Planetary_system - Wikiparency

# Planetary system  **Microsim — three.js (Wikitube framework):** *The orbits (Solar System explorer)* <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/solar/Solar_System.html?view=orbits&embed=1" data-title="The orbits (Solar System explorer)"></div> *The Solar System explorer locked on this article's state (`?view=orbits`); every object and population of the [[PORTAL_Solar_System|Solar System portal]] has its own state in the same scene.*   *Try: drag the view round until it is edge-on and see the eight planetary orbits collapse into one thin line while Pluto's and Eris's orbits tilt out of it; press l to label the bodies and find Halley's Comet on its steep, elongated path; then set the speed to 10 years/s and watch Halley travel the opposite way round the Sun from every planet.* A **planetary system** is a set of non-stellar bodies bound by [[Gravity|gravity]] to a star or group of stars and in orbit around it. Besides planets it can include [[Dwarf_planet|dwarf planets]], [[Asteroid|asteroids]], moons, [[Comet|comets]], [[Meteoroid|meteoroids]], planetesimals and discs of gas and dust.[^darling2004][^iau-oae] The [[PORTAL_Solar_System|Solar System]], with [[Earth]], seven other planets and a great many smaller bodies orbiting the [[Sun]], is the one known in detail; systems around other stars are sometimes called exoplanetary systems, and by convention take the name of their host star.[^nasa-ss] By September 2026 the NASA Exoplanet Archive listed 6,366 confirmed exoplanets around 4,775 stars, of which 1,068 are known to host more than one planet.[^nea] The first planets beyond the Solar System were found in 1992, around a pulsar, and the first around a Sun-like star in 1995.[^wolszczan1992][^mayor1995] The systems found since show that the Solar System's arrangement, small rocky planets inside and giant planets on nearly circular orbits outside, is only one of several common patterns.[^mishra2023a] Of special interest is each system's [[Habitable_zone|habitable zone]], the band of orbits where a planet could keep liquid [[Water|water]] on its surface.[^petigura2013] The explorer at the top of this page opens on the orbits of the Solar System: nearly circular, nearly flat paths for the eight planets, the tilted orbits of [[Pluto]] and [[Eris_(dwarf_planet)|Eris]], and [[Halley's_Comet|Halley's Comet]] circling the wrong way. It shows the one planetary system that can be drawn in full. ## Definition The International Astronomical Union's education office describes a planetary system as the planets orbiting one or more stars, brown dwarfs or stellar remnants, and both the IAU and NASA treat the Solar System as one.[^iau-oae][^nasa-ss] Other definitions are wider and take in every body gravitationally bound to the host, not only the planets.[^pierrehumbert2021] The difference matters little in practice, because in the Solar System the planets hold nearly all of the mass outside the Sun, and Jupiter dominates even them: at about 318 Earth masses it outweighs the other seven planets together by a factor of about 2.5 (derived).[^nasa-fs] A system can have more than one star. [[Alpha_Centauri|Alpha Centauri]], the nearest stellar system to the Sun, is a triple, and one of its stars, Proxima Centauri, has a planet found in 2016; the planets of such systems orbit either one star or the whole group.[^anglada2016] The same logic applies at the smaller scale of a planet's own moons, which form a satellite system inside the planetary one, each held within its planet's [[Hill_sphere|Hill sphere]]. In the explorer, the planets' paths are drawn from JPL orbital elements, and Pluto, Eris and Halley from the JPL Small-Body Database; the view keeps each orbit's shape and tilt, so the flatness of the planetary system and the exceptions to it can be read directly.[^jpl-t1][^jpl-sbdb] ## History ### Heliocentrism The idea that the Earth and the other planets circle the Sun, rather than the Sun and planets circling the Earth, is old. Aristarchus of Samos proposed it in the third century BC; his own account is lost, and it is known from a brief passage in Archimedes' *Sand Reckoner*. Few ancient astronomers accepted it.[^dreyer1953] Some historians have read the Indian astronomer Aryabhata's *Āryabhaṭīya* as implicitly heliocentric, a reading others reject.[^swerdlow1973] ### Discovery of the Solar System Nicolaus Copernicus's *De revolutionibus orbium coelestium* (1543) gave the first mathematically predictive heliocentric model. Over the following century and a half, Galileo's telescopic observations, [[Johannes_Kepler|Kepler]]'s laws of elliptical orbits and [[Isaac_Newton|Newton]]'s [[Newton's_law_of_universal_gravitation|law of universal gravitation]] established that the planets move around the Sun under the same physics that governs bodies on Earth.