
#REDIRECT Solar system
The Solar System consists of the Sun and all the objects that orbit around it, including meteors, asteroids, comets, natural satellites, and planets. The Earth is the third planet of the Solar System. ''Planetary systems'' are a more generic term for stars and the objects that orbit around them. == Solar System objects == The wide variety of objects that exist in the Solar System fall into several categories. In recent years many of these categories have been found to be less clear-cut than once thought. This encyclopedia employs the following divisions: *The Sun (☉) is a Stellar_classification G2 star that contains 99.86% of the system's mass. *The planets of the Solar System are those nine bodies traditionally labelled as such: Mercury (planet) (☿), Venus (planet) (♀), Earth (♁), Mars (planet) (♂), Jupiter (planet) (♃), Saturn (planet) (♄), Uranus (planet) (♅/), Neptune (planet) (♆) and Pluto (planet) (♇). **Sizeable objects that orbit these planets are Natural satellites. For a complete listing, see that article. **Artificial satellites orbiting the planets, mainly Earth, as well as probes heading into deep space. **Dust and other small particles that orbit these planets form planetary rings. **Space debris of artificial origin that can be found in orbit around Earth. **Planetesimals, from which the planets were originally formed, are sub-planetary bodies that accreted during the first years of the Solar System and that no longer exist. The name is also sometimes used to refer to asteroids and comets in general, or to asteroids below 10 km in diameter. *Asteroids are objects smaller than planets that lie roughly within the orbit of Jupiter and are composed in significant part of non-volatile minerals. They are subdivided into asteroid groups and :Category:Asteroid groups and families based on their specific orbital characteristics. **Asteroid moons are asteroids that orbit larger asteroids. They are not as clearly distinguished as planetary moons, sometimes being almost as large as their partners. **Trojan asteroids are located in either of Jupiter's Lagrange point, though the term is also sometimes used for asteroids in any other planetary Lagrange point as well. **Meteoroids are asteroids that range in size from roughly boulder sized to particles as small as dust. *Comets are composed largely of volatile ices and have highly eccentric orbits, generally having a perihelion within the orbit of the inner planets and an aphelion beyond Pluto. Short-period comets exist with apoapses closer than this, however, and old comets that have had most of their volatiles driven out by solar warming are often categorized as asteroids. Some comets with hyperbola orbits may also originate outside the Solar System. *Centaur (planetoid)s are icy comet-like bodies that have less-eccentric orbits so that they remain in the region between Jupiter and Neptune. *Trans-Neptunian objects, which are icy bodies whose semimajor axis lie beyond Neptune's. These are further subdivided: **Kuiper belt objects have orbits lying between 30 and 50 AU (astronomical units, an AU is approximately equal to the mean distance between Earth and Sun). This is thought to be the origin for short-period comets. Pluto is sometimes classified as a Kuiper belt object in addition to being a planet, and the Kuiper belt objects with Pluto-like orbits are called Plutinos. The remaining Kuiper belt objects are classified as Cubewanos in the main belt and scattered disk objects in the outer fringes. **Oort cloud objects, currently hypothetical, have orbits lying between 50,000 and 100,000 AU. This region is thought to be the origin of long-period comets. **The newly discovered object 90377 Sedna, with a highly elliptical orbit extending from about 76 to 928 AU, does not obviously fit in either category, although its discoverers argue that it should be considered a part of the Oort cloud. * Small quantities of dust are present in the interplanetary medium and are responsible for the phenomenon of zodiacal light. Some of the dust is likely interstellar dust from outside the Solar System. Jupiter constitutes most of the mass of the Solar System outside the Sun: 0.1% of the mass of the Solar System. In turn, Saturn constitutes most of the remaining mass, then Uranus and Neptune, then Earth and Venus (see also below). == Origin and evolution of the Solar System == The Solar System is believed to have formed from the Solar Nebula, the collapsing cloud of gas and dust which gave birth to the Sun. As it underwent gravitational collapse, the Solar Nebula would have collapsed into a disk, with the protostar accreting at the centre. As the protosun heated up, volatile substances were driven away from the central regions of the nebula - hence the formation of rocky planets closer to the sun and gas giants further out. For many years, our own system was the only planetary system known, and so theories only had to explain one system to be plausible. The discovery in recent years of many external systems (see Exoplanet) has uncovered systems very different to our own, and theories of planetary system formation have had to be revised accordingly. In particular, many external systems contain a hot Jupiter - a planet comparable to or larger than Jupiter orbiting very close to the parent star, perhaps orbiting it in a matter of days. It has been hypothesised that while the giant planets in these systems formed in the same place as the gas giants in our system did, some sort of migration took place which resulted in the giant planet spiralling in towards the parent star. Any terrestrial planets which had previously existed would presumably either be destroyed or ejected from the system. == Galactic orbit of the Solar System == The Solar System is part of the Milky Way galaxy, a spiral galaxy with a diameter of about 1 E20 m light years containing approximately 200 billion stars, of which our Sun is fairly typical. Estimates place the Solar System at between 25,000 and 28,000 light years from the galactic center. Its speed is about 220 kilometre per second, and it completes one revolution every 1 E15 s. At the galactic location of the Solar System, the escape velocity with regard to the gravity of the Milky Way is about 1000 km/s. The Solar System appears to have a very unusual orbit. It is both extremely close to being circular, and at nearly the exact distance at which the orbital speed matches the speed of the compression waves that form the spiral arms. The Solar System appears to have remained between spiral arms for most of the existence of life on Earth. The radiation from supernova in spiral arms could theoretically sterilize planetary surfaces, preventing the formation of large animal life on land. By remaining out of the spiral arms, Earth may be unusually free to form large animal life on its surface. ==Discovery and exploration of the Solar System== Because of the Geocentric model perspective from which humans viewed the Solar System, its nature and structure were long misperceived. The apparent motions of Solar System objects as viewed from a moving Earth were believed to be their actual motions about a stationary Earth. In addition, many Solar System objects and phenomena are not directly sensible by humans without technical aids. Thus both conceptual and technological advances were required in order for the Solar System to be correctly understood. The first and most fundamental of these advances was the Nicolaus Copernicus Revolution, which adopted a heliocentric model for the motions of the planets. Indeed, the term "Solar System" itself derives from this perspective. But the most important consequences of this new perception came not from the central position of the Sun, but from the orbital position of the Earth, which suggested