# Discovery and exploration of the Solar System <!-- SOLSIM:BEGIN g31 — Solar System explorer state (hand-built on wt-core, specs/solar/); do not hand-edit inside --> **Microsim — three.js (Wikitube framework):** *The edge of the heliosphere in the Solar System explorer* <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/solar/Solar_System.html?obj=heliosphere&embed=1" data-title="The edge of the heliosphere in the Solar System explorer"></div> *The Solar System explorer locked on this article's state (`?obj=heliosphere`); every object and population of the [[PORTAL_Solar_System|Solar System portal]] has its own state in the same scene.* <!-- SOLSIM:END --> *Try: drag the year slider back to 1846 and see where Neptune stood when it was found, then forward to 2026; set show to clouds and boundaries to leave the three heliosphere shells, at 94 AU, 121 AU and near 230 AU, that the Voyager probes were sent to reach; switch the scale to true and compare the whole region explored by spacecraft with the shells.* **Discovery and exploration of the Solar System** is the history of how people came to observe, visit and understand the [[Sun]], [[Earth]] and [[Moon]], the planets and their moons, and the [[Small_Solar_System_body|small bodies]] such as [[Comet|comets]] and [[Asteroid|asteroids]].[^nasa-ss] For most of history only the Sun, the Moon, five planets and the occasional comet were known, and the Solar System was thought to be the whole universe. Precise naked-eye measurements, then the telescope, [[Newton's_law_of_universal_gravitation|Newtonian gravity]] and [[Spectroscopy|spectroscopy]] revealed a system of worlds around one ordinary star; radar and, from 1957, spacecraft turned the planets into places that could be mapped and sampled.[^masip2016][^nssdc-sputnik] The explorer at the top of this page opens on the edge of the [[Heliosphere|heliosphere]], the farthest region spacecraft have reached: its shells mark where [[Voyager_1|Voyager 1]] crossed the termination shock and the [[Heliopause|heliopause]]. The shells are ILLUSTRATIVE spheres; the planets inside them are drawn at their computed positions for the chosen date. ## Pre-telescope The Sun and Moon mattered first. The daily cycle, the points of sunrise and sunset on the horizon and the phases of the Moon gave early calendars and the cardinal directions.[^masip2016] Five "wandering stars", Mercury, Venus, Mars, Jupiter and Saturn, moved against the fixed stars, sometimes looping backwards; the Greek *planētes*, "wanderers", gave the word planet.[^dictionary-planet] Many cultures tied these motions to gods and omens, and early civilizations in Egypt, Mesopotamia, the Levant and China described a flat Earth, while Indian texts proposed several shapes, some of them spherical.[^knudsen2021] The idea of a spherical Earth became dominant in Greece from the Pythagoreans in the 5th century BC.[^pedersen1993] Greek models placed Earth at the centre. Eudoxus, Callippus and Aristotle built nests of concentric spheres, and Ptolemy's *Almagest*, in the 2nd century AD, combined large circles with smaller epicycles into a predictive geocentric system that remained standard, through Greek, Latin, Arabic, Indian and Chinese transmission, until the 16th century.[^masip2016][^pedersen1993] ### Heliocentric model Sun-centred alternatives appeared repeatedly. Aristarchus of Samos proposed one in antiquity, and in late antiquity Martianus Capella taught that Mercury and Venus circle the Sun while the other bodies circle Earth.[^eastwood2007] Nicolaus Copernicus set out a full heliocentric system in 1543. Tycho Brahe rejected it but made the most accurate naked-eye measurements of the age, and his assistant [[Johannes_Kepler|Johannes Kepler]], working on Tycho's observations of Mars, found that planets move on ellipses. [[Kepler's_laws_of_planetary_motion|Kepler's laws]], published between 1609 and 1619, described the motions precisely although their physical cause was still unknown.