Talk:Solar system
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Pluto's size
The table satates that Pluto has a diameter of 0.24 times Earth, while the Pluto (planet) page states that it is only of 0.18 (which is concordant with my own data). The masses also differ but in opposite direction: the table of the article says it's 0.0017 Earths and the Pluto page says it's 0.0021.
I noticed because, comparing the two tables, Pluto seems a lot larger than Sedna or Quaoar, when Quaoar and Ixion are commonly accepted to be about half the size of Pluto and Sedna only slightly smaller than Pluto (estimates).
Would somebody more knowledgeable than myself take a look at Pluto's figures and fix them with authority?
Vandalism
If anyone really wants the vandalism I deleted they can look on the revision page.
Pluto
So it's official? Pluto is not a planet anymore? I know that there has been quite a bit of contraversy about it. I didn't know that the issue was mostly settled in the astronomical community. -- ansible
- "officially," Pluto is a planet. It is also a Trans-Neptunian object, a Plutino, and a Kuiper belt object. Ultimately the only solid criteria for planethood is "what we point to and call 'a planet'," and by that criteria Pluto is unlikely to lose its status as a planet any time soon. By the time it does, nobody will care (by definition :).
- BTW, I checked with Dave Jewitt of UH (author of the Plutino external link) and Pluto is NOT a Plutino -- a Plutino is something in a similar orbit but smaller than Pluto itself. Joelwest 04:54, 24 Mar 2004 (UTC)
- picky detail, just to remind contributors: this is a criterion, not criteria, since it is singular. (Just like phenomenon/phenomena.) Now, if you'll excuse me, I'm going for lunch in the cafeterion...
- as for its location in the list on this page, there isn't a subheading specifically for "planets" so I wouldn't take Pluto's position as being significant.
The controversy over Pluto being a "planet" really belongs on the Pluto page, so the wording has been changed to point to it. As for the substance, some say it never was a "major planet" and should be considered the largest of the "minor planets" which would include things like Sedna (astronomical object) Joelwest 19:19, 20 Mar 2004 (UTC)
Cruithne
Before I swap this, is there any reason Cruithne is listed before the Moon, in the table? Vicki Rosenzweig
Fact tables
I would like to prepose that the planet articles be re-deisgned and have a table to the right giving basic details eg number of satelites(moons), mass, rotation speeed. etc and more detailed info to the left. - fonzy
There already is such a table at Earth for example. But please don't stretch yourself too thin -- you already have several tables you started on Temp on other pages that still need to be filled-out. What works for me is that I take things one step at a time and make sure I do a thorough job. --mav
I like the idea of a more standardized table than the current collection of facts in bulleted lists that most planets and moons have. I'll start working on a template over at Solar system/Factsheet template. Bryan Derksen 18:19 Aug 16, 2002 (PDT)
Solar System vs Solar system
Since this is about the solar system (proper noun) shouldn't it be at Solar System and then solar system can be about solar systems in general? --mav
Hm. I always thought it was the Solar system, since it's named after Sol, and other systems would be "the Rigel system", "the Sirius system", etc. and the general term was "star systems". But I've got nothing to give particular weight to that approach. Bryan
- Fair enough. --mav
Hmm. If the name of the system was named after "Sol" in the same way that the Rigel system is named after Rigel, then it would be the "Sol system", not the "Solar system". But anyway, the Oxford English Dictionary says that the English word "solar" comes from the Latin adjective solar (I'm not sure if that should have an ending because I've forgotten most of my Latin). That's related to the Latin word sol, which means "Sun" in Latin, but that's not the same as saying that the astronomers took the name of the system from the name of the name of the star directly. It seems that the link goes back to the days before the English language even existed. But anyway, the Oxford English Dictionary actually has the "solar system" with lower case letters. So should we go with them? Then again, it also spells "sun" with a lower-case "s". I didn't expect that. Hmm... I think I'll just leave it for now. -- Oliver P. 08:47 12 Jul 2003 (UTC)