that the Earth was itself a planet. This was the first indication of the true nature of the planets. Also, the lack of perceptible stellar parallax despite the Earth's orbital motion indicated the extreme remoteness of the fixed stars, which prompted the speculation that they could be objects similar to the Sun, perhaps with planets of their own. Since the start of the space age, a great deal of exploration has been performed by unmanned space missions that have been organized and executed by various space agencies. The first probe to land on another Solar System body was the Soviet Union's Luna 2 probe, which impacted on the Moon in 1959. Since then, increasingly distant planets have been reached, with probes landing on Venus (planet) in 1965, Mars (planet) in 1976, the asteroid 433 Eros in 2001, and Saturn (planet)'s moon Titan (moon) in 2005. Spacecraft have also made close approaches to other planets: Mariner 10 passed Mercury (planet) in 1973. The first probe to explore the outer planets was Pioneer 10, which flew by Jupiter (planet) in 1973. Pioneer 11 was the first to visit Saturn (planet), in 1979. The Voyager program probes performed a grand tour of the outer planets following their launch in 1977, with both probes passing Jupiter in 1979 and Saturn in 1980-1981. Voyager 2 then went on to make close approaches to Uranus (planet) in 1986 and Neptune (planet) in 1989. The Voyager probes are now far beyond Pluto (planet)'s orbit, and astronomers anticipate that they will encounter the heliopause which defines the outer edge of the Solar System in the next few years. Pluto remains the only planet not having been visited by a man-made spacecraft, though that will change with the launching of New Horizons by NASA in January 2006. It is scheduled to fly by Pluto in July 2015 and then make an extensive study of as many Kuiper Belt objects as it can. Through these unmanned missions, we have been able to get close-up photographs of most of the planets and, in the case of landers, perform tests of their soils and Celestial_body_atmosphere. Manned exploration, meanwhile, has only taken human beings as far as the Moon, in the Apollo program. The last manned landing on the Moon Apollo 17 in 1972, but the recent discovery of ice in deep craters in the polar regions of the Moon has prompted speculation that mankind may return to the Moon in the next decade or so. Manned missions to Mars (planet) have been eagerly anticipated by generations of space enthusiasts, and it was hoped that the first manned interplanetary flights would take place in the 1980's, after the successful Apollo program. The United States now plans manned Lunar and Mars missions as part of the new Vision for Space Exploration. == The Solar System and other planetary systems == Until recently, the Solar System was the only known example of a planetary system, although it was widely believed that other comparable systems did exist. A number of such systems have now been detected, although the information available about them is very limited. See extrasolar planet for more information. == Attributes of major planets == {| cellspacing=2 cellpadding=0 width=200 align=right style="font-size:smaller; clear:right;" |+ style="font-size:larger;"| Scale of planetary orbits.
(million kilometres) |- |colspan=2|
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at:start color:yelloworange
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width:15 color:blue align:left shift:(15,-5)
from:46 till:70 text:"Mercury"
from:107 till:109 align:right shift:(-15,-5) text:"Venus"
from:147 till:152 shift:(15,0) text:"Earth"
from:207 till:249 align:right shift:(-15,0) text:"Mars"
from:314 till:494 shift:(15,5) color:yellow text:"Asteroid~ belt"
from:741 till:816 text:"Jupiter"
from:1347 till:1507 text:"Saturn"
from:2735 till:3004 text:"Uranus"
from:4425 till:7375 color:brightgreen text:"Pluto"
from:4456 till:4537 text:"Neptune"
|}
All attributes below are measured relative to the Earth:
{| class="toccolours" border=1 cellspacing=0 cellpadding=2 style="text-align:center; border-collapse:collapse;"
|+align=bottom style="text-align:left;"|
* See Earth article for absolute values.
** Soon after its discovery in 1930, Pluto was classified a planet by the International Astronomical Union. However, based on additional discoveries since that time, some astronomers have suggested Pluto_(planet)#The_Pluto_debate of that decision. |- bgcolor=#ccccff ! Planet ! Equatorial
diameter ! Mass ! Orbital
radius (Astronomical Unit) ! Orbital period
(years) ! Day
(days) ! List of natural satellites |- | Mercury (planet) | align="center" | 0.382 | align="center" | 0.06 | align="center" | 0.38 | align="center" | 0.241 | align="center" | 58.6 | align="center" | none |- | Venus (planet) | align="center" | 0.949 | align="center" | 0.82 | align="center" | 0.72 | align="center" | 0.615 | align="center" | -243 | align="center" | none |- | Earth* | align="center" | 1.00 | align="center" | 1.00 | align="center" | 1.00 | align="center" | 1.00 | align="center" | 1.00 | align="center" | Moon |- | Mars (planet) | align="center" | 0.53 | align="center" | 0.11 | align="center" | 1.52 | align="center" | 1.88 | align="center" | 1.03 | align="center" | Mars's natural satellites |- | Jupiter (planet) | align="center" | 11.2 | align="center" | 318 | align="center" | 5.20 | align="center" | 11.86 | align="center" | 0.414 | align="center" | Jupiter's natural satellites |- | Saturn (planet) | align="center" | 9.41 | align="center" | 95 | align="center" | 9.54 | align="center" | 29.46 | align="center" | 0.426 | align="center" | Saturn's natural satellites |- | Uranus (planet) | align="center" | 3.98 | align="center" | 14.6 | align="center" | 19.22 | align="center" | 84.01 | align="center" | 0.718 | align="center" | Uranus's natural satellites |- | Neptune (planet) | align="center" | 3.81 | align="center" | 17.2 | align="center" | 30.06 | align="center" | 164.79 | align="center" | 0.671 | align="center" | Neptune's natural satellites |- | Pluto (planet)** | align="center" | 0.24 | align="center" | 0.0017 | align="center" | 39.5 | align="center" | 248.5 | align="center" | 6.5 | align="center" | Charon (moon) |} Of the other objects, Ganymede (moon) has the largest mass (0.02). See Planet (Table) for a more comprehensive table. == Attributes of selected minor planets == Some objects are intermediate in size between planets and the lumps of rock called asteroids. These mid-sized objects are now often called 'planetoids' or minor planets: most scientists consider them too small to be "true" planets, while a few scientists point out that these minor planets exhibit the same gravitational forces which affect major planets. Just one planetoid, 1 Ceres, lies in the inner reaches of the Solar System. All other planetoids occur at the fringe of our planetary system. All attributes below are measured relative to the Earth: {| class="toccolours" border=1 cellspacing=0 cellpadding=2 style="text-align:center; border-collapse:collapse;" |- bgcolor=#ccccff ! Planetoid ! Equatorial
diameter ! Mass ! Orbital radius
(Astronomical unit) ! Orbital period
(years) ! Day