[^newton1999] Seen this way, the Sun's family became the first planetary system to be understood as a system. ### Speculation on extrasolar planetary systems In the sixteenth century Giordano Bruno argued that the stars are suns with planets of their own.[^britannica1991] Newton raised the same possibility in the General Scholium of the *Principia*, suggesting that if the fixed stars are centres of similar systems they would be built on a similar design.[^newton1999] The idea became common in astronomy and fiction long before there was any evidence for it. ### Detection of exoplanets The first confirmed exoplanets were bodies of a few Earth masses orbiting the pulsar PSR B1257+12, announced by Aleksander Wolszczan and Dale Frail in 1992.[^wolszczan1992] In 1995 Michel Mayor and Didier Queloz found 51 Pegasi b, a planet of about half Jupiter's mass circling a Sun-like star every 4.2 days.[^mayor1995] Radial-velocity surveys, and later transit surveys such as NASA's Kepler mission, have since raised the count into the thousands.[^borucki2011][^nea] ## Origin and evolution Planetary systems form in [[Protoplanetary_disk|protoplanetary discs]], the flattened discs of gas and dust that surround young stars. That origin explains the broad features of the Solar System that the explorer shows: the planets orbit in nearly the same plane and in the same direction because they grew in one rotating disc, and the division between rocky and giant planets follows the [[Frost_line_(astrophysics)|frost line]] in that disc. Formation is violent as well as orderly. Much material is scattered into distant orbits, some planets are thrown out altogether to become free-floating, and giant planets can migrate, as in the [[Nice_model|Nice model]] and the [[Grand_tack_hypothesis|grand tack]] proposed for the Solar System.[^weidenschilling1996] The details are covered under [[Formation_and_evolution_of_the_Solar_System|formation and evolution of the Solar System]]. ### Evolved systems A system does not stay fixed after formation. When a massive star explodes as a supernova, most of its planets are likely destroyed or freed, and the planets found around pulsars may have formed afterwards, from the remains of a companion star or from a disc of fallback material.[^podsiadlowski1993][^perna2014] Stars of lower mass have smaller discs, so they tend to form compact systems of rocky and icy planets rather than gas giants.[^miguel2020] When a star like the Sun swells into a red giant, it engulfs its inner planets, and as it loses mass the survivors' orbits widen.[^ferreira2023] ### Planet capture Free-floating planets in young star clusters move at speeds similar to the stars and can be recaptured, usually into wide orbits of roughly 100 to 100,000 AU and at arbitrary tilts to any planets already present. Hagai Perets and Thijs Kouwenhoven found that capture becomes less efficient in larger clusters and more efficient around more massive stars, but hardly depends on the planet's mass.[^perets2012] ## System architectures The Solar System's arrangement, with small rocky planets inside and a gas giant on a near-circular orbit farther out, appears to be uncommon. Many known systems instead contain several super-Earths packed closer to their star than [[Mercury_(planet)|Mercury]] is to the Sun, and others have a hot Jupiter, a giant planet orbiting within a few days of its star.[^borucki2011][^fortney2021] Migration and gravitational scattering have both been proposed to bring giant planets so close in, and models suggest that the conditions in the disc largely set the outcome.[^weidenschilling1996][^hasegawa2011] ### Classification Lokesh Mishra and colleagues sort systems into four classes by how mass is distributed among their planets.[^mishra2023a][^mishra2023b] In *similar* systems all planets have comparable masses; this is the most common class, and TRAPPIST-1 is an example. Such systems show the "peas in a pod" pattern: neighbouring planets tend to be alike in size and mass and evenly spaced.[^mishra2021] In *mixed* systems masses vary widely. In *ordered* systems mass increases with distance from the star, as in the Solar System. *Anti-ordered* systems, with the heaviest planets innermost, have not been observed. ### Components Most known exoplanets orbit F, G and K stars, partly because searches have concentrated on such stars and partly because red dwarfs are less likely to host planets massive enough to show up in radial-velocity surveys.[^cumming2008][^bonfils2005] Many of them are unlike anything in the Solar System: hot Jupiters and hot Neptunes with periods of a few days, and super-Earths between Earth and Neptune in mass.