[^openstax-grav][^masip2016] ## Telescopic observations ### Early telescopic discoveries The telescope appeared in the Netherlands around 1608. Galileo Galilei turned one on the sky in 1609–1610 and found mountains and craters on the Moon, sunspots, four moons circling [[Jupiter]] and the phases of Venus, which the Ptolemaic arrangement could not produce.[^galileo1610][^weisstein-galileo] Christiaan Huygens discovered [[Titan_(moon)|Titan]] in 1655 and explained the shape of Saturn's rings; Giovanni Domenico Cassini found four more moons of Saturn and the gap in the [[Rings_of_Saturn|rings]] that bears his name.[^esa-huygens][^seds-cassini] In 1705 Edmond Halley showed that the comets of 1531, 1607 and 1682 were one object returning every 75 to 76 years, the first proof that bodies other than planets orbit the Sun.[^utk-halley] ### Newtonian physics Isaac Newton's *Principia* of 1687 explained Kepler's laws with one force: every body attracts every other with a force proportional to their masses and inversely proportional to the square of their distance. The same law governs a falling stone and a planet, so one theory now covered terrestrial and celestial motion.[^openstax-grav] It also made the planets predictable enough that their deviations could reveal unseen bodies. ### Discovery of additional planets and moons William Herschel found [[Uranus]] in 1781 while surveying stars in Taurus; he first reported it as a comet, but its orbit showed it to be a planet, the first found with a telescope.[^herschel1781] Giuseppe Piazzi found [[Ceres_(dwarf_planet)|Ceres]] between Mars and Jupiter on 1 January 1801; it was counted as a planet until similar bodies turned up and the class of asteroids was recognized.[^palermo-ceres] Irregularities in Uranus's motion led John Couch Adams and Urbain Le Verrier to predict another planet, and [[Neptune]] was found near Le Verrier's position in 1846.[^oconnor-neptune] New moons followed: two of Uranus's by Herschel in 1787, Neptune's [[Triton_(moon)|Triton]] by William Lassell in 1846 and the [[Moons_of_Mars|moons of Mars]] by Asaph Hall in 1877.[^herschel1787][^lassell1846][^hall1878] A search for a further planet at Lowell Observatory produced [[Pluto]] in 1930; the International Astronomical Union reclassified it as a [[Dwarf_planet|dwarf planet]] in 2006.[^oconnor-neptune][^iau2006] ### More technical improvements Newton built the first working reflecting telescope in 1668, the design used by the largest telescopes today.[^hall1996] John W. Draper photographed the Moon in 1840, beginning astrophotography.[^kalfus2010] In 1859 Robert Bunsen and Gustav Kirchhoff showed that dark lines in the Sun's spectrum match the [[Spectral_line|spectral lines]] of elements known on Earth, so the Sun could be analysed chemically; in 1868 Jules Janssen and Norman Lockyer found in the solar spectrum a line of an element then unknown on Earth, later named [[Helium|helium]].[^aip-spectroscopy][^thomson1871] ### Discovery of the solar system as one among many Copernicans such as Thomas Digges, Giordano Bruno and William Gilbert argued that the stars are distant suns scattered through a vast or infinite space, and Galileo's telescope showed far more stars than the eye can see.[^gilbert1600][^galileo1610] The phrase "solar system" was in English by 1704.[^etymonline-solar] Three 19th-century results fixed the system's place. In 1838–1839 Friedrich Bessel and Thomas Henderson measured the first stellar parallaxes, showing the nearest stars to be hundreds of thousands of [[Astronomical_unit|astronomical units]] away; James Bradley's discovery of the aberration of starlight in 1729 had already confirmed Earth's motion.[^bessel1838][^henderson1839][^bradley1728] Spectroscopy then showed that the Sun is made of the same elements as Earth, and comparisons of solar and stellar spectra, notably by Angelo Secchi, showed the Sun to be a star like the others.