🕷️ Crawler Inspector

URL Lookup

Direct Parameter Lookup

Raw Queries and Responses

1. Shard Calculation

Query:

Response:

Calculated Shard: 62 (from laksa084)

2. Crawled Status Check

Query:

curl -X POST \
  'http://laksa062.int.ahrefs:8124/' \
  -H 'Content-Type: text/plain' \
  -H 'X-ClickHouse-Database: crawler3' \
  -H 'Authorization: Basic YXBpOg==' \
  -d 'SELECT getAhrefsURLFromUnparsed(src_unparsed) AS found_url, ifNull(toUnixTimestamp(download_stamp), 0) AS crawl_time, ifNull(toUnixTimestamp(props_url_first_seen), 0) AS first_indexed_time, download_http_code AS http_code, src_unparsed AS src_unparsed, src_root_hash AS src_root_hash, history_drop_reason AS history_drop_reason, meta_title AS meta_title, meta_descriptions AS meta_descriptions, attrs_boilerpipe_text AS attrs_boilerpipe_text, attrs_markdown AS attrs_markdown, attrs_readable_markdown AS attrs_readable_markdown, meta_canonical AS meta_canonical FROM crawler3.page_info_local FINAL PREWHERE (src_root_hash, src_unparsed) IN ((getAhrefsRootHashFromUnparsed(getAhrefsUnparsedNoserviceFromURL(\'https://www.britannica.com/event/Cassini-Huygens\')), getAhrefsUnparsedNoserviceFromURL(\'https://www.britannica.com/event/Cassini-Huygens\'))) FORMAT JSONEachRow'

Response:

{"found_url":"https:\/\/www.britannica.com\/event\/Cassini-Huygens","crawl_time":1775234284,"first_indexed_time":1475785597,"http_code":200,"src_unparsed":"com,britannica!www,\/event\/Cassini-Huygens s443","src_root_hash":"5455945239613777662","history_drop_reason":null,"meta_title":"Cassini-Huygens | Facts, Dates, & Images | Britannica","meta_descriptions":["Cassini-Huygens, U.S.-European mission to Saturn that consisted of the Cassini orbiter and the Huygens lander."],"attrs_boilerpipe_text":"Top Questions\nWho first observed Saturn with a telescope?\nHow far is Saturn from Earth?\nWhat feature is Saturn known for?\nWhat is Saturn’s largest moon?\nIs Saturn light enough to float?\nNews\n•\nSaturn\n,  second largest\nplanet\nof the\nsolar system\nin mass and size and the sixth nearest planet in distance to the\nSun\n. In the night sky Saturn is easily visible to the unaided\neye\nas a non-twinkling point of light. When viewed through even a small telescope, the planet encircled by its magnificent rings is arguably the most\nsublime\nobject in the solar system. Saturn is designated by the symbol ♄.\nSaturn’s name comes from the Roman god of\nagriculture\n, who is equated with the Greek deity\nCronus\n, one of the Titans and the father of\nZeus\n(the Roman god Jupiter). As the farthest of the planets known to ancient observers, Saturn also was noted to be the slowest-moving. At a distance from the Sun that is 9.5 times as far as\nEarth\n’s, Saturn takes approximately 29.5 Earth years to make one solar revolution. The Italian astronomer\nGalileo\nin 1610 was the first to observe Saturn with a telescope. Although he saw a strangeness in Saturn’s appearance, the low resolution of his instrument did not allow him to discern the true nature of the planet’s rings.\nSaturn occupies almost 60 percent of\nJupiter\n’s volume but has only about one-third of its mass and the lowest mean density—about 70 percent that of water—of any known object in the solar system. Hypothetically, Saturn would float in an ocean large enough to hold it. Both Saturn and Jupiter resemble\nstars\nin that their bulk chemical\ncomposition\nis dominated by\nhydrogen\n. Also, as is the case for Jupiter, the tremendous pressure in Saturn’s deep interior maintains the hydrogen there in a fluid metallic state. Saturn’s structure and evolutionary history, however, differ significantly from those of its larger counterpart. Like the other giant, or Jovian, planets—Jupiter,\nUranus\n, and\nNeptune\n—Saturn has extensive systems of\nmoons\n(natural satellites) and rings, which may provide clues to its origin and evolution as well as to those of the solar system. Saturn’s\nmoon\nTitan\nis distinguished from all other moons in the solar system by the presence of a significant atmosphere, one that is\ndenser\nthan that of any of the terrestrial planets except\nVenus\n.\nThe greatest advances in knowledge of Saturn, as well as of most of the other planets, have come from deep-space probes. Four spacecraft have visited the Saturnian system:\nPioneer\n11 in 1979,\nVoyager\ns 1 and 2 in the two years following, and, after almost a quarter-century,\nCassini-Huygens\n, which arrived in 2004. The first three missions were short-term flybys, but\nCassini\nwent into orbit around Saturn for years of investigations, while its Huygens probe parachuted through the atmosphere of Titan and reached its surface, becoming the first spacecraft to land on a moon other than Earth’s.\nBasic astronomical data\nSaturn orbits the Sun at a mean distance of 1,427,000,000 km (887 million miles). Its closest distance to Earth is about 1.2 billion km (746 million miles), and its\nphase\nangle—the angle that it makes with the Sun and Earth—never exceeds about 6°. Saturn seen from the vicinity of Earth thus always appears nearly fully\nilluminated\n. Only deep\nspace probes\ncan provide sidelit and backlit views.\nBritannica Quiz\nPlanets and the Earth’s Moon\nLike Jupiter and most of the other planets, Saturn has a regular\norbit\n—that is, its motion around the Sun is prograde (in the same direction that the Sun rotates) and has a small eccentricity (noncircularity) and\ninclination\nto the\necliptic\n, the plane of Earth’s orbit. Unlike Jupiter, however, Saturn’s rotational axis is tilted substantially—by 26.7°—to its orbital plane. The tilt gives Saturn seasons, as on Earth, but each season lasts more than seven years. Another result is that Saturn’s rings, which lie in the plane of its equator, are presented to observers on Earth at opening angles ranging from 0° (edge on) to nearly 30°. The view of Saturn’s rings cycles over a 30-year period. Earth-based observers can see the rings’ sunlit northern side for about 15 years and then, in an\nanalogous\nview, the sunlit southern side for the next 15 years. In the short intervals when Earth crosses the ring plane, the rings are all but invisible.\nSaturn’s\nrotation\nperiod was very difficult to determine.\nCloud\nmotions in its massive upper atmosphere trace out a variety of periods, which are as short as about 10 hours 10 minutes near the equator and increase with some oscillation to about 30 minutes longer at latitudes higher than 40°. Scientists attempted to determine the rotation period of Saturn’s deep interior from that of its\nmagnetic field\n, which is\npresumed\nto be rooted in the planet’s metallic-hydrogen outer core. However, direct measurement of the field’s rotation was difficult because the field is highly symmetrical around the rotational axis. At the time of the Voyager encounters, radio outbursts from Saturn, apparently related to small irregularities in the magnetic field, showed a period of 10 hours 39.4 minutes; this value was taken to be the magnetic field rotation period. Measurements made 25 years later by the\nCassini\nspacecraft\nindicated that the field was rotating with a period 6–7 minutes longer. It was believed that the\nsolar wind\nis responsible for some of the difference between these two measurements of the rotational period. Not until Cassini flew inside Saturn’s rings on its final orbits was the rotation period accurately measured. By relating waves observed in the rings to slight variations in Saturn’s gravitational field, the rotation period of the planet was determined to be 10 hours 33 minutes 38 seconds. The time differences between the rotation periods of Saturn’s clouds and of its interior have been used to estimate wind velocities (\nsee below\nThe atmosphere\n).\nGo beyond the basics with trusted, in-depth knowledge for professionals, students, and lifelong learners.\nSUBSCRIBE\nBecause the four giant\nplanets\nhave no solid surface in their outer layers, by\nconvention\nthe values for the radius and gravity of these planets are calculated at the level at which one bar of\natmospheric pressure\nis exerted. By this measure, Saturn’s equatorial diameter is 120,536 km (74,898 miles). In comparison, its polar diameter is only 108,728 km (67,560 miles), or 10 percent smaller, which makes Saturn the most oblate (flattened at the poles) of all the planets in the solar system. Its oblate shape is apparent even in a small\ntelescope\n. Even though Saturn rotates slightly slower than Jupiter, it is more oblate because its rotational\nacceleration\ncancels a larger fraction of the planet’s\ngravity\nat the equator. The equatorial gravity of the planet, 896 cm (29.4 feet) per second per second, is only 74 percent of its polar gravity. Saturn is 95 times as massive as Earth but occupies a volume 766 times greater. Its mean\ndensity\nof 0.69 gram per cubic cm is thus only some 12 percent of Earth’s. Saturn’s equatorial\nescape velocity\n—the velocity needed for an object, which includes individual atoms and molecules, to escape the planet’s gravitational attraction at the equator without having to be further accelerated—is nearly 36 km per second (80,000 miles per hour) at the one-bar level, compared with 11.2 km per second (25,000 miles per hour) for Earth. This high\nvalue\nindicates that there has been no significant loss of atmosphere from Saturn since its formation.\nPlanetary data for Saturn\n*Time required for the planet to return to the same position in the sky relative to the Sun as seen from Earth.\n**Calculated for the altitude at which 1 bar of atmospheric pressure is exerted.\nmean distance from Sun\n1,426,666,000 km (9.5 AU)\neccentricity of orbit\n0.054\ninclination of orbit to ecliptic\n2.49°\nSaturnian year (sidereal period of revolution)\n29.45 Earth years\nvisual magnitude at mean opposition\n0.7\nmean synodic period*\n378.10 Earth days\nmean orbital velocity\n9.6 km\/sec\nequatorial radius**\n60,268 km\npolar radius**\n54,364 km\nmass\n5.683 × 10\n26\nkg\nmean density\n0.69 g\/cm\n3\nequatorial gravity**\n896 cm\/sec\n2\npolar gravity**\n1,214 cm\/sec\n2\nequatorial escape velocity**\n35.5 km\/sec\npolar escape velocity**\n37.4 km\/sec\nrotation period (magnetic field)\n10 hr 39 min 24 sec (Voyager era); about 10 hr 46 min (Cassini-Huygens mission)\ninclination of equator to orbit\n26.7°\nmagnetic field strength at equator\n0.21 gauss\nnumber of known moons\n274\nplanetary ring system\n3 major rings comprising myriad component ringlets; several less-dense rings","attrs_markdown":"[![Encyclopedia Britannica](https:\/\/cdn.britannica.com\/mendel\/eb-logo\/MendelNewThistleLogo.png)](https:\/\/www.britannica.com\/)\n\n[![Encyclopedia Britannica](https:\/\/cdn.britannica.com\/mendel\/eb-logo\/MendelNewThistleLogo.png)](https:\/\/www.britannica.com\/)\n\n[SUBSCRIBE](https:\/\/premium.britannica.com\/premium-membership\/?utm_source=premium&utm_medium=global-nav&utm_campaign=blue-evergreen)\n\n[SUBSCRIBE](https:\/\/premium.britannica.com\/premium-membership\/?utm_source=premium&utm_medium=global-nav-mobile&utm_campaign=blue-evergreen)\n\nLogin\n\nhttps:\/\/premium.britannica.com\/premium-membership\/?utm\\_source=premium\\&utm\\_medium=nav-login-box\\&utm\\_campaign=evergreen\n\n[SUBSCRIBE](https:\/\/premium.britannica.com\/premium-membership\/?utm_source=premium&utm_medium=hamburger-menu&utm_campaign=blue)\n\n[Ask the Chatbot](https:\/\/www.britannica.com\/chatbot)\n\n[Games & Quizzes](https:\/\/www.britannica.com\/quiz\/browse) [History & Society](https:\/\/www.britannica.com\/History-Society) [Science & Tech](https:\/\/www.britannica.com\/Science-Tech) [Biographies](https:\/\/www.britannica.com\/Biographies) [Animals & Nature](https:\/\/www.britannica.com\/Animals-Nature) [Geography & Travel](https:\/\/www.britannica.com\/Geography-Travel) [Arts & Culture](https:\/\/www.britannica.com\/Arts-Culture) [ProCon](https:\/\/www.britannica.com\/procon) [Money](https:\/\/www.britannica.com\/money) [Videos](https:\/\/www.britannica.com\/videos)\n\n[Cassini-Huygens](https:\/\/www.britannica.com\/event\/Cassini-Huygens)\n\n[Introduction](https:\/\/www.britannica.com\/event\/Cassini-Huygens)   [References & Edit History](https:\/\/www.britannica.com\/event\/Cassini-Huygens\/additional-info)  [Quick Facts & Related Topics](https:\/\/www.britannica.com\/facts\/Cassini-Huygens)\n\n[Images & Videos](https:\/\/www.britannica.com\/event\/Cassini-Huygens\/images-videos)\n\n[![Cassini-Huygens spacecraft](https:\/\/cdn.britannica.com\/17\/96617-004-BB6B239F\/probe-Artwork-centre-orbiter-Huygens-Cassini-planet-June-30-2004.jpg)](https:\/\/cdn.britannica.com\/17\/96617-050-7204B281\/probe-Artwork-centre-orbiter-Huygens-Cassini-planet-June-30-2004.jpg)\n\n[![Learn about the Cassini-Huygens mission to Titan, the largest moon of Saturn with an atmosphere of its own](https:\/\/cdn.britannica.com\/82\/186482-138-DA3DC387\/discussion-moon-mission-Titan-Cassini-Huygens-atmosphere-Saturn.jpg?w=400&h=225&c=crop)](https:\/\/www.britannica.com\/video\/discussion-moon-mission-Titan-Cassini-Huygens-atmosphere-Saturn\/-206600)\n\n[![Witness Cassini-Huygens mission to Saturn with an actual sound of ring particles striking Cassini](https:\/\/cdn.britannica.com\/83\/145483-138-3995D132\/Overview-mission-Cassini-Huygens-Saturn.jpg?w=400&h=225&c=crop)](https:\/\/www.britannica.com\/video\/Overview-mission-Cassini-Huygens-Saturn\/-155717)\n\n[![Jupiter as seen by NASA's Cassini spacecraft on Dec. 7, 2000.](https:\/\/cdn.britannica.com\/41\/93241-004-10D698FD\/Jupiter-spacecraft-Cassini-NASA-Dec-7-2000.jpg)](https:\/\/cdn.britannica.com\/41\/93241-050-FD3DB7E9\/Jupiter-spacecraft-Cassini-NASA-Dec-7-2000.jpg)  [![Saturn](https:\/\/cdn.britannica.com\/00\/81400-004-02A7F6CB\/Saturn-rings-composite-images-spacecraft-Cassini-Shadows-October-6-2004.jpg)](https:\/\/cdn.britannica.com\/00\/81400-050-8BBE1CDA\/Saturn-rings-composite-images-spacecraft-Cassini-Shadows-October-6-2004.jpg)  [![View from the Huygens probe of Titan's surface on Jan. 14, 2005.](https:\/\/cdn.britannica.com\/63\/97263-004-BE71CA07\/probe-surface-Huygens-Titan-Jan-14-2005.jpg)](https:\/\/cdn.britannica.com\/63\/97263-050-72AF8096\/probe-surface-Huygens-Titan-Jan-14-2005.jpg)  [![Geysers of ice towering over the south polar region of Enceladus in an image taken by the Cassini spacecraft in 2005. Enceladus is backlit by the Sun.](https:\/\/cdn.britannica.com\/16\/96216-004-7283F5D2\/Geysers-ice-image-region-spacecraft-Enceladus-Cassini-2005.jpg)](https:\/\/cdn.britannica.com\/16\/96216-050-634FC226\/Geysers-ice-image-region-spacecraft-Enceladus-Cassini-2005.jpg)  [![Saturn: Iapetus](https:\/\/cdn.britannica.com\/09\/96609-004-D70FC213\/Image-Iapetus-spacecraft-Cassini-Huygens.jpg)](https:\/\/cdn.britannica.com\/09\/96609-050-AB6B6599\/Image-Iapetus-spacecraft-Cassini-Huygens.jpg)  [![Saturn: Phoebe](https:\/\/cdn.britannica.com\/07\/96607-004-24651A35\/Image-Phoebe-spacecraft-Cassini-Huygens.jpg)](https:\/\/cdn.britannica.com\/07\/96607-050-32FC57DC\/Image-Phoebe-spacecraft-Cassini-Huygens.jpg)  [![Saturn: Rhea](https:\/\/cdn.britannica.com\/08\/96608-004-BDEB476C\/Image-Rhea-spacecraft-Cassini-Huygens.jpg)](https:\/\/cdn.britannica.com\/08\/96608-050-CE90381A\/Image-Rhea-spacecraft-Cassini-Huygens.jpg)\n\nAt a Glance\n\n[![default image](https:\/\/cdn.britannica.com\/mendel-resources\/3-178\/images\/shared\/new-thistle.svg?v=3.178.5)](https:\/\/www.britannica.com\/summary\/Cassini-Huygens)\n\n[Cassini-Huygens summary](https:\/\/www.britannica.com\/summary\/Cassini-Huygens)\n\nRelated Questions\n\n- [How is astronomy different from cosmology?](https:\/\/www.britannica.com\/question\/How-is-astronomy-different-from-cosmology)\n- [What are Dione’s surface features?](https:\/\/www.britannica.com\/question\/What-are-Diones-surface-features)\n- [Where did Titan get its name?](https:\/\/www.britannica.com\/question\/Where-did-Titan-get-its-name)\n- [What is the atmosphere of Titan composed of?](https:\/\/www.britannica.com\/question\/What-is-the-atmosphere-of-Titan-composed-of)\n- [What is Titan’s haze composed of?](https:\/\/www.britannica.com\/question\/What-is-Titans-haze-composed-of)\n\n![Britannica AI Icon](https:\/\/cdn.britannica.com\/mendel-resources\/3-178\/images\/chatbot\/star-ai.svg?v=3.178.5)\n\nContents\n\nAsk Anything\n\n[Science](https:\/\/www.britannica.com\/browse\/Science)    [Astronomy](https:\/\/www.britannica.com\/browse\/Astronomy)\n\nCITE\n\nShare\n\nFeedback\n\nExternal Websites\n\n[![Cassini-Huygens spacecraft](https:\/\/cdn.britannica.com\/17\/96617-050-7204B281\/probe-Artwork-centre-orbiter-Huygens-Cassini-planet-June-30-2004.jpg?w=400&h=300&c=crop)](https:\/\/cdn.britannica.com\/17\/96617-050-7204B281\/probe-Artwork-centre-orbiter-Huygens-Cassini-planet-June-30-2004.jpg)\n\n[Cassini-Huygens spacecraft](https:\/\/cdn.britannica.com\/17\/96617-050-7204B281\/probe-Artwork-centre-orbiter-Huygens-Cassini-planet-June-30-2004.jpg) Artist's conception of the Huygens probe separating from the Cassini orbiter and beginning its descent into the atmosphere of Titan.