[^fortney2021][^nasa-superearth] Discs of debris are common too. The Solar System has four large ones, the [[Asteroid_belt|asteroid belt]], [[Kuiper_belt|Kuiper belt]], [[Scattered_disc|scattered disc]] and [[Oort_cloud|Oort cloud]], and dust analogous to its [[Interplanetary_dust_cloud|zodiacal dust]] has been detected around Fomalhaut and Tau Ceti among others.[^lebreton2013][^difolco2007] Exocomets were first detected in 1987 around the young star Beta Pictoris.[^ferlet1987] ### Orbital configurations The Solar System's orbits are close to circular, but many exoplanets have much more eccentric ones.[^winn2015] Mutual inclinations, the angles between planets' orbital planes, have been measured in only a few systems; in Upsilon Andromedae two planets are tilted about 30° to each other.[^deitrick2015] In resonant systems the orbital periods form simple integer ratios, as in the four planets of Kepler-223, whose periods stand in the ratios 3:4:6:8,[^mills2016] and giant planets are found in resonance more often than small ones.[^winn2015] The Solar System is only weakly interacting: its planets perturb one another slightly, so that [[Kepler's_laws_of_planetary_motion|Kepler's laws]] hold to a good approximation. Its eight planets have inclinations within about 7° of the [[Ecliptic|ecliptic]], Mercury's being the largest, while Pluto's orbit is tilted 17°, Eris's about 44° and Halley's 162°, which means Halley orbits backwards.[^nasa-fs][^jpl-sbdb] ## Zones ### Habitable zone The habitable zone is the range of distances at which a planet could hold liquid water on its surface, neither so close that water boils away nor so far that it freezes. Its location depends on the star's luminosity, which changes with its mass and age, and on the planet's atmosphere, which sets how well it keeps heat.[^petigura2013] If life below the surface is counted, the zone extends much farther out, since more than half of Earth's biomass may be subsurface microbes and temperature rises with depth.[^amend2005] Erik Petigura and colleagues estimated from Kepler data that 22 ± 8% of Sun-like stars have an Earth-sized planet in the habitable zone, with Earth-sized taken as one to two Earth radii and the zone as 0.25 to 4 times the stellar flux Earth receives.[^petigura2013] ### Venus zone The Venus zone is the band closer in, where a rocky planet would suffer a runaway greenhouse like [[Venus]]'s but keep its atmosphere. Stephen Kane and colleagues estimated from Kepler data that about 32% of red dwarfs host potentially Venus-like planets, rising to 45% for G- and K-type stars; confirming any of them needs spectra of their atmospheres.[^kane2014] ## Galactic distribution of planets The [[Milky_Way|Milky Way]] is about 100,000 light-years across, but most planets with known distances lie within a few thousand light-years of the Sun, because the transit and radial-velocity methods favour nearby stars. Gravitational microlensing can find planets much farther away; MOA-2011-BLG-293Lb, about 7.7 kiloparsecs away, was the first planet thought likely to lie in the galactic bulge.[^batista2014] Whether planets are commoner in the disc or the bulge is still being measured. A star's composition matters. Population I stars, young and rich in elements heavier than helium, are more likely to host planets, because planets form from those heavy elements; the Sun is one of them.[^lineweaver2001] The older, metal-poor Population II stars of the halo and bulge should have fewer. The first planets claimed around a halo star, Kapteyn's star, which has about an eighth of the Sun's metal content, were later questioned: the signal of one was traced to stellar activity.[^anglada2014][^robertson2015] The mix of stellar ages and compositions differs between spiral and elliptical galaxies, so planet formation should differ between them too.[^gonzalez2005] ## See also - [[Formation_and_evolution_of_the_Solar_System]] - [[Protoplanetary_disk]] - [[Habitable_zone]] - [[Kepler's_laws_of_planetary_motion]] - List of multiplanetary systems (plain text: not yet on Wikitube) ## Notes The comparison of Jupiter's mass with that of the small-body populations uses the NASA fact sheet value of 1,898 × 10²⁴ kg for Jupiter, 317.8 Earth masses. The exoplanet counts are from the NASA Exoplanet Archive's composite parameters table, queried on 18 September 2026; they change weekly. ## References [^darling2004]: Darling, D. J. (2004). *The Universal Book of Astronomy: From the Andromeda Galaxy to the Zone of Avoidance*. Wiley, p. 394. ISBN 978-0-471-26569-6. [^iau-oae]: IAU Office of Astronomy for Education. "Planetary system" (glossary). https://astro4edu.org/resources/glossary/term/468/ [^nasa-ss]: NASA Science (13 November 2017). "Solar System: Facts". https://science.nasa.gov/solar-system/solar-system-facts/ [^nea]: NASA Exoplanet