- One can imagine, as non-astronomers became more interested in the planets around our star and then around other stars, how the phrase "solar system" would be pressed into use for these others as well. Science fiction, which had reason to make distinctions early on, has used varieties like "star system" and "stellar system". I always thought "stellar system" made the most sense as a generic version, as it follows the form of "solar system". I'm disappointed that it hasn't displaced the ambiguous use of the latter phrase. -- Jeff Q 13:27, 10 Jun 2004 (UTC)
- Is there any way of conclusively determining which it is? If not, can we agree on one? Even within the article itself, capitalisation is fairly random, and it'd be good to standardise on something IMO, even if it's only by vote or whatnot. (Also, is it Solar System vs. Solar system vs. solar system?) -- Wisq 13:51, 2005 May 18 (UTC)
Surface
The bit on surface area seems confusing. How may the surface area of the objects of the solar system be accurately found? Even a single planet, say the Earth. It is not a perfect sphere, it's a fractal. Just like it is not possible to find the length of the coastline of Britain, it is not possible to find the surface area of the Earth. You can start by saying that the Earth is a sphere and measure its area, and then zoom in on a tall mountain, that mountain is, say, in a shape of a cone, and you correct your first measurement with this new detail in mind. But then you zoom in even further to discover other mountains and that mountains aren't really cones and that the landscape is so wrinkly, no one can be sure of its area. You can actually zoom in infinitely. Ah, you get the idea. I, therefore, disagree with the value and the possibility of finding an accurate value, without a suitable restriction, for a surface of a physical, non-classical mathematical object, such as may be found in the solar system. Might I add that the referenced article was written by a geographer, who does not include references to other works, nor an indication of how he was able to come up with the values. Evgeni Sergeev 01:57 18 Jul 2003 (UTC)
- I think Wikipedia can follow the conventions and practices of geography, and ignore the fractal issues unless there's evidence that they are significantly more important on other solar system bodies than they are on earth.
- We don't make a habit of including error bars, or disclaimers about fractals, in the areas in geography articles, and I don't think we should start.Vicki Rosenzweig 02:02 18 Jul 2003 (UTC)
- I think we should. Geography needs a bit of a shake-up. But I'm not editing the article, because it is everyone's encyclopeadia, not just mine. But the fractal matter seems pretty important to me anyway. Evgeni Sergeev 02:31 18 Jul 2003 (UTC)
We should indicate when something is an estimate. Pizza Puzzle
For a start, shapes of planets are not true fractals, they're scale-limited. It gets boring at <1nm. But the usual way to calculate surface areas of such things is to smooth them out at a scale much greater than 1nm. I suspect that from the perfect sphere approximation, down to ~1km resolution, surface area doesn't change very much. Hence, the choice of scale is not as arbitrary as it might at first seem -- a sphere is a good enough approximation for practical purposes. As for indicating when something is an estimate: well, all the figures we give are estimates. Perhaps it would be good to indicate when something is a particularly poor estimate (e.g. worse than +/- 30%). -- Tim Starling 02:54 18 Jul 2003 (UTC)
The fact that we are smoothing out the surface is significant. Now it makes sense. An area measurement like this would be knowledge of some value: eg. to calculate how much energy does the Earth receive from the Sun. I read the source and corrected the statement: this is the surface area of solid objects only. Now, the fractal nature of planets: do we really know that they are boring and non-self-repeating at small scales? That seems to me the limits of our knowledge, not the limits of scale. Yes, there is an upper scale limit. But doesn't the Mandelbrot Set have an upper scale limit? I thought I read somewhere that it wasn't a true fractal, but you still couldn't calculate the length of its borderline. Anyway, at small scales, the whole concept of surface area is shadowy: what is the surface area of an atom, if it is mostly space inside? Hmm... the present value for surface area is fair enough. Evgeni Sergeev 02:28 19 Jul 2003 (UTC)
- The surface area of an atom can be defined by arbitrarily picking an electron density to draw the line at. Chemists do the same thing to calculate volumes. Quantum mechanics gives systems of electrons a characteristic scale: the Bohr radius. According to QM, there is no fine detail below this scale. There is ample experimental evidence to back this up.