(days) |- | 1 Ceres | align="center" | 0.075 | align="center" | 0.000 158 | align="center" | 2.767 | align="center" | 4.603 | align="center" | 0.3781 |- | 90482 Orcus | align="center" | 0.066 - 0.148 | align="center" | 0.000 10 - 0.001 17 | align="center" | 39.47 | align="center" | 248 | align="center" | ? |- | 28978 Ixion | align="center" | ~0.083 | align="center" | 0.000 10 - 0.000 21 | align="center" | 39.49 | align="center" | 248 | align="center" | ? |- | (55636) 2002 TX300 | align="center" | 0.0745 | align="center" | ? | align="center" | 43.102 | align="center" | 283 | align="center" | ? |- | 20000 Varuna | align="center" | 0.066 - 0.097 | align="center" | 0.000 05 - 0.000 33 | align="center" | 43.129 | align="center" | 283 | align="center" | 0.132 or 0.264 |- | 50000 Quaoar | align="center" | 0.078 - 0.106 | align="center" | 0.000 17 - 0.000 44 | align="center" | 43.376 | align="center" | 285 | align="center" | ? |- | 90377 Sedna | align="center" | 0.093 - 0.141 | align="center" | 0.000 14 - 0.001 02 | align="center" | 76-990 | align="center" | 11500 | align="center" | 20 |} == Other facts == The total surface area of the Solar System's objects that have solid surfaces and a diameter greater than 1 km is ~1.7×109 kilometer2 —about 11 times the area of the Earth's land masses. (''[http://uts.cc.utexas.edu/~gwk/images/SolSys/SolSys.html]'') It has been suggested that the Sun may be part of a binary star system, with a distant companion named Nemesis (star). Nemesis was proposed to explain some timing regularities of the great extinctions of life on Earth. The hypothesis says that Nemesis creates periodical perturbations in the Oort cloud of comets surrounding the Solar System, causing a "comet shower". Some of them hit Earth, causing destruction of life. This hypothesis is no longer taken seriously by most scientists. ==Edge of the Solar System== The point at which the Solar System ends and interstellar space begins is not precisely defined, since its outer boundaries are delineated by two separate forces: the solar wind and the Sun's gravity. The charted regions of our Solar System exist within a highly tenuous "atmosphere" of solar wind; charged particles eminating from the Sun that expand outward in a great bubble to about 95 AU (three times the orbit of Pluto). The edge of this bubble is known as the termination shock; the point at which the solar wind collides with the opposing winds of the interstellar medium. Here the wind slows, condenses and becomes more turbulent, forming a great oval structure known as the heliosheath that extends outward for a further 40 AU at its stellar-windward side. The outer boundary of the sheath, the heliopause, is the point at which the solar wind finally terminates, and one enters the environment of interstellar space. Beyond the heliopause, at around 230 AU, lies the bow shock, a plasma "wake" left by the Sun as it travels through the Milky Way. But even at this point, we could not be said to have left the Solar System, for the Sun's gravity will still hold sway even up to the Oort Cloud, the great mass of comets which surrounds our Solar System like a shell and extends from 50,000 to 100,000 AU (nearly a light year) beyond the Sun. == The Solar System in small scales == Scaling down the size of the Solar System makes it easier for students to grasp the relative distances. The enormous ratio of interplanetary distances to planetary diameters makes constructing a scale model of the Solar System a challenging task. (For example, the distance between the Earth and the Sun is almost 12,000 times the diameter of the Earth.) Several places have built such models. ''See main article:'' Solar system model. == See also == * Astrological age * Astronomical symbols * Geological features of the Solar System * Laws of Kepler * :Category:Lists of Solar System objects * Minor planet * Numerical model of Solar System * Origin of life * Planetary system * Planetary pairs * Planetary nomenclature * Solar System by size * Planet (Table) * Timeline of Solar System astronomy * Titius-Bode law * Zodiacal light ==External links== * [http://space.jpl.nasa.gov NASA's Solar System Simulator] * [http://www.jpl.nasa.gov/solar_system NASA/JPL Solar System main page] * [http://members.aol.com/astroequation/ Astronomical Enigma] Mathematical Order in the orbits of the Solar system. * [http://www.solarviews.com Solarviews] * [http://celestia.sourceforge.net Celestia] Free 3D realtime space-simulation (OpenGL) * [http://www.nineplanets.org/ The Nine Planets] Comprehensive Solar system site by Bill Arnett * [http://www.krysstal.com/solarsys_planets.html Planetary data] * [http://www.solstation.com/habitable.htm Stars and Habitable Planets] * [http://www.michaelschultz.de/index_en.html Solar System] An interactive planets animation (145 zoom steps and time effects) * [http://my.execpc.com/~culp/space/timeline.html Timeline of Solar System exploration] * [http://www.anzwers.org/free/universe/index.html An Atlas of the Universe] Solar System fa:سامانه خورشیدی ga:An Grianchóras ms:Sistem suria simple:Solar system th:ระบบสุริยะ vi:Hệ Mặt Trời
== 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. -- User:The_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. User: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) User: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? user: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. --User:Maveric149 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. User: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? --User:Maveric149 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. User:Bryan Derksen :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. -- User:Oliver Pereira 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. -- User:Jeffq 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?) -- User: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. User: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.User: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. User:Evgeni Sergeev 02:31 18 Jul 2003 (UTC) We should indicate when something is an estimate. User: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%). -- User: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. User: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. -- User: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. -- User: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. -- User:Jeffq 13:51, 10 Jun 2004 (UTC) ==Navigation footers== User: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? -- User: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! User: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. -- User: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 natural satellite would be a good replacement? That way, all the major bodies of the solar system are no more than two clicks away. User:Bryan Derksen 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: User: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?! User:Nephelin 09:00, 26 Jan 2004 (UTC) ::the "align" attribute is not a legal part of the <table> tag in HTML 4.01, see [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": [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. :) User:Bryan Derksen 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 Centaur (planetoid)s to fill in the gap between asteroid belt and TNOs and then all the major populations of minor planet would be covered. User:Bryan Derksen 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 User:Bryan Derksen, and grew up independently from asteroid. Asteroid is far meatier. Should we fold asteroid belt back into asteroid? It feels so redundant.) -- User: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 :) User:Bryan Derksen 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. User:Bryan Derksen 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? User:Bryan Derksen 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:
:::Comments? -- User:Hike395 07:56, 28 Jan 2004 (UTC)
::::Looks good. Just tweaked the style to center it, though. :) User:Bryan Derksen 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. -- User:Hike395 03:29, 29 Jan 2004 (UTC)
:::::Yeah, that one's more compact without losing anything. Gets my vote. User:Bryan Derksen 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)... User: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 (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.