Archive. Planetary Systems Composite Parameters table (pscomppars), counts of planets, host stars and hosts with sy_pnum > 1. https://exoplanetarchive.ipac.caltech.edu/ (queried 2026-09-18). [^wolszczan1992]: Wolszczan, A.; Frail, D. A. (1992). "A planetary system around the millisecond pulsar PSR1257+12". *Nature* 355: 145–147. https://doi.org/10.1038/355145a0 [^mayor1995]: Mayor, M.; Queloz, D. (1995). "A Jupiter-mass companion to a solar-type star". *Nature* 378: 355–359. https://doi.org/10.1038/378355a0 [^mishra2023a]: Mishra, L.; Alibert, Y.; Udry, S.; Mordasini, C. (2023). "Framework for the architecture of exoplanetary systems. I. Four classes of planetary system architecture". *Astronomy & Astrophysics* 670: A68. https://doi.org/10.1051/0004-6361/202243751 [^mishra2023b]: Mishra, L.; Alibert, Y.; Udry, S.; Mordasini, C. (2023). "Framework for the architecture of exoplanetary systems. II. Nature versus nurture: Emergent formation pathways of architecture classes". *Astronomy & Astrophysics* 670: A69. https://doi.org/10.1051/0004-6361/202244705 [^mishra2021]: Mishra, L.; Alibert, Y.; Leleu, A.; Emsenhuber, A.; Mordasini, C.; Burn, R.; et al. (2021). "The New Generation Planetary Population Synthesis (NGPPS). VI. Introducing KOBE: Kepler Observes Bern Exoplanets. Theoretical perspectives on the architecture of planetary systems: Peas in a pod". *Astronomy & Astrophysics* 656: A74. https://doi.org/10.1051/0004-6361/202140761 [^petigura2013]: Petigura, E. A.; Howard, A. W.; Marcy, G. W. (2013). "Prevalence of Earth-size planets orbiting Sun-like stars". *Proceedings of the National Academy of Sciences* 110: 19273–19278. https://doi.org/10.1073/pnas.1319909110 [^pierrehumbert2021]: Pierrehumbert, R. T. (2021). *Planetary Systems: A Very Short Introduction*. Oxford University Press, pp. 1–13. https://doi.org/10.1093/actrade/9780198841128.003.0001 [^nasa-fs]: NASA NSSDCA. "Planetary Fact Sheet". https://nssdc.gsfc.nasa.gov/planetary/factsheet/ (fetched 2026-09-18). [^jpl-t1]: JPL Solar System Dynamics. "Approximate Positions of the Planets", Table 1. https://ssd.jpl.nasa.gov/planets/approx_pos.html [^jpl-sbdb]: JPL Solar System Dynamics. Small-Body Database Lookup: 134340 Pluto, 136199 Eris, 1P/Halley. https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html (elements fetched 2026-09-18). [^dreyer1953]: Dreyer, J. L. E. (1953). *A History of Astronomy from Thales to Kepler*. Dover, pp. 135–148. [^swerdlow1973]: Swerdlow, N. (1973). "Review: A lost monument of Indian astronomy". *Isis* 64: 239–243. [^newton1999]: Newton, I.; Cohen, I. B.; Whitman, A. (1999). *The Principia: A New Translation and Guide*. University of California Press, p. 940. ISBN 0-520-20217-1. [^britannica1991]: "Cosmos". *The New Encyclopædia Britannica*, 15th ed. (1991), vol. 16, p. 787. [^borucki2011]: Borucki, W. J.; Koch, D. G.; Basri, G.; Batalha, N.; Brown, T. M.; Bryson, S. T.; et al. (2011). "Characteristics of planetary candidates observed by Kepler. II. Analysis of the first four months of data". *The Astrophysical Journal* 736: 19. https://doi.org/10.1088/0004-637X/736/1/19 [^hasegawa2011]: Hasegawa, Y.; Pudritz, R. E. (2011). "The origin of planetary system architectures. I. Multiple planet traps in gaseous discs". *Monthly Notices of the Royal Astronomical Society* 417: 1236–1259. https://doi.org/10.1111/j.1365-2966.2011.19338.x [^weidenschilling1996]: Weidenschilling, S. J.; Marzari, F. (1996). "Gravitational scattering as a possible origin for giant planets at small stellar distances". *Nature* 384: 619–621. https://doi.org/10.1038/384619a0 [^podsiadlowski1993]: Podsiadlowski, P. (1993). "Planet formation scenarios". In *Planets Around Pulsars*, ASP Conference Series 36: 149. Bibcode 1993ASPC...36..149P. [^perna2014]: Perna, R.; Duffell, P.; Cantiello, M.; MacFadyen, A. (2014). "The fate of fallback matter around newly born compact objects". *The Astrophysical Journal* 781: 119. https://doi.org/10.1088/0004-637X/781/2/119 [^miguel2020]: Miguel, Y.; Cridland, A.; Ormel, C. W.; Fortney, J. J.; Ida, S. (2020). "Diverse outcomes of planet formation and composition around low-mass stars and brown dwarfs". *Monthly Notices of the Royal Astronomical Society* (published online 30 October 2019). https://doi.org/10.1093/mnras/stz3007 [^ferreira2023]: Ferreira, B. (3 May 2023). "It's the end of a world as we know it". *The New York Times*. https://www.nytimes.com/2023/05/03/science/star-eating-planet.html [^perets2012]: Perets, H. B.; Kouwenhoven, M. B. N. (2012). "On the origin of planets at very wide orbits from the recapture of free floating planets". *The Astrophysical Journal* 750: 83. https://doi.org/10.1088/0004-637X/750/1/83 [^fortney2021]: Fortney, J. J.; Dawson, R. I.; Komacek, T. D. (2021). "Hot Jupiters: Origins, structure, atmospheres". *Journal