:Saturn

{{Short description|Sixth planet from the Sun}}

{{About|the planet|the deity|Saturn (mythology)|other uses}}

{{Redirect|Sixth planet|other systems of numbering planets|Planet#History and etymology}}

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{{Use American English|date=August 2024}}

{{Use dmy dates|date=August 2024}}

{{Infobox planet

| name = Saturn

| symbol = File:Saturn symbol (bold).svg

| image = 300px

| caption = Saturn and its prominent rings, as captured by the Cassini orbiterThe dot in the bottom left is Titan

| background = Wheat

| pronounced = {{IPAc-en|audio=en-us-Saturn.ogg|ˈ|s|æ|t|ər|n}}

| named_after = Saturn

| adjectives = Saturnian {{IPAc-en|s|ə|ˈ|t|ɜr|n|i|ə|n}},{{OED|Saturnian}} Cronian{{Cite web |url=http://solarsystem.nasa.gov/multimedia/downloads/Small_RPS_Report.pdf |title=Enabling Exploration with Small Radioisotope Power Systems |date=September 2004 |access-date=26 January 2016 |publisher=NASA |archive-url=https://web.archive.org/web/20161222125722/http://solarsystem.nasa.gov/multimedia/downloads/Small_RPS_Report.pdf |archive-date=22 December 2016 |url-status=dead}} / Kronian{{cite journal |last1=Müller |display-authors=etal |year=2010 |title=Azimuthal plasma flow in the Kronian magnetosphere |doi=10.1029/2009ja015122 |journal=Journal of Geophysical Research |volume=115 |issue=A8 |page=A08203 |bibcode=2010JGRA..115.8203M |doi-access=free |issn=0148-0227 }} {{IPAc-en|'|k|r|ou|n|i|@|n}}{{OED|Cronian}}

| orbit_ref =

| epoch = J2000.0

| aphelion = {{convert|1514.50|e6km|AU|4|abbr=unit}}

| perihelion = {{convert|1352.55|e6km|AU|4|abbr=unit}}

| time_periastron = 2032-Nov-29{{Cite web|url=https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%27699%27&START_TIME=%272032-11-25%27&STOP_TIME=%272032-12-10%27&STEP_SIZE=%273%20hours%27&QUANTITIES=%2719%27|title=HORIZONS Planet-center Batch call for November 2032 Perihelion|website=ssd.jpl.nasa.gov|type=Perihelion for Saturn's planet-center (699) occurs on 2032-Nov-29 at 9.0149170au during a rdot flip from negative to positive|publisher=NASA/JPL|access-date=7 September 2021|archive-date=7 September 2021|archive-url=https://web.archive.org/web/20210907234827/https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%27699%27&START_TIME=%272032-11-25%27&STOP_TIME=%272032-12-10%27&STEP_SIZE=%273%20hours%27&QUANTITIES=%2719%27|url-status=live}}

| semimajor = {{convert|1433.53|e6km|AU|4|abbr=unit}}

| eccentricity = {{val|0.0565}}

| period = {{plainlist |

  • {{val|29.4475|u=yr}}
  • {{val|fmt=commas|10755.70|u=days}}
  • {{val|fmt=commas|24225}} Saturnian solar days{{cite web |title=Planetary Physical Parameters |url=https://ssd.jpl.nasa.gov/planets/phys_par.html |publisher=NASA Jet Propulsion Laboratory}}

}}

| synodic_period = 378.09 days

| avg_speed = {{val|9.68|u=km/s}}

| mean_anomaly = {{val|317.020|u=°}}

| inclination = {{plainlist |

}}

| asc_node = {{val|113.665|u=°}}

| arg_peri = {{val|339.392|u=°}}

| satellites = 274 with formal designations; innumerable additional moonlets.

| physical_ref =

| mean_radius = {{val|58232|u=km}}


{{val|9.1402|u=Earths}}

| equatorial_radius = {{plainlist |

  • {{val|60268|u=km}}Refers to the level of 1 bar atmospheric pressure
  • {{val|9.449}} Earths

}}

| polar_radius = {{plainlist |

  • {{val|54364|u=km}}
  • {{val|8.552|u=Earths}}

}}

| flattening = {{val|0.09796}}

| circumference = {{val|365882.4|u=km}} (equatorial){{cite web |title=By the Numbers – Saturn |url=https://solarsystem.nasa.gov/planets/saturn/by-the-numbers/ |website=NASA Solar System Exploration |date=10 November 2017 |publisher=NASA |access-date=5 August 2020 |archive-date=10 May 2018 |archive-url=https://web.archive.org/web/20180510134619/https://solarsystem.nasa.gov/planets/saturn/by-the-numbers/ |url-status=live }}

| surface_area = {{plainlist |

  • {{val|4.27|e=10|u=km2}}
  • {{val|83.703|u=Earths}}

}}

| volume = {{plainlist |

  • {{val|8.2713|e=14|u=km3}}
  • {{val|763.59|u=Earths}}

}}

| mass = {{plainlist |

  • {{val|5.6834e26|u=kg}}
  • {{val|95.159|u=Earths}}

}}

| density = {{val|0.687|u=g/cm3}}Based on the volume within the level of 1 bar atmospheric pressure

{{val|0.1246}} Earths

| surface_grav = {{cvt|10.44|m/s2|g0|lk=on|disp=br}}

| moment_of_inertia_factor = {{val|0.22|}}{{cite book |last1=Fortney |first1=J.J. |last2=Helled |first2=R. |last3=Nettlemann |first3=N. |last4=Stevenson |first4=D.J. |last5=Marley |first5=M.S. |last6=Hubbard |first6=W.B. |last7=Iess |first7=L. |editor1=Baines, K.H. |editor2=Flasar, F.M. |editor3=Krupp, N. |editor4=Stallard, T. |title=Saturn in the 21st Century |chapter=The Interior of Saturn |chapter-url=https://books.google.com/books?id=p358DwAAQBAJ&pg=PA51 |pages=44–68 |date=6 December 2018 |publisher=Cambridge University Press |isbn=978-1-108-68393-7 |access-date=23 July 2019 |archive-date=2 May 2020 |archive-url=https://web.archive.org/web/20200502010250/https://books.google.com/books?id=p358DwAAQBAJ&pg=PA51 |url-status=live }}

| escape_velocity = {{val|35.5|u=km/s}}

| rotation = 10 h 32 m 36 s;
10.5433 hours, 10 h 39 m;
10.7 hours

| sidereal_day = {{RA|10|33|38}} {{+-|{{RA||1|52}}|{{RA||1|19}}}} {{cite news |last1=McCartney |first1=Gretchen |last2=Wendel |first2=JoAnna |title=Scientists Finally Know What Time It Is on Saturn |url=https://www.jpl.nasa.gov/news/scientists-finally-know-what-time-it-is-on-saturn/ |date=18 January 2019 |work=NASA |access-date=3 January 2025 }}{{cite journal |author=Mankovich, Christopher |display-authors=etal |title=Cassini Ring Seismology as a Probe of Saturn's Interior. I. Rigid Rotation |date=17 January 2019 |journal=The Astrophysical Journal |volume=871 |pages=1 |number=1 |doi=10.3847/1538-4357/aaf798 |arxiv=1805.10286 |bibcode=2019ApJ...871....1M |s2cid=67840660 |doi-access=free }}

| rot_velocity = {{val|9.87|u=km/s}}

| axial_tilt = 26.73° {{small|(to orbit)}}

| right_asc_north_pole = 40.589°; {{RA|2|42|21}}{{Cite journal |last1=Archinal |first1=B. A. |last2=Acton |first2=C. H. |last3=A'Hearn |first3=M. F. |last4=Conrad |first4=A. |last5=Consolmagno |first5=G. J. |last6=Duxbury |first6=T. |last7=Hestroffer |first7=D. |last8=Hilton |first8=J. L. |last9=Kirk |first9=R. L. |last10=Klioner |first10=S. A. |last11=McCarthy |first11=D. |last12=Meech |first12=K. |last13=Oberst |first13=J. |last14=Ping |first14=J. |last15=Seidelmann |first15=P. K. |date=2018 |title=Report of the IAU Working Group on Cartographic Coordinates and Rotational Elements: 2015 |url=http://link.springer.com/10.1007/s10569-017-9805-5 |journal=Celestial Mechanics and Dynamical Astronomy |language=en |volume=130 |issue=3 |page=22 |doi=10.1007/s10569-017-9805-5 |bibcode=2018CeMDA.130...22A |issn=0923-2958}}

| declination = 83.537°

| albedo = {{plainlist |

}}

| temp_name1 = 1 bar

| mean_temp_1 = 134 K

| temp_name2 = 0.1 bar

| min_temp_2 = 88 K{{cite web |title=Saturn's Temperature Ranges |url=https://sciencing.com/saturns-temperature-ranges-7704.html |website=Sciencing |date=20 April 2018 |access-date=26 May 2021 |archive-date=26 May 2021 |archive-url=https://web.archive.org/web/20210526154932/https://sciencing.com/saturns-temperature-ranges-7704.html |url-status=live }}

| mean_temp_2 = 97 K{{cite web |title=The Planet Saturn |url=https://www.weather.gov/fsd/saturn |website=National Weather Service |access-date=26 May 2021 |archive-date=26 May 2021 |archive-url=https://web.archive.org/web/20210526155200/https://www.weather.gov/fsd/saturn |url-status=live }}

| max_temp_2 = 151 K

| magnitude = −0.55 to +1.17

| abs_magnitude = −9.7{{cite web | title=Encyclopedia - the brightest bodies | website=IMCCE | url=https://promenade.imcce.fr/en/pages5/572.html | access-date=29 May 2023}}

| angular_size = 14.5″ to 20.1″ (excludes rings)

| atmosphere_ref =

| surface_pressure = >>1000 bars{{cite web |title=On The Atmospheres Of Different Planets |first=Robin |last=Knecht |date=24 October 2005 |url=http://www.tp.umu.se/space/Proj_05/Robin.K.pdf |access-date=14 October 2017 |archive-url=https://web.archive.org/web/20171014234631/http://www.tp.umu.se/space/Proj_05/Robin.K.pdf |archive-date=14 October 2017 |url-status=dead }}

| scale_height = {{val|59.5|u=km}}

| atmosphere_composition = {{plainlist|

}}

Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about nine times that of Earth.{{cite web |url=http://www.astrophysicsspectator.com/tables/Saturn.html |title=Characteristics of Saturn |access-date=5 July 2010 |last=Brainerd |first=Jerome James |date=24 November 2004 |publisher=The Astrophysics Spectator |archive-url=https://web.archive.org/web/20111001102834/http://www.astrophysicsspectator.com/tables/Saturn.html |archive-date=1 October 2011 |url-status=dead }}{{cite web |url=http://scienceray.com/astronomy/general-information-about-saturn-2/1/ |title=General Information about Saturn |work=Scienceray |date=28 July 2011 |access-date=17 August 2011 |archive-url=https://web.archive.org/web/20111007220627/http://scienceray.com/astronomy/general-information-about-saturn-2/1/ |archive-date=7 October 2011 |url-status=dead }} It has an eighth the average density of Earth, but is over 95 times more massive.{{cite web |url=http://www.astrophysicsspectator.com/tables/PlanetComparativeData.html |title=Solar System Planets Compared to Earth |access-date=5 July 2010 |last=Brainerd |first=Jerome James |date=6 October 2004 |publisher=The Astrophysics Spectator |archive-url=https://web.archive.org/web/20111001102843/http://www.astrophysicsspectator.com/tables/PlanetComparativeData.html |archive-date=1 October 2011 |url-status=dead }}{{cite web |url=http://mynasa.nasa.gov/worldbook/saturn_worldbook.html |title=NASA – Saturn |access-date=21 July 2011 |last=Dunbar |first=Brian |date=29 November 2007 |publisher=NASA |archive-url=https://web.archive.org/web/20110929073208/http://mynasa.nasa.gov/worldbook/saturn_worldbook.html |archive-date=29 September 2011 |url-status=dead }} Even though Saturn is almost as big as Jupiter, Saturn has less than a third its mass. Saturn orbits the Sun at a distance of {{convert|1434|e6km|AU|2|abbr=unit|order=flip|lk=on}}, with an orbital period of 29.45 years.