[^aip-spectroscopy] ### Extrasolar planets and the Kuiper belt The first planets found beyond the Solar System orbit the pulsar PSR B1257+12 (1992); the first around a Sun-like star, 51 Pegasi b, followed in 1995, and the confirmed count passed 5,000 in March 2022.[^wolszczan1992][^mayor1995][^nasa-5000] In 1992 David Jewitt and Jane Luu found 1992 QB1, the first object of the [[Kuiper_belt|Kuiper belt]] beyond Neptune apart from Pluto and Charon.[^jewitt1993][^luu2002] Mike Brown, Chad Trujillo and David Rabinowitz then found large distant bodies including [[Sedna_(dwarf_planet)|Sedna]] in 2003 and [[Eris_(dwarf_planet)|Eris]], announced in 2005, whose size forced the 2006 definition of a planet.[^brown2004][^brown2005][^iau2006] ## Observations by radar Radar astronomy bounces radio waves off a body and analyses the echo, which gives its distance and motion very precisely and, through the spread of echo delays and Doppler shifts, maps shape and surface roughness. The Moon was first detected by radar in 1946.[^mofenson1946] Radar detection of Venus in 1961 fixed the length of the [[Astronomical_unit|astronomical unit]] far more accurately than optical methods.[^butrica1996] | Target | Radar result | Source | |---|---|---| | [[Mercury_(planet)|Mercury]] | Time delay of echoes passing near the Sun, a test of general relativity (1964); bright polar deposits interpreted as ice (1992) | Shapiro 1964; Slade et al. 1992[^shapiro1964][^slade1992] | | [[Venus]] | Distance scale of the Solar System (1961); full surface mapped through the clouds by the Magellan orbiter's radar | Butrica 1996; NSSDCA[^butrica1996][^nssdc-magellan] | | Asteroids and comets | 138 main-belt asteroids, 789 near-Earth asteroids and 20 comets observed by 2018 | JPL Asteroid Radar Research[^jpl-radar] | Radar is especially valuable for bodies hidden by clouds, Venus and Titan, and for small [[Near-Earth_object|near-Earth objects]], whose orbits it can pin down years ahead.[^jpl-radar][^nssdc-magellan] ## Observations by spacecraft The space age began with the Soviet satellite Sputnik 1 on 4 October 1957.[^nssdc-sputnik] Since then robotic spacecraft have visited every planet and many moons, asteroids and comets. ### Flybys Luna 1 passed the Moon in January 1959 and went into orbit around the Sun. Mariner 2 flew past Venus in 1962, Mariner 4 past Mars in 1965 and Mariner 10 past Mercury in 1974.[^nssdc-luna1][^nssdc-mariner2][^nssdc-mariner4][^nssdc-mariner10] Pioneer 10 reached Jupiter in 1973 and Pioneer 11 Saturn in 1979. The two Voyagers flew past Jupiter and Saturn, and Voyager 2 went on to Uranus in 1986 and Neptune in 1989, still the only visits to those planets.[^nssdc-pioneer10][^nssdc-pioneer11][^nssdc-voyager2] New Horizons, launched in 2006, flew past Pluto in July 2015 and the Kuiper belt object Arrokoth on 1 January 2019.[^nssdc-newhorizons][^jhuapl-nh] ### Orbiters, landers, rovers and flying probes Luna 10 became the first spacecraft to orbit the Moon in 1966; Mariner 9 orbited Mars in 1971, Venera 9 Venus in 1975, Galileo Jupiter in 1995, Cassini Saturn in 2004 and MESSENGER Mercury in 2011. Dawn orbited the asteroid Vesta in 2011 and then Ceres, and Rosetta became the first comet orbiter in 2014.[^nssdc-luna10][^nssdc-mariner9][^nssdc-venera9][^nssdc-galileo][^nssdc-cassini][^nssdc-messenger][^nssdc-dawn][^esa-rosetta] Luna 2 struck the Moon in 1959, the first human-made object to reach another body; Venera 3 reached Venus in 1966, Viking 1 made the first fully successful Mars landing in 1976, and Huygens landed on Titan in 2005.[^nssdc-luna2][^nssdc-venera3][^nssdc-viking1][^nssdc-huygens] Lunokhod 1 was the first robotic rover, on the Moon in 1970, and Sojourner the first on another planet, on Mars in 1997.[^nssdc-lunokhod][^nssdc-pathfinder] In 2022 the DART spacecraft struck Dimorphos and changed its orbit, the first deliberate change to the motion of a natural body.