of Geophysical Research: Planets* 126: e2020JE006629. https://doi.org/10.1029/2020JE006629 [^cumming2008]: Cumming, A.; Butler, R. P.; Marcy, G. W.; Vogt, S. S.; Wright, J. T.; Fischer, D. A. (2008). "The Keck Planet Search: Detectability and the minimum mass and orbital period distribution of extrasolar planets". *Publications of the Astronomical Society of the Pacific* 120: 531–554. https://doi.org/10.1086/588487 [^bonfils2005]: Bonfils, X.; Forveille, T.; Delfosse, X.; Udry, S.; Mayor, M.; Perrier, C.; et al. (2005). "The HARPS search for southern extra-solar planets. VI. A Neptune-mass planet around the nearby M dwarf Gl 581". *Astronomy & Astrophysics* 443: L15–L18. https://doi.org/10.1051/0004-6361:200500193 [^nasa-superearth]: NASA Science (22 October 2020). "What is a super-Earth?". https://science.nasa.gov/exoplanets/super-earth/ [^lebreton2013]: Lebreton, J.; van Lieshout, R.; Augereau, J.-C.; Absil, O.; Mennesson, B.; Kama, M.; et al. (2013). "An interferometric study of the Fomalhaut inner debris disk. III. Detailed models of the exozodiacal disk and its origin". *Astronomy & Astrophysics* 555: A146. https://doi.org/10.1051/0004-6361/201321415 [^difolco2007]: di Folco, E.; Absil, O.; Augereau, J.-C.; Mérand, A.; Coudé du Foresto, V.; Thévenin, F.; et al. (2007). "A near-infrared interferometric survey of debris disk stars". *Astronomy & Astrophysics* 475: 243–250. https://doi.org/10.1051/0004-6361:20077625 [^ferlet1987]: Ferlet, R.; Vidal-Madjar, A.; Hobbs, L. M. (1987). "The Beta Pictoris circumstellar disk. V. Time variations of the Ca II-K line". *Astronomy & Astrophysics* 185: 267–270. Bibcode 1987A&A...185..267F. [^winn2015]: Winn, J. N.; Fabrycky, D. C. (2015). "The occurrence and architecture of exoplanetary systems". *Annual Review of Astronomy and Astrophysics* 53: 409–447. https://doi.org/10.1146/annurev-astro-082214-122246 [^deitrick2015]: Deitrick, R.; Barnes, R.; McArthur, B.; Quinn, T. R.; Luger, R.; Antonsen, A.; et al. (2015). "The three-dimensional architecture of the Upsilon Andromedae planetary system". *The Astrophysical Journal* 798: 46. https://doi.org/10.1088/0004-637X/798/1/46 [^anglada2016]: Anglada-Escudé, G.; Amado, P. J.; Barnes, J.; Berdiñas, Z. M.; et al. (2016). "A terrestrial planet candidate in a temperate orbit around Proxima Centauri". *Nature* 536: 437–440. https://doi.org/10.1038/nature19106 [^mills2016]: Mills, S. M.; Fabrycky, D. C.; Migaszewski, C.; Ford, E. B.; et al. (2016). "A resonant chain of four transiting, sub-Neptune planets". *Nature* 533: 509–512. https://doi.org/10.1038/nature17445 [^amend2005]: Amend, J. P.; Teske, A. (2005). "Expanding frontiers in deep subsurface microbiology". *Palaeogeography, Palaeoclimatology, Palaeoecology* 219: 131–155. https://doi.org/10.1016/j.palaeo.2004.10.018 [^kane2014]: Kane, S. R.; Kopparapu, R. K.; Domagal-Goldman, S. D. (2014). "On the frequency of potential Venus analogs from Kepler data". *The Astrophysical Journal Letters* 794: L5. https://doi.org/10.1088/2041-8205/794/1/L5 [^batista2014]: Batista, V.; Beaulieu, J.-P.; Gould, A.; Bennett, D. P.; Yee, J. C.; Fukui, A.; et al. (2014). "MOA-2011-BLG-293Lb: First microlensing planet possibly in the habitable zone". *The Astrophysical Journal* 780: 54. https://doi.org/10.1088/0004-637X/780/1/54 [^lineweaver2001]: Lineweaver, C. H. (2001). "An estimate of the age distribution of terrestrial planets in the universe: Quantifying metallicity as a selection effect". *Icarus* 151: 307–313. https://doi.org/10.1006/icar.2001.6607 [^anglada2014]: Anglada-Escudé, G.; Arriagada, P.; Tuomi, M.; Zechmeister, M.; Jenkins, J. S.; Ofir, A.; et al. (2014). "Two planets around Kapteyn's star: A cold and a temperate super-Earth orbiting the nearest halo red dwarf". *Monthly Notices of the Royal Astronomical Society: Letters* 443: L89–L93. https://doi.org/10.1093/mnrasl/slu076 [^robertson2015]: Robertson, P.; Roy, A.; Mahadevan, S. (2015). "Stellar activity mimics a habitable-zone planet around Kapteyn's star". *The Astrophysical Journal Letters* 805: L22. https://doi.org/10.1088/2041-8205/805/2/L22 [^gonzalez2005]: Gonzalez, G. (2005). "Habitable zones in the universe". *Origins of Life and Evolution of Biospheres* 35: 555–606. https://doi.org/10.1007/s11084-005-5010-8 ## Further reading - Winn, J. N.; Fabrycky, D. C. (2015). "The occurrence and architecture of exoplanetary systems". *Annual Review of Astronomy and Astrophysics* 53: 409–447. https://doi.org/10.1146/annurev-astro-082214-122246 - Pierrehumbert, R. T. (2021). *Planetary Systems: A Very Short Introduction*. Oxford University Press. ISBN 978-0-19-884112-8. - NASA Exoplanet Archive. https://exoplanetarchive.ipac.caltech.edu/ *Article prose: Solar System portal child articles, wave 1, 2026-09-18 · row SOL-007 · strict pair pinned at revision [1372528075](https://en.wikipedia.org/w/index.php?oldid=1372528075). The sections below this block are the page's earlier material, kept in place.