\n\n(more)\n\n# Cassini-Huygens\nspace mission\n\nHomework Help\n\nWritten by\n\n[Dave Dooling Education and Public Outreach Officer, National Solar Observatory, Sacramento Peak, New Mexico. Coauthor of *Engineering Tomorrow.*](https:\/\/www.britannica.com\/contributor\/Dave-Dooling\/764)\n\nDave Dooling\n\nFact-checked by\n\n[Britannica Editors Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....](https:\/\/www.britannica.com\/editor\/The-Editors-of-Encyclopaedia-Britannica\/4419)\n\nBritannica Editors\n\nLast updated\n\nMar. 10, 2026\n\n•[History](https:\/\/www.britannica.com\/event\/Cassini-Huygens\/additional-info#history)\n\n![Britannica AI Icon](https:\/\/cdn.britannica.com\/mendel-resources\/3-178\/images\/chatbot\/star-ai.svg?v=3.178.5) Britannica AI\n\nAsk Anything\n\nTable of Contents\n\nTable of Contents\n\nAsk Anything\n\nTop Questions\n\n- What was the Cassini-Huygens mission?\n- Which planets or moons did Cassini-Huygens study?\n- Who were the main organizations involved in the Cassini-Huygens mission?\n- What did the Cassini spacecraft do while orbiting Saturn?\n- What was special about the Huygens probe?\n- What were some important discoveries made by Cassini-Huygens about Saturn and its moons?\n\nShow more\n\nShow less\n\n**Cassini-Huygens**, U.S.-European space mission to [Saturn](https:\/\/www.britannica.com\/place\/Saturn-planet), launched on October 15, 1997. The mission consisted of the U.S. [National Aeronautics and Space Administration](https:\/\/www.britannica.com\/topic\/NASA)’s (NASA’s) [Cassini](https:\/\/www.britannica.com\/topic\/Cassini) orbiter, which was the first space [probe](https:\/\/www.britannica.com\/dictionary\/probe) to [orbit](https:\/\/www.britannica.com\/science\/orbit-astronomy) Saturn, and the [European Space Agency](https:\/\/www.britannica.com\/topic\/European-Space-Agency)’s [Huygens](https:\/\/www.britannica.com\/topic\/Huygens) probe, which landed on [Titan](https:\/\/www.britannica.com\/place\/Titan-astronomy), Saturn’s largest [moon](https:\/\/www.britannica.com\/science\/moon-natural-satellite). Cassini was named for the French astronomer [Gian Domenico Cassini](https:\/\/www.britannica.com\/biography\/Gian-Domenico-Cassini), who discovered four of Saturn’s moons and the Cassini division, a large gap in [Saturn’s rings](https:\/\/www.britannica.com\/place\/Saturn-planet\/The-ring-system#ref54286). Huygens was named for the Dutch scientist [Christiaan Huygens](https:\/\/www.britannica.com\/biography\/Christiaan-Huygens), who discovered Saturn’s rings and Titan.\n\n[![Learn about the Cassini-Huygens mission to Titan, the largest moon of Saturn with an atmosphere of its own](https:\/\/cdn.britannica.com\/82\/186482-138-DA3DC387\/discussion-moon-mission-Titan-Cassini-Huygens-atmosphere-Saturn.jpg?w=800&h=450&c=crop)1 of 2](https:\/\/www.britannica.com\/video\/discussion-moon-mission-Titan-Cassini-Huygens-atmosphere-Saturn\/-206600)\n\nLearn about the Cassini-Huygens mission to Titan, the largest moon of Saturn with an atmosphere of its ownA discussion of the Cassini-Huygens mission to Titan, a moon of Saturn with its own atmosphere.\n\n(more)\n\n[See all videos for this article](https:\/\/www.britannica.com\/event\/Cassini-Huygens\/images-videos)\n\n[![Witness Cassini-Huygens mission to Saturn with an actual sound of ring particles striking Cassini](https:\/\/cdn.britannica.com\/83\/145483-138-3995D132\/Overview-mission-Cassini-Huygens-Saturn.jpg?w=800&h=450&c=crop)2 of 2](https:\/\/www.britannica.com\/video\/Overview-mission-Cassini-Huygens-Saturn\/-155717)\n\nWitness Cassini-Huygens mission to Saturn with an actual sound of ring particles striking CassiniOverview of the Cassini-Huygens mission to Saturn.\n\n(more)\n\n[See all videos for this article](https:\/\/www.britannica.com\/event\/Cassini-Huygens\/images-videos)\n\nCassini-Huygens was one of the largest interplanetary spacecraft. The Cassini orbiter weighed 2,125 kg (4,685 pounds) and was 6.7 metres (22 feet) long and 4 metres (13 feet) wide. The instruments on board Cassini included [radar](https:\/\/www.britannica.com\/technology\/radar) to map the cloud-covered surface of Titan and a [magnetometer](https:\/\/www.britannica.com\/technology\/magnetometer) to study Saturn’s [magnetic field](https:\/\/www.britannica.com\/science\/magnetic-field). The disk-shaped Huygens probe was [mounted](https:\/\/www.britannica.com\/dictionary\/mounted) on the side of Cassini. It weighed 349 kg (769 pounds), was 2.7 metres (8.9 feet) across, and carried six instruments designed to study the atmosphere and surface of Titan.\n\n[![Jupiter as seen by NASA's Cassini spacecraft on Dec. 7, 2000.](https:\/\/cdn.britannica.com\/41\/93241-050-FD3DB7E9\/Jupiter-spacecraft-Cassini-NASA-Dec-7-2000.jpg?w=300)](https:\/\/cdn.britannica.com\/41\/93241-050-FD3DB7E9\/Jupiter-spacecraft-Cassini-NASA-Dec-7-2000.jpg)\n\n[Jupiter as seen by NASA's Cassini spacecraft on Dec. 7, 2000.](https:\/\/cdn.britannica.com\/41\/93241-050-FD3DB7E9\/Jupiter-spacecraft-Cassini-NASA-Dec-7-2000.jpg)\n\n(more)\n\nCassini drew its [electric power](https:\/\/www.britannica.com\/technology\/electric-power) from the heat generated by the decay of 33 kg (73 pounds) of [plutonium](https:\/\/www.britannica.com\/science\/plutonium), the largest amount of a [radioactive](https:\/\/www.britannica.com\/science\/radioactivity) element ever launched into space. Protesters had claimed that an accident during launch or Cassini’s flyby of [Earth](https:\/\/www.britannica.com\/place\/Earth) could expose Earth’s population to harmful plutonium dust and tried to block the launch with a flurry of demonstrations and lawsuits, but NASA countered that the casks encasing the plutonium were [robust](https:\/\/www.merriam-webster.com\/dictionary\/robust) enough to survive any mishap. Cassini-Huygens flew past [Venus](https:\/\/www.britannica.com\/place\/Venus-planet) for a [gravity](https:\/\/www.britannica.com\/science\/gravity-physics) assist in April 1998 and did the same with Earth and [Jupiter](https:\/\/www.britannica.com\/place\/Jupiter-planet) in August 1999 and December 2000, respectively. During its flyby of Earth, Cassini’s [spectrometer](https:\/\/www.britannica.com\/science\/spectrometer) observed water on the surface of the [Moon](https:\/\/www.britannica.com\/science\/moon-natural-satellite); this data was later used in 2009 to confirm the Indian probe [Chandrayaan-1](https:\/\/www.britannica.com\/technology\/Chandrayaan)’s finding of small amounts of water on the lunar surface.\n\n[![Saturn](https:\/\/cdn.britannica.com\/00\/81400-050-8BBE1CDA\/Saturn-rings-composite-images-spacecraft-Cassini-Shadows-October-6-2004.jpg?w=300)1 of 2](https:\/\/cdn.britannica.com\/00\/81400-050-8BBE1CDA\/Saturn-rings-composite-images-spacecraft-Cassini-Shadows-October-6-2004.jpg)\n\n[Saturn](https:\/\/cdn.britannica.com\/00\/81400-050-8BBE1CDA\/Saturn-rings-composite-images-spacecraft-Cassini-Shadows-October-6-2004.jpg)Saturn and its spectacular rings, in a natural-color composite of 126 images taken by the Cassini spacecraft on October 6, 2004. The view is directed toward Saturn's southern hemisphere, which is tipped toward the Sun. Shadows cast by the rings are visible against the bluish northern hemisphere, while the planet's shadow is projected on the rings to the left.\n\n(more)\n\n[![View from the Huygens probe of Titan's surface on Jan. 14, 2005.](https:\/\/cdn.britannica.com\/63\/97263-050-72AF8096\/probe-surface-Huygens-Titan-Jan-14-2005.jpg?w=300)2 of 2](https:\/\/cdn.britannica.com\/63\/97263-050-72AF8096\/probe-surface-Huygens-Titan-Jan-14-2005.jpg)\n\n[View from the Huygens probe of Titan's surface on Jan. 14, 2005.](https:\/\/cdn.britannica.com\/63\/97263-050-72AF8096\/probe-surface-Huygens-Titan-Jan-14-2005.jpg)\n\n(more)\n\nCassini-Huygens entered [Saturn](https:\/\/www.britannica.com\/place\/Saturn-planet) orbit on July 1, 2004. Huygens was released on December 25, 2004, and landed on [Titan](https:\/\/www.britannica.com\/place\/Titan-astronomy) on January 14, 2005—the first landing on any celestial body beyond [Mars](https:\/\/www.britannica.com\/place\/Mars-planet). Data that Huygens transmitted during its final descent and for 72 minutes from the surface included 350 pictures that showed a shoreline with [erosion](https:\/\/www.britannica.com\/science\/erosion-geology) features and a river [delta](https:\/\/www.britannica.com\/science\/delta-river-system-component). In error, one radio channel on the satellite was not turned on, and data were lost concerning the winds Huygens encountered during its descent.\n\n[![Geysers of ice towering over the south polar region of Enceladus in an image taken by the Cassini spacecraft in 2005. Enceladus is backlit by the Sun.](https:\/\/cdn.britannica.com\/16\/96216-050-634FC226\/Geysers-ice-image-region-spacecraft-Enceladus-Cassini-2005.jpg?w=300)](https:\/\/cdn.britannica.com\/16\/96216-050-634FC226\/Geysers-ice-image-region-spacecraft-Enceladus-Cassini-2005.jpg)\n\n[Geysers of ice towering over the south polar region of Enceladus in an image taken by the Cassini spacecraft in 2005. Enceladus is backlit by the Sun.](https:\/\/cdn.britannica.com\/16\/96216-050-634FC226\/Geysers-ice-image-region-spacecraft-Enceladus-Cassini-2005.jpg)\n\n(more)\n\nCassini continued to orbit Saturn and complete many flybys of Saturn’s moons. A particularly exciting discovery during its mission was that of [geysers](https:\/\/www.britannica.com\/science\/geyser) of water ice and organic molecules at the south pole of [Enceladus](https:\/\/www.britannica.com\/place\/Enceladus), which erupt from an underground global ocean that could be a possible [environment](https:\/\/www.merriam-webster.com\/dictionary\/environment) for life. Cassini’s radar mapped much of Titan’s surface and found large lakes of liquid [methane](https:\/\/www.britannica.com\/science\/methane). Cassini also discovered six new moons and two new rings of Saturn. In July 2008 Cassini’s mission was extended to 2010, and in February 2010 it was extended for another seven years.\n\nQuick Facts\n\nDate:\n\nOctober 15, 1997 - September 15, 2017\n\n*(Show more)*\n\nParticipants:\n\n[Cassini](https:\/\/www.britannica.com\/topic\/Cassini)\n\n[Huygens](https:\/\/www.britannica.com\/topic\/Huygens)\n\n*(Show more)*\n\nContext:\n\n[Gian Domenico Cassini](https:\/\/www.britannica.com\/biography\/Gian-Domenico-Cassini)\n\n[Christiaan Huygens](https:\/\/www.britannica.com\/biography\/Christiaan-Huygens)\n\n*(Show more)*\n\nOn the Web:\n\n[BBC - BBC Inside Science - Farewell to Cassini, the epic 20 year mission to Saturn](https:\/\/www.bbc.com\/audio\/play\/b093104w) (Mar. 10, 2026)\n\n*(Show more)*\n\n[See all related content](https:\/\/www.britannica.com\/facts\/Cassini-Huygens)\n\nBeginning in April 2017, Cassini’s orbit was altered by a close encounter with Titan so that it passed inside Saturn’s innermost ring at a distance of 3,800 km (2,400 miles) from the [planet](https:\/\/www.britannica.com\/science\/planet). After 23 such “proximal” orbits, a final [encounter](https:\/\/www.britannica.com\/dictionary\/encounter) with Titan changed Cassini’s orbit so that on September 15, 2017, it ended its mission by plunging into Saturn, which allowed Cassini to sample Saturn’s atmosphere directly and avoid any possible future contamination of Enceladus and Titan.\n\n[Dave Dooling](https:\/\/www.britannica.com\/contributor\/Dave-Dooling\/764)\n\n![Britannica AI Icon](https:\/\/cdn.britannica.com\/mendel-resources\/3-178\/images\/chatbot\/star-ai.svg?v=3.178.5)Britannica AI\n\n*chevron\\_right*\n\nCassini-Huygens\n\n*close*\n\n[AI-generated answers](https:\/\/www.britannica.com\/about-britannica-ai) from Britannica articles. AI makes mistakes, so verify using Britannica articles.\n\n[Saturn](https:\/\/www.britannica.com\/place\/Saturn-planet)\n\n- [Introduction & Top Questions](https:\/\/www.britannica.com\/place\/Saturn-planet)\n- [Basic astronomical data](https:\/\/www.britannica.com\/place\/Saturn-planet#ref54278)\n- [The atmosphere](https:\/\/www.britannica.com\/place\/Saturn-planet\/The-atmosphere)\n  - [Composition and structure](https:\/\/www.britannica.com\/place\/Saturn-planet\/The-atmosphere#ref298253)\n  \n  - [Dynamics](https:\/\/www.britannica.com\/place\/Saturn-planet\/The-atmosphere#ref298254)\n- [The magnetic field and magnetosphere](https:\/\/www.britannica.com\/place\/Saturn-planet\/The-magnetic-field-and-magnetosphere)\n- [The interior](https:\/\/www.britannica.com\/place\/Saturn-planet\/The-interior)\n- [Saturn’s rings and moons](https:\/\/www.britannica.com\/place\/Saturn-planet\/Saturns-rings-and-moons)\n  - [The ring system](https:\/\/www.britannica.com\/place\/Saturn-planet\/The-ring-system)\n  \n  - [Moons](https:\/\/www.britannica.com\/place\/Saturn-planet\/Moons)\n    - [Significant satellites](https:\/\/www.britannica.com\/place\/Saturn-planet\/Moons#ref253150)\n    - [Orbital and rotational dynamics](https:\/\/www.britannica.com\/place\/Saturn-planet\/Orbital-and-rotational-dynamics)\n- [Observations from Earth](https:\/\/www.britannica.com\/place\/Saturn-planet\/Orbital-and-rotational-dynamics#ref54287)\n- [Spacecraft exploration](https:\/\/www.britannica.com\/place\/Saturn-planet\/Spacecraft-exploration)\n\n[References & Edit History](https:\/\/www.britannica.com\/place\/Saturn-planet\/additional-info)  [Related Topics](https:\/\/www.britannica.com\/facts\/Saturn-planet)\n\n[Images, Videos & Interactives](https:\/\/www.britannica.com\/place\/Saturn-planet\/images-videos)\n\n[![Saturn](https:\/\/cdn.britannica.com\/00\/81400-004-02A7F6CB\/Saturn-rings-composite-images-spacecraft-Cassini-Shadows-October-6-2004.jpg)](https:\/\/cdn.britannica.com\/00\/81400-050-8BBE1CDA\/Saturn-rings-composite-images-spacecraft-Cassini-Shadows-October-6-2004.jpg)  [![Interactive comparing planet sizes in the solar system from left to right: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.](https:\/\/cdn.britannica.com\/18\/238518-049-AC2B446B\/planets-solar-system-size-comparison.jpg)](https:\/\/www.britannica.com\/event\/Cassini-Huygens)  [![Saturn](https:\/\/cdn.britannica.com\/67\/21167-004-6B1CF05E\/Saturn-storm-Earth-region-observations-image-Hubble-December-1-1994.jpg)](https:\/\/cdn.britannica.com\/67\/21167-004-6B1CF05E\/Saturn-storm-Earth-region-observations-image-Hubble-December-1-1994.jpg)  [![Cassini: Saturn](https:\/\/cdn.britannica.com\/81\/145481-004-354D226E\/Image-Saturn-radio-occultation-observation-planet-Cassini-2005.jpg)](https:\/\/cdn.britannica.com\/81\/145481-050-F73198DB\/Image-Saturn-radio-occultation-observation-planet-Cassini-2005.jpg)  [![Saturn's three main rings](https:\/\/cdn.britannica.com\/66\/91966-004-377C0F3C\/rings-Details-Saturn-spacecraft-images-composite-Cassini-December-12-2004.jpg)](https:\/\/cdn.britannica.com\/66\/91966-004-377C0F3C\/rings-Details-Saturn-spacecraft-images-composite-Cassini-December-12-2004.jpg)  [![Hubble Space Telescope: Saturn and moons](https:\/\/cdn.britannica.com\/80\/145480-004-25D44084\/image-Hubble-Space-Telescope-Saturn-moons-shadow.jpg)](https:\/\/cdn.britannica.com\/80\/145480-050-24BF0658\/image-Hubble-Space-Telescope-Saturn-moons-shadow.jpg)  [![Saturn: Titan](https:\/\/cdn.britannica.com\/03\/96603-004-4286BF16\/view-moon-Titan-Saturn-Cassini-orbiter-Feb-15-2005.jpg)](https:\/\/cdn.britannica.com\/03\/96603-050-CD67246C\/view-moon-Titan-Saturn-Cassini-orbiter-Feb-15-2005.jpg)  [![Saturn: surface of Titan](https:\/\/cdn.britannica.com\/12\/96612-004-20AD7080\/Image-surface-probe-Titan-Huygens-High-Resolution.jpg)](https:\/\/cdn.britannica.com\/12\/96612-004-20AD7080\/Image-surface-probe-Titan-Huygens-High-Resolution.jpg)\n\n[![Learn about the Cassini-Huygens mission to Titan, the largest moon of Saturn with an atmosphere of its own](https:\/\/cdn.britannica.com\/82\/186482-138-DA3DC387\/discussion-moon-mission-Titan-Cassini-Huygens-atmosphere-Saturn.jpg?w=400&h=225&c=crop)](https:\/\/www.britannica.com\/video\/discussion-moon-mission-Titan-Cassini-Huygens-atmosphere-Saturn\/-206600)\n\n[![moons of Saturn: Mimas](https:\/\/cdn.britannica.com\/82\/145482-004-CEA104B9\/Image-Mimas-atmosphere-Saturn-Cassini-camera-2006.jpg)](https:\/\/cdn.britannica.com\/82\/145482-050-00AF58A0\/Image-Mimas-atmosphere-Saturn-Cassini-camera-2006.jpg)\n\nAt a Glance\n\n[![Saturn](https:\/\/cdn.britannica.com\/67\/21167-004-6B1CF05E\/Saturn-storm-Earth-region-observations-image-Hubble-December-1-1994.jpg?w=200&h=200&c=crop)](https:\/\/www.britannica.com\/summary\/Saturn-planet)\n\n[Saturn summary](https:\/\/www.britannica.com\/summary\/Saturn-planet)\n\nQuizzes\n\n[![View of the Andromeda Galaxy (Messier 31, M31).](https:\/\/cdn.britannica.com\/41\/155241-131-FB2C633F\/View-Andromeda-Galaxy.jpg?w=200&h=200&c=crop)](https:\/\/www.britannica.com\/quiz\/astronomy-and-space-quiz)\n\n[Astronomy and Space Quiz](https:\/\/www.britannica.com\/quiz\/astronomy-and-space-quiz)\n\n[![The orbits of the planets and other elements of the solar system, including asteroids, Kuiper belt, Oort cloud, comet](https:\/\/cdn.britannica.com\/92\/95392-131-F6284677\/orbits-planets-bodies-solar-system.jpg?w=200&h=200&c=crop)](https:\/\/www.britannica.com\/quiz\/space-odyssey)\n\n[Space Odyssey](https:\/\/www.britannica.com\/quiz\/space-odyssey)\n\n[![Saturn. Saturn and its rings. Second largest planet of the solar system. Space Art](https:\/\/cdn.britannica.com\/74\/166074-131-677298A0\/Saturn-rings-planet-solar-system-Space-Art.jpg?w=200&h=200&c=crop)](https:\/\/www.britannica.com\/quiz\/planets-and-the-earths-moon)\n\n[Planets and the Earth’s Moon](https:\/\/www.britannica.com\/quiz\/planets-and-the-earths-moon)\n\n[![1 July 2002: The Solar and Heliospheric Observatory (SOHO) satellite reveals a massive solar eruption more than 30 times the Earth's diameter. The eruption formed when a loop of a magnetic field over the surface of the Sun trapped hot gas.](https:\/\/cdn.britannica.com\/19\/73319-131-21DE8879\/Sun-ultraviolet-light-satellite-Earth-Solar-and.jpg?w=200&h=200&c=crop)](https:\/\/www.britannica.com\/quiz\/brightest-star-in-the-solar-system)\n\n[Brightest Star in the Solar System](https:\/\/www.britannica.com\/quiz\/brightest-star-in-the-solar-system)\n\n[![Nicolaus Copernicus. Nicolas Copernicus (1473-1543) Polish astronomer. In 1543 he published, forward proof of a Heliocentric (sun centered) universe. Coloured stipple engraving published London 1802. De revolutionibus orbium coelestium libri vi.](https:\/\/cdn.britannica.com\/54\/102254-131-ED1A2CE1\/Nicolaus-Copernicus.jpg?w=200&h=200&c=crop)](https:\/\/www.britannica.com\/quiz\/all-about-astronomy)\n\n[All About Astronomy](https:\/\/www.britannica.com\/quiz\/all-about-astronomy)\n\nRelated Questions\n\n- [How far is Saturn from Earth?](https:\/\/www.britannica.com\/question\/How-far-is-Saturn-from-Earth)\n- [What is Saturn’s largest moon?](https:\/\/www.britannica.com\/question\/What-is-Saturns-largest-moon)\n- [How did James Clerk Maxwell die?](https:\/\/www.britannica.com\/question\/How-did-James-Clerk-Maxwell-die)\n\n![Britannica AI Icon](https:\/\/cdn.britannica.com\/mendel-resources\/3-178\/images\/chatbot\/star-ai.svg?v=3.178.5)\n\nAsk Anything\n\nQuick Summary\n\n[Science](https:\/\/www.britannica.com\/browse\/Science)    [Astronomy](https:\/\/www.britannica.com\/browse\/Astronomy)\n\nCITE\n\nShare\n\nFeedback\n\nExternal Websites\n\n[![Saturn](https:\/\/cdn.britannica.com\/00\/81400-050-8BBE1CDA\/Saturn-rings-composite-images-spacecraft-Cassini-Shadows-October-6-2004.jpg?w=400&h=300&c=crop)](https:\/\/cdn.britannica.com\/00\/81400-050-8BBE1CDA\/Saturn-rings-composite-images-spacecraft-Cassini-Shadows-October-6-2004.jpg)\n\n[Saturn](https:\/\/cdn.britannica.com\/00\/81400-050-8BBE1CDA\/Saturn-rings-composite-images-spacecraft-Cassini-Shadows-October-6-2004.jpg) Saturn and its spectacular rings, in a natural-color composite of 126 images taken by the Cassini spacecraft on October 6, 2004. The view is directed toward Saturn's southern hemisphere, which is tipped toward the Sun. Shadows cast by the rings are visible against the bluish northern hemisphere, while the planet's shadow is projected on the rings to the left.\n\n(more)\n\n# Saturn\nplanet\n\nHomework Help\n\nWritten by\n\n[Mark Marley Scientist, Space Science and Astrobiology Division, NASA Ames Research Center, Moffet Field, California. Consulting Professor, Geological Sciences, Stanford University.](https:\/\/www.britannica.com\/contributor\/Mark-Marley\/8078335)\n\nMark Marley[All](https:\/\/www.britannica.com\/place\/Saturn-planet\/additional-info#contributors)\n\nFact-checked by\n\n[Britannica Editors Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....](https:\/\/www.britannica.com\/editor\/The-Editors-of-Encyclopaedia-Britannica\/4419)\n\nBritannica Editors\n\n[History](https:\/\/www.britannica.com\/place\/Saturn-planet\/additional-info#history)\n\n![Britannica AI Icon](https:\/\/cdn.britannica.com\/mendel-resources\/3-178\/images\/chatbot\/star-ai.svg?v=3.178.5) Britannica AI\n\nAsk Anything\n\nQuick Summary\n\nTable of Contents\n\nTable of Contents\n\nQuick Summary\n\nAsk Anything\n\nTop Questions\n\n### Who first observed Saturn with a telescope?\nThe Italian astronomer [Galileo](https:\/\/www.britannica.com\/biography\/Galileo-Galilei) in 1610 was the first to observe Saturn with a telescope. Although he saw a strangeness in Saturn’s appearance, the low resolution of his instrument did not allow him to discern the true nature of the planet’s rings.\n\n### How far is Saturn from Earth?\nSaturn orbits the Sun at a mean distance of 1,427,000,000 km (887 million miles). Its closest distance to Earth is about 1.2 billion km (746 million miles), and its phase angle—the angle that it makes with the Sun and Earth—never exceeds about 6°. Saturn, seen from the vicinity of Earth, thus always appears nearly fully illuminated.\n\n### What feature is Saturn known for?\nSaturn is surrounded by a ring system. The entire ring system spans nearly 26,000,000 km (16,000,000 miles) when the faint outer rings are included. When viewed through even a small telescope, the planet encircled by its magnificent rings is arguably the most sublime object in the solar system.\n\n### What is Saturn’s largest moon?\n[Titan](https:\/\/www.britannica.com\/place\/Titan-astronomy) is Saturn’s largest moon and the only moon in the solar system known to have clouds, a dense atmosphere, and liquid lakes. The diameter of its solid body is 5,150 km (3,200 miles) making it the second-largest moon in the solar system. It was discovered telescopically in 1655 by the Dutch scientist Christiaan Huygen.\n\n### Is Saturn light enough to float?\nSaturn has the lowest mean density—about 70 percent that of water—of any known object in the solar system. Hypothetically, Saturn would float in an ocean large enough to hold it.\n\n## News •\n[Most powerful space telescope ever built solves decades-long planet mystery](https:\/\/www.newsweek.com\/jwst-saturn-solves-decades-long-planet-mystery-11756944)\n\n• Mar. 30, 2026, 11:23 AM ET (Newsweek)\n\n...(Show more)\n\n[NASA telescopes team up for clearest view of Saturn ever. See images](https:\/\/www.usatoday.com\/story\/news\/nation\/2026\/03\/26\/webb-hubble-nasa-saturn\/89328253007\/)  • Mar. 26, 2026, 7:51 AM ET (USA Today)\n\n[NASA Webb, Hubble Share Most Comprehensive View of Saturn to Date](https:\/\/science.nasa.gov\/missions\/webb\/nasa-webb-hubble-share-most-comprehensive-view-of-saturn-to-date\/)  • Mar. 25, 2026, 2:00 PM ET (NASA Science (.gov))\n\n[Jupiter and Saturn gain more moons: Solar system count rises to 442](https:\/\/indianexpress.com\/article\/technology\/science\/jupiter-and-saturn-gain-more-moons-solar-system-count-rises-to-442-10594184\/)  • Mar. 21, 2026, 8:00 AM ET (The Indian Express)\n\n[NASA begins building nuclear-powered Dragonfly drone for 2028 launch to Saturn moon Titan](https:\/\/www.space.com\/space-exploration\/missions\/nasa-begins-building-nuclear-powered-dragonfly-drone-for-2028-launch-to-saturn-moon-titan)  • Mar. 13, 2026, 9:00 AM ET (Space)\n\nShow less\n\n**Saturn**, second largest [planet](https:\/\/www.britannica.com\/science\/planet) of the [solar system](https:\/\/www.britannica.com\/science\/solar-system) in mass and size and the sixth nearest planet in distance to the [Sun](https:\/\/www.britannica.com\/place\/Sun). In the night sky Saturn is easily visible to the unaided [eye](https:\/\/www.britannica.com\/science\/human-eye) as a non-twinkling point of light. When viewed through even a small telescope, the planet encircled by its magnificent rings is arguably the most [sublime](https:\/\/www.merriam-webster.com\/dictionary\/sublime) object in the solar system. Saturn is designated by the symbol ♄.\n\nSaturn’s name comes from the Roman god of [agriculture](https:\/\/www.britannica.com\/topic\/agriculture), who is equated with the Greek deity [Cronus](https:\/\/www.britannica.com\/topic\/Cronus), one of the Titans and the father of [Zeus](https:\/\/www.britannica.com\/topic\/Zeus) (the Roman god Jupiter). As the farthest of the planets known to ancient observers, Saturn also was noted to be the slowest-moving. At a distance from the Sun that is 9.5 times as far as [Earth](https:\/\/www.britannica.com\/place\/Earth)’s, Saturn takes approximately 29.5 Earth years to make one solar revolution. The Italian astronomer [Galileo](https:\/\/www.britannica.com\/biography\/Galileo-Galilei) in 1610 was the first to observe Saturn with a telescope. Although he saw a strangeness in Saturn’s appearance, the low resolution of his instrument did not allow him to discern the true nature of the planet’s rings.\n\nSaturn occupies almost 60 percent of [Jupiter](https:\/\/www.britannica.com\/place\/Jupiter-planet)’s volume but has only about one-third of its mass and the lowest mean density—about 70 percent that of water—of any known object in the solar system. Hypothetically, Saturn would float in an ocean large enough to hold it. Both Saturn and Jupiter resemble [stars](https:\/\/www.britannica.com\/science\/star-astronomy) in that their bulk chemical [composition](https:\/\/www.merriam-webster.com\/dictionary\/composition) is dominated by [hydrogen](https:\/\/www.britannica.com\/science\/hydrogen). Also, as is the case for Jupiter, the tremendous pressure in Saturn’s deep interior maintains the hydrogen there in a fluid metallic state. Saturn’s structure and evolutionary history, however, differ significantly from those of its larger counterpart. Like the other giant, or Jovian, planets—Jupiter, [Uranus](https:\/\/www.britannica.com\/place\/Uranus-planet), and [Neptune](https:\/\/www.britannica.com\/place\/Neptune-planet)—Saturn has extensive systems of [moons](https:\/\/www.britannica.com\/science\/moon-natural-satellite) (natural satellites) and rings, which may provide clues to its origin and evolution as well as to those of the solar system. Saturn’s [moon](https:\/\/www.britannica.com\/science\/moon-natural-satellite) [Titan](https:\/\/www.britannica.com\/place\/Titan-astronomy) is distinguished from all other moons in the solar system by the presence of a significant atmosphere, one that is [denser](https:\/\/www.britannica.com\/dictionary\/denser) than that of any of the terrestrial planets except [Venus](https:\/\/www.britannica.com\/place\/Venus-planet).\n\nThe greatest advances in knowledge of Saturn, as well as of most of the other planets, have come from deep-space probes. Four spacecraft have visited the Saturnian system: [Pioneer](https:\/\/www.britannica.com\/technology\/Pioneer-space-probes) 11 in 1979, [Voyager](https:\/\/www.britannica.com\/technology\/Voyager-space-probes)s 1 and 2 in the two years following, and, after almost a quarter-century, [Cassini-Huygens](https:\/\/www.britannica.com\/event\/Cassini-Huygens), which arrived in 2004. The first three missions were short-term flybys, but [Cassini](https:\/\/www.britannica.com\/event\/Cassini-Huygens) went into orbit around Saturn for years of investigations, while its Huygens probe parachuted through the atmosphere of Titan and reached its surface, becoming the first spacecraft to land on a moon other than Earth’s.\n\n## Basic astronomical data\nSaturn orbits the Sun at a mean distance of 1,427,000,000 km (887 million miles). Its closest distance to Earth is about 1.2 billion km (746 million miles), and its [phase](https:\/\/www.britannica.com\/science\/phase-state-of-matter) angle—the angle that it makes with the Sun and Earth—never exceeds about 6°. Saturn seen from the vicinity of Earth thus always appears nearly fully [illuminated](https:\/\/www.merriam-webster.com\/dictionary\/illuminated). Only deep [space probes](https:\/\/www.britannica.com\/technology\/space-probe) can provide sidelit and backlit views.\n\n[![Saturn. Saturn and its rings. Second largest planet of the solar system. Space Art](https:\/\/cdn.britannica.com\/74\/166074-131-677298A0\/Saturn-rings-planet-solar-system-Space-Art.jpg) Britannica Quiz Planets and the Earth’s Moon](https:\/\/www.britannica.com\/quiz\/planets-and-the-earths-moon)\n\nLike Jupiter and most of the other planets, Saturn has a regular [orbit](https:\/\/www.britannica.com\/science\/orbit-astronomy)—that is, its motion around the Sun is prograde (in the same direction that the Sun rotates) and has a small eccentricity (noncircularity) and [inclination](https:\/\/www.britannica.com\/science\/inclination-of-equator-to-orbit) to the [ecliptic](https:\/\/www.britannica.com\/science\/ecliptic), the plane of Earth’s orbit. Unlike Jupiter, however, Saturn’s rotational axis is tilted substantially—by 26.7°—to its orbital plane. The tilt gives Saturn seasons, as on Earth, but each season lasts more than seven years. Another result is that Saturn’s rings, which lie in the plane of its equator, are presented to observers on Earth at opening angles ranging from 0° (edge on) to nearly 30°. The view of Saturn’s rings cycles over a 30-year period. Earth-based observers can see the rings’ sunlit northern side for about 15 years and then, in an [analogous](https:\/\/www.merriam-webster.com\/dictionary\/analogous) view, the sunlit southern side for the next 15 years. In the short intervals when Earth crosses the ring plane, the rings are all but invisible.\n\nSaturn’s [rotation](https:\/\/www.britannica.com\/science\/rotation-physics) period was very difficult to determine. [Cloud](https:\/\/www.britannica.com\/science\/cloud-meteorology) motions in its massive upper atmosphere trace out a variety of periods, which are as short as about 10 hours 10 minutes near the equator and increase with some oscillation to about 30 minutes longer at latitudes higher than 40°. Scientists attempted to determine the rotation period of Saturn’s deep interior from that of its [magnetic field](https:\/\/www.britannica.com\/science\/magnetic-field), which is [presumed](https:\/\/www.britannica.com\/dictionary\/presumed) to be rooted in the planet’s metallic-hydrogen outer core. However, direct measurement of the field’s rotation was difficult because the field is highly symmetrical around the rotational axis. At the time of the Voyager encounters, radio outbursts from Saturn, apparently related to small irregularities in the magnetic field, showed a period of 10 hours 39.4 minutes; this value was taken to be the magnetic field rotation period. Measurements made 25 years later by the [Cassini](https:\/\/www.britannica.com\/topic\/Cassini) [spacecraft](https:\/\/www.britannica.com\/technology\/spacecraft) indicated that the field was rotating with a period 6–7 minutes longer. It was believed that the [solar wind](https:\/\/www.britannica.com\/science\/solar-wind) is responsible for some of the difference between these two measurements of the rotational period. Not until Cassini flew inside Saturn’s rings on its final orbits was the rotation period accurately measured. By relating waves observed in the rings to slight variations in Saturn’s gravitational field, the rotation period of the planet was determined to be 10 hours 33 minutes 38 seconds. The time differences between the rotation periods of Saturn’s clouds and of its interior have been used to estimate wind velocities (*see below* [The atmosphere](https:\/\/www.britannica.com\/place\/Saturn-planet\/The-atmosphere#ref54279)).\n\nExplore Britannica Premium\\!\n\nGo beyond the basics with trusted, in-depth knowledge for professionals, students, and lifelong learners.