Saturn's interior is thought to be composed of a rocky core, surrounded by a deep layer of metallic hydrogen, an intermediate layer of liquid hydrogen and liquid helium, and an outer layer of gas. Saturn has a pale yellow hue, due to ammonia crystals in its upper atmosphere. An electrical current in the metallic hydrogen layer is thought to give rise to Saturn's planetary magnetic field, which is weaker than Earth's, but has a magnetic moment 580 times that of Earth because of Saturn's greater size. Saturn's magnetic field strength is about a twentieth that of Jupiter. The outer atmosphere is generally bland and lacking in contrast, although long-lived features can appear. Wind speeds on Saturn can reach {{convert|1800|km/h|abbr=off}}.

The planet has a bright and extensive system of rings, composed mainly of ice particles, with a smaller amount of rocky debris and dust. At least 274 moons{{cite news |author=Jonathan O'Callaghan |date=March 11, 2025 |title=Saturn Gains 128 New Moons, Bringing Its Total to 274 |newspaper=The New York Times |url=https://www.nytimes.com/2025/03/11/science/saturn-new-moons.html |access-date=March 13, 2025}}{{cite web|title=MPEC 2023-J49 : S/2006 S 12|url=https://minorplanetcenter.net/mpec/K23/K23J49.html|work=Minor Planet Electronic Circulars |publisher=Minor Planet Center |date=7 May 2023 |access-date=7 May 2023}}{{cite web | url=https://www.minorplanetcenter.net/mpec/K25/K25EF3.html | title=Mpec 2025-E153 : Sixty-One New Saturnian Satellites }}{{cite web | url=https://www.minorplanetcenter.net/mpec/K25/K25EF4.html | title=Mpec 2025-E154 : Thirty-Four New Saturnian Satellites }}{{cite web | url=https://www.minorplanetcenter.net/mpec/K25/K25EF5.html | title=Mpec 2025-E155 : Thirty-Three New Saturnian Satellites }} orbit the planet, of which 63 are officially named; these do not include the hundreds of moonlets in the rings. Titan, Saturn's largest moon and the second largest in the Solar System, is larger (but less massive) than the planet Mercury and is the only moon in the Solar System that has a substantial atmosphere.{{cite web |url=http://saturn.jpl.nasa.gov/news/features/saturn-story/moons.cfm |title=The Story of Saturn |access-date=7 July 2007 |last=Munsell |first=Kirk |date=6 April 2005 |publisher=NASA Jet Propulsion Laboratory; California Institute of Technology |archive-url=https://web.archive.org/web/20080816074342/http://saturn.jpl.nasa.gov/news/features/saturn-story/moons.cfm |archive-date=16 August 2008 |url-status=dead }}

Name and symbol

Saturn is named after the Roman god of wealth and agriculture, who was the father of the god Jupiter. Its astronomical symbol {{nowrap|(file:Saturn symbol (fixed width).svg)}} has been traced back to the Greek Oxyrhynchus Papyri, where it can be seen to be a Greek kappa-rho ligature with a horizontal stroke, as an abbreviation for Κρονος (Cronus), the Greek name for the planet (41px).{{cite book

| title=Astronomical papyri from Oxyrhynchus

| last=Jones

| first=Alexander

| date=1999

| pages=62–63

| publisher=American Philosophical Society

| isbn=9780871692337

| url=https://books.google.com/books?id=8MokzymQ43IC

| quote=

| access-date=28 September 2021

| archive-date=30 April 2021

| archive-url=https://web.archive.org/web/20210430052052/https://books.google.com/books?id=8MokzymQ43IC

| url-status=live

}} It later came to look like a lower-case Greek eta, with the cross added at the top in the 16th century to Christianize this pagan symbol.

The Romans named the seventh day of the week Saturday, Sāturni diēs, "Saturn's Day", for the planet Saturn.{{citation |last=Falk |first=Michael |title=Astronomical Names for the Days of the Week |url=http://articles.adsabs.harvard.edu/pdf/1999JRASC..93..122F |journal=Journal of the Royal Astronomical Society of Canada |volume=93 |pages=122–133 |date=June 1999 |bibcode=1999JRASC..93..122F |access-date=18 November 2020 |archive-date=25 February 2021 |archive-url=https://web.archive.org/web/20210225172054/http://articles.adsabs.harvard.edu/pdf/1999JRASC..93..122F |url-status=live }}

Physical characteristics

File:Saturn compared to Earth and the Moon.png

Saturn is a gas giant, composed predominantly of hydrogen and helium. It lacks a definite surface, though it is likely to have a solid core. The planet's rotation makes it an oblate spheroid—a ball flattened at the poles and bulging at the equator. Its equatorial radius is more than 10% larger than the polar radius: 60,268 km versus 54,364 km (37,449 mi versus 33,780 mi). Jupiter, Uranus, and Neptune, the other giant planets in the Solar System, are less oblate. The combination of the bulge and the rotation rate means that the effective surface gravity along the equator, {{Val|8.96|u=m/s2}}, is 74% of what it is at the poles and is lower than the surface gravity of Earth. However, the equatorial escape velocity, nearly {{Val|36|u=km/s}}, is much higher than that of Earth.{{cite book |url=https://books.google.com/books?id=ptLFDN0z8gQC&pg=PA119 |title=Outer Solar System: Jupiter, Saturn, Uranus, Neptune, and the Dwarf Planets |publisher=The Rosen Publishing Group |editor1-first=Erik |editor1-last=Gregersen |page=119 |year=2010 |isbn=978-1615300143 |access-date=17 February 2018 |archive-date=10 June 2020 |archive-url=https://web.archive.org/web/20200610170554/https://books.google.com/books?id=ptLFDN0z8gQC&pg=PA119 |url-status=live }}

Saturn is the only planet of the Solar System that is less dense than water—about 30% less. Although Saturn's core is considerably denser than water, the average specific density of the planet is {{val|0.69|u=g/cm3}}, because of the atmosphere. Jupiter has 318 times Earth's mass, and Saturn is 95 times Earth's mass. Together, Jupiter and Saturn hold 92% of the total planetary mass in the Solar System.

= Internal structure =

File:Saturn diagram.svgDespite consisting mostly of hydrogen and helium, most of Saturn's mass is not in the gas phase, because hydrogen becomes a non-ideal liquid when the density is above {{val|0.01|u=g/cm3}}, which is reached at a radius containing 99.9% of Saturn's mass. The temperature, pressure, and density inside Saturn all rise steadily toward the core, which causes hydrogen to be a metal in the deeper layers.

Standard planetary models suggest that the interior of Saturn is similar to that of Jupiter, having a small rocky core surrounded by hydrogen and helium, with trace amounts of various volatiles. Analysis of the distortion shows that Saturn is substantially more centrally condensed than Jupiter and therefore contains much more material denser than hydrogen near its center. Saturn's central regions are about 50% hydrogen by mass, and Jupiter's are about 67% hydrogen.{{Cite web |title=Saturn - The interior {{!}} Britannica |url=https://www.britannica.com/place/Saturn-planet/The-interior |access-date=14 April 2022 |website=www.britannica.com |language=en}}

This core is similar in composition to Earth, but is more dense. The examination of Saturn's gravitational moment, in combination with physical models of the interior, has allowed constraints to be placed on the mass of Saturn's core. In 2004, scientists estimated that the core must be 9–22 times the mass of Earth, which corresponds to a diameter of about {{Convert|25000|km|abbr=on}}.{{cite web |url=https://www.bbc.co.uk/dna/h2g2/A383960 |title=Saturn |publisher=BBC |access-date=19 July 2011 |date=2000 |archive-url=https://web.archive.org/web/20110101024556/http://www.bbc.co.uk/dna/h2g2/A383960 |archive-date=1 January 2011 |url-status=live }} However, measurements of Saturn's rings suggest a much more diffuse core, with a mass equal to about 17 Earths and a radius equal to about 60% of Saturn's entire radius.{{cite journal |last1=Mankovich |first1=Christopher R. |last2=Fuller |first2=Jim |title=A diffuse core in Saturn revealed by ring seismology |url=https://www.nature.com/articles/s41550-021-01448-3 |journal=Nature Astronomy |year=2021 |volume=5 |issue=11 |pages=1103–1109 |doi=10.1038/s41550-021-01448-3 |arxiv=2104.13385 |bibcode=2021NatAs...5.1103M |s2cid=233423431 |access-date=22 August 2021 |archive-date=20 August 2021 |archive-url=https://web.archive.org/web/20210820195416/https://www.nature.com/articles/s41550-021-01448-3 |url-status=live }} This is surrounded by a thicker, liquid metallic hydrogen layer, followed by a liquid layer of helium-saturated molecular hydrogen, which gradually transitions to a gas as altitude increases. The outermost layer spans about {{Convert|1000|km|abbr=on}} and consists of gas.{{cite web |url=http://www.windows2universe.org/saturn/interior/S_int_structure_overview.html |title=Structure of Saturn's Interior |publisher=Windows to the Universe |access-date=19 July 2011 |archive-url=https://web.archive.org/web/20110917140427/http://www.windows2universe.org/saturn/interior/S_int_structure_overview.html |archive-date=17 September 2011 |url-status=dead }}

Saturn has a hot interior, reaching {{Convert|11700|C}} at its core, and radiates 2.5 times more energy into space than it receives from the Sun. Jupiter's thermal energy is generated by the Kelvin–Helmholtz mechanism of slow gravitational compression; but such a process alone may not be sufficient to explain heat production for Saturn, because it is less massive. An alternative or additional mechanism may be the generation of heat through the "raining out" of droplets of helium deep in Saturn's interior. As the droplets descend through the lower-density hydrogen, the process releases heat by friction and leaves Saturn's outer layers depleted of helium. These descending droplets may have accumulated into a helium shell surrounding the core. Rainfalls of diamonds have been suggested to occur within Saturn, as well as in Jupiter{{cite news |last=Kramer |first=Miriam |title=Diamond Rain May Fill Skies of Jupiter and Saturn |url=https://www.space.com/23135-diamond-rain-jupiter-saturn.html |date=9 October 2013 |work=Space.com |access-date=27 August 2017 |archive-date=27 August 2017 |archive-url=https://web.archive.org/web/20170827171415/https://www.space.com/23135-diamond-rain-jupiter-saturn.html |url-status=live }} and ice giants Uranus and Neptune.{{cite news |last=Kaplan |first=Sarah |title=It rains solid diamonds on Uranus and Neptune |url=https://www.washingtonpost.com/news/speaking-of-science/wp/2017/08/25/it-rains-solid-diamonds-on-uranus-and-neptune/ |date=25 August 2017 |newspaper=The Washington Post |access-date=27 August 2017 |archive-date=27 August 2017 |archive-url=https://web.archive.org/web/20170827011901/https://www.washingtonpost.com/news/speaking-of-science/wp/2017/08/25/it-rains-solid-diamonds-on-uranus-and-neptune/ |url-status=live }}

= Atmosphere =

The outer atmosphere of Saturn contains 96.3% molecular hydrogen and 3.25% helium by volume. The proportion of helium is significantly deficient compared to the abundance of this element in the Sun. The quantity of elements heavier than helium (metallicity) is not known precisely, but the proportions are assumed to match the primordial abundances from the formation of the Solar System. The total mass of these heavier elements is estimated to be 19–31 times the mass of Earth, with a significant fraction located in Saturn's core region.