*  ## Links (Wikipedia order)  `51_Pegasi` · `51_Pegasi_b` · `A-type_main-sequence_star` · `Absolute_magnitude` · `Accretion_(astrophysics)` · `Accretion_disk` · `Alfvén_surface` · `Alpha_process` · `Am_star` · `Amorphous_carbon` · `Ap_and_Bp_stars` · `Apparent_magnitude` · `Archimedes` · `Aristarchus_of_Samos` · `Asterism_(astronomy)` · `Asteroid` · `Asteroid_belt` · `Asteroseismology` · `Astrobiology` · `Astrometry` · `Astronomical_object` · `Asymptotic_giant_branch` · `B(e)_star` · `B-type_main-sequence_star` · `Barium_star` · `Be_star` · `Beta_Pictoris` · `Binary_pulsar` · `Binary_star` · `Bipolar_outflow` · `Black_dwarf` · `Black_hole` · `Black_star_(semiclassical_gravity)` · `Blanet` · `Blitzar` · `Blue_dwarf_(red-dwarf_stage)` · `Blue_giant` · `Blue_loop` · `Blue_straggler` · `Blue_supergiant` · `Bok_globule` · `Brown-dwarf_desert` · `Brown_dwarf` · `CEMP_star` · `CH_star` · `CNO_cycle` · `CN_star` · `Carbon-burning_process` · `Carbon_planet` · `Carbon_star` · `Carl_Sagan_Institute` · `Catastrophically_evaporating_planet` · `Centaurus` · `Chemically_peculiar_star` · `Chromosphere` · `Chthonian_planet` · `Circumbinary_planet` · `Circumplanetary_disk` · `Circumpolar_star` · `Circumstellar_disc` · `Circumstellar_dust` · `Circumstellar_envelope` · `Circumtriple_planet` · `Co-orbital_configuration` · `Color_index` · `Color–color_diagram` · `Comet` · `Common_envelope` · `Constellation` · `Contact_binary` · `Convection_zone` · `Coreless_planet` · `Cosmic_dust` · `Cosmic_shoreline` · `Dark-energy_star` · `Dark_globular_cluster` · `Dark_star_(dark_matter)` · `De_revolutionibus_orbium_coelestium` · `Debra_Fischer` · `Debris_disk` · `Definition_of_planet` · `Desert_planet` · `Detached_object` · `Deuterium_fusion` · `Discoveries_of_exoplanets` · `Discovery_and_exploration_of_the_Solar_System` · `Disrupted_planet` · `Doppler_spectroscopy` · `Double_planet` · `Double_star` · `Dredge-up` · `Dwarf_galaxy` · `Dwarf_planet` · [[Earth]] · `Earth_analog` · `Eccentric_Jupiter` · `Ecumenopolis` · `Eddington_luminosity` · `Effective_temperature` · `Elliptical_galaxy` · `Exocomet` · `Exomoon` · `Exoplanet` · `Exoplanet_Data_Explorer` · `Exoplanet_interiors` · `Exoplanet_naming_convention` · `Exoplanet_orbital_and_physical_parameters` · `Exoplanetary_Circumstellar_Environments_and_Disk_Explorer` · `Exotic_star` · `Exozodiacal_dust` · `Extinction_(astronomy)` · `Extragalactic_planet` · `Extrasolar_planets_in_fiction` · `Extraterrestrial_liquid_water` · `Extraterrestrial_materials` · `Extraterrestrial_sample_curation` · `Extreme_helium_star` · `Eyeball_planet` · `F-type_main-sequence_star` · `Formation_and_evolution_of_the_Solar_System` · `G-type_main-sequence_star` · `Galactic_Center` · `Galactic_bulge` · `Galactic_habitable_zone` · `Galactic_tide` · `Galactic_year` · `Galaxy` · `Galaxy_cluster` · `Galaxy_morphological_classification` · `Galileo_Galilei` · `Gas_giant` · `General_Scholium` · `Geocentrism` · `Geodynamics_of_terrestrial_exoplanets` · `Giant-impact_hypothesis` · `Giant_planet` · `Giant_star` · `Giordano_Bruno` · `Globular_cluster` · `Gravastar` · `Gravitational_collapse` · `Gravitational_microlensing` · `Gravity` · `Gravity_darkening` · `Guest_star_(astronomy)` · `Habitability_of_F-type_main-sequence_star_systems` · `Habitability_of_K-type_main-sequence_star_systems` · `Habitability_of_binary_star_systems` · `Habitability_of_brown_dwarf_systems` · `Habitability_of_natural_satellites` · `Habitability_of_neutron_star_systems` · `Habitability_of_red_dwarf_systems` · `Habitable_zone` · `Habitable_zone_for_complex_life` · `Hayashi_track` · `Heliocentrism` · `Helioseismology` · `Helium-weak_star` · `Helium_flash` · `Helium_planet` · `Helium_star` · `Henyey_track` · `Herbig_Ae/Be_star` · `Herbig–Haro_object` · `Hertzsprung_gap` · `Hertzsprung–Russell_diagram` · `Hills_cloud` · `Historical_brightest_stars` · `Horizontal_branch` · `Hot_Jupiter` · `Hot_Neptune` · `Hubble_Space_Telescope` · `Hycean_planet` · `Hypercompact_stellar_system` · `Hypergiant` · `Hypernova` · `Hypothetical_star` · `IAU_definition_of_planet` · `Ice_giant` · `Ice_planet` · `Infrared_cluster` · `Instability_strip` · `Intergalactic_star` · `International_Astronomical_Union` · `Interplanetary_dust_cloud` · `Interplanetary_medium` · `Interstellar_cloud` · `Interstellar_medium` · `Iron_planet` · `Iron_star` · [[Johannes_Kepler]] · `Jupiter-mass_binary_object` · `Jupiter_analogue` · `K-type_main-sequence_star` · `Kelvin–Helmholtz_mechanism` · `Kepler_space_telescope` · `Kraft_break` · `Kuiper_belt` · `Lambda_Boötis_star` · `Lava_planet` · `Lead_star` · `List_of_Arabic_star_names` · `List