\n\n[SUBSCRIBE](https:\/\/premium.britannica.com\/premium-membership\/?utm_source=premium&utm_medium=inline-cta&utm_campaign=basics-2026)\n\n![Penguin, ship, mountain, atlas](https:\/\/cdn.britannica.com\/marketing\/inline-left.webp)\n\n![shohei ohtani, plants, andy wharhol art](https:\/\/cdn.britannica.com\/marketing\/inline-right.webp)\n\n![Mobile](https:\/\/cdn.britannica.com\/marketing\/inline-mobile.webp?w=400)\n\nBecause the four giant [planets](https:\/\/www.britannica.com\/science\/planet) have no solid surface in their outer layers, by [convention](https:\/\/www.britannica.com\/dictionary\/convention) the values for the radius and gravity of these planets are calculated at the level at which one bar of [atmospheric pressure](https:\/\/www.britannica.com\/science\/atmospheric-pressure) is exerted. By this measure, Saturn’s equatorial diameter is 120,536 km (74,898 miles). In comparison, its polar diameter is only 108,728 km (67,560 miles), or 10 percent smaller, which makes Saturn the most oblate (flattened at the poles) of all the planets in the solar system. Its oblate shape is apparent even in a small [telescope](https:\/\/www.britannica.com\/science\/optical-telescope). Even though Saturn rotates slightly slower than Jupiter, it is more oblate because its rotational [acceleration](https:\/\/www.britannica.com\/science\/acceleration) cancels a larger fraction of the planet’s [gravity](https:\/\/www.britannica.com\/science\/gravity-physics) at the equator. The equatorial gravity of the planet, 896 cm (29.4 feet) per second per second, is only 74 percent of its polar gravity. Saturn is 95 times as massive as Earth but occupies a volume 766 times greater. Its mean [density](https:\/\/www.britannica.com\/science\/density) of 0.69 gram per cubic cm is thus only some 12 percent of Earth’s. Saturn’s equatorial [escape velocity](https:\/\/www.britannica.com\/science\/escape-velocity)—the velocity needed for an object, which includes individual atoms and molecules, to escape the planet’s gravitational attraction at the equator without having to be further accelerated—is nearly 36 km per second (80,000 miles per hour) at the one-bar level, compared with 11.2 km per second (25,000 miles per hour) for Earth. This high [value](https:\/\/www.britannica.com\/dictionary\/value) indicates that there has been no significant loss of atmosphere from Saturn since its formation.\n\n| Planetary data for Saturn |   |\n|---|---|\n| \\*Time required for the planet to return to the same position in the sky relative to the Sun as seen from Earth. |   |\n| \\*\\*Calculated for the altitude at which 1 bar of atmospheric pressure is exerted. |   |\n| mean distance from Sun | 1,426,666,000 km (9.5 AU) |\n| eccentricity of orbit | 0\\.054 |\n| inclination of orbit to ecliptic | 2\\.49° |\n| Saturnian year (sidereal period of revolution) | 29\\.45 Earth years |\n| visual magnitude at mean opposition | 0\\.7 |\n| mean synodic period\\* | 378\\.10 Earth days |\n| mean orbital velocity | 9\\.6 km\/sec |\n| equatorial radius\\*\\* | 60,268 km |\n| polar radius\\*\\* | 54,364 km |\n| mass | 5\\.683 × 1026 kg |\n| mean density | 0\\.69 g\/cm3 |\n| equatorial gravity\\*\\* | 896 cm\/sec2 |\n| polar gravity\\*\\* | 1,214 cm\/sec2 |\n| equatorial escape velocity\\*\\* | 35\\.5 km\/sec |\n| polar escape velocity\\*\\* | 37\\.4 km\/sec |\n| rotation period (magnetic field) | 10 hr 39 min 24 sec (Voyager era); about 10 hr 46 min (Cassini-Huygens mission) |\n| inclination of equator to orbit | 26\\.7° |\n| magnetic field strength at equator | 0\\.21 gauss |\n| number of known moons | 274 |\n| planetary ring system | 3 major rings comprising myriad component ringlets; several less-dense rings |\n\n![Britannica AI Icon](https:\/\/cdn.britannica.com\/mendel-resources\/3-178\/images\/chatbot\/star-ai.svg?v=3.178.5)Britannica AI\n\n*chevron\\_right*\n\nSaturn\n\n*close*\n\n[AI-generated answers](https:\/\/www.britannica.com\/about-britannica-ai) from Britannica articles. AI makes mistakes, so verify using Britannica articles.\n\nLoad Next Page\n\nFeedback\n\nThank you for your feedback\n\nOur editors will review what you’ve submitted and determine whether to revise the article.\n\n*verified*Cite\n\nWhile every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions.\n\nSelect Citation Style\n\nDooling, Dave. \"Cassini-Huygens\". *Encyclopedia Britannica*, 10 Mar. 2026, https:\/\/www.britannica.com\/event\/Cassini-Huygens. Accessed 3 April 2026.\n\nCopy Citation\n\nShare\n\nShare to social media\n\n[Facebook](https:\/\/www.facebook.com\/BRITANNICA\/) [X](https:\/\/x.com\/britannica)\n\nURL\n\n<https:\/\/www.britannica.com\/event\/Cassini-Huygens>\n\nExternal Websites\n\n- [National Center for Biotechnology Information - PubMed Central - Cassini Exploration of the Planet Saturn: A Comprehensive Review](https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC8753610\/)\n- [CNN World - WhatÂ’s happening inside SaturnÂ’s rings? The Cassini mission dove between them to find out](https:\/\/edition.cnn.com\/2019\/06\/13\/world\/cassini-saturn-rings-scn-trnd)\n- [BBC - BBC Inside Science - Farewell to Cassini, the epic 20 year mission to Saturn](https:\/\/www.bbc.com\/audio\/play\/b093104w)\n- [Imperial College London - The Cassini Mission](https:\/\/www.imperial.ac.uk\/space-and-atmospheric-physics\/research\/missions-and-projects\/space-missions\/cassini\/the_mission\/)\n- [Deutsches Zentrum fur Luft- und Raumfahrt - Destination Saturn ï¿½ The Casï¿½siï¿½ni-Huyï¿½gens mission](https:\/\/www.dlr.de\/en\/research-and-transfer\/projects-and-missions\/cassini-huygens)\n- [NASA - Cassini-Huygens](https:\/\/science.nasa.gov\/mission\/cassini\/)\n- [American Association for the Advancement of Science - Cassini-Huygensï¿½ exploration of the Saturn system: 13 years of discovery](https:\/\/www.science.org\/doi\/10.1126\/science.aat3760)\n- [The European Space Agency - Cassini\/Huygens (PDF)](https:\/\/sci.esa.int\/documents\/33648\/36003\/1567254416901-cassini-huygens.pdf)\n- [The Planetary Society - Cassini, the mission that revealed Saturn](https:\/\/www.planetary.org\/space-missions\/cassini)\n- [NASA Technical Reports Server - Cassini-Huygens Aerodynamics with Comparison to Flight (PDF)](https:\/\/ntrs.nasa.gov\/api\/citations\/20060047648\/downloads\/20060047648.pdf)\n\nBritannica Websites\n\nArticles from Britannica Encyclopedias for elementary and high school students.\n\n- [Cassini-Huygens - Children's Encyclopedia (Ages 8-11)](https:\/\/kids.britannica.com\/kids\/article\/Cassini-Huygens\/544855)\n- [Cassini-Huygens - Student Encyclopedia (Ages 11 and up)](https:\/\/kids.britannica.com\/students\/article\/Cassini-Huygens\/544804)\n\nFeedback\n\nThank you for your feedback\n\nOur editors will review what you’ve submitted and determine whether to revise the article.\n\n*print* Print\n\nPlease select which sections you would like to print:\n\n*verified*Cite\n\nWhile every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions.\n\nSelect Citation Style\n\nMarley, Mark, Hubbard, William B., Buratti, Bonnie. \"Saturn\". *Encyclopedia Britannica*, 15 Jan. 2026, https:\/\/www.britannica.com\/place\/Saturn-planet. Accessed 3 April 2026.\n\nCopy Citation\n\nShare\n\nShare to social media\n\n[Facebook](https:\/\/www.facebook.com\/BRITANNICA\/) [X](https:\/\/x.com\/britannica)\n\nURL\n\n<https:\/\/www.britannica.com\/place\/Saturn-planet>\n\nExternal Websites\n\n- [The Planetary Society - Saturn, planet of rings, moons and more to explore](https:\/\/www.planetary.org\/worlds\/saturn)\n- [NASA - Saturn](https:\/\/science.nasa.gov\/saturn\/)\n- [Live Science - Saturn: Facts about the ringed planet](https:\/\/www.livescience.com\/facts-about-saturn)\n- [The Planets - Saturn Facts](https:\/\/theplanets.org\/saturn\/)\n- [HyperPhysics - Saturn](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Solar\/saturn.html)\n- [Space.com - Saturn: Facts about the ringed planet](https:\/\/www.space.com\/48-saturn-the-solar-systems-major-ring-bearer.html)\n- [National Geographic - Science - Saturn](https:\/\/www.nationalgeographic.com\/science\/space\/solar-system\/saturn\/)\n\nBritannica Websites\n\nArticles from Britannica Encyclopedias for elementary and high school students.\n\n- [Saturn - Children's Encyclopedia (Ages 8-11)](https:\/\/kids.britannica.com\/kids\/article\/Saturn\/353745)\n- [Saturn - Student Encyclopedia (Ages 11 and up)](https:\/\/kids.britannica.com\/students\/article\/Saturn\/345008)","attrs_readable_markdown":"Top Questions\n\n### Who first observed Saturn with a telescope?\n### How far is Saturn from Earth?\n### What feature is Saturn known for?\n### What is Saturn’s largest moon?\n### Is Saturn light enough to float?\n## News •\n**Saturn**, second largest [planet](https:\/\/www.britannica.com\/science\/planet) of the [solar system](https:\/\/www.britannica.com\/science\/solar-system) in mass and size and the sixth nearest planet in distance to the [Sun](https:\/\/www.britannica.com\/place\/Sun). In the night sky Saturn is easily visible to the unaided [eye](https:\/\/www.britannica.com\/science\/human-eye) as a non-twinkling point of light. When viewed through even a small telescope, the planet encircled by its magnificent rings is arguably the most [sublime](https:\/\/www.merriam-webster.com\/dictionary\/sublime) object in the solar system. Saturn is designated by the symbol ♄.\n\nSaturn’s name comes from the Roman god of [agriculture](https:\/\/www.britannica.com\/topic\/agriculture), who is equated with the Greek deity [Cronus](https:\/\/www.britannica.com\/topic\/Cronus), one of the Titans and the father of [Zeus](https:\/\/www.britannica.com\/topic\/Zeus) (the Roman god Jupiter). As the farthest of the planets known to ancient observers, Saturn also was noted to be the slowest-moving. At a distance from the Sun that is 9.5 times as far as [Earth](https:\/\/www.britannica.com\/place\/Earth)’s, Saturn takes approximately 29.5 Earth years to make one solar revolution. The Italian astronomer [Galileo](https:\/\/www.britannica.com\/biography\/Galileo-Galilei) in 1610 was the first to observe Saturn with a telescope. Although he saw a strangeness in Saturn’s appearance, the low resolution of his instrument did not allow him to discern the true nature of the planet’s rings.\n\nSaturn occupies almost 60 percent of [Jupiter](https:\/\/www.britannica.com\/place\/Jupiter-planet)’s volume but has only about one-third of its mass and the lowest mean density—about 70 percent that of water—of any known object in the solar system. Hypothetically, Saturn would float in an ocean large enough to hold it. Both Saturn and Jupiter resemble [stars](https:\/\/www.britannica.com\/science\/star-astronomy) in that their bulk chemical [composition](https:\/\/www.merriam-webster.com\/dictionary\/composition) is dominated by [hydrogen](https:\/\/www.britannica.com\/science\/hydrogen). Also, as is the case for Jupiter, the tremendous pressure in Saturn’s deep interior maintains the hydrogen there in a fluid metallic state. Saturn’s structure and evolutionary history, however, differ significantly from those of its larger counterpart. Like the other giant, or Jovian, planets—Jupiter, [Uranus](https:\/\/www.britannica.com\/place\/Uranus-planet), and [Neptune](https:\/\/www.britannica.com\/place\/Neptune-planet)—Saturn has extensive systems of [moons](https:\/\/www.britannica.com\/science\/moon-natural-satellite) (natural satellites) and rings, which may provide clues to its origin and evolution as well as to those of the solar system. Saturn’s [moon](https:\/\/www.britannica.com\/science\/moon-natural-satellite) [Titan](https:\/\/www.britannica.com\/place\/Titan-astronomy) is distinguished from all other moons in the solar system by the presence of a significant atmosphere, one that is [denser](https:\/\/www.britannica.com\/dictionary\/denser) than that of any of the terrestrial planets except [Venus](https:\/\/www.britannica.com\/place\/Venus-planet).\n\nThe greatest advances in knowledge of Saturn, as well as of most of the other planets, have come from deep-space probes. Four spacecraft have visited the Saturnian system: [Pioneer](https:\/\/www.britannica.com\/technology\/Pioneer-space-probes) 11 in 1979, [Voyager](https:\/\/www.britannica.com\/technology\/Voyager-space-probes)s 1 and 2 in the two years following, and, after almost a quarter-century, [Cassini-Huygens](https:\/\/www.britannica.com\/event\/Cassini-Huygens), which arrived in 2004. The first three missions were short-term flybys, but [Cassini](https:\/\/www.britannica.com\/event\/Cassini-Huygens) went into orbit around Saturn for years of investigations, while its Huygens probe parachuted through the atmosphere of Titan and reached its surface, becoming the first spacecraft to land on a moon other than Earth’s.\n\n## Basic astronomical data\nSaturn orbits the Sun at a mean distance of 1,427,000,000 km (887 million miles). Its closest distance to Earth is about 1.2 billion km (746 million miles), and its [phase](https:\/\/www.britannica.com\/science\/phase-state-of-matter) angle—the angle that it makes with the Sun and Earth—never exceeds about 6°. Saturn seen from the vicinity of Earth thus always appears nearly fully [illuminated](https:\/\/www.merriam-webster.com\/dictionary\/illuminated). Only deep [space probes](https:\/\/www.britannica.com\/technology\/space-probe) can provide sidelit and backlit views.\n\n[![Saturn. Saturn and its rings. Second largest planet of the solar system. Space Art](https:\/\/cdn.britannica.com\/74\/166074-131-677298A0\/Saturn-rings-planet-solar-system-Space-Art.jpg) Britannica Quiz Planets and the Earth’s Moon](https:\/\/www.britannica.com\/quiz\/planets-and-the-earths-moon)\n\nLike Jupiter and most of the other planets, Saturn has a regular [orbit](https:\/\/www.britannica.com\/science\/orbit-astronomy)—that is, its motion around the Sun is prograde (in the same direction that the Sun rotates) and has a small eccentricity (noncircularity) and [inclination](https:\/\/www.britannica.com\/science\/inclination-of-equator-to-orbit) to the [ecliptic](https:\/\/www.britannica.com\/science\/ecliptic), the plane of Earth’s orbit. Unlike Jupiter, however, Saturn’s rotational axis is tilted substantially—by 26.7°—to its orbital plane. The tilt gives Saturn seasons, as on Earth, but each season lasts more than seven years. Another result is that Saturn’s rings, which lie in the plane of its equator, are presented to observers on Earth at opening angles ranging from 0° (edge on) to nearly 30°. The view of Saturn’s rings cycles over a 30-year period. Earth-based observers can see the rings’ sunlit northern side for about 15 years and then, in an [analogous](https:\/\/www.merriam-webster.com\/dictionary\/analogous) view, the sunlit southern side for the next 15 years. In the short intervals when Earth crosses the ring plane, the rings are all but invisible.\n\nSaturn’s [rotation](https:\/\/www.britannica.com\/science\/rotation-physics) period was very difficult to determine. [Cloud](https:\/\/www.britannica.com\/science\/cloud-meteorology) motions in its massive upper atmosphere trace out a variety of periods, which are as short as about 10 hours 10 minutes near the equator and increase with some oscillation to about 30 minutes longer at latitudes higher than 40°. Scientists attempted to determine the rotation period of Saturn’s deep interior from that of its [magnetic field](https:\/\/www.britannica.com\/science\/magnetic-field), which is [presumed](https:\/\/www.britannica.com\/dictionary\/presumed) to be rooted in the planet’s metallic-hydrogen outer core. However, direct measurement of the field’s rotation was difficult because the field is highly symmetrical around the rotational axis. At the time of the Voyager encounters, radio outbursts from Saturn, apparently related to small irregularities in the magnetic field, showed a period of 10 hours 39.4 minutes; this value was taken to be the magnetic field rotation period. Measurements made 25 years later by the [Cassini](https:\/\/www.britannica.com\/topic\/Cassini) [spacecraft](https:\/\/www.britannica.com\/technology\/spacecraft) indicated that the field was rotating with a period 6–7 minutes longer. It was believed that the [solar wind](https:\/\/www.britannica.com\/science\/solar-wind) is responsible for some of the difference between these two measurements of the rotational period. Not until Cassini flew inside Saturn’s rings on its final orbits was the rotation period accurately measured. By relating waves observed in the rings to slight variations in Saturn’s gravitational field, the rotation period of the planet was determined to be 10 hours 33 minutes 38 seconds. The time differences between the rotation periods of Saturn’s clouds and of its interior have been used to estimate wind velocities (*see below* [The atmosphere](https:\/\/www.britannica.com\/place\/Saturn-planet\/The-atmosphere#ref54279)).