- Sometimes you hear things like "this object is 99.99999999% empty space". That's not really true -- under standard QM, it's 100% empty space. A definition by electron density, rather than by the amount of non-existent "extended" matter, restores the common sense definition of volume. -- Tim Starling 10:00 19 Jul 2003 (UTC)
By approximating all solar system bodies as spheres, you avoid one fractal problem. But, there is another: there is a huge amount of surface area of dust and grains in the Solar System. The source from U. Texas explicitly gives a lower cutoff of 1km. I'll put that in, also. -- hike395 04:41 19 Jul 2003 (UTC)
- By the way, the amount of energy the Earth receives from the Sun is not related to its surface area; it's proportional to the solid angle it cuts out of the sphere of radiating energy from the Sun. Even when you calculate energy per square meter of the Earth's surface, what you're really doing is determining the solid angle formed by an ideal square meter of surface with the Sun in a specific position in the sky and distance from the Earth. None of these quantities can be considered precise or constant enough to worry about fractal scales. -- Jeff Q 13:51, 10 Jun 2004 (UTC)
Navigation footers
Nephelin has updated the footers for all Solar system related pages. I like the light cyan box. However, I disagree with some of the additional links. I believe that one of asteroid or asteroid belt should be removed from the list, because they are redundant. I would suggest keeping asteroid, because it is a more developed article. I also would like to remove planet and star, since they are generic articles (hypernyms of objects in the Solar system). Comments? -- hike395 20:27, 25 Jan 2004 (UTC)
- The first line contains only the astronomical objects of the solar system (heliocentric view), the second line contains the transneptunal objects and general astronomical objects. And sorry, asteroids are not equal with the asteroid belt! Nephelin 21:13, 25 Jan 2004 (UTC)
- Here's the problem: there are many solar-system related articles. What criterion should be used to include them in the box? Should we include Near-Earth asteroids? How about Alinda asteroids? Or Quaoar? Or zodiacal light?
- To me, highlighting in a box or footer suggests an overall navigation aid, rather than an exhaustive list of topics. I believe that an overall navigation aid should list just the planets, plus perhaps asteroid. IMO, more links than that makes the navigational aid less useful for novice astronomy people.
- If you'd like to make a separate page of Solar system topics and create a more complete list, I would be in favor of that. -- hike395 05:28, 26 Jan 2004 (UTC)
The current footer has Kuiper belt, Oort cloud and Trans-Neptunian object, but Kuiper belt and Oort cloud are both subsets of Trans-Neptunian objects. I'd suggest either getting rid of TNOs, or getting rid of Kuiper and Oort. Also, I agree that "planet" and "star" don't really belong in a navigation bar like this; they're too generic. Perhaps a link to moons would be a good replacement? That way, all the major bodies of the solar system are no more than two clicks away. Bryan 06:51, 26 Jan 2004 (UTC)
- Planet and Star are too generic... but Moons are not? I agree with Kuiper belt and Oort clound to replace them by Trans-Neptunian object. And Asteroid and Comet could be replaced by Astronomical objects. But the Asteroid belt is a part of our solar system among the sun and the planets (an the Trans-Neptunian objects). A suggestion:
| The Solar System |
|---|
| Sun | Mercury | Venus | Earth | Mars | Asteroid belt | Jupiter | Saturn | Uranus | Neptune | Pluto |
| Trans-Neptunian objects | Astronomical objects |
- Nephelin 07:22, 26 Jan 2004 (UTC)
- The table is left aligned by mozilla though the align attribute of the table tag is set to center... Why? Is this another mozilla bug or a feature?! Nephelin 09:00, 26 Jan 2004 (UTC)
- the "align" attribute is not a legal part of the <table> tag in HTML 4.01, see [1] (http://www.w3.org/TR/html401/struct/tables.html#h-11.2.1). Mozilla obeys the official specs for HTML a lot more closely than other popular browsers (*cough*IE*cough* :), so what you're seeing isn't actually a bug in Mozilla - it's correct behavior, and the bug is in the other browsers that show the table centered. :) I found a short discussion on this page on how to center tables "properly": [2] (http://debin.org/2002/aligntable/). I've taken the liberty of implementing it by adding style="margin-left:auto; margin-right:auto; text-align: center;" to your table above, and it seems to work on Mozilla here. Hope it works on other browsers too. :) Bryan 01:07, 27 Jan 2004 (UTC)