_of_brightest_stars` · `List_of_brown_dwarfs` · `List_of_coolest_stars` · `List_of_directly_imaged_exoplanets` · `List_of_exoplanet_extremes` · `List_of_exoplanet_firsts` · `List_of_exoplanet_search_projects` · `List_of_exoplanets_detected_by_microlensing` · `List_of_exoplanets_detected_by_radial_velocity` · `List_of_exoplanets_detected_by_timing` · `List_of_exoplanets_discovered_before_2000` · `List_of_exoplanets_discovered_between_2000–2009` · `List_of_exoplanets_discovered_by_the_Kepler_space_telescope` · `List_of_exoplanets_discovered_by_the_Kepler_space_telescope:_1001–1500` · `List_of_exoplanets_discovered_by_the_Kepler_space_telescope:_1501–2000` · `List_of_exoplanets_discovered_by_the_Kepler_space_telescope:_1–500` · `List_of_exoplanets_discovered_by_the_Kepler_space_telescope:_2001–2500` · `List_of_exoplanets_discovered_by_the_Kepler_space_telescope:_501–1000` · `List_of_exoplanets_discovered_in_2010` · `List_of_exoplanets_discovered_in_2011` · `List_of_exoplanets_discovered_in_2012` · `List_of_exoplanets_discovered_in_2013` · `List_of_exoplanets_discovered_in_2014` · `List_of_exoplanets_discovered_in_2015` · `List_of_exoplanets_discovered_in_2016` · `List_of_exoplanets_discovered_in_2017` · `List_of_exoplanets_discovered_in_2018` · `List_of_exoplanets_discovered_in_2019` · `List_of_exoplanets_discovered_in_2020` · `List_of_exoplanets_discovered_in_2021` · `List_of_exoplanets_discovered_in_2022` · `List_of_exoplanets_discovered_in_2023` · `List_of_exoplanets_discovered_in_2024` · `List_of_exoplanets_discovered_in_2025` · `List_of_exoplanets_discovered_in_2026` · `List_of_exoplanets_observed_during_Kepler's_K2_mission` · `List_of_hottest_stars` · `List_of_interstellar_and_circumstellar_molecules` · `List_of_largest_exoplanets` · `List_of_largest_star_clusters` · `List_of_largest_stars` · `List_of_most_distant_stars` · `List_of_most_luminous_stars` · `List_of_most_massive_star_clusters` · `List_of_most_massive_stars` · `List_of_multiplanetary_systems` · `List_of_nearest_bright_stars` · `List_of_nearest_exoplanets` · `List_of_nearest_stars` · `List_of_nearest_terrestrial_exoplanet_candidates` · `List_of_novae_in_the_Milky_Way_galaxy` · `List_of_planet_types` · `List_of_planetary_nebulae` · `List_of_potentially_habitable_exoplanets` · `List_of_proper_names_of_exoplanets` · `List_of_proper_names_of_stars` · `List_of_red_dwarfs` · `List_of_resolved_circumstellar_disks` · `List_of_smallest_known_stars` · `List_of_star_extremes` · `List_of_stars_with_resolved_images` · `List_of_supernova_candidates` · `List_of_supernova_remnants` · `List_of_supernovae` · `List_of_transiting_exoplanets` · `List_of_white_dwarfs` · `Lists_of_planets` · `Lists_of_stars` · `Lithium_burning` · `Luminosity` · `Luminous_blue_variable` · `Luminous_red_nova` · `Magnetar` · `Magnitude_(astronomy)` · `Main_sequence` · `Manuscript` · `Mega-Earth` · `Mercury_(planet)` · `Mercury–manganese_star` · `Mesoplanet` · `Metallicity` · `Meteoroid` · `Methods_of_detecting_exoplanets` · `Micronova` · `Microturbulence` · `Milky_Way` · `Molecular_cloud` · `NASA` · `NASA_Exoplanet_Archive` · `NASA_Star_and_Exoplanet_Database` · `Nancy_Grace_Roman_Space_Telescope` · `Natural_satellite` · `Nebular_hypothesis` · `Neon-burning_process` · `Neptunian_desert` · `Neptunian_exoplanet` · `Neutron_star` · `Neutron_star_merger` · `Nexus_for_Exoplanet_System_Science` · `Nicolaus_Copernicus` · `Nova` · `Nova_remnant` · `O-type_main-sequence_star` · `OB_star` · `OH/IR_star` · `Ocean_world` · `Oort_cloud` · `Open_Exoplanet_Catalogue` · `Open_cluster` · `Orbit` · `Orbital_eccentricity` · `Orbital_plane` · `Orbital_resonance` · `Outer_space` · `Oxygen-burning_process` · `P-process` · `PG_1159_star` · `PSR_B1257+12` · `Phase_curve_(astronomy)` · `Photographic_magnitude` · `Photometric-standard_star` · `Photometric_system` · `Photosphere` · [[Physics]] · `Planck_star` · `Planet` · `Planet-hosting_star` · `Planetary-mass_object` · `Planetary_habitability` · `Planetary_migration` · `Planetary_nebula` · `Planetary_science` · `Planetesimal` · `Polarimetry` · `Pole_star` · `Post-AGB_star` · `Pre-main-sequence_star` · `Proper_motion` · `Proplyd` · `Proton–proton_chain` · `Protoplanet` · `Protoplanetary_disk` · `Protoplanetary_nebula` · `Protostar` · `Publications_of_the_Astronomical_Society_of_the_Pacific` · `Pulsar` · `Pulsar_planet` · `Q_star` · `Quark_star` · `Quasi-star` · `R-process` · `Radial_drift` · `Radial_velocity` · `Radio-quiet_neutron_star` · `Red-giant_branch` · `Red_clump` · `Red_dwarf` · `Red_giant` · `Red_supergiant` · `Relative_velocity` · `Retrograde_and_prograde_motion` · `Ring_system` · `Rogue_planet` · `Rubble_pile` · `S-process` · `S-type_star` · `Sample-return_mission` · `Scattered_disc` · `Search_for_extraterrestrial_intelligence` · `Second_generation_planet` · `Shell_star` · `Silicate` · `Silicon-burning_process` · `Small_planet_radius_gap` · `Soft_gamma_repeater` · `Solar-like_oscillations` · `Solar_System` · `Solar_eclipse` · `Solar_radio_emission` · `Spiral_galaxy` · `Spitzer_Space_Telescope` · `Star` · `Star_cluster` · `Star_formation` · `Star_system` · `Starlight` · `Starspot` · `Steam_world` · `Stellar-wind_bubble` · `Stellar_association` · `Stellar_atmosphere` · `Stellar_black_hole` · `Stellar_classification` · `Stellar_collision` · `Stellar_core` · `Stellar_corona` · `Stellar_designations_and_names` · `Stellar_dynamics` · `Stellar_engulfment` · `Stellar_evolution` · `Stellar_kinematics` · `Stellar_magnetic_field` · `Stellar_mass` · `Stellar_mass_loss` · `Stellar_nucleosynthesis` · `Stellar_parallax` · `Stellar_population` · `Stellar_rotation` · `Stellar_structure` · `Stellar_wind` · `Strange_star` · `Strömgren_sphere` · `Sub-Earth` · `Sub-Neptune` · `Sub-brown_dwarf` · `Subdwarf` · `Subdwarf_B_star` · `Subdwarf_O_star` · `Subgiant` · `Substellar_object` · `Sudarsky's_gas_giant_classification` · [[Sun]] · `Sunlight` · `Super-AGB_star` · `Super-Earth` · `Super-Jupiter` · `Super-Neptune` · `Super-puff` · `Super_star_cluster` · `Supergiant` · `Superluminous_supernova` · `Supermassive_black_hole` · `Supernova` · `Supernova_nucleosynthesis` · `Symbiotic_binary` · `Symbiotic_nova` · `TRAPPIST-1` · `T_Tauri_star` · `Technetium_star` · `Terrestrial_planet` · `The_New_York_Times` · `The_Sand_Reckoner` · `Tholin` · `Thorne–Żytkow_object` · `Tidal_disruption_event` · `Tidally_detached_exomoon` · `Timeline_of_stellar_astronomy` · `Titan-like_exoplanet` · `Titius–Bode_law` · `Toroidal_planet` · `Transit-timing_variation` · `Triple-alpha_process` · `Ultra-cool_dwarf` · `Ultra-short_period_planet` · `Universe` · `Variable_star` · [[Venus]] · `Venus-like_exoplanet` · `Very_Large_Telescope` · [[Wayback_Machine]] · `Western_philosophy` · `White_dwarf` · `White_hole` · `Wolf–Rayet_nebula` · `Wolf–Rayet_star` · `X-ray_binary` · `X-ray_burster` · `X-ray_pulsar` · `Yellow_hypergiant` · `Yellow_supergiant` · `Young_stellar_object` > Summary stub · part of Systems Thinking · [Wikipedia source](https://en.wikipedia.org/wiki/Planetary_system) ## Summary A planetary system consists of a set of non-stellar bodies which are gravitationally bound to and in orbit of a star or star [[System|system]]. Generally speaking, such systems will include planets, and may include other objects such as dwarf planets, asteroids, natural satellites, meteoroids, comets, planetesimals,[1][2] and circumstellar disks. The Solar System is an example of a planetary system, in which [[Earth]], seven other planets, and other celestial objects are bound to and revolve around the Sun.[3][4] The term exoplanetary system is sometimes used in reference to planetary systems other than the Solar System. By convention planetary systems are named after their host, or parent, star, as is the case with the Solar System being named after "Sol" (Latin for sun). ## Key points - A planetary system consists of a set of non-stellar bodies which are gravitationally bound to and in orbit of a star or star system. - Generally speaking, such systems will include planets, and may include other objects such as dwarf planets, asteroids, natural satellites, meteoroids, comets, planetesimals, and circumstellar disks. - The Solar System is an example of a planetary system, in which Earth, seven other planets, and other celestial objects are bound to and revolve around the Sun. - The term exoplanetary system is sometimes used in reference to planetary systems other than the Solar System. - By convention planetary systems are named after their host, or parent, star, as is the case with the Solar System being named after "Sol" (Latin for sun). ## Relation to Systems Thinking Planetary system sits within the Systems Thinking cluster of related concepts. Its principles contribute to understanding [[Feedback|feedback]], [[Emergence|emergence]], and dynamic behavior in complex adaptive systems. ## Sources - [Planetary system — Wikipedia](https://en.wikipedia.org/wiki/Planetary_system) Back to Systems Thinking ---  ## Semiotic profile > *The semiotic universals this article invokes, machine-derived from the crossref — **unverified** (born so). Populated 2026-07-06 for the Systems room.* **Universals (3):** 🟡 system (31) · 🟢 emergence (2) · 🟢 feedback (2) **Enter by sign:** Systems Semiotic Gateway · Alphabetum · Icon Registry · ← Systems Portal  ## Wikipedia : Wikitube **Strict pair:** [Wikipedia](https://en.wikipedia.org/wiki/Planetary_system) : [Wikitube](https://en.wikitube.io/wiki/Planetary_system) ## Previous hub tags Tree parent: [[Systems_theory]]. Legacy hubs: none. --- *Sources: 1 legacy note. Minted wave 1, 2026-07-30 (v1.6 order).*