\n\nGo beyond the basics with trusted, in-depth knowledge for professionals, students, and lifelong learners.\n\n[SUBSCRIBE](https:\/\/premium.britannica.com\/premium-membership\/?utm_source=premium&utm_medium=inline-cta&utm_campaign=basics-2026)\n\n![Penguin, ship, mountain, atlas](https:\/\/cdn.britannica.com\/marketing\/inline-left.webp)\n\n![shohei ohtani, plants, andy wharhol art](https:\/\/cdn.britannica.com\/marketing\/inline-right.webp)\n\n![Mobile](https:\/\/cdn.britannica.com\/marketing\/inline-mobile.webp?w=400)\n\nBecause the four giant [planets](https:\/\/www.britannica.com\/science\/planet) have no solid surface in their outer layers, by [convention](https:\/\/www.britannica.com\/dictionary\/convention) the values for the radius and gravity of these planets are calculated at the level at which one bar of [atmospheric pressure](https:\/\/www.britannica.com\/science\/atmospheric-pressure) is exerted. By this measure, Saturn’s equatorial diameter is 120,536 km (74,898 miles). In comparison, its polar diameter is only 108,728 km (67,560 miles), or 10 percent smaller, which makes Saturn the most oblate (flattened at the poles) of all the planets in the solar system. Its oblate shape is apparent even in a small [telescope](https:\/\/www.britannica.com\/science\/optical-telescope). Even though Saturn rotates slightly slower than Jupiter, it is more oblate because its rotational [acceleration](https:\/\/www.britannica.com\/science\/acceleration) cancels a larger fraction of the planet’s [gravity](https:\/\/www.britannica.com\/science\/gravity-physics) at the equator. The equatorial gravity of the planet, 896 cm (29.4 feet) per second per second, is only 74 percent of its polar gravity. Saturn is 95 times as massive as Earth but occupies a volume 766 times greater. Its mean [density](https:\/\/www.britannica.com\/science\/density) of 0.69 gram per cubic cm is thus only some 12 percent of Earth’s. Saturn’s equatorial [escape velocity](https:\/\/www.britannica.com\/science\/escape-velocity)—the velocity needed for an object, which includes individual atoms and molecules, to escape the planet’s gravitational attraction at the equator without having to be further accelerated—is nearly 36 km per second (80,000 miles per hour) at the one-bar level, compared with 11.2 km per second (25,000 miles per hour) for Earth. This high [value](https:\/\/www.britannica.com\/dictionary\/value) indicates that there has been no significant loss of atmosphere from Saturn since its formation.\n\n| Planetary data for Saturn |   |\n|---|---|\n| \\*Time required for the planet to return to the same position in the sky relative to the Sun as seen from Earth. |   |\n| \\*\\*Calculated for the altitude at which 1 bar of atmospheric pressure is exerted. |   |\n| mean distance from Sun | 1,426,666,000 km (9.5 AU) |\n| eccentricity of orbit | 0\\.054 |\n| inclination of orbit to ecliptic | 2\\.49° |\n| Saturnian year (sidereal period of revolution) | 29\\.45 Earth years |\n| visual magnitude at mean opposition | 0\\.7 |\n| mean synodic period\\* | 378\\.10 Earth days |\n| mean orbital velocity | 9\\.6 km\/sec |\n| equatorial radius\\*\\* | 60,268 km |\n| polar radius\\*\\* | 54,364 km |\n| mass | 5\\.683 × 1026 kg |\n| mean density | 0\\.69 g\/cm3 |\n| equatorial gravity\\*\\* | 896 cm\/sec2 |\n| polar gravity\\*\\* | 1,214 cm\/sec2 |\n| equatorial escape velocity\\*\\* | 35\\.5 km\/sec |\n| polar escape velocity\\*\\* | 37\\.4 km\/sec |\n| rotation period (magnetic field) | 10 hr 39 min 24 sec (Voyager era); about 10 hr 46 min (Cassini-Huygens mission) |\n| inclination of equator to orbit | 26\\.7° |\n| magnetic field strength at equator | 0\\.21 gauss |\n| number of known moons | 274 |\n| planetary ring system | 3 major rings comprising myriad component ringlets; several less-dense rings |","meta_canonical":null}

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Boilerpipe Text	Top Questions Who first observed Saturn with a telescope? How far is Saturn from Earth? What feature is Saturn known for? What is Saturn’s largest moon? Is Saturn light enough to float? News • Saturn , second largest planet of the solar system in mass and size and the sixth nearest planet in distance to the Sun . In the night sky Saturn is easily visible to the unaided eye as a non-twinkling point of light. When viewed through even a small telescope, the planet encircled by its magnificent rings is arguably the most sublime object in the solar system. Saturn is designated by the symbol ♄. Saturn’s name comes from the Roman god of agriculture , who is equated with the Greek deity Cronus , one of the Titans and the father of Zeus (the Roman god Jupiter). As the farthest of the planets known to ancient observers, Saturn also was noted to be the slowest-moving. At a distance from the Sun that is 9.5 times as far as Earth ’s, Saturn takes approximately 29.5 Earth years to make one solar revolution. The Italian astronomer Galileo in 1610 was the first to observe Saturn with a telescope. Although he saw a strangeness in Saturn’s appearance, the low resolution of his instrument did not allow him to discern the true nature of the planet’s rings. Saturn occupies almost 60 percent of Jupiter ’s volume but has only about one-third of its mass and the lowest mean density—about 70 percent that of water—of any known object in the solar system. Hypothetically, Saturn would float in an ocean large enough to hold it. Both Saturn and Jupiter resemble stars in that their bulk chemical composition is dominated by hydrogen . Also, as is the case for Jupiter, the tremendous pressure in Saturn’s deep interior maintains the hydrogen there in a fluid metallic state. Saturn’s structure and evolutionary history, however, differ significantly from those of its larger counterpart. Like the other giant, or Jovian, planets—Jupiter, Uranus , and Neptune —Saturn has extensive systems of moons (natural satellites) and rings, which may provide clues to its origin and evolution as well as to those of the solar system. Saturn’s moon Titan is distinguished from all other moons in the solar system by the presence of a significant atmosphere, one that is denser than that of any of the terrestrial planets except Venus . The greatest advances in knowledge of Saturn, as well as of most of the other planets, have come from deep-space probes. Four spacecraft have visited the Saturnian system: Pioneer 11 in 1979, Voyager s 1 and 2 in the two years following, and, after almost a quarter-century, Cassini-Huygens , which arrived in 2004. The first three missions were short-term flybys, but Cassini went into orbit around Saturn for years of investigations, while its Huygens probe parachuted through the atmosphere of Titan and reached its surface, becoming the first spacecraft to land on a moon other than Earth’s. Basic astronomical data Saturn orbits the Sun at a mean distance of 1,427,000,000 km (887 million miles). Its closest distance to Earth is about 1.2 billion km (746 million miles), and its phase angle—the angle that it makes with the Sun and Earth—never exceeds about 6°. Saturn seen from the vicinity of Earth thus always appears nearly fully illuminated . Only deep space probes can provide sidelit and backlit views. Britannica Quiz Planets and the Earth’s Moon Like Jupiter and most of the other planets, Saturn has a regular orbit —that is, its motion around the Sun is prograde (in the same direction that the Sun rotates) and has a small eccentricity (noncircularity) and inclination to the ecliptic , the plane of Earth’s orbit. Unlike Jupiter, however, Saturn’s rotational axis is tilted substantially—by 26.7°—to its orbital plane. The tilt gives Saturn seasons, as on Earth, but each season lasts more than seven years. Another result is that Saturn’s rings, which lie in the plane of its equator, are presented to observers on Earth at opening angles ranging from 0° (edge on) to nearly 30°. The view of Saturn’s rings cycles over a 30-year period. Earth-based observers can see the rings’ sunlit northern side for about 15 years and then, in an analogous view, the sunlit southern side for the next 15 years. In the short intervals when Earth crosses the ring plane, the rings are all but invisible. Saturn’s rotation period was very difficult to determine. Cloud motions in its massive upper atmosphere trace out a variety of periods, which are as short as about 10 hours 10 minutes near the equator and increase with some oscillation to about 30 minutes longer at latitudes higher than 40°. Scientists attempted to determine the rotation period of Saturn’s deep interior from that of its magnetic field , which is presumed to be rooted in the planet’s metallic-hydrogen outer core. However, direct measurement of the field’s rotation was difficult because the field is highly symmetrical around the rotational axis. At the time of the Voyager encounters, radio outbursts from Saturn, apparently related to small irregularities in the magnetic field, showed a period of 10 hours 39.4 minutes; this value was taken to be the magnetic field rotation period. Measurements made 25 years later by the Cassini spacecraft indicated that the field was rotating with a period 6–7 minutes longer. It was believed that the solar wind is responsible for some of the difference between these two measurements of the rotational period. Not until Cassini flew inside Saturn’s rings on its final orbits was the rotation period accurately measured. By relating waves observed in the rings to slight variations in Saturn’s gravitational field, the rotation period of the planet was determined to be 10 hours 33 minutes 38 seconds. The time differences between the rotation periods of Saturn’s clouds and of its interior have been used to estimate wind velocities ( see below The atmosphere ). Go beyond the basics with trusted, in-depth knowledge for professionals, students, and lifelong learners. SUBSCRIBE Because the four giant planets have no solid surface in their outer layers, by convention the values for the radius and gravity of these planets are calculated at the level at which one bar of atmospheric pressure is exerted. By this measure, Saturn’s equatorial diameter is 120,536 km (74,898 miles). In comparison, its polar diameter is only 108,728 km (67,560 miles), or 10 percent smaller, which makes Saturn the most oblate (flattened at the poles) of all the planets in the solar system. Its oblate shape is apparent even in a small telescope . Even though Saturn rotates slightly slower than Jupiter, it is more oblate because its rotational acceleration cancels a larger fraction of the planet’s gravity at the equator. The equatorial gravity of the planet, 896 cm (29.4 feet) per second per second, is only 74 percent of its polar gravity. Saturn is 95 times as massive as Earth but occupies a volume 766 times greater. Its mean density of 0.69 gram per cubic cm is thus only some 12 percent of Earth’s. Saturn’s equatorial escape velocity —the velocity needed for an object, which includes individual atoms and molecules, to escape the planet’s gravitational attraction at the equator without having to be further accelerated—is nearly 36 km per second (80,000 miles per hour) at the one-bar level, compared with 11.2 km per second (25,000 miles per hour) for Earth. This high value indicates that there has been no significant loss of atmosphere from Saturn since its formation. Planetary data for Saturn Time required for the planet to return to the same position in the sky relative to the Sun as seen from Earth. Calculated for the altitude at which 1 bar of atmospheric pressure is exerted. mean distance from Sun 1,426,666,000 km (9.5 AU) eccentricity of orbit 0.054 inclination of orbit to ecliptic 2.49° Saturnian year (sidereal period of revolution) 29.45 Earth years visual magnitude at mean opposition 0.7 mean synodic period 378.10 Earth days mean orbital velocity 9.6 km/sec equatorial radius 60,268 km polar radius 54,364 km mass 5.683 × 10 26 kg mean density 0.69 g/cm 3 equatorial gravity 896 cm/sec 2 polar gravity 1,214 cm/sec 2 equatorial escape velocity 35.5 km/sec polar escape velocity 37.4 km/sec rotation period (magnetic field) 10 hr 39 min 24 sec (Voyager era); about 10 hr 46 min (Cassini-Huygens mission) inclination of equator to orbit 26.7° magnetic field strength at equator 0.21 gauss number of known moons 274 planetary ring system 3 major rings comprising myriad component ringlets; several less-dense rings
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Enceladus is backlit by the Sun.](https://cdn.britannica.com/16/96216-004-7283F5D2/Geysers-ice-image-region-spacecraft-Enceladus-Cassini-2005.jpg)](https://cdn.britannica.com/16/96216-050-634FC226/Geysers-ice-image-region-spacecraft-Enceladus-Cassini-2005.jpg) [![Saturn: Iapetus](https://cdn.britannica.com/09/96609-004-D70FC213/Image-Iapetus-spacecraft-Cassini-Huygens.jpg)](https://cdn.britannica.com/09/96609-050-AB6B6599/Image-Iapetus-spacecraft-Cassini-Huygens.jpg) [![Saturn: Phoebe](https://cdn.britannica.com/07/96607-004-24651A35/Image-Phoebe-spacecraft-Cassini-Huygens.jpg)](https://cdn.britannica.com/07/96607-050-32FC57DC/Image-Phoebe-spacecraft-Cassini-Huygens.jpg) [![Saturn: Rhea](https://cdn.britannica.com/08/96608-004-BDEB476C/Image-Rhea-spacecraft-Cassini-Huygens.jpg)](https://cdn.britannica.com/08/96608-050-CE90381A/Image-Rhea-spacecraft-Cassini-Huygens.jpg) At a Glance [![default image](https://cdn.britannica.com/mendel-resources/3-178/images/shared/new-thistle.svg?v=3.178.5)](https://www.britannica.com/summary/Cassini-Huygens) [Cassini-Huygens summary](https://www.britannica.com/summary/Cassini-Huygens) Related Questions - [How is astronomy different from cosmology?](https://www.britannica.com/question/How-is-astronomy-different-from-cosmology) - [What are Dione’s surface features?](https://www.britannica.com/question/What-are-Diones-surface-features) - [Where did Titan get its name?](https://www.britannica.com/question/Where-did-Titan-get-its-name) - [What is the atmosphere of Titan composed of?](https://www.britannica.com/question/What-is-the-atmosphere-of-Titan-composed-of) - [What is Titan’s haze composed of?](https://www.britannica.com/question/What-is-Titans-haze-composed-of) ![Britannica AI Icon](https://cdn.britannica.com/mendel-resources/3-178/images/chatbot/star-ai.svg?v=3.178.5) Contents Ask Anything [Science](https://www.britannica.com/browse/Science) [Astronomy](https://www.britannica.com/browse/Astronomy) CITE Share Feedback External Websites [![Cassini-Huygens spacecraft](https://cdn.britannica.com/17/96617-050-7204B281/probe-Artwork-centre-orbiter-Huygens-Cassini-planet-June-30-2004.jpg?w=400&h=300&c=crop)](https://cdn.britannica.com/17/96617-050-7204B281/probe-Artwork-centre-orbiter-Huygens-Cassini-planet-June-30-2004.jpg) [Cassini-Huygens spacecraft](https://cdn.britannica.com/17/96617-050-7204B281/probe-Artwork-centre-orbiter-Huygens-Cassini-planet-June-30-2004.jpg) Artist's conception of the Huygens probe separating from the Cassini orbiter and beginning its descent into the atmosphere of Titan. (more) # Cassini-Huygens space mission Homework Help Written by [Dave Dooling Education and Public Outreach Officer, National Solar Observatory, Sacramento Peak, New Mexico. Coauthor of Engineering Tomorrow.](https://www.britannica.com/contributor/Dave-Dooling/764) Dave Dooling Fact-checked by [Britannica Editors Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....](https://www.britannica.com/editor/The-Editors-of-Encyclopaedia-Britannica/4419) Britannica Editors Last updated Mar. 10, 2026 •[History](https://www.britannica.com/event/Cassini-Huygens/additional-info#history) ![Britannica AI Icon](https://cdn.britannica.com/mendel-resources/3-178/images/chatbot/star-ai.svg?v=3.178.5) Britannica AI Ask Anything Table of Contents Table of Contents Ask Anything Top Questions - What was the Cassini-Huygens mission? - Which planets or moons did Cassini-Huygens study? - Who were the main organizations involved in the Cassini-Huygens mission? - What did the Cassini spacecraft do while orbiting Saturn? - What was special about the Huygens probe? - What were some important discoveries made by Cassini-Huygens about Saturn and its moons? Show more Show less Cassini-Huygens, U.S.