[^nasa-dart] ### Sample return Samples of the Moon came back with the Apollo astronauts and with robotic Luna and Chang'e missions. Hayabusa returned the first asteroid grains in 2010; Hayabusa2 and OSIRIS-REx returned samples of Ryugu and Bennu, Stardust brought back comet dust, and Genesis captured particles of the [[Solar_wind|solar wind]].[^nssdc-hayabusa][^nssdc-hayabusa2][^nssdc-osirisrex][^nssdc-stardust][^nssdc-change5] ### Spacecraft exploration | First | Spacecraft | Year | Source | |---|---|---|---| | Artificial satellite | Sputnik 1 | 1957 | NSSDCA[^nssdc-sputnik] | | Planetary flyby (Venus) | Mariner 2 | 1962 | NSSDCA[^nssdc-mariner2] | | Orbiter of another world (Moon) | Luna 10 | 1966 | NSSDCA[^nssdc-luna10] | | Planetary orbiter (Mars) | Mariner 9 | 1971 | NSSDCA[^nssdc-mariner9] | | Outer-planet flyby (Jupiter) | Pioneer 10 | 1973 | NSSDCA[^nssdc-pioneer10] | | Landing on the outer Solar System (Titan) | Huygens | 2005 | NSSDCA[^nssdc-huygens] | | Comet orbiter | Rosetta | 2014 | ESA[^esa-rosetta] | | Kuiper belt flyby (Pluto) | New Horizons | 2015 | NSSDCA[^nssdc-newhorizons] | The explorer above draws the outcome of this work in its data: planet positions from JPL orbital elements and small-body orbits from the JPL Small-Body Database, both products of centuries of observation and decades of spacecraft tracking.[^jpl-t1][^jpl-sbdb] ## Crewed exploration Yuri Gagarin became the first person in space and in orbit on Vostok 1 on 12 April 1961.[^nssdc-vostok1] Apollo 11 landed on the Moon on 20 July 1969, and Neil Armstrong and Buzz Aldrin walked on its surface early on 21 July (UTC); five more Apollo landings followed by 1972.[^nssdc-apollo11] For more than half a century after Apollo, crewed flight was confined to low Earth orbit. NASA's Space Shuttle flew 135 missions between its first launch on 12 April 1981 and its final landing on 21 July 2011, carrying 852 people and helping to build the International Space Station.[^nasa-shuttle] Among the stations, Skylab hosted three crews in 1973–1974, the Soviet station Mir was occupied almost continuously for about a decade, and the International Space Station has been continuously inhabited since 2000.[^nssdc-skylab][^nssdc-mir][^nssdc-iss] In April 2026 Artemis II carried four astronauts around the Moon, reaching about 406,771 km from Earth, the farthest people have travelled.[^nasa-artemis2] Even that is only 0.0027 AU (derived: 406,771 km ÷ 149.6 million km), far too small to see on the explorer's scale.[^nasa-fs] ## Exploration by country The Soviet Union and the United States carried out almost all planetary exploration in the 20th century, but by the 2020s many agencies had reached other worlds.[^nasa-ss] Every spacecraft to reach the outer planets so far, from Pioneer 10 and the Voyagers to Galileo, Cassini and New Horizons, has been a NASA mission, the Cassini–Huygens mission in partnership with the European Space Agency, while the Soviet Venera landers returned the first data from the surface of Venus.[^nssdc-pioneer10][^nssdc-voyager2][^nssdc-cassini][^nssdc-newhorizons][^nssdc-venera9] The European Space Agency flew Rosetta to a comet and Huygens to Titan.[^esa-rosetta][^nssdc-huygens] Japan pioneered asteroid sample return with Hayabusa and Hayabusa2.[^nssdc-hayabusa][^nssdc-hayabusa2] China landed Chang'e 4 on the far side of the Moon in 2019 and returned lunar samples with Chang'e 5 in 2020; India placed Mangalyaan in orbit around Mars in 2014 and landed Chandrayaan-3 near the lunar south pole in 2023; the United Arab Emirates put the Hope orbiter around Mars in 2021.[^nssdc-change4][^nssdc-change5][^nssdc-mangalyaan][^nssdc-chandrayaan3][^nssdc-hope] ## See also - [[Timeline_of_Solar_System_exploration]] - [[Voyager_1]] - [[Formation_and_evolution_of_the_Solar_System]] - [[Kepler's_laws_of_planetary_motion]] - [[Planetary_system]] - Historical models of the Solar System · List of Solar System probes · Timeline of discovery of Solar System planets and their moons ## References [^nasa-ss]: NASA Science. 