Trace amounts of ammonia, acetylene, ethane, propane, phosphine, and methane have been detected in Saturn's atmosphere. The upper clouds are composed of ammonia crystals, while the lower level clouds appear to consist of either ammonium hydrosulfide ({{chem2|NH4SH}}) or water. Ultraviolet radiation from the Sun causes methane photolysis in the upper atmosphere, leading to a series of hydrocarbon chemical reactions with the resulting products being carried downward by eddies and diffusion. This photochemical cycle is modulated by Saturn's annual seasonal cycle. Cassini observed a series of cloud features found in northern latitudes, nicknamed the "String of Pearls". These features are cloud clearings that reside in deeper cloud layers.{{cite press release |title=Cassini Image Shows Saturn Draped in a String of Pearls |url=http://www.nasa.gov/mission_pages/cassini/media/cassini-20061011a.html |publisher=Carolina Martinez, NASA |date=10 November 2006 |access-date=3 March 2013 |archive-date=1 May 2013 |archive-url=https://web.archive.org/web/20130501174037/http://www.nasa.gov/mission_pages/cassini/media/cassini-20061011a.html |url-status=live}}

== Cloud layers ==

File:Saturn Storm.jpg

Saturn's atmosphere exhibits a banded pattern similar to Jupiter's, but Saturn's bands are much fainter and are much wider near the equator. The nomenclature used to describe these bands is the same as on Jupiter. Saturn's finer cloud patterns were not observed until the flybys of the Voyager spacecraft during the 1980s. Since then, Earth-based telescopy has improved to the point where regular observations can be made.

The composition of the clouds varies with depth and increasing pressure. In the upper cloud layers, with temperatures in the range of 100–160 K and pressures extending between 0.5–2 bar, the clouds consist of ammonia ice. Water ice clouds begin at a level where the pressure is about 2.5 bar and extend down to 9.5 bar, where temperatures range from 185 to 270 K. Intermixed in this layer is a band of ammonium hydrosulfide ice, lying in the pressure range 3–6 bar with temperatures of 190–235 K. Finally, the lower layers, where pressures are between 10 and 20 bar and temperatures are 270–330 K, contains a region of water droplets with ammonia in aqueous solution.

Saturn's usually bland atmosphere occasionally exhibits long-lived ovals and other features common on Jupiter. In 1990, the Hubble Space Telescope imaged an enormous white cloud near Saturn's equator that was not present during the Voyager encounters, and in 1994 another smaller storm was observed. The 1990 storm was an example of a Great White Spot, a short-lived phenomenon that occurs once every Saturnian year, roughly every 30 Earth years, around the time of the northern hemisphere's summer solstice. Previous Great White Spots were observed in 1876, 1903, 1933, and 1960, with the 1933 storm being the best observed.{{cite book |editor1-link=Patrick Moore |editor1-last=Moore |editor1-first=Patrick |title=1993 Yearbook of Astronomy |location=London |publisher=W.W. Norton & Company |date=1992 |first1=Mark |last1=Kidger |chapter=The 1990 Great White Spot of Saturn |pages=176–215|bibcode=1992ybas.conf.....M }} The latest giant storm was observed in 2010. In 2015, researchers used Very Large Array telescope to study Saturnian atmosphere, and reported that they found "long-lasting signatures of all mid-latitude giant storms, a mixture of equatorial storms up to hundreds of years old, and potentially an unreported older storm at 70°N".{{cite journal |last1=Li |first1=Cheng |last2=de Pater |first2=Imke |last3=Moeckel |first3=Chris |last4=Sault |first4=R. J. |last5=Butler |first5=Bryan |last6=deBoer |first6=David |last7=Zhang |first7=Zhimeng |title=Long-lasting, deep effect of Saturn's giant storms |journal=Science Advances |date=11 August 2023 |volume=9 |issue=32 |pages=eadg9419 |doi=10.1126/sciadv.adg9419 |pmid=37566653 |pmc=10421028 |bibcode=2023SciA....9G9419L }}

The winds on Saturn are the second fastest among the Solar System's planets, after Neptune's. Voyager data indicate peak easterly winds of {{convert|500|m/s|km/h|abbr=on}}.{{cite web |title=Voyager Saturn Science Summary |url=http://www.solarviews.com/eng/vgrsat.htm |first=Calvin J. |last=Hamilton |access-date=5 July 2007 |date=1997 |publisher=Solarviews |archive-url=https://web.archive.org/web/20110926211656/http://www.solarviews.com/eng/vgrsat.htm |archive-date=26 September 2011 |url-status=dead }} In images from the Cassini spacecraft during 2007, Saturn's northern hemisphere displayed a bright blue hue, similar to Uranus. The color was most likely caused by Rayleigh scattering.{{cite web |url=http://www.nasa.gov/mission_pages/cassini/multimedia/pia09188.html |title=Saturn's Strange Hexagon |access-date=6 July 2007 |date=27 March 2007 |last=Watanabe |first=Susan |publisher=NASA |archive-url=https://web.archive.org/web/20100116155833/http://www.nasa.gov/mission_pages/cassini/multimedia/pia09188.html |archive-date=16 January 2010 |url-status=live }} Thermography has shown that Saturn's south pole has a warm polar vortex, the only known example of such a phenomenon in the Solar System.{{cite web |url=http://www.mcpstars.org/node/353 |title=Warm Polar Vortex on Saturn |date=2007 |publisher=Merrillville Community Planetarium |access-date=25 July 2007 |archive-url=https://web.archive.org/web/20110921212018/http://www.mcpstars.org/node/353 |archive-date=21 September 2011 |url-status=dead }} Whereas temperatures on Saturn are normally −185 °C, temperatures on the vortex often reach as high as −122 °C, suspected to be the warmest spot on Saturn.

== Hexagonal cloud patterns ==

{{main|Saturn's hexagon}}

{{multiple image

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| image1 = Rotatingsaturnhexagon.gif

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| caption3 = Hexagonal storm pattern around the north pole of Saturn

| footer = Saturn's north and south pole in infrared

}}

{{Anchor|North pole hexagonal cloud pattern|South pole vortex}}A persisting hexagonal wave pattern around the north polar vortex in the atmosphere at about 78°N was first noted in the Voyager images.{{cite journal |bibcode=1988Icar...76..335G |doi=10.1016/0019-1035(88)90075-9 |title=A hexagonal feature around Saturn's North Pole |date=1988 |page=335 |author=Godfrey, D. A. |volume=76 |journal=Icarus |issue=2}}{{cite journal |title=Ground-based observations of Saturn's north polar SPOT and hexagon |first4=P. |last4=Laques |first3=F. |last3=Colas |first2=J. |last2=Lecacheux |journal=Science |display-authors=1 |first1=A. |last1=Sanchez-Lavega |volume=260 |issue=5106 |date=1993 |pmid=17838249 |doi=10.1126/science.260.5106.329 |bibcode=1993Sci...260..329S |pages=329–32|s2cid=45574015 }}{{cite news |last=Overbye |first=Dennis |author-link=Dennis Overbye |title=Storm Chasing on Saturn |url=https://www.nytimes.com/2014/08/06/science/space/storm-chasing-on-saturn.html |date=6 August 2014 |work=New York Times |access-date=6 August 2014 |archive-date=12 July 2018 |archive-url=https://web.archive.org/web/20180712004804/https://www.nytimes.com/2014/08/06/science/space/storm-chasing-on-saturn.html |url-status=live }} The sides of the hexagon are each about {{Convert|14500|km|mi|-2|abbr=on}} long, which is longer than the diameter of the Earth.{{cite news |url=https://www.nbcnews.com/id/wbna34352533 |title=New images show Saturn's weird hexagon cloud |publisher=NBC News |date=12 December 2009 |access-date=29 September 2011 |archive-date=21 October 2020 |archive-url=https://web.archive.org/web/20201021075355/http://www.nbcnews.com/id/34352533 |url-status=live }} The entire structure rotates with a period of {{RA|10|39|24}} (the same period as that of the planet's radio emissions) which is assumed to be equal to the period of rotation of Saturn's interior. The hexagonal feature does not shift in longitude like the other clouds in the visible atmosphere. The pattern's origin is a matter of much speculation. Most scientists think it is a standing wave pattern in the atmosphere. Polygonal shapes have been replicated in the laboratory through differential rotation of fluids.{{cite journal |doi=10.1038/news060515-17 |last1=Ball |first1=Philip |title=Geometric whirlpools revealed |journal=Nature |date=19 May 2006|s2cid=129016856 |doi-access=free }} Bizarre geometric shapes that appear at the center of swirling vortices in planetary atmospheres might be explained by a simple experiment with a bucket of water but correlating this to Saturn's pattern is by no means certain.{{cite journal |doi=10.1016/j.icarus.2009.10.022 |display-authors=1 |last1=Aguiar |first1=Ana C. Barbosa |last2=Read |first2=Peter L. |last3=Wordsworth |first3=Robin D |title=A laboratory model of Saturn's North Polar Hexagon |volume=206 |issue=2 |date=April 2010 |pages=755–763 |last4=Salter |first4=Tara |last5=Hiro Yamazaki |first5=Y. |journal=Icarus |bibcode=2010Icar..206..755B}} Laboratory experiment of spinning disks in a liquid solution forms vortices around a stable hexagonal pattern similar to that of Saturn's.

HST imaging of the south polar region indicates the presence of a jet stream, but no strong polar vortex nor any hexagonal standing wave.{{Cite journal |display-authors=1 |author=Sánchez-Lavega, A. |author2=Pérez-Hoyos, S. |author3=French, R. G. |url=http://aas.org/archives/BAAS/v34n3/dps2002/10.htm |title=Hubble Space Telescope Observations of the Atmospheric Dynamics in Saturn's South Pole from 1997 to 2002 |journal=Bulletin of the American Astronomical Society |volume=34 |page=857 |access-date=6 July 2007 |date=8 October 2002 |bibcode=2002DPS....34.1307S |archive-date=30 June 2010 |archive-url=https://web.archive.org/web/20100630162647/http://aas.org/archives/BAAS/v34n3/dps2002/10.htm |url-status=live }} NASA reported in November 2006 that Cassini had observed a "hurricane-like" storm locked to the south pole that had a clearly defined eyewall.{{cite web |url=http://photojournal.jpl.nasa.gov/catalog/PIA09187 |title=NASA catalog page for image PIA09187 |access-date=23 May 2007 |publisher=NASA Planetary Photojournal |archive-url=https://web.archive.org/web/20111109044235/http://photojournal.jpl.nasa.gov/catalog/PIA09187 |archive-date=9 November 2011 |url-status=live }}{{cite news |url=http://news.bbc.co.uk/2/hi/6135450.stm?lsm |title=Huge 'hurricane' rages on Saturn |work=BBC News |date=10 November 2006 |access-date=29 September 2011 |archive-url=https://web.archive.org/web/20120803115422/http://news.bbc.co.uk/2/hi/6135450.stm?lsm |archive-date=3 August 2012 |url-status=live }} Eyewall clouds had not previously been seen on any planet other than Earth. For example, images from the Galileo spacecraft did not show an eyewall in the Great Red Spot of Jupiter.{{cite web |url=http://saturn.jpl.nasa.gov/news/press-release-details.cfm?newsID=703 |title=NASA Sees into the Eye of a Monster Storm on Saturn |publisher=NASA |date=9 November 2006 |access-date=20 November 2006 |archive-url=https://web.archive.org/web/20080507154317/http://saturn.jpl.nasa.gov/news/press-release-details.cfm?newsID=703 |archive-date=7 May 2008 |url-status=dead }}

The south pole storm may have been present for billions of years. This vortex is comparable to the size of Earth, and it has winds of 550 km/h.{{Cite APOD | title=A Hurricane Over the South Pole of Saturn | date=13 November 2006 | access-date=1 May 2013}}

= Magnetosphere =

{{Main|Magnetosphere of Saturn}}

File:Hubble sees a flickering light display on Saturn.jpg

Saturn has an intrinsic magnetic field that has a simple, symmetric shape—a magnetic dipole. Its strength at the equator—0.2 gauss (20 μT)—is approximately one twentieth of that of the field around Jupiter and slightly weaker than Earth's magnetic field. As a result, Saturn's magnetosphere is much smaller than Jupiter's.{{cite web |url=http://library.thinkquest.org/C005921/Saturn/satuAtmo.htm |title=Saturn: Atmosphere and Magnetosphere |publisher=Thinkquest Internet Challenge |access-date=15 July 2007 |last=McDermott |first=Matthew |date=2000 |archive-url=https://web.archive.org/web/20111020053039/http://library.thinkquest.org/C005921/Saturn/satuAtmo.htm |archive-date=20 October 2011 |url-status=live }}