-European space mission to [Saturn](https://www.britannica.com/place/Saturn-planet), launched on October 15, 1997. The mission consisted of the U.S. [National Aeronautics and Space Administration](https://www.britannica.com/topic/NASA)’s (NASA’s) [Cassini](https://www.britannica.com/topic/Cassini) orbiter, which was the first space [probe](https://www.britannica.com/dictionary/probe) to [orbit](https://www.britannica.com/science/orbit-astronomy) Saturn, and the [European Space Agency](https://www.britannica.com/topic/European-Space-Agency)’s [Huygens](https://www.britannica.com/topic/Huygens) probe, which landed on [Titan](https://www.britannica.com/place/Titan-astronomy), Saturn’s largest [moon](https://www.britannica.com/science/moon-natural-satellite). Cassini was named for the French astronomer [Gian Domenico Cassini](https://www.britannica.com/biography/Gian-Domenico-Cassini), who discovered four of Saturn’s moons and the Cassini division, a large gap in [Saturn’s rings](https://www.britannica.com/place/Saturn-planet/The-ring-system#ref54286). Huygens was named for the Dutch scientist [Christiaan Huygens](https://www.britannica.com/biography/Christiaan-Huygens), who discovered Saturn’s rings and Titan. [![Learn about the Cassini-Huygens mission to Titan, the largest moon of Saturn with an atmosphere of its own](https://cdn.britannica.com/82/186482-138-DA3DC387/discussion-moon-mission-Titan-Cassini-Huygens-atmosphere-Saturn.jpg?w=800&h=450&c=crop)1 of 2](https://www.britannica.com/video/discussion-moon-mission-Titan-Cassini-Huygens-atmosphere-Saturn/-206600) Learn about the Cassini-Huygens mission to Titan, the largest moon of Saturn with an atmosphere of its ownA discussion of the Cassini-Huygens mission to Titan, a moon of Saturn with its own atmosphere. (more) [See all videos for this article](https://www.britannica.com/event/Cassini-Huygens/images-videos) [![Witness Cassini-Huygens mission to Saturn with an actual sound of ring particles striking Cassini](https://cdn.britannica.com/83/145483-138-3995D132/Overview-mission-Cassini-Huygens-Saturn.jpg?w=800&h=450&c=crop)2 of 2](https://www.britannica.com/video/Overview-mission-Cassini-Huygens-Saturn/-155717) Witness Cassini-Huygens mission to Saturn with an actual sound of ring particles striking CassiniOverview of the Cassini-Huygens mission to Saturn. (more) [See all videos for this article](https://www.britannica.com/event/Cassini-Huygens/images-videos) Cassini-Huygens was one of the largest interplanetary spacecraft. The Cassini orbiter weighed 2,125 kg (4,685 pounds) and was 6.7 metres (22 feet) long and 4 metres (13 feet) wide. The instruments on board Cassini included [radar](https://www.britannica.com/technology/radar) to map the cloud-covered surface of Titan and a [magnetometer](https://www.britannica.com/technology/magnetometer) to study Saturn’s [magnetic field](https://www.britannica.com/science/magnetic-field). The disk-shaped Huygens probe was [mounted](https://www.britannica.com/dictionary/mounted) on the side of Cassini. It weighed 349 kg (769 pounds), was 2.7 metres (8.9 feet) across, and carried six instruments designed to study the atmosphere and surface of Titan. [![Jupiter as seen by NASA's Cassini spacecraft on Dec. 7, 2000.](https://cdn.britannica.com/41/93241-050-FD3DB7E9/Jupiter-spacecraft-Cassini-NASA-Dec-7-2000.jpg?w=300)](https://cdn.britannica.com/41/93241-050-FD3DB7E9/Jupiter-spacecraft-Cassini-NASA-Dec-7-2000.jpg) [Jupiter as seen by NASA's Cassini spacecraft on Dec. 7, 2000.](https://cdn.britannica.com/41/93241-050-FD3DB7E9/Jupiter-spacecraft-Cassini-NASA-Dec-7-2000.jpg) (more) Cassini drew its [electric power](https://www.britannica.com/technology/electric-power) from the heat generated by the decay of 33 kg (73 pounds) of [plutonium](https://www.britannica.com/science/plutonium), the largest amount of a [radioactive](https://www.britannica.com/science/radioactivity) element ever launched into space. Protesters had claimed that an accident during launch or Cassini’s flyby of [Earth](https://www.britannica.com/place/Earth) could expose Earth’s population to harmful plutonium dust and tried to block the launch with a flurry of demonstrations and lawsuits, but NASA countered that the casks encasing the plutonium were [robust](https://www.merriam-webster.com/dictionary/robust) enough to survive any mishap. Cassini-Huygens flew past [Venus](https://www.britannica.com/place/Venus-planet) for a [gravity](https://www.britannica.com/science/gravity-physics) assist in April 1998 and did the same with Earth and [Jupiter](https://www.britannica.com/place/Jupiter-planet) in August 1999 and December 2000, respectively. During its flyby of Earth, Cassini’s [spectrometer](https://www.britannica.com/science/spectrometer) observed water on the surface of the [Moon](https://www.britannica.com/science/moon-natural-satellite); this data was later used in 2009 to confirm the Indian probe [Chandrayaan-1](https://www.britannica.com/technology/Chandrayaan)’s finding of small amounts of water on the lunar surface. [![Saturn](https://cdn.britannica.com/00/81400-050-8BBE1CDA/Saturn-rings-composite-images-spacecraft-Cassini-Shadows-October-6-2004.jpg?w=300)1 of 2](https://cdn.britannica.com/00/81400-050-8BBE1CDA/Saturn-rings-composite-images-spacecraft-Cassini-Shadows-October-6-2004.jpg) [Saturn](https://cdn.britannica.com/00/81400-050-8BBE1CDA/Saturn-rings-composite-images-spacecraft-Cassini-Shadows-October-6-2004.jpg)Saturn and its spectacular rings, in a natural-color composite of 126 images taken by the Cassini spacecraft on October 6, 2004. The view is directed toward Saturn's southern hemisphere, which is tipped toward the Sun. Shadows cast by the rings are visible against the bluish northern hemisphere, while the planet's shadow is projected on the rings to the left. (more) [![View from the Huygens probe of Titan's surface on Jan. 14, 2005.](https://cdn.britannica.com/63/97263-050-72AF8096/probe-surface-Huygens-Titan-Jan-14-2005.jpg?w=300)2 of 2](https://cdn.britannica.com/63/97263-050-72AF8096/probe-surface-Huygens-Titan-Jan-14-2005.jpg) [View from the Huygens probe of Titan's surface on Jan. 14, 2005.](https://cdn.britannica.com/63/97263-050-72AF8096/probe-surface-Huygens-Titan-Jan-14-2005.jpg) (more) Cassini-Huygens entered [Saturn](https://www.britannica.com/place/Saturn-planet) orbit on July 1, 2004. Huygens was released on December 25, 2004, and landed on [Titan](https://www.britannica.com/place/Titan-astronomy) on January 14, 2005—the first landing on any celestial body beyond [Mars](https://www.britannica.com/place/Mars-planet). Data that Huygens transmitted during its final descent and for 72 minutes from the surface included 350 pictures that showed a shoreline with [erosion](https://www.britannica.com/science/erosion-geology) features and a river [delta](https://www.britannica.com/science/delta-river-system-component). In error, one radio channel on the satellite was not turned on, and data were lost concerning the winds Huygens encountered during its descent. [![Geysers of ice towering over the south polar region of Enceladus in an image taken by the Cassini spacecraft in 2005. Enceladus is backlit by the Sun.](https://cdn.britannica.com/16/96216-050-634FC226/Geysers-ice-image-region-spacecraft-Enceladus-Cassini-2005.jpg?w=300)](https://cdn.britannica.com/16/96216-050-634FC226/Geysers-ice-image-region-spacecraft-Enceladus-Cassini-2005.jpg) [Geysers of ice towering over the south polar region of Enceladus in an image taken by the Cassini spacecraft in 2005. Enceladus is backlit by the Sun.](https://cdn.britannica.com/16/96216-050-634FC226/Geysers-ice-image-region-spacecraft-Enceladus-Cassini-2005.jpg) (more) Cassini continued to orbit Saturn and complete many flybys of Saturn’s moons. A particularly exciting discovery during its mission was that of [geysers](https://www.britannica.com/science/geyser) of water ice and organic molecules at the south pole of [Enceladus](https://www.britannica.com/place/Enceladus), which erupt from an underground global ocean that could be a possible [environment](https://www.merriam-webster.com/dictionary/environment) for life. Cassini’s radar mapped much of Titan’s surface and found large lakes of liquid [methane](https://www.britannica.com/science/methane). Cassini also discovered six new moons and two new rings of Saturn. In July 2008 Cassini’s mission was extended to 2010, and in February 2010 it was extended for another seven years. Quick Facts Date: October 15, 1997 - September 15, 2017 (Show more) Participants: [Cassini](https://www.britannica.com/topic/Cassini) [Huygens](https://www.britannica.com/topic/Huygens) (Show more) Context: [Gian Domenico Cassini](https://www.britannica.com/biography/Gian-Domenico-Cassini) [Christiaan Huygens](https://www.britannica.com/biography/Christiaan-Huygens) (Show more) On the Web: [BBC - BBC Inside Science - Farewell to Cassini, the epic 20 year mission to Saturn](https://www.bbc.com/audio/play/b093104w) (Mar. 10, 2026) (Show more) [See all related content](https://www.britannica.com/facts/Cassini-Huygens) Beginning in April 2017, Cassini’s orbit was altered by a close encounter with Titan so that it passed inside Saturn’s innermost ring at a distance of 3,800 km (2,400 miles) from the [planet](https://www.britannica.com/science/planet). After 23 such “proximal” orbits, a final [encounter](https://www.britannica.com/dictionary/encounter) with Titan changed Cassini’s orbit so that on September 15, 2017, it ended its mission by plunging into Saturn, which allowed Cassini to sample Saturn’s atmosphere directly and avoid any possible future contamination of Enceladus and Titan. [Dave Dooling](https://www.britannica.com/contributor/Dave-Dooling/764) ![Britannica AI Icon](https://cdn.britannica.com/mendel-resources/3-178/images/chatbot/star-ai.svg?v=3.178.5)Britannica AI chevron\_right Cassini-Huygens close [AI-generated answers](https://www.britannica.com/about-britannica-ai) from Britannica articles. AI makes mistakes, so verify using Britannica articles. [Saturn](https://www.britannica.com/place/Saturn-planet) - [Introduction & Top Questions](https://www.britannica.com/place/Saturn-planet) - [Basic astronomical data](https://www.britannica.com/place/Saturn-planet#ref54278) - [The atmosphere](https://www.britannica.com/place/Saturn-planet/The-atmosphere) - [Composition and structure](https://www.britannica.com/place/Saturn-planet/The-atmosphere#ref298253) - [Dynamics](https://www.britannica.com/place/Saturn-planet/The-atmosphere#ref298254) - [The magnetic field and magnetosphere](https://www.britannica.com/place/Saturn-planet/The-magnetic-field-and-magnetosphere) - [The interior](https://www.britannica.com/place/Saturn-planet/The-interior) - [Saturn’s rings and moons](https://www.britannica.com/place/Saturn-planet/Saturns-rings-and-moons) - [The ring system](https://www.britannica.com/place/Saturn-planet/The-ring-system) - [Moons](https://www.britannica.com/place/Saturn-planet/Moons) - [Significant satellites](https://www.britannica.com/place/Saturn-planet/Moons#ref253150) - [Orbital and rotational dynamics](https://www.britannica.com/place/Saturn-planet/Orbital-and-rotational-dynamics) - [Observations from Earth](https://www.britannica.com/place/Saturn-planet/Orbital-and-rotational-dynamics#ref54287) - [Spacecraft exploration](https://www.britannica.com/place/Saturn-planet/Spacecraft-exploration) [References & Edit History](https://www.britannica.com/place/Saturn-planet/additional-info) [Related Topics](https://www.britannica.com/facts/Saturn-planet) [Images, Videos & Interactives](https://www.britannica.com/place/Saturn-planet/images-videos) [![Saturn](https://cdn.britannica.com/00/81400-004-02A7F6CB/Saturn-rings-composite-images-spacecraft-Cassini-Shadows-October-6-2004.jpg)](https://cdn.britannica.com/00/81400-050-8BBE1CDA/Saturn-rings-composite-images-spacecraft-Cassini-Shadows-October-6-2004.jpg) [![Interactive comparing planet sizes in the solar system from left to right: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.](https://cdn.britannica.com/18/238518-049-AC2B446B/planets-solar-system-size-comparison.jpg)](https://www.britannica.com/event/Cassini-Huygens) [![Saturn](https://cdn.britannica.com/67/21167-004-6B1CF05E/Saturn-storm-Earth-region-observations-image-Hubble-December-1-1994.jpg)](https://cdn.britannica.com/67/21167-004-6B1CF05E/Saturn-storm-Earth-region-observations-image-Hubble-December-1-1994.jpg) [![Cassini: Saturn](https://cdn.britannica.com/81/145481-004-354D226E/Image-Saturn-radio-occultation-observation-planet-Cassini-2005.jpg)](https://cdn.britannica.com/81/145481-050-F73198DB/Image-Saturn-radio-occultation-observation-planet-Cassini-2005.jpg) [![Saturn's three main rings](https://cdn.britannica.com/66/91966-004-377C0F3C/rings-Details-Saturn-spacecraft-images-composite-Cassini-December-12-2004.jpg)](https://cdn.britannica.com/66/91966-004-377C0F3C/rings-Details-Saturn-spacecraft-images-composite-Cassini-December-12-2004.jpg) [![Hubble Space Telescope: Saturn and moons](https://cdn.britannica.com/80/145480-004-25D44084/image-Hubble-Space-Telescope-Saturn-moons-shadow.jpg)](https://cdn.britannica.com/80/145480-050-24BF0658/image-Hubble-Space-Telescope-Saturn-moons-shadow.jpg) [![Saturn: Titan](https://cdn.britannica.com/03/96603-004-4286BF16/view-moon-Titan-Saturn-Cassini-orbiter-Feb-15-2005.jpg)](https://cdn.britannica.com/03/96603-050-CD67246C/view-moon-Titan-Saturn-Cassini-orbiter-Feb-15-2005.jpg) [![Saturn: surface of Titan](https://cdn.britannica.com/12/96612-004-20AD7080/Image-surface-probe-Titan-Huygens-High-Resolution.jpg)](https://cdn.britannica.com/12/96612-004-20AD7080/Image-surface-probe-Titan-Huygens-High-Resolution.jpg) [![Learn about the Cassini-Huygens mission to Titan, the largest moon of Saturn with an atmosphere of its own](https://cdn.britannica.com/82/186482-138-DA3DC387/discussion-moon-mission-Titan-Cassini-Huygens-atmosphere-Saturn.jpg?w=400&h=225&c=crop)](https://www.britannica.com/video/discussion-moon-mission-Titan-Cassini-Huygens-atmosphere-Saturn/-206600) [![moons of Saturn: Mimas](https://cdn.britannica.com/82/145482-004-CEA104B9/Image-Mimas-atmosphere-Saturn-Cassini-camera-2006.jpg)](https://cdn.britannica.com/82/145482-050-00AF58A0/Image-Mimas-atmosphere-Saturn-Cassini-camera-2006.jpg) At a Glance [![Saturn](https://cdn.britannica.com/67/21167-004-6B1CF05E/Saturn-storm-Earth-region-observations-image-Hubble-December-1-1994.jpg?w=200&h=200&c=crop)](https://www.britannica.com/summary/Saturn-planet) [Saturn summary](https://www.britannica.com/summary/Saturn-planet) Quizzes [![View of the Andromeda Galaxy (Messier 31, M31).](https://cdn.britannica.com/41/155241-131-FB2C633F/View-Andromeda-Galaxy.jpg?w=200&h=200&c=crop)](https://www.britannica.com/quiz/astronomy-and-space-quiz) [Astronomy and Space Quiz](https://www.britannica.com/quiz/astronomy-and-space-quiz) [![The orbits of the planets and other elements of the solar system, including asteroids, Kuiper belt, Oort cloud, comet](https://cdn.britannica.com/92/95392-131-F6284677/orbits-planets-bodies-solar-system.jpg?w=200&h=200&c=crop)](https://www.britannica.com/quiz/space-odyssey) [Space Odyssey](https://www.britannica.com/quiz/space-odyssey) [![Saturn. Saturn and its rings. Second largest planet of the solar system. Space Art](https://cdn.britannica.com/74/166074-131-677298A0/Saturn-rings-planet-solar-system-Space-Art.jpg?w=200&h=200&c=crop)](https://www.britannica.com/quiz/planets-and-the-earths-moon) [Planets and the Earth’s Moon](https://www.britannica.com/quiz/planets-and-the-earths-moon) [![1 July 2002: The Solar and Heliospheric Observatory (SOHO) satellite reveals a massive solar eruption more than 30 times the Earth's diameter. The eruption formed when a loop of a magnetic field over the surface of the Sun trapped hot gas.](https://cdn.britannica.com/19/73319-131-21DE8879/Sun-ultraviolet-light-satellite-Earth-Solar-and.jpg?w=200&h=200&c=crop)](https://www.britannica.com/quiz/brightest-star-in-the-solar-system) [Brightest Star in the Solar System](https://www.britannica.com/quiz/brightest-star-in-the-solar-system) [![Nicolaus Copernicus. Nicolas Copernicus (1473-1543) Polish astronomer. In 1543 he published, forward proof of a Heliocentric (sun centered) universe. Coloured stipple engraving published London 1802. De revolutionibus orbium coelestium libri vi.](https://cdn.britannica.com/54/102254-131-ED1A2CE1/Nicolaus-Copernicus.jpg?w=200&h=200&c=crop)](https://www.britannica.com/quiz/all-about-astronomy) [All About Astronomy](https://www.britannica.com/quiz/all-about-astronomy) Related Questions - [How far is Saturn from Earth?](https://www.britannica.com/question/How-far-is-Saturn-from-Earth) - [What is Saturn’s largest moon?](https://www.britannica.com/question/What-is-Saturns-largest-moon) - [How