::::--User: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 -- User: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
Planetary systems Orion arm Planetary science th:Category:ระบบสุริยะ vi:Category:Thái Dương Hệ
Before I go hog wild and add all the solar system objects to this category, instead of just the planets (which I did largely as an experiment to see how these category things work), I'm starting to think that this may be a good opportunity to work out a different categorization scheme. Perhaps instead of just one generic "solar system" category, we could have a sort of heirarchy: *Solar system - generic concepts like asteroid, natural satellite, gegenschein, Yarkovsky effect, etc. *Solar system object - All the specific individual chunks of matter orbiting the Sun **Planet **Moon **Asteroid I haven't checked yet whether categories can be ''nested'', which would be really cool; "Solar system object" could mostly just contain sub-categories that way. So, what do people think? User:Bryan Derksen 15:11, 30 May 2004 (UTC) :Apparently they can be nested :Category:Japanese food that has for example :Category:Japan inside. User:Kpjas 15:17, 30 May 2004 (UTC) :Categories seem potentially cool. I think it would be better to put articles into a hierarchy, rather than pile everything into Solar System. And, of course, Solar System should be a sub-category of Astronomy (sub-category of Science, etc.). :The thing that confuses me is: are users going to use this for navigation or not? It isn't very prominent on the Monobook page. If this catches on, we can probably eliminate the navigation footer. I'm not sure. -- User:Hike395 15:20, 30 May 2004 (UTC) ::At the moment, I'm thinking that categories aren't really a replacement for the navigation bar footers - though perhaps they will help take some of the pressure off for adding huge numbers of them to articles, which IMO will be nice. I think categories are more likely to serve as a replacement for things like List of astronomical topics - if each of the articles listed here hadAstronomy in it, then the old list page becomes virtually obsolete. User:Bryan Derksen 15:26, 30 May 2004 (UTC)
:::That seems right. If so, we should make a category hierarchy of solar system objects that reflects the hierarchy we present in our List of solar system objects, right? So, would Moons be a sub-category here? Should we make one for the Kuiper Belt? --- User:Hike395 05:12, 1 Jun 2004 (UTC)
::::Yeah, I was thinking sub-categories like that. I'm not sure what would be the best way to divide up the minor planets; perhaps :Category:Asteroids, :Category:Centaur planetoids and :Category:Kuiper belt objects would be a good way to chop them up (perhaps with all of those as sub-categories of :Category:Minor planets)? :Category:Asteroids could get further sub-categories, but I don't imagine there are enough articles in the other two to warrant that for them just yet. A further issue; should there be a :Category:Planets, and should it contain exoplanets? If it doesn't, then there's only nine - a pretty small category. User:Bryan Derksen 07:56, 1 Jun 2004 (UTC)
:::::One cool feature about categories is that they don't have to be a strict hierarchy. So, we can make :Category:Planets, which can contain the 9 + exoplanets and :Category:Planets can belong to :Category:Astronomy ''and'' the 9 planets can just belong at the top level of :Category:Solar system (which makes sense from the Solar System way of looking at things). Under this scheme, Jupiter (planet) would belong to two categories, Solar System and Planet, which are both sub-categories of Astronomy (are categories singular or plural?).
:::::To solve the Centaur problem, we could have :Category:Minor planets, which can include :Category:Asteroids, :Category:Trans-Neptunian objects, and all of the misc minor planets like Centaurs. Are comets Minor Planets? --- User:Hike395 16:17, 1 Jun 2004 (UTC)
::::::I've generally been giving categories plural names when they're closely analogous to the "List of" articles. There's a lot of discussion about this kind of thing over on Wikipedia:Categorization, which I haven't been following very closely but which generally seems to conform to my expectations of how this will all play out (Wikipedia:Categorization#Naming_conventions, in the case above). This page also suggests that categories should be "as heirarchical as possible", but I don't think that impacts your suggestion above; most articles will likely belong to several distinct branches of whatever category tree gets cobbled together. Mars is both :Category:Planets and :Category:Red things, for example, which I'm sure must share a common root ''somewhere'' along the line. Re: comets as minor planets, the intro paragraph of minor planet says they are but I have a sneaking suspicion that I'm the one that wrote that so don't necessarily trust it. :) Should :Category:Minor planets be capitalized, BTW? I was under the impression not, but it's not my field. (edit: it just occurred to me that :Category:Planetology will probably be handy, too. So many categories, so little time. :) User:Bryan Derksen 23:56, 1 Jun 2004 (UTC)
:::::::The Minor Planet Center seems to draw a distinction between minor planets and comets, see first paragraph of [http://cfa-www.harvard.edu/iau/mpc.html] and [http://cfa-www.harvard.edu/iau/services/MPC.html]. So, comets should probably belong to :Category:Solar system, not :Category:Minor planets. Of course, this throws a spanner into Centaur (planetoid) What do you think? --- User:Hike395 04:26, 2 Jun 2004 (UTC)
== Minor planets ==
I agree with User:Hike395. Comets are not minor planets. The objects smaller than the planets would be clumped into minor objects like this, for example:
:Category:Solar System
::Category:Solar System planets
::Category:Minor objects
:::Category:Asteroids (Main belt/near Earth/Trojan asteroids)
:::Category:Comets
:::Category:Centaurs (possibly asteroid sub-group?)
:::Category:Kuiper Belt Objects (possibly asteroid sub-group?)
