Could someone edit the image to include the missing planets? I notice someone has edited the lead image to update the dwarf planets. The image would have to be fairly large though, it's barely legible as it is on the heliosphere page. As for the Sun, the scale between the Earth and the Sun is still logarithmic so I'd say the Sun's surface appears to be at about 1e-3AU, which about as accurate as you could get on this scale. Feyrauth (talk) 02:45, 3 September 2008 (UTC)
You could get Mercury and Venus in it, but on that scale, Uranus and Neptune would be on top of each other. Serendipodous 08:15, 3 September 2008 (UTC)

Further work

Nice work; I think the article reads better now. Two further organization-related points to think about (which I'll stew over before making changes myself):
  1. Could the "Definition of planet" section be folded in somewhere else, like to the first mention of planet? It's hanging a bit as it is now.
  2. The interplanetary medium section is also hanging a bit; perhaps it should be merged with the content in Solar System#Heliosheath?. Also, I'm not sure the "heliospheric current sheet" image is terribly helpful here; it's too small to see the orbits.
Both of these issues may be unavoidable because the article is largely organized (logically, I think) "geographically", from the center out, but both planets and the interplanetary medium cover a range of regions. —Alex (ASHill | talk | contribs) 19:09, 28 August 2008 (UTC)

Right now, I think "Heliopause" is the correct title for that section, since it is the boundary between the Solar wind and the interstellar medium. I don't like the idea of merging the interplanetary medium into heliopause, because that would mean dismantling the "farthest regions" section, and I think the section's lead paragraph, with its discussion of what constitutes the boundary of the Solar System, is rather important. Serendipodous 19:16, 28 August 2008 (UTC)

Possibility for mediation?

Hi all — having had my attention brought here by a post on wp:ani, I've looked over the back and forth here, and it seems to me that there is a possibility of smoothing things out by informal mediation. I would be willing to give it a shot, if all parties agree — in particular, HaffyAlffa would need to agree. Here are some relevant factors:

  1. To make it clear, I am not an admin.
  2. I don't intend to edit the article myself, in any case.
  3. I am a neuroscientist with a pretty strong background in general science, but not an expert on this topic, so I would not express opinions about who is right when there is a content dispute — I might express an opinion about how to resolve the question, though.
  4. I would express opinions about whether a given change is helpful or hurtful to the structure of the article, and whether instances of conduct are appropriate.
  5. I would resolutely avoid coming down hard on one side or the other, even if I think one is more correct, because doing so destroys a mediation process.
  6. I would ask people to try to make concrete assertions and proposals, and to defend them as tersely as possible.
  7. It is my opinion that all parties here are intelligent and reasonable, and committed to creating a good article, but that the arguments about how to do it have become a bit too hot-tempered and assertive. Fixing that would be my main goal.
  8. To be concrete, the first thing I would do is ask HarryAlffa to apologize for this [5], which was disrespectful.

What do you think? Looie496 (talk) 20:29, 28 August 2008 (UTC)

I'm perfectly fine with it. Serendipodous 20:31, 28 August 2008 (UTC)
Sure, me too. —Alex (ASHill | talk | contribs) 20:39, 28 August 2008 (UTC)
A welcome step indeed; thanks for offering to help out. --Ckatzchatspy 20:45, 28 August 2008 (UTC)
May I ask what is so wrong with computer tecnicians? 67.212.185.186 (talk) 22:15, 29 August 2008 (UTC)
Nothing. But he was accusing Ashill of being dishonest, and disrespecting his scientific credentials. Serendipodous 06:43, 30 August 2008 (UTC)

8. See No 5. -HarryAlffa (talk) 11:27, 30 August 2008 (UTC)

No. 8 is not coming down hard against you. As I see it, you lost your temper and said some things that were over the top, and made the others angry. Even if you think you were justified, I hope you will acknowledge, for the sake of harmony, that you could have said it in a less provocative tone. That's all. Looie496 (talk) 16:33, 30 August 2008 (UTC)
Let me add that the goal of that is to enable this to move forward, without getting into any more arguments about who did what bad thing to who in the past—arguments about that are always unproductive. Looie496 (talk) 16:38, 30 August 2008 (UTC)
I would say I was justifiably exasperated by stupidity! But then I would say that! But seriously, I said, "From what you have written then, if you really are a scientist, it has to be concluded ...". You can see that my target was his analysis, if he had come back with a better analysis then this would have forced me to say something like "Ok. You're not that bad then", but he didn't and I haven't. -HarryAlffa (talk) 13:38, 31 August 2008 (UTC)
I am unclear if you have agreed to mediation; could you please clarify? —Alex (ASHill | talk | contribs) 14:01, 31 August 2008 (UTC)
I haven't met 8. -HarryAlffa (talk) 14:22, 31 August 2008 (UTC)
It seems that things have been calm for the past few days. Let's let it rest, and I'll keep my eye on the discussion here and step in if it looks like there is going to be a flareup. Or is there still a content issue under dispute here? Looie496 (talk) 16:46, 31 August 2008 (UTC)
    • ^ Zeilik, Michael A.; Gregory, Stephan A. (1998). Introductory Astronomy & Astrophysics (4th ed. ed.). Saunders College Publishing. pp. p. G–32. ISBN 0030062284.