When Voyager 2 entered the magnetosphere, the solar wind pressure was high and the magnetosphere extended only 19 Saturn radii, or 1.1 million km (684,000 mi),{{cite web |url=http://voyager.jpl.nasa.gov/science/saturn_magnetosphere.html |title=Voyager – Saturn's Magnetosphere |publisher=NASA Jet Propulsion Laboratory |date=18 October 2010 |access-date=19 July 2011 |archive-url=https://web.archive.org/web/20120319151942/http://voyager.jpl.nasa.gov/science/saturn_magnetosphere.html |archive-date=19 March 2012 |url-status=dead }} although it enlarged within several hours, and remained so for about three days. Most probably, the magnetic field is generated similarly to that of Jupiter—by currents in the liquid metallic-hydrogen layer called a metallic-hydrogen dynamo. This magnetosphere is efficient at deflecting the solar wind particles from the Sun. The moon Titan orbits within the outer part of Saturn's magnetosphere and contributes plasma from the ionized particles in Titan's outer atmosphere.{{cite journal |display-authors=1 |author=Russell, C. T. |author2=Luhmann, J. G. |date=1997 |url=http://www-ssc.igpp.ucla.edu/personnel/russell/papers/sat_mag.html |title=Saturn: Magnetic Field and Magnetosphere |journal=Science |volume=207 |issue=4429 |pages=407–10 |access-date=29 April 2007 |archive-url=https://web.archive.org/web/20110927165242/http://www-ssc.igpp.ucla.edu/personnel/russell/papers/sat_mag.html |archive-date=27 September 2011 |url-status=live |bibcode=1980Sci...207..407S |doi=10.1126/science.207.4429.407 |pmid=17833549 |s2cid=41621423 }} Saturn's magnetosphere, like Earth's, produces aurorae.{{cite web |url=http://www.windows2universe.org/saturn/upper_atmosphere.html |title=Saturn Magnetosphere Overview |author=Russell, Randy |publisher=Windows to the Universe |date=3 June 2003 |access-date=19 July 2011 |archive-url=https://web.archive.org/web/20110906031014/http://www.windows2universe.org/saturn/upper_atmosphere.html |archive-date=6 September 2011 |url-status=dead }}

Orbit and rotation

File:Solar system orrery outer planets.gifs orbiting around the Sun]]

File:Saturnoppositions-animated.gif) during an orbit of Saturn, 2001–2029]]

The average distance between Saturn and the Sun is over 1.4 billion kilometers (9 AU). With an average orbital speed of 9.68 km/s, it takes Saturn 10,759 Earth days (or about {{frac|29|1|2}} years) to finish one revolution around the Sun. As a consequence, it forms a near 5:2 mean-motion resonance with Jupiter.{{cite journal |title=Modeling the 5 : 2 Mean-Motion Resonance in the Jupiter-Saturn Planetary System |last1=Michtchenko |first1=T. A. |last2=Ferraz-Mello |first2=S. |journal=Icarus |volume=149 |issue=2 |pages=357–374 |date=February 2001 |doi=10.1006/icar.2000.6539 |bibcode=2001Icar..149..357M}} The elliptical orbit of Saturn is inclined 2.48° relative to the orbital plane of the Earth. The perihelion and aphelion distances are, respectively, 9.195 and 9.957 AU, on average.Jean Meeus, Astronomical Algorithms (Richmond, VA: Willmann-Bell, 1998). Average of the nine extremes on p 273. All are within 0.02 AU of the averages. The visible features on Saturn rotate at different rates depending on latitude, and multiple rotation periods have been assigned to various regions (as in Jupiter's case).

Astronomers use three different systems for specifying the rotation rate of Saturn. System I has a period of {{RA|10|14|00}} (844.3°/d) and encompasses the Equatorial Zone, the South Equatorial Belt, and the North Equatorial Belt. The polar regions are considered to have rotation rates similar to System I. All other Saturnian latitudes, excluding the north and south polar regions, are indicated as System II and have been assigned a rotation period of {{RA|10|38|25.4}} (810.76°/d). System III refers to Saturn's internal rotation rate. Based on radio emissions from the planet detected by Voyager 1 and Voyager 2,{{cite journal|doi=10.1126/science.209.4462.1238|pmid=17811197|bibcode=1980Sci...209.1238K|title=Voyager Detection of Nonthermal Radio Emission from Saturn|journal=Science|volume=209|issue=4462|pages=1238–40|last1=Kaiser|first1=M. L.|last2=Desch|first2=M. D.|last3=Warwick|first3=J. W.|last4=Pearce|first4=J. B.|year=1980|hdl=2060/19800013712|s2cid=44313317|hdl-access=free}} System III has a rotation period of {{RA|10|39|22.4}} (810.8°/d). System III has largely superseded System II.

A precise value for the rotation period of the interior remains elusive. While approaching Saturn in 2004, Cassini found that the radio rotation period of Saturn had increased appreciably, to approximately {{RA|10|45|45}} {{+-|{{RA|||36}}}}.{{cite web |url=http://www.nasa.gov/mission_pages/cassini/media/cassini-062804.html |title=Scientists Find That Saturn's Rotation Period is a Puzzle |date=28 June 2004 |publisher=NASA |access-date=22 March 2007 |archive-url=https://web.archive.org/web/20110729155336/http://www.nasa.gov/mission_pages/cassini/media/cassini-062804.html |archive-date=29 July 2011 |url-status=live }} An estimate of Saturn's rotation (as an indicated rotation rate for Saturn as a whole) based on a compilation of various measurements from the Cassini, Voyager, and Pioneer probes is {{RA|10|32|35}}. Studies of the planet's C Ring yield a rotation period of {{RA|10|33|38}} {{+-|{{RA||1|52}}|{{RA||1|19}}}} .

In March 2007, it was found that the variation in radio emissions from the planet did not match Saturn's rotation rate. This variance may be caused by geyser activity on Saturn's moon Enceladus. The water vapor emitted into Saturn's orbit by this activity becomes charged and creates a drag upon Saturn's magnetic field, slowing its rotation slightly relative to the rotation of the planet.{{cite press release |url=http://www.nasa.gov/mission_pages/cassini/media/cassini-20070322.html |title=Enceladus Geysers Mask the Length of Saturn's Day |date=22 March 2007 |publisher=NASA Jet Propulsion Laboratory |access-date=22 March 2007 |url-status=dead |archive-url=https://web.archive.org/web/20081207134416/http://saturn.jpl.nasa.gov/news/press-release-details.cfm?newsID=733 |archive-date=7 December 2008 }}

An apparent oddity for Saturn is that it does not have any known trojan asteroids. These are minor planets that orbit the Sun at the stable Lagrangian points, designated L4 and L5, located at 60° angles to the planet along its orbit. Trojan asteroids have been discovered for Mars, Jupiter, Uranus, and Neptune. Orbital resonance mechanisms, including secular resonance, are believed to be the cause of the missing Saturnian trojans.{{cite journal |title=Saturn Trojans: a dynamical point of view |journal=Monthly Notices of the Royal Astronomical Society |display-authors=1 |last1=Hou |first1=X. Y. |last2=Scheeres |first2=D. J. |last3=Liu |first3=L. |volume=437 |issue=2 |pages=1420–1433 |date=January 2014 |doi=10.1093/mnras/stt1974 |bibcode=2014MNRAS.437.1420H|doi-access=free }}

Natural satellites

{{Main|Moons of Saturn}}

File:Saturn's Rings PIA03550.jpg

Saturn has 274 known moons, 63 of which have formal names.{{cite news|title=Saturn now leads moon race with 62 newly discovered moons|url=https://science.ubc.ca/news/saturn-now-leads-moon-race-62-newly-discovered-satellites|work=UBC Science|publisher=University of British Columbia|date=11 May 2023|access-date=11 May 2023}}{{cite web |title=Solar System Dynamics – Planetary Satellite Discovery Circumstances |url=https://ssd.jpl.nasa.gov/sats/discovery.html |publisher=NASA |access-date=4 June 2022 |date=15 November 2021}} In addition, there is evidence of dozens to hundreds of moonlets with diameters of 40–500 meters in Saturn's rings,{{cite journal |arxiv=0710.4547 |last=Tiscareno |first=Matthew |title=The population of propellers in Saturn's A Ring |date=17 July 2013 |doi=10.1088/0004-6256/135/3/1083 |volume=135 |issue=3 |journal=The Astronomical Journal |pages=1083–1091 |bibcode=2008AJ....135.1083T|s2cid=28620198 }} which are not considered to be true moons. Titan, the largest moon, comprises more than 90% of the mass in orbit around Saturn, including the rings. Saturn's second-largest moon, Rhea, may have a tenuous ring system of its own, along with a tenuous atmosphere.{{cite web |url=http://www.sciencedaily.com/releases/2010/11/101128222041.htm |title=Thin air: Oxygen atmosphere found on Saturn's moon Rhea |website=ScienceDaily |author=NASA |date=30 November 2010 |access-date=23 July 2011 |archive-url=https://web.archive.org/web/20111108215855/http://www.sciencedaily.com/releases/2010/11/101128222041.htm |archive-date=8 November 2011 |url-status=live }}

Many of the other moons are small: 131 are less than 50 km in diameter.{{cite web |url=http://www.dtm.ciw.edu/users/sheppard/satellites/satsatdata.html |title=Saturn's Known Satellites |publisher=Department of Terrestrial Magnetism |access-date=22 June 2010 |archive-url=https://web.archive.org/web/20110926210000/http://www.dtm.ciw.edu/users/sheppard/satellites/satsatdata.html |archive-date=26 September 2011 |url-status=dead }} Traditionally, most of Saturn's moons have been named after Titans of Greek mythology. Titan is the only satellite in the Solar System with a major atmosphere,{{cite web |url=http://www.sciencedaily.com/releases/2009/01/090129182514.htm |title=Cassini Finds Hydrocarbon Rains May Fill Titan Lakes |website=ScienceDaily |date=30 January 2009 |access-date=19 July 2011 |archive-url=https://web.archive.org/web/20111109045639/http://www.sciencedaily.com/releases/2009/01/090129182514.htm |archive-date=9 November 2011 |url-status=live }}{{cite web |url=http://voyager.jpl.nasa.gov/science/saturn_titan.html |title=Voyager – Titan |publisher=NASA Jet Propulsion Laboratory |date=18 October 2010 |access-date=19 July 2011 |archive-url=https://web.archive.org/web/20111026090736/http://voyager.jpl.nasa.gov/science/saturn_titan.html |archive-date=26 October 2011 |url-status=dead }} in which a complex organic chemistry occurs. It is the only satellite with hydrocarbon lakes.{{cite news |url=https://www.nbcnews.com/id/wbna14029488 |title=Evidence of hydrocarbon lakes on Titan |publisher=NBC News |agency=Associated Press |date=25 July 2006 |access-date=19 July 2011 |archive-date=24 August 2014 |archive-url=https://web.archive.org/web/20140824105749/http://www.nbcnews.com/id/14029488/ |url-status=live }}{{cite news |url=http://www.cosmosmagazine.com/news/2109/ethane-lake-finally-confirmed-titan |title=Hydrocarbon lake finally confirmed on Titan |work=Cosmos Magazine |date=31 July 2008 |access-date=19 July 2011 |archive-url=https://web.archive.org/web/20111101134216/http://www.cosmosmagazine.com/news/2109/ethane-lake-finally-confirmed-titan |archive-date=1 November 2011 |url-status=dead }}