:Category:Planets (all planets)
As far as I know, all the bodies have been officially classified as asteroids unless a coma is found. Then they're (re)classified as comets. User:Jyril 12:48, 16 Jun 2004 (UTC)
:Hi, Jyril. Saw your comments at Talk:Asteroid and Talk:Minor planet, but haven't had time to respond. So, let's separate issues of categorization (here) and naming of articles (over at Talk:Asteroid?).
:I think that the primary goal of categories is to be reader-friendly. One aspect of being user-friendly is to not hide information that doesn't need to be hidden. Right now, there are only 23 articles in :Category:Solar System (and a lot of those are articles about transits). So, we don't need to hide the most common ones (the 9 planets) in a sub-category -- they just don't take up that much room. If anything, the less common articles (like the transits) belong in their own sub-category.
:After writing and browsing Wiki-categories for a while, I don't think we need to make a special "Minor objects" sub-category.. I would be happy with Asteroids, Comets, Centaurs, and TNOs (or KBOs) to live directly under Solar System. I would not hide Centaurs and KBOs under Asteroids, because most people would not think of looking there.
:Another possibility is to have Centaurs and KBOs live in both Asteroids and Solar System, although that is sort of redundant. It's a pity that Wikipedia does not permit 2-level-deep category browsing (like Yahoo)
:In summary, I think that reader-friendliness should be foremost in the design of the categorization.
:-- User:Hike395 15:46, 16 Jun 2004 (UTC)
== Moons ==
What should we do about :Category:Moons ? I can imagine a :Category:Saturn or a :Category:Saturn's moons, only the latter should be a sub-category of :Category:Moons. And it seems silly to have both kinds of Saturn categories, since they overlap 98%. -- User:Hike395 04:11, 2 Jun 2004 (UTC)
::Category:Saturn's moons would be a subcategory of :Category:Saturn as well, so the overlap is more a feature than a bug IMO. That way the root Saturn category wouldn't be cluttered full of moons, and the handful of other Saturn-related topics (Voyagers I and II, Cassini-Huygens, etc.) would be easier to read (assuming there are enough to warrant a Saturn category, that is). User:Bryan Derksen 04:17, 2 Jun 2004 (UTC)
::Cool! and :Category:Saturn's moons can be a child of both :Category:Saturn and :Category:Moons. This is actually working! I bet there is enough for a Saturn category. -- User:Hike395 04:26, 2 Jun 2004 (UTC)
==Categories that are "list of" versus categories that are "articles about"==
Been doing a lot of thinking about categories lately, and I think I may have been mixing two different philosophies inappropriately. For example, I put all of the articles whose primary subjects were moons of Jupiter in :Category:Jupiter's moons, but then I also added all the articles whose primary subjects were some specific aspect of one of Jupiter's moons or were about Jupiter's moons in general (eg, List of craters on Ganymede or Galilean moons). If Category:Jupiter's moons is meant to be interpreted as "list of Jupiter's moons", then this was incorrect. If on the other hand it's meant to be interpreted as "List of articles about Jupiter's moons", they should be there. I've currently "demoted" those non-moon articles down to the root Category:Jupiter, which I feel much safer in interpreting as "list of articles about Jupiter," but before I start doing that on a wider scale I figured I'd mention my indecision here and see what others think. User:Bryan Derksen 01:31, 10 Jun 2004 (UTC)
See other meanings of words starting from letter:
Words begining with Solar_system:
Solar_System
Solar_system
Solar_system
Solar_system
Solar_system
Solar_system/Factsheet_template
Solar_system/Factsheet_template
Solar_systems
Solar_system_by_size
Solar_system_by_size
Solar_system_by_volume
Solar_system_images
Solar_system_in_astrology
Solar_system_in_astrology
Solar_system_model
Solar_system_model
Solar System
#REDIRECT Solar system
Solar system
The Solar System consists of the Sun and all the objects that orbit around it, including meteors, asteroids, comets, natural satellites, and planets. The Earth is the third planet of the Solar System. ''Planetary systems'' are a more generic term for stars and the objects that orbit around them. == Solar System objects == The wide variety of objects that exist in the Solar System fall into several categories. In recent years many of these categories have been found to be less clear-cut than once thought. This encyclopedia employs the following divisions: *The Sun (☉) is a Stellar_classification G2 star that contains 99.86% of the system's mass. *The planets of the Solar System are those nine bodies traditionally labelled as such: Mercury (planet) (☿), Venus (planet) (♀), Earth (♁), Mars (planet) (♂), Jupiter (planet) (♃), Saturn (planet) (♄), Uranus (planet) (♅/), Neptune (planet) (♆) and Pluto (planet) (♇). **Sizeable objects that orbit these planets are Natural satellites. For a complete listing, see that article. **Artificial satellites orbiting the planets, mainly Earth, as well as probes heading into deep space. **Dust and other small particles that orbit these planets form planetary rings. **Space debris of artificial origin that can be found in orbit around Earth. **Planetesimals, from which the planets were originally formed, are sub-planetary bodies that accreted during the first years of the Solar System and that no longer exist. The name is also sometimes used to refer to asteroids and comets in general, or to asteroids below 10 km in diameter. *Asteroids are objects smaller than planets that lie roughly within the orbit of Jupiter and are composed in significant part of non-volatile minerals. They are subdivided into asteroid groups and :Category:Asteroid groups and families based on their specific orbital characteristics. **Asteroid moons are asteroids that orbit larger asteroids. They are not as clearly distinguished as planetary moons, sometimes being almost as large as their partners. **Trojan asteroids are located in either of Jupiter's Lagrange point, though the term is also sometimes used for asteroids in any other planetary Lagrange point as well. **Meteoroids are asteroids that range in size from roughly boulder sized to particles as small as dust. *Comets are composed largely of volatile ices and have highly eccentric orbits, generally having a perihelion within the orbit of the inner planets and an aphelion beyond Pluto. Short-period comets exist with apoapses closer than this, however, and old comets that have had most of their volatiles driven out by solar warming are often categorized as asteroids. Some comets with hyperbola orbits may also originate outside the Solar System. *Centaur (planetoid)s are icy comet-like bodies that have less-eccentric orbits so that they remain in the region between Jupiter and Neptune. *Trans-Neptunian objects, which are icy bodies whose semimajor axis lie beyond Neptune's. These are further subdivided: **Kuiper belt objects have orbits lying between 30 and 50 AU (astronomical units, an AU is approximately equal to the mean distance between Earth and Sun). This is thought to be the origin for short-period comets. Pluto is sometimes classified as a Kuiper belt object in addition to being a planet, and the Kuiper belt objects with Pluto-like orbits are called Plutinos. The remaining Kuiper belt objects are classified as Cubewanos in the main belt and scattered disk objects in the outer fringes. **Oort