- "Moon" is no more generic than "asteroid" or "trans-Neptunian object", IMO. If there were a specific "moons of the solar system" article that dealt only with moons in our solar system rather than moons in general I would have suggested that instead, but the current "natural satellite" article fills that role right now. As for the changes to the asteroid links, I just finished adding a huge listing of asteroid groups to the asteroid article and am currently pondering splitting it off into a separate asteroid group article to reduce the clutter in the main article. I was going to sleep on it, but since this is Wikipedia who knows what the situation will be in the morning. :) You may want to have a look at that listing to see if there are any other ways of dividing up the minor planets; for example, you could throw in Centaurs to fill in the gap between asteroid belt and TNOs and then all the major populations of minor planet would be covered. Bryan 07:37, 26 Jan 2004 (UTC)
- You know, this discussion illustrated something for me. I suspect we need both a List of solar system objects (a hierarchical page) in addition toAstronomical objects (planet,moon,star,galaxy, etc.) This would allow a sophisticated user (college graduate, e.g.) to navigate. I think we should aim the footer at schoolkids. So, how about for the footer, listing the nine planets plus List of solar system objects? We can have a see also for Astronomical objects.
- I guess we could leave off both asteroid belt and asteroid from the footer, if we're going to write a nice hierarchical solar system object page. (Asteroid belt started out as a stub written by Bryan, and grew up independently from asteroid. Asteroid is far meatier. Should we fold asteroid belt back into asteroid? It feels so redundant.) -- hike395 04:53, 27 Jan 2004 (UTC)
- Asteroid belt could be turned into an article on the Main belt fairly easily, I think, which is a topic reasonably far removed from plain old generic asteroids to maintain its independance. As for a list of solar system objects, there's an outline of such objects over on solar system that I created a while back that may make a good start for a more detailed list. Mix in the list of asteroid groups I recently completed on asteroid, and I can't think of any class of matter in the solar system that is omitted. (otherwise I would have included it in one of those lists already :) Bryan 05:21, 27 Jan 2004 (UTC)
- Actually, as I look at it, I'm not sure asteroid belt needs any changing. The subject it covers is broader than just the main belt. Bryan 05:27, 27 Jan 2004 (UTC)
- OK --- we don't have to fold asteroid belt. I agree that your taxonomy is pretty good. A few questions lurk for a prospective article: should we make an exhaustive list of moons? Or just the largeish ones? Ditto for asteroids?
- natural satellite has a table with what seems to be an exhaustive list of the moons, grouped by planet and by size ranges. List of asteroids in our Solar System has a list of large and/or noteworthy asteroids that have articles in Wikipedia (I know of at least one with an article that isn't in here, 141 Lumen) but an exhaustive list may not be a good idea - there are over 10,000 minor planets known, IIRC, and the number's growing by hundreds every year. :) Perhaps simply linking to these articles from the main list will suffice? Bryan 07:50, 27 Jan 2004 (UTC)
- I made a first cut at a List of solar system objects. I would propose that the footer should read:
| The Solar System |
|---|
| Sun | Mercury | Venus | Earth | Mars | Asteroids | Jupiter | Saturn | Uranus | Neptune | Pluto |
| See also List of solar system objects | Astronomical objects |
- Comments? -- hike395 07:56, 28 Jan 2004 (UTC)
- Looks good. Just tweaked the style to center it, though. :) Bryan 08:16, 28 Jan 2004 (UTC)
- I slept on it and thought it was too verbose. Cut the extra words out of the See also list, since the article titles are self-explanatory. See above. If everyone likes it, I'll implement sometime soon. -- hike395 03:29, 29 Jan 2004 (UTC)
- Yeah, that one's more compact without losing anything. Gets my vote. Bryan 04:15, 29 Jan 2004 (UTC)
- I think asteroids are too generic. the region between mars and jupiter is called main belt or asteroid belt - but not asteroids. both, solar system objects and astronomical objects matches asteroid... there are asteroids outside the solar system! the context of the quick-nav is solar system - it's a pity that you cannot reach transneptunian-objects or kuiper belt/oort cloud directly anymore. the reason for a quick-nav about solar system is to quick navigate between solar system objects - like one-click-buy on amazon - and not three or two clicks or one more list (the "See also" is for a nav-bar obsolete imho)... Nephelin 07:42, 29 Jan 2004 (UTC)
- I'm thinking of this list something for high school students. I'm betting that they don't often need quick one-click access to TNOs, so they get to be hidden inside List of solar system objects, where the undergraduate and graduate students will look.