On 6 June 2013, scientists at the IAA-CSIC reported the detection of polycyclic aromatic hydrocarbons in the upper atmosphere of Titan, a possible precursor for life.{{cite news |last=López-Puertas |first=Manuel |url=http://www.iaa.es/content/pahs-titans-upper-atmosphere |title=PAH's in Titan's Upper Atmosphere |date=6 June 2013 |work=CSIC |access-date=6 June 2013 |archive-date=22 August 2016 |archive-url=https://web.archive.org/web/20160822010505/http://www.iaa.es/content/pahs-titans-upper-atmosphere |url-status=live }} On 23 June 2014, NASA claimed to have strong evidence that nitrogen in the atmosphere of Titan came from materials in the Oort cloud, associated with comets, and not from the materials that formed Saturn in earlier times.{{cite web |display-authors=1 |last1=Dyches |first1=Preston |last2=Clavin |first2=Clavin |title=Titan's Building Blocks Might Pre-date Saturn |url=http://www.jpl.nasa.gov/news/news.php?release=2014-200 |date=23 June 2014 |work=NASA |access-date=24 June 2014 |archive-date=9 September 2018 |archive-url=https://web.archive.org/web/20180909162240/https://www.jpl.nasa.gov/news/news.php?release=2014-200 |url-status=live }}

Saturn's moon Enceladus, which seems similar in chemical makeup to comets,{{cite web |last=Battersby |first=Stephen |title=Saturn's moon Enceladus surprisingly comet-like |url=https://www.newscientist.com/article/dn13541-saturns-moon-enceladus-surprisingly-cometlike.html |date=26 March 2008 |work=New Scientist |access-date=16 April 2015 |archive-date=30 June 2015 |archive-url=https://web.archive.org/web/20150630011601/http://www.newscientist.com/article/dn13541-saturns-moon-enceladus-surprisingly-cometlike.html |url-status=live }} has often been regarded as a potential habitat for microbial life.{{cite web |url=http://www.sciencedaily.com/releases/2008/04/080420122601.htm |title=Could There Be Life On Saturn's Moon Enceladus? |website=ScienceDaily |author=NASA |date=21 April 2008 |access-date=19 July 2011 |archive-url=https://web.archive.org/web/20111109041043/http://www.sciencedaily.com/releases/2008/04/080420122601.htm |archive-date=9 November 2011 |url-status=live }}{{cite web |url=http://scienceray.com/astronomy/enceladus-saturns-moon-has-liquid-ocean-of-water/ |title=Enceladus: Saturn′s Moon, Has Liquid Ocean of Water |last=Pili |first=Unofre |work=Scienceray |date=9 September 2009 |access-date=21 July 2011 |archive-url=https://web.archive.org/web/20111007220555/http://scienceray.com/astronomy/enceladus-saturns-moon-has-liquid-ocean-of-water/ |archive-date=7 October 2011 |url-status=dead }} Evidence of this possibility includes the satellite's salt-rich particles having an "ocean-like" composition that indicates most of Enceladus's expelled ice comes from the evaporation of liquid salt water.{{cite news |url=http://www.physorg.com/news/2011-06-strongest-evidence-icy-saturn-moon.html |title=Strongest evidence yet indicates Enceladus hiding saltwater ocean |publisher=Physorg |date=22 June 2011 |access-date=19 July 2011 |archive-url=https://web.archive.org/web/20111019155718/http://www.physorg.com/news/2011-06-strongest-evidence-icy-saturn-moon.html |archive-date=19 October 2011 |url-status=live }}{{cite news |url=https://www.washingtonpost.com/national/health-science/saturns-moon-enceladus-shows-evidence-of-an-ocean-beneath-its-surface/2011/06/22/AGWYaPgH_story.html |title=Saturn′s moon Enceladus shows evidence of an ocean beneath its surface |newspaper=The Washington Post |last=Kaufman |first=Marc |date=22 June 2011 |access-date=19 July 2011 |archive-url=https://web.archive.org/web/20121112193955/http://www.washingtonpost.com/national/health-science/saturns-moon-enceladus-shows-evidence-of-an-ocean-beneath-its-surface/2011/06/22/AGWYaPgH_story.html |archive-date=12 November 2012 |url-status=live }}{{cite news |url=http://www.nasa.gov/mission_pages/cassini/whycassini/cassini20110622.html |title=Cassini Captures Ocean-Like Spray at Saturn Moon |publisher=NASA |display-authors=1 |author=Greicius, Tony |author2=Dunbar, Brian |date=22 June 2011 |access-date=17 September 2011 |archive-url=https://web.archive.org/web/20110914203739/http://www.nasa.gov/mission_pages/cassini/whycassini/cassini20110622.html |archive-date=14 September 2011 |url-status=live }}

A 2015 flyby by Cassini through a plume on Enceladus found most of the ingredients to sustain life forms that live by methanogenesis.{{cite web |url=https://www.nasa.gov/press-release/nasa-missions-provide-new-insights-into-ocean-worlds-in-our-solar-system |title=NASA Missions Provide New Insights into 'Ocean Worlds' in Our Solar System |first1=Felicia |last1=Chou |first2=Preston |last2=Dyches |first3=Donna |last3=Weaver |first4=Ray |last4=Villard |publisher=NASA |date=13 April 2017 |access-date=20 April 2017 |archive-date=20 April 2017 |archive-url=https://web.archive.org/web/20170420143202/https://www.nasa.gov/press-release/nasa-missions-provide-new-insights-into-ocean-worlds-in-our-solar-system/ |url-status=live }}

In April 2014, NASA scientists reported the possible beginning of a new moon within the A Ring, which was imaged by Cassini on 15 April 2013.{{cite web |display-authors=1 |last1=Platt |first1=Jane |last2=Brown |first2=Dwayne |title=NASA Cassini Images May Reveal Birth of a Saturn Moon |url=http://www.jpl.nasa.gov/news/news.php?release=2014-112 |date=14 April 2014 |work=NASA |access-date=14 April 2014 |archive-date=10 April 2019 |archive-url=https://web.archive.org/web/20190410120305/https://www.jpl.nasa.gov/news/news.php?release=2014-112 |url-status=live }}

Planetary rings

{{Main|Rings of Saturn}}

File:Saturn from Cassini Orbiter (2004-10-06).jpg (imaged here by Cassini in October 2004) are the most massive and conspicuous in the Solar System.]]

Saturn is probably best known for the system of planetary rings that makes it visually unique.{{cite web |title=Saturn |url=http://www.nmm.ac.uk/server/show/conWebDoc.286 |publisher=National Maritime Museum |access-date=6 July 2007 |archive-url=https://web.archive.org/web/20080623204304/http://www.nmm.ac.uk/server/show/conWebDoc.286 |archive-date=23 June 2008 |url-status=dead |date=20 August 2015 }} The rings extend from {{convert|6630|to|120700|km|mi}} outward from Saturn's equator and average approximately {{convert|20|m|ft}} in thickness. They are composed predominantly of water ice, with trace amounts of tholin impurities and a peppered coating of approximately 7% amorphous carbon.{{cite journal |title=The Composition of Saturn's Rings |display-authors=1 |author=Poulet F. |author2=Cuzzi J.N. |journal=Icarus |doi=10.1006/icar.2002.6967 |volume=160 |page=350 |date=2002 |bibcode=2002Icar..160..350P |issue=2 |url=https://zenodo.org/record/1229856 |access-date=28 June 2019 |archive-date=29 July 2019 |archive-url=https://web.archive.org/web/20190729190601/https://zenodo.org/record/1229856 |url-status=live }} The particles that make up the rings range in size from specks of dust up to 10 m.{{cite web |last=Porco |first=Carolyn |author-link=Carolyn Porco |title=Questions about Saturn's rings |website=CICLOPS web site |url=http://www.ciclops.org/sci/common_questions.php#ring |access-date=18 June 2017 |archive-date=3 October 2012 |archive-url=https://web.archive.org/web/20121003073842/http://www.ciclops.org/sci/common_questions.php#ring |url-status=live }} While the other gas giants also have ring systems, Saturn's is the largest and most visible.

There is a debate on the age of the rings. One side supports that they are ancient, and were created simultaneously with Saturn from the original nebular material (around 4.6 billion years ago),{{cite journal |last1=Canup |first1=Robin M. |title=Origin of Saturn's rings and inner moons by mass removal from a lost Titan-sized satellite |journal=Nature |date=December 2010 |volume=468 |issue=7326 |pages=943–946 |doi=10.1038/nature09661 |pmid=21151108 |bibcode=2010Natur.468..943C |url=https://www.nature.com/articles/nature09661 |access-date=22 May 2024 |language=en |issn=1476-4687}} or shortly after the LHB (around 4.1 to 3.8 billion years ago).{{cite journal |last1=Crida |first1=A. |last2=Charnoz |first2=S. |title=Formation of Regular Satellites from Ancient Massive Rings in the Solar System |journal=Science |date=30 November 2012 |volume=338 |issue=6111 |pages=1196–1199 |doi=10.1126/science.1226477 |pmid=23197530 |url=https://doi.org/10.1126/science.1226477 |access-date=22 May 2024|arxiv=1301.3808 |bibcode=2012Sci...338.1196C }}{{cite journal |last1=Charnoz |first1=Sébastien |last2=Morbidelli |first2=Alessandro |last3=Dones |first3=Luke |last4=Salmon |first4=Julien |title=Did Saturn's rings form during the Late Heavy Bombardment? |url=https://www.sciencedirect.com/science/article/abs/pii/S0019103508003825 |journal=Icarus |date=February 2009 |volume=199 |issue=2 |pages=413–428 |doi=10.1016/j.icarus.2008.10.019 |access-date=22 May 2024 |arxiv=0809.5073 |bibcode=2009Icar..199..413C }} The other side supports that they are much younger, created around 100 million years ago.{{cite journal |last1=Kempf |first1=Sascha |last2=Altobelli |first2=Nicolas |last3=Schmidt |first3=Jürgen |last4=Cuzzi |first4=Jeffrey N. |last5=Estrada |first5=Paul R. |last6=Srama |first6=Ralf |title=Micrometeoroid infall onto Saturn's rings constrains their age to no more than a few hundred million years |journal=Science Advances |date=12 May 2023 |volume=9 |issue=19 |pages=eadf8537 |doi=10.1126/sciadv.adf8537 |pmid=37172091 |pmc=10181170 |bibcode=2023SciA....9F8537K }}{{cite news |last=Andrew |first=Robin George |title=Saturn's Rings May Have Formed in a Surprisingly Recent Crash of 2 Moons - Researchers completed a complex simulation that supports the idea that the giant planet's jewelry emerged hundreds of millions of years ago, not billions. |url=https://www.nytimes.com/2023/09/28/science/saturn-rings-moons-formation.html |date=28 September 2023 |work=The New York Times |url-status=live |archiveurl=https://archive.today/20230929044637/https://www.nytimes.com/2023/09/28/science/saturn-rings-moons-formation.html |archivedate=29 September 2023 |access-date=29 September 2023 }}{{cite journal |author=Teodoro, L.F.A. |display-authors=et al |title=A Recent Impact Origin of Saturn's Rings and Mid-sized Moons |date=27 September 2023 |journal=The Astrophysical Journal|volume=955 |number=2 |page=137 |doi=10.3847/1538-4357/acf4ed |arxiv=2309.15156 |bibcode=2023ApJ...955..137T |doi-access=free }} An MIT research team, supporting the latter theory, proposed that the rings are remnant of a destroyed moon of Saturn, named ″Chrysalis″.{{Cite journal|url=https://www.science.org/doi/10.1126/science.abn1234|title=Loss of a satellite could explain Saturn's obliquity and young rings|first1=Jack|last1=Wisdom|first2=Rola|last2=Dbouk|first3=Burkhard|last3=Militzer|first4=William B.|last4=Hubbard|first5=Francis|last5=Nimmo|first6=Brynna G.|last6=Downey|first7=Richard G.|last7=French|date=16 September 2022|journal=Science|volume=377|issue=6612|pages=1285–1289|doi=10.1126/science.abn1234|pmid=36107998|bibcode=2022Sci...377.1285W |hdl=1721.1/148216 |s2cid=252310492 |url-access=subscription|hdl-access=free}}