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"Discovery of a candidate inner Oort cloud planetoid". *The Astrophysical Journal* 617: 645–649. https://doi.org/10.1086/422095 [^brown2005]: Brown, M. E.; Trujillo, C. A.; Rabinowitz, D. L. (2005). "Discovery of a planetary-sized object in the scattered Kuiper belt". *The Astrophysical Journal* 635: L97–L100. https://doi.org/10.1086/499336 [^mofenson1946]: Mofenson, J. (1946). "Radar echoes from the Moon". *Electronics* 19: 92–98. [^butrica1996]: Butrica, A. J. (1996). *To See the Unseen: A History of Planetary Radar Astronomy*. NASA SP-4218. https://history.nasa.gov/SP-4218/sp4218.htm [^shapiro1964]: Shapiro, I. I. (1964). "Fourth test of general relativity". *Physical Review Letters* 13: 789–791. https://doi.org/10.1103/PhysRevLett.13.789 [^slade1992]: Slade, M. A.; Butler, B. J.; Muhleman, D. O. (1992). "Mercury radar imaging: evidence for polar ice". *Science* 258: 635–640. https://doi.org/10.1126/science.258.5082.635 [^nssdc-magellan]: NASA NSSDCA Master Catalog. "Magellan" (1989-033B). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1989-033B [^jpl-radar]: NASA/JPL Asteroid Radar Research. "Radar-detected asteroids and comets". http://echo.jpl.nasa.gov/asteroids/ [^nssdc-luna1]: NASA NSSDCA Master Catalog. "Luna 1" (1959-012A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1959-012A [^nssdc-mariner2]: NASA NSSDCA Master Catalog. "Mariner 2" (1962-041A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1962-041A [^nssdc-mariner4]: NASA NSSDCA Master Catalog. "Mariner 4" (1964-077A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1964-077A [^nssdc-mariner10]: NASA NSSDCA Master Catalog. "Mariner 10" (1973-085A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1973-085A [^nssdc-pioneer10]: NASA NSSDCA Master Catalog. "Pioneer 10" (1972-012A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1972-012A [^nssdc-pioneer11]: NASA NSSDCA Master Catalog. "Pioneer 11" (1973-019A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1973-019A [^nssdc-voyager2]: NASA NSSDCA Master Catalog. "Voyager 2" (1977-076A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1977-076A [^nssdc-newhorizons]: NASA NSSDCA Master Catalog. "New Horizons Pluto Kuiper Belt Flyby" (2006-001A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2006-001A [^jhuapl-nh]: Johns Hopkins University Applied Physics Laboratory. "New Horizons: NASA's mission to Pluto and the Kuiper belt". http://pluto.jhuapl.edu/ [^nssdc-luna10]: NASA NSSDCA Master Catalog. "Luna 10" (1966-027A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1966-027A [^nssdc-mariner9]: NASA NSSDCA Master Catalog. "Mariner 9" (1971-051A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1971-051A [^nssdc-venera9]: NASA NSSDCA Master Catalog. "Venera 9" (1975-050A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1975-050A [^nssdc-galileo]: NASA NSSDCA Master Catalog. "Galileo Orbiter" (1989-084B). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1989-084B [^nssdc-cassini]: NASA NSSDCA Master Catalog. "Cassini" (1997-061A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1997-061A [^nssdc-messenger]: NASA NSSDCA Master Catalog. "MESSENGER" (2004-030A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2004-030A [^nssdc-dawn]: NASA NSSDCA Master Catalog. "Dawn" (2007-043A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2007-043A [^esa-rosetta]: European Space Agency. "Rosetta's frequently asked questions". http://www.esa.int/Our_Activities/Space_Science/Rosetta/Frequently_asked_questions [^nssdc-luna2]: NASA NSSDCA Master Catalog. "Luna 2" (1959-014A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1959-014A [^nssdc-venera3]: NASA NSSDCA Master Catalog. "Venera 3" (1965-092A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1965-092A [^nssdc-viking1]: NASA NSSDCA Master Catalog. "Viking 1 Lander" (1975-075C). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1975-075C [^nssdc-huygens]: NASA NSSDCA Master Catalog. "Huygens" (1997-061C). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1997-061C [^nssdc-lunokhod]: NASA NSSDCA Master Catalog. "Luna 17/Lunokhod 1" (1970-095A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1970-095A [^nssdc-pathfinder]: NASA NSSDCA Master Catalog. "Mars Pathfinder" (1996-068A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1996-068A [^nasa-dart]: NASA (11 October 2022). "NASA confirms DART mission impact changed asteroid's motion in space". https://www.nasa.gov/news-release/nasa-confirms-dart-mission-impact-changed-asteroids-motion-in-space/ [^nssdc-hayabusa]: NASA NSSDCA Master Catalog. "Hayabusa" (2003-019A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2003-019A [^nssdc-hayabusa2]: NASA NSSDCA Master Catalog. "Hayabusa2" (2014-076A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2014-076A [^nssdc-osirisrex]: NASA NSSDCA Master Catalog. "OSIRIS-REx" (2016-055A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2016-055A [^nssdc-stardust]: NASA NSSDCA Master Catalog. "Stardust/NExT" (1999-003A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1999-003A [^nssdc-change5]: NASA NSSDCA Master Catalog. "Chang'e 5" (2020-087A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2020-087A [^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" (elements fetched 2026-09-18). https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html [^nasa-artemis2]: NASA (6 April 2026). "NASA's Artemis II crew eclipses record for farthest human spaceflight". https://www.nasa.gov/news-release/nasas-artemis-ii-crew-eclipses-record-for-farthest-human-spaceflight/ [^nasa-shuttle]: NASA. "The Space Shuttle". https://www.nasa.gov/space-shuttle/ [^nssdc-vostok1]: NASA NSSDCA Master Catalog. "Vostok 1" (1961-012A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1961-012A [^nssdc-apollo11]: NASA NSSDCA Master Catalog. "Apollo 11 Command and Service Module" (1969-059A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1969-059A [^nssdc-skylab]: NASA NSSDCA Master Catalog. "Skylab" (1973-027A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1973-027A [^nssdc-mir]: NASA NSSDCA Master Catalog. "Mir" (1986-017A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1986-017A [^nssdc-iss]: NASA NSSDCA Master Catalog. "International Space Station" (1998-067A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1998-067A [^nasa-fs]: NASA NSSDCA. "Moon fact sheet" and "Planetary fact sheet" (fetched 2026-09-18). https://nssdc.gsfc.nasa.gov/planetary/factsheet/ [^nssdc-change4]: NASA NSSDCA Master Catalog. "Chang'e 4" (2018-103A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2018-103A [^nssdc-mangalyaan]: NASA NSSDCA Master Catalog. "Mangalyaan" (2013-060A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2013-060A [^nssdc-chandrayaan3]: NASA NSSDCA Master Catalog. "Chandrayaan 3" (2023-098A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2023-098A [^nssdc-hope]: NASA NSSDCA Master Catalog. "Emirates Mars Mission (Hope)" (2020-047A). https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2020-047A ## Bibliography - Masip, J. G. (2016). *El sistema solar, un rincón particular de la Vía Láctea* [The Solar System, a special place of the Milky Way]. RBA. ISBN 978-84-473-8562-1. - Butrica, A. J. (1996). *To See the Unseen: A History of Planetary Radar Astronomy*. NASA SP-4218. ## Wikipedia : Wikitube **Strict pair:** [Wikipedia](https://en.wikipedia.org/wiki/Discovery_and_exploration_of_the_Solar_System) : [Wikitube](https://en.wikitube.io/wiki/Discovery_and_exploration_of_the_Solar_System) · pinned revision [1369966624](https://en.wikipedia.org/w/index.php?oldid=1369966624) · 2026-09-18 ## Previous hub tags Hubs: `Life_Physics`. Portals: [[PORTAL_Solar_System]]. --- *Solar System portal child articles, wave 1 · 2026-09-18 · drafted · row SOL-030 · explorer state `?obj=heliosphere`.* <!-- hub_tags: Life_Physics · PORTAL_Solar_System -->