cloud objects, currently hypothetical, have orbits lying between 50,000 and 100,000 AU. This region is thought to be the origin of long-period comets. **The newly discovered object 90377 Sedna, with a highly elliptical orbit extending from about 76 to 928 AU, does not obviously fit in either category, although its discoverers argue that it should be considered a part of the Oort cloud. * Small quantities of dust are present in the interplanetary medium and are responsible for the phenomenon of zodiacal light. Some of the dust is likely interstellar dust from outside the Solar System. Jupiter constitutes most of the mass of the Solar System outside the Sun: 0.1% of the mass of the Solar System. In turn, Saturn constitutes most of the remaining mass, then Uranus and Neptune, then Earth and Venus (see also below). == Origin and evolution of the Solar System == The Solar System is believed to have formed from the Solar Nebula, the collapsing cloud of gas and dust which gave birth to the Sun. As it underwent gravitational collapse, the Solar Nebula would have collapsed into a disk, with the protostar accreting at the centre. As the protosun heated up, volatile substances were driven away from the central regions of the nebula - hence the formation of rocky planets closer to the sun and gas giants further out. For many years, our own system was the only planetary system known, and so theories only had to explain one system to be plausible. The discovery in recent years of many external systems (see Exoplanet) has uncovered systems very different to our own, and theories of planetary system formation have had to be revised accordingly. In particular, many external systems contain a hot Jupiter - a planet comparable to or larger than Jupiter orbiting very close to the parent star, perhaps orbiting it in a matter of days. It has been hypothesised that while the giant planets in these systems formed in the same place as the gas giants in our system did, some sort of migration took place which resulted in the giant planet spiralling in towards the parent star. Any terrestrial planets which had previously existed would presumably either be destroyed or ejected from the system. == Galactic orbit of the Solar System == The Solar System is part of the Milky Way galaxy, a spiral galaxy with a diameter of about 1 E20 m light years containing approximately 200 billion stars, of which our Sun is fairly typical. Estimates place the Solar System at between 25,000 and 28,000 light years from the galactic center. Its speed is about 220 kilometre per second, and it completes one revolution every 1 E15 s. At the galactic location of the Solar System, the escape velocity with regard to the gravity of the Milky Way is about 1000 km/s. The Solar System appears to have a very unusual orbit. It is both extremely close to being circular, and at nearly the exact distance at which the orbital speed matches the speed of the compression waves that form the spiral arms. The Solar System appears to have remained between spiral arms for most of the existence of life on Earth. The radiation from supernova in spiral arms could theoretically sterilize planetary surfaces, preventing the formation of large animal life on land. By remaining out of the spiral arms, Earth may be unusually free to form large animal life on its surface. ==Discovery and exploration of the Solar System== Because of the Geocentric model perspective from which humans viewed the Solar System, its nature and structure were long misperceived. The apparent motions of Solar System objects as viewed from a moving Earth were believed to be their actual motions about a stationary Earth. In addition, many Solar System objects and phenomena are not directly sensible by humans without technical aids. Thus both conceptual and technological advances were required in order for the Solar System to be correctly understood. The first and most fundamental of these advances was the Nicolaus Copernicus Revolution, which adopted a heliocentric model for the motions of the planets. Indeed, the term "Solar System" itself derives from this perspective. But the most important consequences of this new perception came not from the central position of the Sun, but from the orbital position of the Earth, which suggested that the Earth was itself a planet. This was the first indication of the true nature of the planets. Also, the lack of perceptible stellar parallax despite the Earth's orbital motion indicated the extreme remoteness of the fixed stars, which prompted the speculation that they could be objects similar to the Sun, perhaps with planets of their own. Since the start of the space age, a great deal of exploration has been performed by unmanned space missions that have been organized and executed by various space agencies. The first probe to land on another Solar System body was the Soviet Union's Luna 2 probe, which impacted on the Moon in 1959. Since then, increasingly distant planets have been reached, with probes landing on Venus (planet) in 1965, Mars (planet) in 1976, the asteroid 433 Eros in 2001, and Saturn (planet)'s moon Titan (moon) in 2005. Spacecraft have also made close approaches to other planets: Mariner 10 passed Mercury (planet) in 1973. The first probe to explore the outer planets was Pioneer 10, which flew by Jupiter (planet) in 1973. Pioneer 11 was the first to visit Saturn (planet), in 1979. The Voyager program probes performed a grand tour of the outer planets following their launch in 1977, with both probes passing Jupiter in 1979 and Saturn in 1980-1981. Voyager 2 then went on to make close approaches to Uranus (planet) in 1986 and Neptune (planet) in 1989. The Voyager probes are now far beyond Pluto (planet)'s orbit, and astronomers anticipate that they will encounter the heliopause which defines the outer edge of the Solar System in the next few years. Pluto remains the only planet not having been visited by a man-made spacecraft, though that will change with the launching of New Horizons by NASA in January 2006. It is scheduled to fly by Pluto in July 2015 and then make an extensive study of as many Kuiper Belt objects as it can. Through these unmanned missions, we have been able to get close-up photographs of most of the planets and, in the case of landers, perform tests of their soils and Celestial_body_atmosphere. Manned exploration, meanwhile, has only taken human beings as far as the Moon, in the Apollo program. The last manned landing on the Moon Apollo 17 in 1972, but the recent discovery of ice in deep craters in the polar regions of the Moon has prompted speculation that mankind may return to the Moon in the next decade or so. Manned missions to Mars (planet) have been eagerly anticipated by generations of space enthusiasts, and it was hoped that the first manned interplanetary flights would take place in the 1980's, after the successful Apollo program. The United States now plans manned Lunar and Mars missions as part of the new Vision for Space Exploration. == The Solar System and other planetary systems == Until recently, the Solar System was the only known example of a planetary system, although it was widely believed that other comparable systems did exist. A number of such systems have now been detected, although the information available about them is very limited. See extrasolar planet for more information. == Attributes of major planets == {| cellspacing=2 cellpadding=0 width=200 align=right style="font-size:smaller; clear:right;" |+ style="font-size:larger;"| Scale of planetary orbits.