Beyond the main rings, at a distance of 12 million km (7.5 million mi) from the planet is the sparse Phoebe ring. It is tilted at an angle of 27° to the other rings and, like Phoebe, orbits in retrograde fashion.{{cite web |first=Rob |last=Cowen |date=7 November 1999 |url=http://www.sciencenews.org/view/generic/id/48097/title/Largest_known_planetary_ring_discovered |title=Largest known planetary ring discovered |work=Science News |access-date=9 April 2010 |archive-url=https://web.archive.org/web/20110822023022/http://www.sciencenews.org/view/generic/id/48097/title/Largest_known_planetary_ring_discovered |archive-date=22 August 2011 |url-status=live }}

Some of the moons of Saturn, including Pandora and Prometheus, act as shepherd moons to confine the rings and prevent them from spreading out. Pan and Atlas cause weak, linear density waves in Saturn's rings that have yielded more reliable calculations of their masses.{{cite web |url=http://www.sciencedaily.com/releases/2005/02/050225110106.htm |title=NASA's Cassini Spacecraft Continues Making New Discoveries |website=ScienceDaily |author=NASA Jet Propulsion Laboratory |date=3 March 2005 |access-date=19 July 2011 |archive-url=https://web.archive.org/web/20111108223641/http://www.sciencedaily.com/releases/2005/02/050225110106.htm |archive-date=8 November 2011 |url-status=live }}

{{wide image|Saturn's rings dark side mosaic.jpg|2200px|Natural-color mosaic of Cassini narrow-angle camera images of the unilluminated side of Saturn's D, C, B, A, and F rings (left to right) taken on 9 May 2007 (distances are to the planet's center).}}

History of observation and exploration

The observation and exploration of Saturn can be divided into three phases: (1) pre-modern observations with the naked eye, (2) telescopic observations from Earth beginning in the 17th century, and (3) visitation by space probes, in orbit or on flyby. In the 21st century, telescopic observations continue from Earth (including Earth-orbiting observatories like the Hubble Space Telescope) and, until its 2017 retirement, from the Cassini orbiter around Saturn.

= Pre-telescopic observation =

{{See also|Saturn (mythology)|Planets in astrology#Saturn}}

Saturn has been known since prehistoric times,{{cite web |title=Observing Saturn |url=http://www.nmm.ac.uk/server/show/conWebDoc.13852/viewPage/5 |publisher=National Maritime Museum |access-date=6 July 2007 |archive-url=https://web.archive.org/web/20070422014136/http://www.nmm.ac.uk/server/show/conWebDoc.13852/viewPage/5 |archive-date=22 April 2007|date=20 August 2015 }} and in early recorded history it was a major character in various mythologies. Babylonian astronomers systematically observed and recorded the movements of Saturn. In ancient Greek, the planet was known as {{lang|grc|Φαίνων}} Phainon,{{LSJ|*fai/nwn|Φαίνων|ref|mLSJ}}. and in Roman times it was known as the "star of Saturn" or the "star of the Sun (i.e. Helios)".Cicero, De Natura Deorum.{{Cite journal |last1=Neuhäuser |first1=R |last2=Torres |first2=G |last3=Mugrauer |first3=M |last4=Neuhäuser |first4=D L |last5=Chapman |first5=J |last6=Luge |first6=D |last7=Cosci |first7=M |date=2022-10-11 |title=Colour evolution of Betelgeuse and Antares over two millennia, derived from historical records, as a new constraint on mass and age |url=https://academic.oup.com/mnras/article/516/1/693/6651563 |journal=Monthly Notices of the Royal Astronomical Society |volume=516 |issue=1 |pages=693–719 |doi=10.1093/mnras/stac1969 |doi-access=free |issn=0035-8711|arxiv=2207.04702 }} In ancient Roman mythology, the planet Phainon was sacred to this agricultural god, from which the planet takes its modern name. The Romans considered the god Saturnus the equivalent of the Greek god Cronus; in modern Greek, the planet retains the name Cronus—{{Langx|el|Κρόνος|label=none}}: Kronos.{{cite web |url=http://www.greek-names.info/greek-names-of-the-planets/ |title=Greek Names of the Planets |access-date=14 July 2012 |quote=The Greek name of the planet Saturn is Kronos. The Titan Cronus was the father of Zeus, while Saturn was the Roman God of agriculture. |date=25 April 2010 |archive-date=9 May 2010 |archive-url=https://web.archive.org/web/20100509164917/http://www.greek-names.info/greek-names-of-the-planets/ |url-status=live }} See also the Greek article about the planet.

The Greek scientist Ptolemy based his calculations of Saturn's orbit on observations he made while it was in opposition. In Hindu astrology, there are nine astrological objects, known as Navagrahas. Saturn is known as "Shani" and judges everyone based on the good and bad deeds performed in life.{{cite web |title=Starry Night Times |url=http://www.starrynight.com/sntimes/2006/2006-01-full.html |access-date=5 July 2007 |date=2006 |publisher=Imaginova Corp. |archive-url=https://web.archive.org/web/20091001001723/http://starrynight.com/sntimes/2006/2006-01-full.html |archive-date=1 October 2009 |url-status=dead }} Ancient Chinese and Japanese culture designated the planet Saturn as the "earth star" ({{lang|zh|土星}}). This was based on Five Elements which were traditionally used to classify natural elements.{{cite book |first=Jan Jakob Maria |last=De Groot |year=1912 |title=Religion in China: universism. a key to the study of Taoism and Confucianism |series=American lectures on the history of religions |volume=10 |page=300 |publisher=G. P. Putnam's Sons |url=https://books.google.com/books?id=ZAaP7dyjCrAC&pg=PA300 |access-date=8 January 2010 |archive-date=22 July 2011 |archive-url=https://web.archive.org/web/20110722005812/http://books.google.com/books?id=ZAaP7dyjCrAC&pg=PA300 |url-status=live }}{{cite book |first=Thomas |last=Crump |year=1992 |title=The Japanese numbers game: the use and understanding of numbers in modern Japan |pages=39–40 |publisher=Routledge |isbn=978-0415056090}}{{cite book |first=Homer Bezaleel |last=Hulbert |year=1909 |title=The passing of Korea |page=[https://archive.org/details/passingkorea01hulbgoog/page/n538 426] |publisher=Doubleday, Page & company |url=https://archive.org/details/passingkorea01hulbgoog |access-date=8 January 2010}}

In Hebrew, Saturn is called Shabbathai.{{cite news |url=http://www.universetoday.com/45087/when-was-saturn-discovered/ |title=When Was Saturn Discovered? |work=Universe Today |last=Cessna |first=Abby |date=15 November 2009 |access-date=21 July 2011 |archive-url=https://web.archive.org/web/20120214113458/http://www.universetoday.com/45087/when-was-saturn-discovered/ |archive-date=14 February 2012 |url-status=live }} Its angel is Cassiel. Its intelligence or beneficial spirit is 'Agȋȇl ({{langx|he|אגיאל|ʿAgyal}}), and its darker spirit (demon) is Zȃzȇl ({{langx|he|זאזל|Zazl}}).{{cite web |title=The Magus, Book I: The Celestial Intelligencer: Chapter XXVIII |url=http://www.sacred-texts.com/grim/magus/ma150.htm |work=Sacred-Text.com |access-date=4 August 2018 |archive-date=19 June 2018 |archive-url=https://web.archive.org/web/20180619080731/http://www.sacred-texts.com/grim/magus/ma150.htm |url-status=live }}{{cite web |title=Saturn in Mythology |url=http://www.crystalinks.com/saturn.mythology.html |work=CrystalLinks.com |access-date=5 August 2018 |archive-date=8 July 2018 |archive-url=https://web.archive.org/web/20180708190230/http://crystalinks.com/saturn.mythology.html |url-status=live }}{{cite web |last=Beyer |first=Catherine |title=Planetary Spirit Sigils – 01 Spirit of Saturn |url=https://www.thoughtco.com/planetary-spirit-sigils-4123081 |date=8 March 2017 |work=ThoughtCo.com |access-date=3 August 2018 |archive-date=4 August 2018 |archive-url=https://web.archive.org/web/20180804014119/https://www.thoughtco.com/planetary-spirit-sigils-4123081 |url-status=live }} Zazel has been described as a great angel, invoked in Solomonic magic, who is "effective in love conjurations".{{cite web |url=http://baby-names.familyeducation.com/name-meaning/zazel |title=Meaning and Origin of: Zazel |work=FamilyEducation.com |date=2014 |access-date=3 August 2018 |quote=Latin: Angel summoned for love invocations |archive-date=2 January 2015 |archive-url=https://web.archive.org/web/20150102063304/http://baby-names.familyeducation.com/name-meaning/zazel |url-status=live }}{{cite web |url=http://hafapea.com/angelpages/angels7.html |title=Angelic Beings |work=Hafapea.com |date=1998 |access-date=3 August 2018 |quote=a Solomonic angel of love rituals |archive-date=22 July 2018 |archive-url=https://web.archive.org/web/20180722154808/http://hafapea.com/angelpages/angels7.html |url-status=dead }} In Ottoman Turkish, Urdu, and Malay, the name of Zazel is 'Zuhal', derived from the Arabic language ({{langx|ar|زحل|Zuhal}}).

= Telescopic pre-spaceflight observations =

File:Galileo.arp.300pix.jpg observed the rings of Saturn in 1610, but was unable to determine what they were.]]

File:Saturn Robert Hooke 1666.jpg noted the shadows ({{Var|a}} and {{Var|b}}) cast by both the globe and the rings on each other in this drawing of Saturn in 1666.|left]]

Saturn's rings require at least a 15-mm-diameter telescope to resolve and thus were not known to exist until Christiaan Huygens saw them in 1655 and published his observations in 1659. Galileo, with his primitive telescope in 1610, incorrectly thought of Saturn's appearing not quite round as two moons on Saturn's sides. It was not until Huygens used greater telescopic magnification that this notion was refuted, and the rings were truly seen for the first time. Huygens also discovered Saturn's moon Titan; Giovanni Domenico Cassini later discovered four other moons: Iapetus, Rhea, Tethys, and Dione. In 1675, Cassini discovered the gap now known as the Cassini Division.

No further discoveries of significance were made until 1789 when William Herschel discovered two further moons, Mimas and Enceladus. The irregularly shaped satellite Hyperion, which has a resonance with Titan, was discovered in 1848 by a British team.

In 1899, William Henry Pickering discovered Phoebe, a highly irregular satellite that does not rotate synchronously with Saturn as the larger moons do. Phoebe was the first such satellite found and it took more than a year to orbit Saturn in a retrograde orbit. During the early 20th century, research on Titan led to the confirmation in 1944 that it had a thick atmosphere—a feature unique among the Solar System's moons.

= Spaceflight missions =

{{main|Exploration of Saturn}}

== ''Pioneer 11'' flyby ==

File:P11saturnb.jpg

Pioneer 11 made the first flyby of Saturn in September 1979, when it passed within {{Convert|20000|km|abbr=on}} of the planet's cloud tops. Images were taken of the planet and a few of its moons, although their resolution was too low to discern surface detail. The spacecraft also studied Saturn's rings, revealing the thin F-ring and the fact that dark gaps in the rings are bright when viewed at a high phase angle (towards the Sun), meaning that they contain fine light-scattering material. In addition, Pioneer 11 measured the temperature of Titan.{{cite web |url=http://spaceprojects.arc.nasa.gov/Space_Projects/pioneer/PN10&11.html |title=The Pioneer 10 & 11 Spacecraft |access-date=5 July 2007 |publisher=Mission Descriptions |archive-url=https://web.archive.org/web/20060130100401/http://spaceprojects.arc.nasa.gov/Space_Projects/pioneer/PN10%2611.html |archive-date=30 January 2006 |url-status=dead }}

== ''Voyager'' flybys ==

In November 1980, the Voyager 1 probe visited the Saturn system. It sent back the first high-resolution images of the planet, its rings and satellites. Surface features of various moons were seen for the first time. Voyager 1 performed a close flyby of Titan, increasing knowledge of the atmosphere of the moon. It proved that Titan's atmosphere is impenetrable at visible wavelengths; therefore no surface details were seen. The flyby changed the spacecraft's trajectory out of the plane of the Solar System.{{cite web |url=http://www.planetary.org/explore/topics/saturn/missions.html |title=Missions to Saturn |publisher=The Planetary Society |date=2007 |access-date=24 July 2007 |archive-url=https://web.archive.org/web/20110728044450/http://www.planetary.org/explore/topics/saturn/missions.html |archive-date=28 July 2011 |url-status=live }}

Almost a year later, in August 1981, Voyager 2 continued the study of the Saturn system. More close-up images of Saturn's moons were acquired, as well as evidence of changes in the atmosphere and the rings. During the flyby, the probe's turnable camera platform stuck for a couple of days and some planned imaging was lost. Saturn's gravity was used to direct the spacecraft's trajectory towards Uranus.