- As for asteroids vs asteroid belt: My main motivation is that the asteroids article is a lot more complete than asteroid belt. Further logic: Notice that all of the other entries on the first line are objects, asteroids are objects, too. No one has detected an asteroid outside of the solar system, so I doubt if people will be confused by that. One possible compromise is that we could use asteroid belt (pointing to the asteroid article), but that is kind of inelegant.
- Re: see also. Obsolete? I'm not sure what you mean. I can drop it, but I wanted to indicate that other stuff that you don't see on the list above is hidden in these following articles. I can expand it to say "For other objects and regions, see:" ... More verbose, but clearer.
| The Solar System |
|---|
| Sun | Mercury | Venus | Earth | Mars | Asteroid Belt | Jupiter | Saturn | Uranus | Neptune | Pluto |
| For other objects and regions, see: List of solar system objects | Astronomical objects |
- --hike395 16:36, 29 Jan 2004 (UTC)
- Updated Sun,Mercury (planet),Venus (planet),Earth,Mars (planet),Asteroid,Asteroid Belt,Jupiter (planet),Saturn (planet),Uranus (planet),Neptune (planet),Pluto (planet),Asteroid moon,Centaur (planetoid),Comet,Cubewano,Kuiper belt,Natural satellite,Planetary ring,Plutino,Scattered disk object,Solar system,Trans-Neptunian object,Trojan asteroid,Zodiacal light,Quaoar to use the above footer -- hike395 05:00, 31 Jan 2004 (UTC)
I have just copied this table over to MediaWiki:Solar system. To place a copy of it on a page, one now simply has to type {{msg:Solar_system}} and it will magically appear. The underscore is necessary, it seems. Bryan 01:41, 16 Feb 2004 (UTC) (note: deleted that particular page since the one below got used instead. Bryan 07:58, 16 Feb 2004 (UTC))
- Really cool! Thanks!!! -- hike395
- No problem. If you want, I can do the work of switching the existing footers over to the msg version instead; that way if we decide to change the footer in the future, all of the articles will change automatically to reflect it. Bryan 02:16, 16 Feb 2004 (UTC)
- Looks like Timwi changed them all over, but to yet another different footer :-(. I prefer the footer that we built by consensus here. I copied our consensus footer over to Template:Footer_SolarSystem. I'm happy to continue the discussion over at MediaWiki talk:Footer_SolarSystem. -- hike395
Overlap with Asteroid Entry
This lists the Solar System as having 7 types of objects, from the Sun to dust. Meanwhile, the asteroid entry subsumes comets, Centaurs and TNOs as types of asteroids. There seems to be some disagreement (whether among astronomers or just in common English usage) as to whether asteroid subsumes all planetoids or just the rocky ones or just the ones in the asteroid belt.