(million kilometres) |- |colspan=2|
** Soon after its discovery in 1930, Pluto was classified a planet by the International Astronomical Union. However, based on additional discoveries since that time, some astronomers have suggested Pluto_(planet)#The_Pluto_debate of that decision. |- bgcolor=#ccccff ! Planet ! Equatorial
diameter ! Mass ! Orbital
radius (Astronomical Unit) ! Orbital period
(years) ! Day
(days) ! List of natural satellites |- | Mercury (planet) | align="center" | 0.382 | align="center" | 0.06 | align="center" | 0.38 | align="center" | 0.241 | align="center" | 58.6 | align="center" | none |- | Venus (planet) | align="center" | 0.949 | align="center" | 0.82 | align="center" | 0.72 | align="center" | 0.615 | align="center" | -243 | align="center" | none |- | Earth* | align="center" | 1.00 | align="center" | 1.00 | align="center" | 1.00 | align="center" | 1.00 | align="center" | 1.00 | align="center" | Moon |- | Mars (planet) | align="center" | 0.53 | align="center" | 0.11 | align="center" | 1.52 | align="center" | 1.88 | align="center" | 1.03 | align="center" | Mars's natural satellites |- | Jupiter (planet) | align="center" | 11.2 | align="center" | 318 | align="center" | 5.20 | align="center" | 11.86 | align="center" | 0.414 | align="center" | Jupiter's natural satellites |- | Saturn (planet) | align="center" | 9.41 | align="center" | 95 | align="center" | 9.54 | align="center" | 29.46 | align="center" | 0.426 | align="center" | Saturn's natural satellites |- | Uranus (planet) | align="center" | 3.98 | align="center" | 14.6 | align="center" | 19.22 | align="center" | 84.01 | align="center" | 0.718 | align="center" | Uranus's natural satellites |- | Neptune (planet) | align="center" | 3.81 | align="center" | 17.2 | align="center" | 30.06 | align="center" | 164.79 | align="center" | 0.671 | align="center" | Neptune's natural satellites |- | Pluto (planet)** | align="center" | 0.24 | align="center" | 0.0017 | align="center" | 39.5 | align="center" | 248.5 | align="center" | 6.5 | align="center" | Charon (moon) |} Of the other objects, Ganymede (moon) has the largest mass (0.02). See Planet (Table) for a more comprehensive table. == Attributes of selected minor planets == Some objects are intermediate in size between planets and the lumps of rock called asteroids. These mid-sized objects are now often called 'planetoids' or minor planets: most scientists consider them too small to be "true" planets, while a few scientists point out that these minor planets exhibit the same gravitational forces which affect major planets. Just one planetoid, 1 Ceres, lies in the inner reaches of the Solar System. All other planetoids occur at the fringe of our planetary system. All attributes below are measured relative to the Earth: {| class="toccolours" border=1 cellspacing=0 cellpadding=2 style="text-align:center; border-collapse:collapse;" |- bgcolor=#ccccff ! Planetoid ! Equatorial
diameter ! Mass ! Orbital radius
(Astronomical unit) ! Orbital period
(years) ! Day
(days) |- | 1 Ceres | align="center" | 0.075 | align="center" | 0.000 158 | align="center" | 2.767 | align="center" | 4.603 | align="center" | 0.3781 |- | 90482 Orcus | align="center" | 0.066 - 0.148 | align="center" | 0.000 10 - 0.001 17 | align="center" | 39.47 | align="center" | 248 | align="center" | ? |- | 28978 Ixion | align="center" | ~0.083 | align="center" | 0.000 10 - 0.000 21 | align="center" | 39.49 | align="center" | 248 | align="center" | ? |- | (55636) 2002 TX300 | align="center" | 0.0745 | align="center" | ? | align="center" | 43.102 | align="center" | 283 | align="center" | ? |- | 20000 Varuna | align="center" | 0.066 - 0.097 | align="center" | 0.000 05 - 0.000 33 | align="center" | 43.129 | align="center" | 283 | align="center" | 0.132 or 0.264 |- | 50000 Quaoar | align="center" | 0.078 - 0.106 | align="center" | 0.000 17 - 0.000 44 | align="center" | 43.376 | align="center" | 285 | align="center" | ? |- | 90377 Sedna | align="center" | 0.093 - 0.141 | align="center" | 0.000 14 - 0.001 02 | align="center" | 76-990 | align="center" | 11500 | align="center" | 20 |} == Other facts == The total surface area of the Solar System's objects that have solid surfaces and a diameter greater than 1 km is ~1.7×109 kilometer2 —about 11 times the area of the Earth's land masses. (''[http://uts.cc.utexas.edu/~gwk/images/SolSys/SolSys.html]'') It has been suggested that the Sun may be part of a binary star system, with a distant companion named Nemesis (star). Nemesis was proposed to explain some timing regularities of the great extinctions of life on Earth. The hypothesis says that Nemesis creates periodical perturbations in the Oort cloud of comets surrounding the Solar System, causing a "comet shower". Some of them hit Earth, causing destruction of life. This hypothesis is no longer taken seriously by most scientists. ==Edge of the Solar System== The point at which the Solar System ends and interstellar space begins is not precisely defined, since its outer boundaries are delineated by two separate forces: the solar wind and the Sun's gravity. The charted regions of our Solar System exist within a highly tenuous "atmosphere" of solar wind; charged particles eminating from the Sun that expand outward in a great bubble to about 95 AU (three times the orbit of Pluto). The edge of this bubble is known as the termination shock; the point at which the solar wind collides with the opposing winds of the interstellar medium. Here the wind slows, condenses and becomes more turbulent, forming a great oval structure known as the heliosheath that extends outward for a further 40 AU at its stellar-windward side. The outer boundary of the sheath, the heliopause, is the point at which the solar wind finally terminates, and one enters the environment of interstellar space. Beyond the heliopause, at around 230 AU, lies the bow shock, a plasma "wake" left by the Sun as it travels through the Milky Way. But even at this point, we could not be said to have left the Solar System, for the Sun's gravity will still hold sway even up to the Oort Cloud, the great mass of comets which surrounds our Solar System like a shell and extends from 50,000 to 100,000 AU (nearly a light year) beyond the Sun. == The Solar System in small scales == Scaling down the size of the Solar System makes it easier for students to grasp the relative distances. The enormous ratio of interplanetary distances to planetary diameters makes constructing a scale model of the Solar System a challenging task. (For example, the distance between the Earth and the Sun is almost 12,000 times the diameter of the Earth.) Several places have built such models. ''See main article:'' Solar system model. == See also == * Astrological age * Astronomical symbols * Geological features of the Solar System * Laws of Kepler * :Category:Lists of Solar System objects * Minor planet * Numerical model of Solar System * Origin of life * Planetary system * Planetary pairs * Planetary nomenclature * Solar System by size * Planet (Table) * Timeline of Solar System astronomy * Titius-Bode law * Zodiacal light ==External links== * [http://space.jpl.nasa.gov NASA's Solar System Simulator] * [http://www.jpl.nasa.gov/solar_system NASA/JPL Solar System main page] * [http://members.aol.com/astroequation/ Astronomical Enigma] Mathematical Order in the orbits of the Solar system. * [http://www.solarviews.com Solarviews] * [http://celestia.sourceforge.net Celestia] Free 3D realtime space-simulation (OpenGL) * [http://www.nineplanets.org/ The Nine Planets] Comprehensive Solar system site by Bill Arnett * [http://www.krysstal.com/solarsys_planets.html Planetary data] * [http://www.solstation.com/habitable.htm Stars and Habitable Planets] * [http://www.michaelschultz.de/index_en.html Solar System] An interactive planets animation (145 zoom steps and time effects) * [http://my.execpc.com/~culp/space/timeline.html Timeline of Solar System exploration] * [http://www.anzwers.org/free/universe/index.html An Atlas of the Universe] Solar System fa:سامانه خورشیدی ga:An Grianchóras ms:Sistem suria simple:Solar system th:ระบบสุริยะ vi:Hệ Mặt Trời
Solar system
== 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. -- User:The_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. User: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) User: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? user: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. --User:Maveric149 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. User: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? --User:Maveric149 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. User:Bryan Derksen :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. -- User:Oliver Pereira 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. -- User:Jeffq 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?) -- User: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. User: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.User: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. User:Evgeni Sergeev 02:31 18 Jul 2003 (UTC) We should indicate when something is an estimate. User: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%). -- User: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. User: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. -- User: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. -- User: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. -- User:Jeffq 13:51, 10 Jun 2004 (UTC) ==Navigation footers== User: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? -- User: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! User: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. -- User: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 natural satellite would be a good replacement? That way, all the major bodies of the solar system are no more than two clicks away. User:Bryan Derksen 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: User: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?! User:Nephelin 09:00, 26 Jan 2004 (UTC) ::the "align" attribute is not a legal part of the <table> tag in HTML 4.01, see [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": [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. :) User:Bryan Derksen 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 Centaur (planetoid)s to fill in the gap between asteroid belt and TNOs and then all the major populations of minor planet would be covered. User:Bryan Derksen 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 User:Bryan Derksen, and grew up independently from asteroid. Asteroid is far meatier. Should we fold asteroid belt back into asteroid? It feels so redundant.) -- User: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 :) User:Bryan Derksen 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. User:Bryan Derksen 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? User:Bryan Derksen 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 (planet) | Venus (planet) | Earth | Mars (planet) | Asteroids | Jupiter (planet) | Saturn (planet) | Uranus (planet) | Neptune (planet) | Pluto (planet) |
| ''See also'' List of solar system objects | Astronomical objects |
| The Solar System |
|---|
| Sun | Mercury (planet) | Venus (planet) | Earth | Mars (planet) | Asteroid | Jupiter (planet) | Saturn (planet) | Uranus (planet) | Neptune (planet) | Pluto (planet) |
| For other objects and regions, see: List of solar system objects | Astronomical objects |
Solar system
Planetary systems Orion arm Planetary science th:Category:ระบบสุริยะ vi:Category:Thái Dương Hệ
Solar system
Before I go hog wild and add all the solar system objects to this category, instead of just the planets (which I did largely as an experiment to see how these category things work), I'm starting to think that this may be a good opportunity to work out a different categorization scheme. Perhaps instead of just one generic "solar system" category, we could have a sort of heirarchy: *Solar system - generic concepts like asteroid, natural satellite, gegenschein, Yarkovsky effect, etc. *Solar system object - All the specific individual chunks of matter orbiting the Sun **Planet **Moon **Asteroid I haven't checked yet whether categories can be ''nested'', which would be really cool; "Solar system object" could mostly just contain sub-categories that way. So, what do people think? User:Bryan Derksen 15:11, 30 May 2004 (UTC) :Apparently they can be nested :Category:Japanese food that has for example :Category:Japan inside. User:Kpjas 15:17, 30 May 2004 (UTC) :Categories seem potentially cool. I think it would be better to put articles into a hierarchy, rather than pile everything into Solar System. And, of course, Solar System should be a sub-category of Astronomy (sub-category of Science, etc.). :The thing that confuses me is: are users going to use this for navigation or not? It isn't very prominent on the Monobook page. If this catches on, we can probably eliminate the navigation footer. I'm not sure. -- User:Hike395 15:20, 30 May 2004 (UTC) ::At the moment, I'm thinking that categories aren't really a replacement for the navigation bar footers - though perhaps they will help take some of the pressure off for adding huge numbers of them to articles, which IMO will be nice. I think categories are more likely to serve as a replacement for things like List of astronomical topics - if each of the articles listed here had
See other meanings of words starting from letter:
S
SB | SC | SD | SE | SF | SG | SH | SI | SJ | SK | SL | SM | SN | SO | SP | SR | SS | ST | SU | SW | SX | SY | SZ |Words begining with Solar_system:
Solar_System
Solar_system
Solar_system
Solar_system
Solar_system
Solar_system/Factsheet_template
Solar_system/Factsheet_template
Solar_systems
Solar_system_by_size
Solar_system_by_size
Solar_system_by_volume
Solar_system_images
Solar_system_in_astrology
Solar_system_in_astrology
Solar_system_model
Solar_system_model
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