The probes discovered and confirmed several new satellites orbiting near or within the planet's rings, as well as the small Maxwell Gap (a gap within the C Ring) and Keeler gap (a 42 km-wide gap in the A Ring).{{Cite book |last=Spence |first=Pam |url=https://books.google.com/books?id=DwR7JtuXnaQC |title=The Universe Revealed |date=1999 |publisher=Cambridge University Press |isbn=978-0-521-64239-2 |pages=64 |language=en}}

== ''Cassini–Huygens'' spacecraft ==

{{main|Cassini–Huygens}}File:Enceladus geysers June 2009.jpg.|left]]

The Cassini–Huygens space probe entered orbit around Saturn on 1 July 2004. In June 2004, it conducted a close flyby of Phoebe, sending back high-resolution images and data. Cassini{{'s}} flyby of Saturn's largest moon, Titan, captured radar images of large lakes and their coastlines with numerous islands and mountains. The orbiter completed two Titan flybys before releasing the Huygens probe on 25 December 2004. Huygens descended onto the surface of Titan on 14 January 2005.

Starting in early 2005, scientists used Cassini to track lightning on Saturn. The power of the lightning is approximately 1,000 times that of lightning on Earth.{{cite web |url=http://www.sciencedaily.com/releases/2006/02/060215090726.htm |title=Astronomers Find Giant Lightning Storm At Saturn |date=2007 |access-date=27 July 2007 |publisher=ScienceDaily LLC |archive-url=https://web.archive.org/web/20110828092204/http://www.sciencedaily.com/releases/2006/02/060215090726.htm |archive-date=28 August 2011 |url-status=live }}

In 2006, NASA reported that Cassini had found evidence of liquid water reservoirs no more than tens of meters below the surface that erupt in geysers on Saturn's moon Enceladus. These jets of icy particles are emitted into orbit around Saturn from vents in the moon's south polar region.{{cite web |last1=Pence |first1=Michael |url=http://www.nasa.gov/mission_pages/cassini/media/cassini-20060309.html |title=NASA's Cassini Discovers Potential Liquid Water on Enceladus |date=9 March 2006 |publisher=NASA Jet Propulsion Laboratory |access-date=3 June 2011 |archive-url=https://web.archive.org/web/20110811013419/http://www.nasa.gov/mission_pages/cassini/media/cassini-20060309.html |archive-date=11 August 2011 |url-status=live }} Over 100 geysers have been identified on Enceladus.{{cite web |display-authors=1 |last1=Dyches |first1=Preston |last2=Brown |first2=Dwayne |last3=Mullins |first3=Steve |title=Cassini Spacecraft Reveals 101 Geysers and More on Icy Saturn Moon |url=http://www.jpl.nasa.gov/news/news.php?release=2014-246&2 |date=28 July 2014 |work=NASA |access-date=29 July 2014 |archive-date=14 July 2017 |archive-url=https://web.archive.org/web/20170714031155/https://www.jpl.nasa.gov/news/news.php?release=2014-246&2 |url-status=live }} In May 2011, NASA scientists reported that Enceladus "is emerging as the most habitable spot beyond Earth in the Solar System for life as we know it".{{cite journal |last1=Lovett |first1=Richard A. |title=Enceladus named sweetest spot for alien life |url=http://www.nature.com/news/2011/110531/full/news.2011.337.html |date=31 May 2011 |access-date=3 June 2011 |doi=10.1038/news.2011.337 |archive-url=https://web.archive.org/web/20110905061010/http://www.nature.com/news/2011/110531/full/news.2011.337.html |archive-date=5 September 2011 |url-status=live |journal=Nature |pages=news.2011.337 }}{{cite web |last1=Kazan |first1=Casey |title=Saturn's Enceladus Moves to Top of "Most-Likely-to-Have-Life" List |url=http://www.dailygalaxy.com/my_weblog/2011/06/saturns-enceladus-moves-to-top-of-most-likely-to-have-life-list.html |date=2 June 2011 |publisher=The Daily Galaxy |access-date=3 June 2011 |archive-url=https://web.archive.org/web/20110806103640/http://www.dailygalaxy.com/my_weblog/2011/06/saturns-enceladus-moves-to-top-of-most-likely-to-have-life-list.html |archive-date=6 August 2011 |url-status=live }}File:Saturn eclipse.jpg. The rings are visible, including the F Ring.]]

Cassini photographs have revealed a previously undiscovered planetary ring, outside the brighter main rings of Saturn and inside the G and E rings. The source of this ring is hypothesized to be the crashing of a meteoroid off Janus and Epimetheus.{{cite web |url=https://www.newscientist.com/article/dn10124-faint-new-ring-discovered-around-saturn/ |title=Faint new ring discovered around Saturn |access-date=8 July 2007 |date=20 September 2007 |last=Shiga |first=David |publisher=NewScientist.com |archive-url=https://web.archive.org/web/20080503212602/http://space.newscientist.com/channel/solar-system/cassini-huygens/dn10124-faint-new-ring-discovered-around-saturn.html |archive-date=3 May 2008 |url-status=live }} In July 2006, images were returned of hydrocarbon lakes near Titan's north pole, the presence of which were confirmed in January 2007. In March 2007, hydrocarbon seas were found near the North pole, the largest of which is almost the size of the Caspian Sea.{{cite news |url=http://news.bbc.co.uk/2/hi/science/nature/6449081.stm |title=Probe reveals seas on Saturn moon |publisher=BBC |last=Rincon |first=Paul |access-date=26 September 2007 |date=14 March 2007 |archive-url=https://web.archive.org/web/20111111135219/http://news.bbc.co.uk/2/hi/science/nature/6449081.stm |archive-date=11 November 2011 |url-status=live }} In October 2006, the probe detected an {{Convert|8000|km|abbr=on}} diameter cyclone-like storm with an eyewall at Saturn's south pole.{{cite news |url=http://news.bbc.co.uk/2/hi/science/nature/6135450.stm |title=Huge 'hurricane' rages on Saturn |publisher=BBC |last=Rincon |first=Paul |access-date=12 July 2007 |date=10 November 2006 |archive-url=https://web.archive.org/web/20110902214204/http://news.bbc.co.uk/2/hi/science/nature/6135450.stm |archive-date=2 September 2011 |url-status=live }}

From 2004 to 2 November 2009, the probe discovered and confirmed eight new satellites.{{cite web |url=http://saturn.jpl.nasa.gov/mission/introduction/ |title=Mission overview – introduction |date=2010 |work=Cassini Solstice Mission |publisher=NASA / JPL |access-date=23 November 2010 |archive-url=https://web.archive.org/web/20110807005756/http://saturn.jpl.nasa.gov/mission/introduction/ |archive-date=7 August 2011 |url-status=dead }} In April 2013, Cassini sent back images of a hurricane at the planet's north pole 20 times larger than those found on Earth, with winds faster than {{convert|530|km/h|mph|abbr=on}}.{{cite news |url=http://www.3news.co.nz/Massive-storm-at-Saturns-north-pole/tabid/1160/articleID/296026/Default.aspx |work=3 News NZ |title=Massive storm at Saturn's north pole |date=30 April 2013 |access-date=30 April 2013 |archive-date=19 July 2014 |archive-url=https://web.archive.org/web/20140719200738/http://www.3news.co.nz/Massive-storm-at-Saturns-north-pole/tabid/1160/articleID/296026/Default.aspx |url-status=live }} On 15 September 2017, the Cassini–Huygens spacecraft performed the "Grand Finale" of its mission: a number of passes through gaps between Saturn and Saturn's inner rings.{{cite news |last1=Brown |first1=Dwayne |last2=Cantillo |first2=Laurie |last3=Dyches |first3=Preston |title=NASA's Cassini Spacecraft Ends Its Historic Exploration of Saturn |url=https://www.jpl.nasa.gov/news/news.php?feature=6948 |date=15 September 2017 |work=NASA |access-date=15 September 2017 |archive-date=9 May 2019 |archive-url=https://web.archive.org/web/20190509044122/https://www.jpl.nasa.gov/news/news.php?feature=6948 |url-status=live }}{{cite news |last=Chang |first=Kenneth |title=Cassini Vanishes Into Saturn, Its Mission Celebrated and Mourned |url=https://www.nytimes.com/2017/09/14/science/cassini-grand-finale-saturn.html |date=14 September 2017 |work=The New York Times |access-date=15 September 2017 |archive-date=8 July 2018 |archive-url=https://web.archive.org/web/20180708162700/https://www.nytimes.com/2017/09/14/science/cassini-grand-finale-saturn.html |url-status=live }} The atmospheric entry of Cassini ended the mission.

== Possible future missions ==

The continued exploration of Saturn is still considered to be a viable option for NASA as part of their ongoing New Frontiers program of missions. NASA previously requested for plans to be put forward for a mission to Saturn that included the Saturn Atmospheric Entry Probe, and possible investigations into the habitability and possible discovery of life on Saturn's moons Titan and Enceladus by Dragonfly.{{cite news |url=http://spacenews.com/nasa-expands-frontiers-of-next-new-frontiers-competition/ |title=NASA Expands Frontiers of Next New Frontiers Competition |work=SpaceNews |first=Jeff |last=Foust |date=8 January 2016 |access-date=20 April 2017 |archive-date=18 August 2017 |archive-url=https://wayback.archive-it.org/all/20170818112258/http://spacenews.com/nasa-expands-frontiers-of-next-new-frontiers-competition/ |url-status=live }}{{Cite web |author=Nola Taylor Redd |date=25 April 2017 |title='Dragonfly' Drone Could Explore Saturn Moon Titan |url=https://www.space.com/36598-dragonfly-quadcopter-saturn-moon-titan-explorer.html |access-date=13 June 2020 |website=Space.com |language=en |archive-date=30 June 2019 |archive-url=https://web.archive.org/web/20190630035114/https://www.space.com/36598-dragonfly-quadcopter-saturn-moon-titan-explorer.html|url-status=live}}

Observation

File:Saturn-27-03-04.jpeg

Saturn is the most distant of the five planets easily visible to the naked eye from Earth, the other four being Mercury, Venus, Mars, and Jupiter. (Uranus, and occasionally 4 Vesta, are visible to the naked eye in dark skies.) Saturn appears to the naked eye in the night sky as a bright, yellowish point of light. The mean apparent magnitude of Saturn is 0.46 with a standard deviation of 0.34. Most of the magnitude variation is due to the inclination of the ring system relative to the Sun and Earth. The brightest magnitude, −0.55, occurs near the time when the plane of the rings is inclined most highly, and the faintest magnitude, 1.17, occurs around the time when they are least inclined. It takes approximately 29.4 years for the planet to complete an entire circuit of the ecliptic against the background constellations of the zodiac. Most people will require an optical aid (very large binoculars or a small telescope) that magnifies at least 30 times to achieve an image of Saturn's rings in which a clear resolution is present. When Earth passes through the ring plane, which occurs twice every Saturnian year (roughly every 15 Earth years), the rings briefly disappear from view because they are so thin. Such a "disappearance" will next occur in 2025, but Saturn will be too close to the Sun for observations.{{cite web |url=http://www.classicalastronomy.com/news/anmviewer.asp?a=313&z=28 |title=Saturn's Rings Edge-On |date=2013 |publisher=Classical Astronomy |archive-url=https://web.archive.org/web/20131105231722/http://www.classicalastronomy.com/news/anmviewer.asp?a=313&z=28 |archive-date=5 November 2013 |access-date=4 August 2013 |url-status=dead }}

Saturn and its rings are best seen when the planet is at, or near, opposition, the configuration of a planet when it is at an elongation of 180°, and thus appears opposite the Sun in the sky. A Saturnian opposition occurs every year—approximately every 378 days—and results in the planet appearing at its brightest. Both the Earth and Saturn orbit the Sun on eccentric orbits, which means their distances from the Sun vary over time, and therefore so do their distances from each other, hence varying the brightness of Saturn from one opposition to the next. Saturn also appears brighter when the rings are angled such that they are more visible. For example, during the opposition of 17 December 2002, Saturn appeared at its brightest due to the favorable orientation of its rings relative to the Earth,{{cite journal |title=Saturn in 2002–03 |last=Schmude |first=Richard W. Jr. |date=Winter 2003 |journal=Georgia Journal of Science |issn=0147-9369 |volume=61 |issue=4 |url=http://www.freepatentsonline.com/article/Georgia-Journal-Science/113429393.html |access-date=29 June 2015 |archive-date=24 September 2015 |archive-url=https://web.archive.org/web/20150924052153/http://www.freepatentsonline.com/article/Georgia-Journal-Science/113429393.html |url-status=live }} even though Saturn was closer to the Earth and Sun in late 2003.