That said, this section heavily overlaps and contradicts the asteroid entry. This appears more authoritative (e.g. a clean distinction within the TNOs) but that doesn't guarantee it's right. The contradictions need to be straightened out (preferrably by someone with real knowledge) and the definitions should be only in one place. Joelwest 19:42, 20 Mar 2004 (UTC)
- When I did the asteroid groups I got all the information from [3] (http://www.projectpluto.com/mp_group.htm), which uses the title "Minor planet groups/families." Minor planet looks like a broader term than asteroid, but currently minor planet simply redirects to asteroid. Perhaps a separate article is in order. Bryan 22:13, 20 Mar 2004 (UTC)
- I wouldn't want to just delete the beyond-Jupiter groups, though, since it lists more categories and details than is present in other Wikipedia articles on the subject. I'd prefer to move it somewhere. How about using minor planet for listing all of the various groups of minor planet currently at the asteroid article, turning it into a sort of huge disambiguation page? Bryan 05:17, 21 Mar 2004 (UTC)
- Yes, I see --- I made a poor assumption about duplication. A huge minor planet page may be OK. --- hike395 06:39, 21 Mar 2004 (UTC)
- Done, how's it look? Bryan 07:51, 21 Mar 2004 (UTC)
Solar system model name
Does anyone know the Greek or Latin neologism for a mobile-like 3D model of the solar system? I can't quite recall it, and search engines suggest that people typically just call them "solar system models". Since virtual solar system apps are called the same thing, it's useful to know the specific word for the physical model. -- Jeff Q 14:00, 10 Jun 2004 (UTC)
- I believe it would be an "orrery". Apparently named after Charles Boyle, 4th Earl of Orrery, who had one made for him, rather than Greek or Latin. -- Curps 14:26, 10 Jun 2004 (UTC)
- Already an article at Orrery, so perhaps Solar system model could disambig. -- hike395 14:31, 10 Jun 2004 (UTC)
- Well, that explains why I couldn't remember it! Greek or Latin, indeed. ☺ I went ahead a made Solar system model a redirect for Orrery, until somebody decides to expand upon the generic concept of "solar system model". Thanks a bunch! -- Jeff Q 19:49, 10 Jun 2004 (UTC)
I just fixed the solar system model table. I feel it should be moved into a separate article so it can include more information about the models and links to model homepages where they exist. (e.g. mos.org) I would use Solar system model. Any objections or comments? --agr 01:44, 26 Dec 2004 (UTC)
Minor Planet Table Reorganized
I've altered the minor planet table and added an introduction. I hope I don't step on anyone's toes with this. I changed the order of the data in the minor planet table so that it matches that of the major planet table: starting with the inner bodies and working outward. The minor planet bodies were previously arranged by number only.
Probes in Solar System
Does anyone know why it is almost impossible for probes visiting planets beyond Earth to return? Is it because of some unknown force that pulls the probe forward? Why is it easy for probes going to planets in front of Earth to return? Is this unknown force pulling the probes forward into the Earth? Could it be that this force is pulling probes visiting planets beyond Earth forward and farther and farther away from Earth? Why isn't there another force that goes the other way around?
- What probes do you have in mind? I'm not aware of any probes that have gone to other planets and returned. Worldtraveller 17:23, 16 Apr 2005 (UTC)
- No spacecraft has gone beyond Moon and returned to Earth's surface (well, Stardust and Hayabusa are going to return some samples from a comet and an asteroid, respectively; and let's not forget Genesis probe which collected solar wind particles. Of these, only Hayabusa is actually going to land). But to land on another planet, and then return to Earth (for example, Mars sample return mission) is very hard to carry out. Reason? They must get to the target planet, collect some samples, launch the sample back to space (the fuel must be carried all the way on the planet) and then return to Earth. That means more massive and complex spacecraft, which means larger launch vehicles, which in turn means more costly missions. On the other hand, Earth has been frequently used as a gravitational slingshot for probes going elsewhere (for example Galileo and Cassini-Huygens probes have visited Earth's vicinity since they left Earth), because to conduct a flyby you don't need much fuel to change your speed and direction. That's why they're so handy.--Jyril 17:59, Apr 16, 2005 (UTC)
The Edge of the Solar System
I was wondering if there could be a debate about what constitutes the "edge" of the Solar System. You still hear in the media that the Voyagers and the Pioneers have "left" the Solar System, when it is difficult to claim that they have. But what *is* the edge of the Solar System? The heliopause? The Oort Cloud? Could there be anything beyond that?
- Well, the Voyagers at least have certainly left the orbital plane of the system, which would suggest they've 'left the system'. But yes, it's ambiguous, as far as I can see. -- Wisq 20:56, 2005 May 25 (UTC)
Yes, they've left the ecliptic, but the Oort Cloud is not on the ecliptic, it surrounds the Solar System like a shell, does it not? If so, then no matter where these probes are headed, they still have to pass through the Oort Cloud. 157.140.6.143 14:05, 27 May 2005 (UTC)