did James Clerk Maxwell die?](https://www.britannica.com/question/How-did-James-Clerk-Maxwell-die) ![Britannica AI Icon](https://cdn.britannica.com/mendel-resources/3-178/images/chatbot/star-ai.svg?v=3.178.5) Ask Anything Quick Summary [Science](https://www.britannica.com/browse/Science) [Astronomy](https://www.britannica.com/browse/Astronomy) CITE Share Feedback External Websites [![Saturn](https://cdn.britannica.com/00/81400-050-8BBE1CDA/Saturn-rings-composite-images-spacecraft-Cassini-Shadows-October-6-2004.jpg?w=400&h=300&c=crop)](https://cdn.britannica.com/00/81400-050-8BBE1CDA/Saturn-rings-composite-images-spacecraft-Cassini-Shadows-October-6-2004.jpg) [Saturn](https://cdn.britannica.com/00/81400-050-8BBE1CDA/Saturn-rings-composite-images-spacecraft-Cassini-Shadows-October-6-2004.jpg) Saturn and its spectacular rings, in a natural-color composite of 126 images taken by the Cassini spacecraft on October 6, 2004. The view is directed toward Saturn's southern hemisphere, which is tipped toward the Sun. Shadows cast by the rings are visible against the bluish northern hemisphere, while the planet's shadow is projected on the rings to the left. (more) # Saturn planet Homework Help Written by [Mark Marley Scientist, Space Science and Astrobiology Division, NASA Ames Research Center, Moffet Field, California. Consulting Professor, Geological Sciences, Stanford University.](https://www.britannica.com/contributor/Mark-Marley/8078335) Mark Marley[All](https://www.britannica.com/place/Saturn-planet/additional-info#contributors) Fact-checked by [Britannica Editors Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....](https://www.britannica.com/editor/The-Editors-of-Encyclopaedia-Britannica/4419) Britannica Editors [History](https://www.britannica.com/place/Saturn-planet/additional-info#history) ![Britannica AI Icon](https://cdn.britannica.com/mendel-resources/3-178/images/chatbot/star-ai.svg?v=3.178.5) Britannica AI Ask Anything Quick Summary Table of Contents Table of Contents Quick Summary Ask Anything Top Questions ### Who first observed Saturn with a telescope? The Italian astronomer [Galileo](https://www.britannica.com/biography/Galileo-Galilei) in 1610 was the first to observe Saturn with a telescope. Although he saw a strangeness in Saturn’s appearance, the low resolution of his instrument did not allow him to discern the true nature of the planet’s rings. ### How far is Saturn from Earth? Saturn orbits the Sun at a mean distance of 1,427,000,000 km (887 million miles). Its closest distance to Earth is about 1.2 billion km (746 million miles), and its phase angle—the angle that it makes with the Sun and Earth—never exceeds about 6°. Saturn, seen from the vicinity of Earth, thus always appears nearly fully illuminated. ### What feature is Saturn known for? Saturn is surrounded by a ring system. The entire ring system spans nearly 26,000,000 km (16,000,000 miles) when the faint outer rings are included. When viewed through even a small telescope, the planet encircled by its magnificent rings is arguably the most sublime object in the solar system. ### What is Saturn’s largest moon? [Titan](https://www.britannica.com/place/Titan-astronomy) is Saturn’s largest moon and the only moon in the solar system known to have clouds, a dense atmosphere, and liquid lakes. The diameter of its solid body is 5,150 km (3,200 miles) making it the second-largest moon in the solar system. It was discovered telescopically in 1655 by the Dutch scientist Christiaan Huygen. ### Is Saturn light enough to float? Saturn has the lowest mean density—about 70 percent that of water—of any known object in the solar system. Hypothetically, Saturn would float in an ocean large enough to hold it. ## News • [Most powerful space telescope ever built solves decades-long planet mystery](https://www.newsweek.com/jwst-saturn-solves-decades-long-planet-mystery-11756944) • Mar. 30, 2026, 11:23 AM ET (Newsweek) ...(Show more) [NASA telescopes team up for clearest view of Saturn ever. See images](https://www.usatoday.com/story/news/nation/2026/03/26/webb-hubble-nasa-saturn/89328253007/) • Mar. 26, 2026, 7:51 AM ET (USA Today) [NASA Webb, Hubble Share Most Comprehensive View of Saturn to Date](https://science.nasa.gov/missions/webb/nasa-webb-hubble-share-most-comprehensive-view-of-saturn-to-date/) • Mar. 25, 2026, 2:00 PM ET (NASA Science (.gov)) [Jupiter and Saturn gain more moons: Solar system count rises to 442](https://indianexpress.com/article/technology/science/jupiter-and-saturn-gain-more-moons-solar-system-count-rises-to-442-10594184/) • Mar. 21, 2026, 8:00 AM ET (The Indian Express) [NASA begins building nuclear-powered Dragonfly drone for 2028 launch to Saturn moon Titan](https://www.space.com/space-exploration/missions/nasa-begins-building-nuclear-powered-dragonfly-drone-for-2028-launch-to-saturn-moon-titan) • Mar. 13, 2026, 9:00 AM ET (Space) Show less Saturn, second largest [planet](https://www.britannica.com/science/planet) of the [solar system](https://www.britannica.com/science/solar-system) in mass and size and the sixth nearest planet in distance to the [Sun](https://www.britannica.com/place/Sun). In the night sky Saturn is easily visible to the unaided [eye](https://www.britannica.com/science/human-eye) as a non-twinkling point of light. When viewed through even a small telescope, the planet encircled by its magnificent rings is arguably the most [sublime](https://www.merriam-webster.com/dictionary/sublime) object in the solar system. Saturn is designated by the symbol ♄. Saturn’s name comes from the Roman god of [agriculture](https://www.britannica.com/topic/agriculture), who is equated with the Greek deity [Cronus](https://www.britannica.com/topic/Cronus), one of the Titans and the father of [Zeus](https://www.britannica.com/topic/Zeus) (the Roman god Jupiter). As the farthest of the planets known to ancient observers, Saturn also was noted to be the slowest-moving. At a distance from the Sun that is 9.5 times as far as [Earth](https://www.britannica.com/place/Earth)’s, Saturn takes approximately 29.5 Earth years to make one solar revolution. The Italian astronomer [Galileo](https://www.britannica.com/biography/Galileo-Galilei) in 1610 was the first to observe Saturn with a telescope. Although he saw a strangeness in Saturn’s appearance, the low resolution of his instrument did not allow him to discern the true nature of the planet’s rings. Saturn occupies almost 60 percent of [Jupiter](https://www.britannica.com/place/Jupiter-planet)’s volume but has only about one-third of its mass and the lowest mean density—about 70 percent that of water—of any known object in the solar system. Hypothetically, Saturn would float in an ocean large enough to hold it. Both Saturn and Jupiter resemble [stars](https://www.britannica.com/science/star-astronomy) in that their bulk chemical [composition](https://www.merriam-webster.com/dictionary/composition) is dominated by [hydrogen](https://www.britannica.com/science/hydrogen). Also, as is the case for Jupiter, the tremendous pressure in Saturn’s deep interior maintains the hydrogen there in a fluid metallic state. Saturn’s structure and evolutionary history, however, differ significantly from those of its larger counterpart. Like the other giant, or Jovian, planets—Jupiter, [Uranus](https://www.britannica.com/place/Uranus-planet), and [Neptune](https://www.britannica.com/place/Neptune-planet)—Saturn has extensive systems of [moons](https://www.britannica.com/science/moon-natural-satellite) (natural satellites) and rings, which may provide clues to its origin and evolution as well as to those of the solar system. Saturn’s [moon](https://www.britannica.com/science/moon-natural-satellite) [Titan](https://www.britannica.com/place/Titan-astronomy) is distinguished from all other moons in the solar system by the presence of a significant atmosphere, one that is [denser](https://www.britannica.com/dictionary/denser) than that of any of the terrestrial planets except [Venus](https://www.britannica.com/place/Venus-planet). The greatest advances in knowledge of Saturn, as well as of most of the other planets, have come from deep-space probes. Four spacecraft have visited the Saturnian system: [Pioneer](https://www.britannica.com/technology/Pioneer-space-probes) 11 in 1979, [Voyager](https://www.britannica.com/technology/Voyager-space-probes)s 1 and 2 in the two years following, and, after almost a quarter-century, [Cassini-Huygens](https://www.britannica.com/event/Cassini-Huygens), which arrived in 2004. The first three missions were short-term flybys, but [Cassini](https://www.britannica.com/event/Cassini-Huygens) went into orbit around Saturn for years of investigations, while its Huygens probe parachuted through the atmosphere of Titan and reached its surface, becoming the first spacecraft to land on a moon other than Earth’s. ## Basic astronomical data Saturn orbits the Sun at a mean distance of 1,427,000,000 km (887 million miles). Its closest distance to Earth is about 1.2 billion km (746 million miles), and its [phase](https://www.britannica.com/science/phase-state-of-matter) angle—the angle that it makes with the Sun and Earth—never exceeds about 6°. Saturn seen from the vicinity of Earth thus always appears nearly fully [illuminated](https://www.merriam-webster.com/dictionary/illuminated). Only deep [space probes](https://www.britannica.com/technology/space-probe) can provide sidelit and backlit views. [![Saturn. Saturn and its rings. Second largest planet of the solar system. Space Art](https://cdn.britannica.com/74/166074-131-677298A0/Saturn-rings-planet-solar-system-Space-Art.jpg) Britannica Quiz Planets and the Earth’s Moon](https://www.britannica.com/quiz/planets-and-the-earths-moon) Like Jupiter and most of the other planets, Saturn has a regular [orbit](https://www.britannica.com/science/orbit-astronomy)—that is, its motion around the Sun is prograde (in the same direction that the Sun rotates) and has a small eccentricity (noncircularity) and [inclination](https://www.britannica.com/science/inclination-of-equator-to-orbit) to the [ecliptic](https://www.britannica.com/science/ecliptic), the plane of Earth’s orbit. Unlike Jupiter, however, Saturn’s rotational axis is tilted substantially—by 26.7°—to its orbital plane. The tilt gives Saturn seasons, as on Earth, but each season lasts more than seven years. Another result is that Saturn’s rings, which lie in the plane of its equator, are presented to observers on Earth at opening angles ranging from 0° (edge on) to nearly 30°. The view of Saturn’s rings cycles over a 30-year period. Earth-based observers can see the rings’ sunlit northern side for about 15 years and then, in an [analogous](https://www.merriam-webster.com/dictionary/analogous) view, the sunlit southern side for the next 15 years. In the short intervals when Earth crosses the ring plane, the rings are all but invisible. Saturn’s [rotation](https://www.britannica.com/science/rotation-physics) period was very difficult to determine. [Cloud](https://www.britannica.com/science/cloud-meteorology) motions in its massive upper atmosphere trace out a variety of periods, which are as short as about 10 hours 10 minutes near the equator and increase with some oscillation to about 30 minutes longer at latitudes higher than 40°. Scientists attempted to determine the rotation period of Saturn’s deep interior from that of its [magnetic field](https://www.britannica.com/science/magnetic-field), which is [presumed](https://www.britannica.com/dictionary/presumed) to be rooted in the planet’s metallic-hydrogen outer core. However, direct measurement of the field’s rotation was difficult because the field is highly symmetrical around the rotational axis. At the time of the Voyager encounters, radio outbursts from Saturn, apparently related to small irregularities in the magnetic field, showed a period of 10 hours 39.4 minutes; this value was taken to be the magnetic field rotation period. Measurements made 25 years later by the [Cassini](https://www.britannica.com/topic/Cassini) [spacecraft](https://www.britannica.com/technology/spacecraft) indicated that the field was rotating with a period 6–7 minutes longer. It was believed that the [solar wind](https://www.britannica.com/science/solar-wind) is responsible for some of the difference between these two measurements of the rotational period. Not until Cassini flew inside Saturn’s rings on its final orbits was the rotation period accurately measured. By relating waves observed in the rings to slight variations in Saturn’s gravitational field, the rotation period of the planet was determined to be 10 hours 33 minutes 38 seconds. The time differences between the rotation periods of Saturn’s clouds and of its interior have been used to estimate wind velocities (see below [The atmosphere](https://www.britannica.com/place/Saturn-planet/The-atmosphere#ref54279)). Explore Britannica Premium\! Go beyond the basics with trusted, in-depth knowledge for professionals, students, and lifelong learners. [SUBSCRIBE](https://premium.britannica.com/premium-membership/?utm_source=premium&utm_medium=inline-cta&utm_campaign=basics-2026) ![Penguin, ship, mountain, atlas](https://cdn.britannica.com/marketing/inline-left.webp) ![shohei ohtani, plants, andy wharhol art](https://cdn.britannica.com/marketing/inline-right.webp) ![Mobile](https://cdn.britannica.com/marketing/inline-mobile.webp?w=400) Because the four giant [planets](https://www.britannica.com/science/planet) have no solid surface in their outer layers, by [convention](https://www.britannica.com/dictionary/convention) the values for the radius and gravity of these planets are calculated at the level at which one bar of [atmospheric pressure](https://www.britannica.com/science/atmospheric-pressure) is exerted. By this measure, Saturn’s equatorial diameter is 120,536 km (74,898 miles). In comparison, its polar diameter is only 108,728 km (67,560 miles), or 10 percent smaller, which makes Saturn the most oblate (flattened at the poles) of all the planets in the solar system. Its oblate shape is apparent even in a small [telescope](https://www.britannica.com/science/optical-telescope). Even though Saturn rotates slightly slower than Jupiter, it is more oblate because its rotational [acceleration](https://www.britannica.com/science/acceleration) cancels a larger fraction of the planet’s [gravity](https://www.britannica.com/science/gravity-physics) at the equator. The equatorial gravity of the planet, 896 cm (29.4 feet) per second per second, is only 74 percent of its polar gravity. Saturn is 95 times as massive as Earth but occupies a volume 766 times greater. Its mean [density](https://www.britannica.com/science/density) of 0.69 gram per cubic cm is thus only some 12 percent of Earth’s. Saturn’s equatorial [escape velocity](https://www.britannica.com/science/escape-velocity)—the velocity needed for an object, which includes individual atoms and molecules, to escape the planet’s gravitational attraction at the equator without having to be further accelerated—is nearly 36 km per second (80,000 miles per hour) at the one-bar level, compared with 11.2 km per second (25,000 miles per hour) for Earth. This high [value](https://www.britannica.com/dictionary/value) indicates that there has been no significant loss of atmosphere from Saturn since its formation. \| Planetary data for Saturn \| \| \|---\|---\| \| \Time required for the planet to return to the same position in the sky relative to the Sun as seen from Earth. \| \| \| \\Calculated for the altitude at which 1 bar of atmospheric pressure is exerted. \| \| \| mean distance from Sun \| 1,426,666,000 km (9.5 AU) \| \| eccentricity of orbit \| 0\.054 \| \| inclination of orbit to ecliptic \| 2\.49° \| \| Saturnian year (sidereal period of revolution) \| 29\.45 Earth years \| \| visual magnitude at mean opposition \| 0\.7 \| \| mean synodic period\ \| 378\.10 Earth days \| \| mean orbital velocity \| 9\.6 km/sec \| \| equatorial radius\\ \| 60,268 km \| \| polar radius\\ \| 54,364 km \| \| mass \| 5\.683 × 1026 kg \| \| mean density \| 0\.69 g/cm3 \| \| equatorial gravity\\ \| 896 cm/sec2 \| \| polar gravity\\ \| 1,214 cm/sec2 \| \| equatorial escape velocity\\ \| 35\.5 km/sec \| \| polar escape velocity\\ \| 37\.4 km/sec \| \| rotation period (magnetic field) \| 10 hr 39 min 24 sec (Voyager era); about 10 hr 46 min (Cassini-Huygens mission) \| \| inclination of equator to orbit \| 26\.7° \| \| magnetic field strength at equator \| 0\.21 gauss \| \| number of known moons \| 