From time to time, Saturn is occulted by the Moon (that is, the Moon covers up Saturn in the sky). As with all the planets in the Solar System, occultations of Saturn occur in "seasons". Saturnian occultations will take place monthly for about a 12-month period, followed by about a five-year period in which no such activity is registered. The Moon's orbit is inclined by several degrees relative to Saturn's, so occultations will only occur when Saturn is near one of the points in the sky where the two planes intersect (both the length of Saturn's year and the 18.6-Earth-year nodal precession period of the Moon's orbit influence the periodicity).{{cite news |title=Bright Saturn will blink out across Australia – for an hour, anyway |url=http://theconversation.com/bright-saturn-will-blink-out-across-australia-for-an-hour-anyway-26217 |access-date=11 May 2014 |newspaper=The Conversation |date=9 May 2014 |display-authors=1 |author=Tanya Hill |author2=Jonti Horner |archive-date=10 May 2014 |archive-url=https://web.archive.org/web/20140510214258/http://theconversation.com/bright-saturn-will-blink-out-across-australia-for-an-hour-anyway-26217 |url-status=live }}

In fiction

{{main|Saturn in fiction}}

Saturn has frequently appeared in fiction since at least 1752, when Voltaire published his novel Micromégas.{{Cite book |last=McKinney |first=Richard L. |title=The Greenwood Encyclopedia of Science Fiction and Fantasy: Themes, Works, and Wonders |date=2005 |publisher=Greenwood Publishing Group |isbn=978-0-313-32951-7 |editor-last=Westfahl |editor-first=Gary |editor-link=Gary Westfahl |page=449 |language=en |chapter=Jupiter and the Outer Planets |quote=The earliest fiction featuring Saturn is probably Voltaire's Micromégas (1750). Much later, Saturn is central in Poul Anderson's "The Saturn Game" (1981) and Michael A. McCollum's The Clouds of Saturn (1991), where human cities float in Saturn's atmosphere. The planet's atmosphere is also the home of the two-brained, four-kilometer-wide creatures of Robert F. Forward's Saturn Rukh (1997). Saturn's largest satellite, Titan—interesting because of its thick atmosphere—is colonized in Alan E Nourse's 1954 juvenile novel, Trouble on Titan, while Stephen Baxter's Titan (1997) is about a space mission to the satellite. |chapter-url=https://archive.org/details/greenwoodencyclo0000unse_k2b9/page/449/mode/2up}} Early works generally depicted it as solid,{{Cite book |last=Westfahl |first=Gary |author-link=Gary Westfahl |title=Science Fiction Literature through History: An Encyclopedia |date=2021 |publisher=ABC-CLIO |isbn=978-1-4408-6617-3 |pages=553–555 |language=en |chapter=Saturn |chapter-url=https://books.google.com/books?id=WETPEAAAQBAJ&pg=PA554}} whereas Saturn is later correctly described as a gaseous planet. Saturn's moons are also featured in fiction, especially Titan.{{Cite book |last=Stableford |first=Brian |author-link=Brian Stableford |title=Science Fact and Science Fiction: An Encyclopedia |date=2006 |publisher=Taylor & Francis |isbn=978-0-415-97460-8 |pages=458–459 |language=en |chapter=Saturn |chapter-url=https://books.google.com/books?id=uefwmdROKTAC&pg=PA458}}

See also

Notes

{{reflist|group=lower-alpha}}

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{{cite journal |display-authors=1 |last1=Gurnett |first1=D. A. |last2=Persoon |first2=A. M. |last3=Kurth |first3=W. S. |last4=Groene |first4=J. B. |last5=Averkamp |first5=T. F. |last6=Dougherty |first6=M. K. |last7=Southwood |first7=D. J. |title=The Variable Rotation Period of the Inner Region of Saturn's Plasma Disc |date=2007 |volume=316 |journal=Science |pmid=17379775 |issue=5823 |pages=442–5 |bibcode=2007Sci...316..442G |doi=10.1126/science.1138562|s2cid=46011210 |url=https://pdfs.semanticscholar.org/50a8/0b218aefb851697d4916558fef1c61b03f0c.pdf |archive-url=https://web.archive.org/web/20200212013130/https://pdfs.semanticscholar.org/50a8/0b218aefb851697d4916558fef1c61b03f0c.pdf |url-status=dead |archive-date=12 February 2020 }}

{{cite journal |last1=Bagenal |first1=F. |pmid=17446379 |title=A New Spin on Saturn's Rotation |journal=Science |volume=316 |issue=5823 |pages=380–1 |date=2007 |doi=10.1126/science.1142329|s2cid=118878929 }}

{{cite journal |journal=Science |title=Saturn's gravitational field, internal rotation and interior structure |volume=317 |pages=1384–1387 |date=2007 |doi=10.1126/science.1144835 |pmid=17823351 |first1=J. D. |last1=Anderson |first2=G. |last2=Schubert |issue=5843 |bibcode=2007Sci...317.1384A|s2cid=19579769 |url=http://pdfs.semanticscholar.org/98cf/84491154ff17b7a0596d5150f9029512d682.pdf |archive-url=https://web.archive.org/web/20200412141659/http://pdfs.semanticscholar.org/98cf/84491154ff17b7a0596d5150f9029512d682.pdf |url-status=dead |archive-date=12 April 2020 }}

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{{cite news |url=http://www.nasa.gov/mission_pages/cassini/whycassini/cassini20101126.html |title=Cassini reveals oxygen atmosphere of Saturn′s moon Rhea |publisher=UCL Mullard Space Science Laboratory |first1=Clare |last1=Ryan |date=26 November 2010 |access-date=23 July 2011 |archive-url=https://web.archive.org/web/20110916174510/http://www.nasa.gov/mission_pages/cassini/whycassini/cassini20101126.html |archive-date=16 September 2011 |url-status=live }}

{{cite news |url=https://www.wired.com/wiredscience/2009/06/enceladusocean/ |title=Hunt for Life on Saturnian Moon Heats Up |publisher=Wired Science |first1=Alexis |last1=Madrigal |date=24 June 2009 |access-date=19 July 2011 |archive-url=https://web.archive.org/web/20110904152001/http://www.wired.com/wiredscience/2009/06/enceladusocean/ |archive-date=4 September 2011 |url-status=live }}

{{cite news |url=http://www.universetoday.com/24168/orbit-of-saturn/ |title=Orbit of Saturn |work=Universe Today |first1=Fraser |last1=Cain |date=26 January 2009 |access-date=19 July 2011 |archive-url=https://web.archive.org/web/20110123084633/http://www.universetoday.com/24168/orbit-of-saturn/ |archive-date=23 January 2011 |url-status=live }}

{{cite journal |title=Popular Miscellany – Superstitions about Saturn |journal=The Popular Science Monthly |page=862 |date=April 1893 |url=https://books.google.com/books?id=cSADAAAAMBAJ&pg=PA862 |last1=Corporation |first1=Bonnier |access-date=9 February 2016 |archive-date=17 February 2017 |archive-url=https://web.archive.org/web/20170217001247/https://books.google.com/books?id=cSADAAAAMBAJ&pg=PA862 |url-status=live }}

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{{cite web |url=http://www.nasa.gov/worldbook/saturn_worldbook.html |title=NASA – Saturn |publisher=NASA |access-date=27 July 2007 |date=2004 |archive-url=https://web.archive.org/web/20101229031643/http://www.nasa.gov/worldbook/saturn_worldbook.html |archive-date=29 December 2010 |url-status=dead }}

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{{cite journal |last1=Saumon |first1=D. |last2=Guillot |first2=T. |title=Shock Compression of Deuterium and the Interiors of Jupiter and Saturn |journal=The Astrophysical Journal |volume=609 |issue=2 |pages=1170–1180 |date=July 2004 |doi=10.1086/421257 |bibcode=2004ApJ...609.1170S |arxiv=astro-ph/0403393|s2cid=119325899 }}

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}}

Further reading

  • {{cite book |last=Alexander |first=Arthur Francis O'Donel |author-link=Arthur Francis O'Donel Alexander |title=The Planet Saturn – A History of Observation, Theory and Discovery |publisher=Dover |date=1980 |orig-year=1962 |isbn=978-0-486-23927-9}}
  • {{cite magazine |last=Gore |first=Rick |title=Voyager 1 at Saturn: Riddles of the Rings |magazine=National Geographic |volume=160 |issue=1 |pages=3–31 |date=July 1981 |issn=0027-9358 |oclc=643483454}}
  • {{cite book |last1=Lovett |first1=L. |last2=Horvath |first2=J. |last3=Cuzzi |first3=J. |display-authors=1 |title=Saturn: A New View |publisher=Harry N. Abrams |date=2006 |isbn=978-0-8109-3090-2}}
  • {{cite book |last1=Karttunen |first1=H. |last2=Kröger |first2=P. |display-authors=1 |title=Fundamental Astronomy |publisher=Springer |edition=5th |date=2007 |isbn=978-3-540-34143-7}}
  • {{cite journal |last1=Seidelmann |first1=P. Kenneth |last2=Archinal |first2=Brent A. |last3=A'Hearn |first3=Michael F. |last4=Conrad |first4=Albert R. |last5=Consolmagno |first5=Guy J. |last6=Hestroffer |first6=Daniel |last7=Hilton |first7=James L. |last8=Krasinsky |first8=Georgij A. |last9=Neumann |first9=Gregory A. |last10=Oberst |first10=Jürgen |last11=Stooke |first11=Philip J. |last12=Tedesco |first12=Edward F. |last13=Tholen |first13=David J. |last14=Thomas |first14=Peter C. |last15=Williams |first15=Iwan P. |display-authors=1 |title=Report of the IAU/IAG Working Group on cartographic coordinates and rotational elements: 2006 |journal=Celestial Mechanics and Dynamical Astronomy |volume=98 |issue=3 |pages=155–180 |date=2007 |doi=10.1007/s10569-007-9072-y |bibcode=2007CeMDA..98..155S|doi-access=free }}
  • {{cite book |last1=de Pater |first1=Imke |last2=Lissauer |first2=Jack J. |url=https://books.google.com/books?id=stFpBgAAQBAJ&pg=PA250 |title=Planetary Sciences |publisher=Cambridge University Press |edition=2nd updated |page=250 |date=2015 |isbn=978-0-521-85371-2}}