274 \| \| planetary ring system \| 3 major rings comprising myriad component ringlets; several less-dense rings \| ![Britannica AI Icon](https://cdn.britannica.com/mendel-resources/3-178/images/chatbot/star-ai.svg?v=3.178.5)Britannica AI chevron\_right Saturn close [AI-generated answers](https://www.britannica.com/about-britannica-ai) from Britannica articles. AI makes mistakes, so verify using Britannica articles. Load Next Page Feedback Thank you for your feedback Our editors will review what you’ve submitted and determine whether to revise the article. verifiedCite While every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions. Select Citation Style Dooling, Dave. "Cassini-Huygens". Encyclopedia Britannica, 10 Mar. 2026, https://www.britannica.com/event/Cassini-Huygens. Accessed 3 April 2026. Copy Citation Share Share to social media [Facebook](https://www.facebook.com/BRITANNICA/) [X](https://x.com/britannica) URL <https://www.britannica.com/event/Cassini-Huygens> External Websites - [National Center for Biotechnology Information - PubMed Central - Cassini Exploration of the Planet Saturn: A Comprehensive Review](https://pmc.ncbi.nlm.nih.gov/articles/PMC8753610/) - [CNN World - WhatÂ’s happening inside SaturnÂ’s rings? The Cassini mission dove between them to find out](https://edition.cnn.com/2019/06/13/world/cassini-saturn-rings-scn-trnd) - [BBC - BBC Inside Science - Farewell to Cassini, the epic 20 year mission to Saturn](https://www.bbc.com/audio/play/b093104w) - [Imperial College London - The Cassini Mission](https://www.imperial.ac.uk/space-and-atmospheric-physics/research/missions-and-projects/space-missions/cassini/the_mission/) - [Deutsches Zentrum fur Luft- und Raumfahrt - Destination Saturn ï¿½ The Casï¿½siï¿½ni-Huyï¿½gens mission](https://www.dlr.de/en/research-and-transfer/projects-and-missions/cassini-huygens) - [NASA - Cassini-Huygens](https://science.nasa.gov/mission/cassini/) - [American Association for the Advancement of Science - Cassini-Huygensï¿½ exploration of the Saturn system: 13 years of discovery](https://www.science.org/doi/10.1126/science.aat3760) - [The European Space Agency - Cassini/Huygens (PDF)](https://sci.esa.int/documents/33648/36003/1567254416901-cassini-huygens.pdf) - [The Planetary Society - Cassini, the mission that revealed Saturn](https://www.planetary.org/space-missions/cassini) - [NASA Technical Reports Server - Cassini-Huygens Aerodynamics with Comparison to Flight (PDF)](https://ntrs.nasa.gov/api/citations/20060047648/downloads/20060047648.pdf) Britannica Websites Articles from Britannica Encyclopedias for elementary and high school students. - [Cassini-Huygens - Children's Encyclopedia (Ages 8-11)](https://kids.britannica.com/kids/article/Cassini-Huygens/544855) - [Cassini-Huygens - Student Encyclopedia (Ages 11 and up)](https://kids.britannica.com/students/article/Cassini-Huygens/544804) Feedback Thank you for your feedback Our editors will review what you’ve submitted and determine whether to revise the article. print Print Please select which sections you would like to print: verifiedCite While every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions. Select Citation Style Marley, Mark, Hubbard, William B., Buratti, Bonnie. "Saturn". Encyclopedia Britannica, 15 Jan. 2026, https://www.britannica.com/place/Saturn-planet. Accessed 3 April 2026. Copy Citation Share Share to social media [Facebook](https://www.facebook.com/BRITANNICA/) [X](https://x.com/britannica) URL <https://www.britannica.com/place/Saturn-planet> External Websites - [The Planetary Society - Saturn, planet of rings, moons and more to explore](https://www.planetary.org/worlds/saturn) - [NASA - Saturn](https://science.nasa.gov/saturn/) - [Live Science - Saturn: Facts about the ringed planet](https://www.livescience.com/facts-about-saturn) - [The Planets - Saturn Facts](https://theplanets.org/saturn/) - [HyperPhysics - Saturn](http://hyperphysics.phy-astr.gsu.edu/hbase/Solar/saturn.html) - [Space.com - Saturn: Facts about the ringed planet](https://www.space.com/48-saturn-the-solar-systems-major-ring-bearer.html) - [National Geographic - Science - Saturn](https://www.nationalgeographic.com/science/space/solar-system/saturn/) Britannica Websites Articles from Britannica Encyclopedias for elementary and high school students. - [Saturn - Children's Encyclopedia (Ages 8-11)](https://kids.britannica.com/kids/article/Saturn/353745) - [Saturn - Student Encyclopedia (Ages 11 and up)](https://kids.britannica.com/students/article/Saturn/345008)
Readable Markdown	Top Questions ### Who first observed Saturn with a telescope? ### How far is Saturn from Earth? ### What feature is Saturn known for? ### What is Saturn’s largest moon? ### Is Saturn light enough to float? ## News • Saturn, second largest [planet](https://www.britannica.com/science/planet) of the [solar system](https://www.britannica.com/science/solar-system) in mass and size and the sixth nearest planet in distance to the [Sun](https://www.britannica.com/place/Sun). In the night sky Saturn is easily visible to the unaided [eye](https://www.britannica.com/science/human-eye) as a non-twinkling point of light. When viewed through even a small telescope, the planet encircled by its magnificent rings is arguably the most [sublime](https://www.merriam-webster.com/dictionary/sublime) object in the solar system. Saturn is designated by the symbol ♄. Saturn’s name comes from the Roman god of [agriculture](https://www.britannica.com/topic/agriculture), who is equated with the Greek deity [Cronus](https://www.britannica.com/topic/Cronus), one of the Titans and the father of [Zeus](https://www.britannica.com/topic/Zeus) (the Roman god Jupiter). As the farthest of the planets known to ancient observers, Saturn also was noted to be the slowest-moving. At a distance from the Sun that is 9.5 times as far as [Earth](https://www.britannica.com/place/Earth)’s, Saturn takes approximately 29.5 Earth years to make one solar revolution. The Italian astronomer [Galileo](https://www.britannica.com/biography/Galileo-Galilei) in 1610 was the first to observe Saturn with a telescope. Although he saw a strangeness in Saturn’s appearance, the low resolution of his instrument did not allow him to discern the true nature of the planet’s rings. Saturn occupies almost 60 percent of [Jupiter](https://www.britannica.com/place/Jupiter-planet)’s volume but has only about one-third of its mass and the lowest mean density—about 70 percent that of water—of any known object in the solar system. Hypothetically, Saturn would float in an ocean large enough to hold it. Both Saturn and Jupiter resemble [stars](https://www.britannica.com/science/star-astronomy) in that their bulk chemical [composition](https://www.merriam-webster.com/dictionary/composition) is dominated by [hydrogen](https://www.britannica.com/science/hydrogen). Also, as is the case for Jupiter, the tremendous pressure in Saturn’s deep interior maintains the hydrogen there in a fluid metallic state. Saturn’s structure and evolutionary history, however, differ significantly from those of its larger counterpart. Like the other giant, or Jovian, planets—Jupiter, [Uranus](https://www.britannica.com/place/Uranus-planet), and [Neptune](https://www.britannica.com/place/Neptune-planet)—Saturn has extensive systems of [moons](https://www.britannica.com/science/moon-natural-satellite) (natural satellites) and rings, which may provide clues to its origin and evolution as well as to those of the solar system. Saturn’s [moon](https://www.britannica.com/science/moon-natural-satellite) [Titan](https://www.britannica.com/place/Titan-astronomy) is distinguished from all other moons in the solar system by the presence of a significant atmosphere, one that is [denser](https://www.britannica.com/dictionary/denser) than that of any of the terrestrial planets except [Venus](https://www.britannica.com/place/Venus-planet). The greatest advances in knowledge of Saturn, as well as of most of the other planets, have come from deep-space probes. Four spacecraft have visited the Saturnian system: [Pioneer](https://www.britannica.com/technology/Pioneer-space-probes) 11 in 1979, [Voyager](https://www.britannica.com/technology/Voyager-space-probes)s 1 and 2 in the two years following, and, after almost a quarter-century, [Cassini-Huygens](https://www.britannica.com/event/Cassini-Huygens), which arrived in 2004. The first three missions were short-term flybys, but [Cassini](https://www.britannica.com/event/Cassini-Huygens) went into orbit around Saturn for years of investigations, while its Huygens probe parachuted through the atmosphere of Titan and reached its surface, becoming the first spacecraft to land on a moon other than Earth’s. ## Basic astronomical data Saturn orbits the Sun at a mean distance of 1,427,000,000 km (887 million miles). Its closest distance to Earth is about 1.2 billion km (746 million miles), and its [phase](https://www.britannica.com/science/phase-state-of-matter) angle—the angle that it makes with the Sun and Earth—never exceeds about 6°. Saturn seen from the vicinity of Earth thus always appears nearly fully [illuminated](https://www.merriam-webster.com/dictionary/illuminated). Only deep [space probes](https://www.britannica.com/technology/space-probe) can provide sidelit and backlit views. [![Saturn. Saturn and its rings. Second largest planet of the solar system. Space Art](https://cdn.britannica.com/74/166074-131-677298A0/Saturn-rings-planet-solar-system-Space-Art.jpg) Britannica Quiz Planets and the Earth’s Moon](https://www.britannica.com/quiz/planets-and-the-earths-moon) Like Jupiter and most of the other planets, Saturn has a regular [orbit](https://www.britannica.com/science/orbit-astronomy)—that is, its motion around the Sun is prograde (in the same direction that the Sun rotates) and has a small eccentricity (noncircularity) and [inclination](https://www.britannica.com/science/inclination-of-equator-to-orbit) to the [ecliptic](https://www.britannica.com/science/ecliptic), the plane of Earth’s orbit. Unlike Jupiter, however, Saturn’s rotational axis is tilted substantially—by 26.7°—to its orbital plane. The tilt gives Saturn seasons, as on Earth, but each season lasts more than seven years. Another result is that Saturn’s rings, which lie in the plane of its equator, are presented to observers on Earth at opening angles ranging from 0° (edge on) to nearly 30°. The view of Saturn’s rings cycles over a 30-year period. Earth-based observers can see the rings’ sunlit northern side for about 15 years and then, in an [analogous](https://www.merriam-webster.com/dictionary/analogous) view, the sunlit southern side for the next 15 years. In the short intervals when Earth crosses the ring plane, the rings are all but invisible. Saturn’s [rotation](https://www.britannica.com/science/rotation-physics) period was very difficult to determine. [Cloud](https://www.britannica.com/science/cloud-meteorology) motions in its massive upper atmosphere trace out a variety of periods, which are as short as about 10 hours 10 minutes near the equator and increase with some oscillation to about 30 minutes longer at latitudes higher than 40°. Scientists attempted to determine the rotation period of Saturn’s deep interior from that of its [magnetic field](https://www.britannica.com/science/magnetic-field), which is [presumed](https://www.britannica.com/dictionary/presumed) to be rooted in the planet’s metallic-hydrogen outer core. However, direct measurement of the field’s rotation was difficult because the field is highly symmetrical around the rotational axis. At the time of the Voyager encounters, radio outbursts from Saturn, apparently related to small irregularities in the magnetic field, showed a period of 10 hours 39.4 minutes; this value was taken to be the magnetic field rotation period. Measurements made 25 years later by the [Cassini](https://www.britannica.com/topic/Cassini) [spacecraft](https://www.britannica.com/technology/spacecraft) indicated that the field was rotating with a period 6–7 minutes longer. It was believed that the [solar wind](https://www.britannica.com/science/solar-wind) is responsible for some of the difference between these two measurements of the rotational period. Not until Cassini flew inside Saturn’s rings on its final orbits was the rotation period accurately measured. By relating waves observed in the rings to slight variations in Saturn’s gravitational field, the rotation period of the planet was determined to be 10 hours 33 minutes 38 seconds. The time differences between the rotation periods of Saturn’s clouds and of its interior have been used to estimate wind velocities (see below [The atmosphere](https://www.britannica.com/place/Saturn-planet/The-atmosphere#ref54279)). Go beyond the basics with trusted, in-depth knowledge for professionals, students, and lifelong learners. [SUBSCRIBE](https://premium.britannica.com/premium-membership/?utm_source=premium&utm_medium=inline-cta&utm_campaign=basics-2026) ![Penguin, ship, mountain, atlas](https://cdn.britannica.com/marketing/inline-left.webp) ![shohei ohtani, plants, andy wharhol art](https://cdn.britannica.com/marketing/inline-right.webp) ![Mobile](https://cdn.britannica.com/marketing/inline-mobile.webp?w=400) Because the four giant [planets](https://www.britannica.com/science/planet) have no solid surface in their outer layers, by [convention](https://www.britannica.com/dictionary/convention) the values for the radius and gravity of these planets are calculated at the level at which one bar of [atmospheric pressure](https://www.britannica.com/science/atmospheric-pressure) is exerted. By this measure, Saturn’s equatorial diameter is 120,536 km (74,898 miles). In comparison, its polar diameter is only 108,728 km (67,560 miles), or 10 percent smaller, which makes Saturn the most oblate (flattened at the poles) of all the planets in the solar system. Its oblate shape is apparent even in a small [telescope](https://www.britannica.com/science/optical-telescope). Even though Saturn rotates slightly slower than Jupiter, it is more oblate because its rotational [acceleration](https://www.britannica.com/science/acceleration) cancels a larger fraction of the planet’s [gravity](https://www.britannica.com/science/gravity-physics) at the equator. The equatorial gravity of the planet, 896 cm (29.4 feet) per second per second, is only 74 percent of its polar gravity. Saturn is 95 times as massive as Earth but occupies a volume 766 times greater. Its mean [density](https://www.britannica.com/science/density) of 0.69 gram per cubic cm is thus only some 12 percent of Earth’s. Saturn’s equatorial [escape velocity](https://www.britannica.com/science/escape-velocity)—the velocity needed for an object, which includes individual atoms and molecules, to escape the planet’s gravitational attraction at the equator without having to be further accelerated—is nearly 36 km per second (80,000 miles per hour) at the one-bar level, compared with 11.2 km per second (25,000 miles per hour) for Earth. This high [value](https://www.britannica.com/dictionary/value) indicates that there has been no significant loss of atmosphere from Saturn since its formation. \| Planetary data for Saturn \| \| \|---\|---\| \| \Time required for the planet to return to the same position in the sky relative to the Sun as seen from Earth. \| \| \| \\Calculated for the altitude at which 1 bar of atmospheric pressure is exerted. \| \| \| mean distance from Sun \| 1,426,666,000 km (9.5 AU) \| \| eccentricity of orbit \| 0\.054 \| \| inclination of orbit to ecliptic \| 2\.49° \| \| Saturnian year (sidereal period of revolution) \| 29\.45 Earth years \| \| visual magnitude at mean opposition \| 0\.7 \| \| mean synodic period\ \| 378\.10 Earth days \| \| mean orbital velocity \| 9\.6 km/sec \| \| equatorial radius\\ \| 60,268 km \| \| polar radius\\ \| 54,364 km \| \| mass \| 5\.683 × 1026 kg \| \| mean density \| 0\.69 g/cm3 \| \| equatorial gravity\\ \| 896 cm/sec2 \| \| polar gravity\\ \| 1,214 cm/sec2 \| \| equatorial escape velocity\\ \| 35\.5 km/sec \| \| polar escape velocity\\ \| 37\.4 km/sec \| \| rotation period (magnetic field) \| 10 hr 39 min 24 sec (Voyager era); about 10 hr 46 min (Cassini-Huygens mission) \| \| inclination of equator to orbit \| 26\.7° \| \| magnetic field strength at equator \| 0\.21 gauss \| \| number of known moons \| 274 \| \| planetary ring system \| 3 major rings comprising myriad component ringlets; several less-dense rings \|
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