Saturn

"Sixth planet" redirects here. For other systems of numbering planets, see Planet § History and etymology.

Saturn
Saturn and its prominent rings, as captured by the Cassini orbiter[a]
Designations
Pronunciation/ˈsætərn/ ⓘ[1]
Named after
Saturn
AdjectivesSaturnian /səˈtɜːrniən/,[2] Cronian[3] / Kronian[4] /ˈkroʊniən/[5]
Symbol
Orbital characteristics[6]
Epoch J2000.0
Aphelion1,514.50 million km (10.1238 AU)
Perihelion1,352.55 million km (9.0412 AU)
1,433.53 million km (9.5826 AU)
Eccentricity0.0565
  • 29.4475 yr
  • 10,755.70 d
  • 24,225 Saturnian solar days[7]
378.09 days
Average orbital speed
9.68 km/s
317.020°[8]
Inclination
113.665°
2032-Nov-29[10]
Argument of perihelion
339.392°[8]
Known satellites274 with formal designations; innumerable additional moonlets.[11][12]
Physical characteristics[6]
Mean radius
58232 km[b]
9.1402 Earths
Equatorial radius
  • 60268 km[b]
  • 9.449 Earths
Polar radius
  • 54364 km[b]
  • 8.552 Earths
Flattening0.09796
Circumference365882.4 km (equatorial)[13]
  • 4.27×1010 km2[14][b]
  • 83.703 Earths
Volume
  • 8.2713×1014 km3[b]
  • 763.59 Earths
Mass
  • 5.6834×1026 kg
  • 95.159 Earths
Mean density
0.687 g/cm3[c]
0.1246 Earths
Surface gravity
10.44 m/s2
1.065 g0[b]
Moment of inertia factor
0.22[15]
35.5 km/s[b]
Synodic rotation period
10 h 32 m 36 s;
10.5433 hours,[16] 10 h 39 m;
10.7 hours[7]
Sidereal rotation period
10h 33m 38s + 1m 52s
− 1m 19s [17][18]
Equatorial rotation velocity
9.87 km/s[b]
26.73° (to orbit)
North pole right ascension
40.589°; 2h 42m 21s[19]
North pole declination
83.537°[19]
Albedo
Surface temp. min mean max
1 bar 134 K
0.1 bar 88 K[22] 97 K[23] 151 K[22]
−0.55[24] to +1.17[24]
−9.7[25]
Angular diameter
14.5″ to 20.1″ (excludes rings)
Atmosphere[6]
Surface pressure
>>1000 bars[26]
Scale height
59.5 km
Composition by volume
  • 96.3%±2.4% hydrogen
  • 3.25%±2.4% helium
  • 0.45%±0.2% methane
  • 0.0125%±0.0075% ammonia
  • 0.0110%±0.0058% hydrogen deuteride
  • 0.0007%±0.00015% ethane
  • Icy volatiles:
    • ammonia
    • water ice
    • ammonium hydrosulfide

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 9 times that of Earth. It has an eighth the average density of Earth, but is over 95 times more massive. 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 9.59 AU (1,434 million km), 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.[27] The outer atmosphere is generally bland and lacking in contrast, although long-lived features can appear. Wind speeds on Saturn can reach 1,800 kilometres per hour (1,100 miles per hour).

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 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.[28]


Cite error: There are <ref group=lower-alpha> tags or {{efn}} templates on this page, but the references will not show without a {{reflist|group=lower-alpha}} template or {{notelist}} template (see the help page).

  1. ^ Cite error: The named reference walter2003 was invoked but never defined (see the help page).
  2. ^ "Saturnian". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
  3. ^ "Enabling Exploration with Small Radioisotope Power Systems" (PDF). NASA. September 2004. Archived from the original (PDF) on 22 December 2016. Retrieved 26 January 2016.
  4. ^ Müller; et al. (2010). "Azimuthal plasma flow in the Kronian magnetosphere". Journal of Geophysical Research. 115 (A8) 2009JA015122: A08203. Bibcode:2010JGRA..115.8203M. doi:10.1029/2009ja015122. ISSN 0148-0227.
  5. ^ "Cronian". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
  6. ^ a b c Cite error: The named reference fact was invoked but never defined (see the help page).
  7. ^ a b "Planetary Physical Parameters". NASA Jet Propulsion Laboratory.
  8. ^ a b c d Cite error: The named reference VSOP87 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Souami_Souchay_2012 was invoked but never defined (see the help page).
  10. ^ "HORIZONS Planet-center Batch call for November 2032 Perihelion". ssd.jpl.nasa.gov (Perihelion for Saturn's planet-center (699) occurs on 2032-Nov-29 at 9.0149170au during a rdot flip from negative to positive). NASA/JPL. Archived from the original on 7 September 2021. Retrieved 7 September 2021.
  11. ^ Cite error: The named reference JPLmoons was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference UBC-20230511 was invoked but never defined (see the help page).
  13. ^ "By the Numbers – Saturn". NASA Solar System Exploration. NASA. 10 November 2017. Archived from the original on 10 May 2018. Retrieved 5 August 2020.
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  15. ^ Fortney, J.J.; Helled, R.; Nettlemann, N.; Stevenson, D.J.; Marley, M.S.; Hubbard, W.B.; Iess, L. (6 December 2018). "The Interior of Saturn". In Baines, K.H.; Flasar, F.M.; Krupp, N.; Stallard, T. (eds.). Saturn in the 21st Century. Cambridge University Press. pp. 44–68. ISBN 978-1-108-68393-7. Archived from the original on 2 May 2020. Retrieved 23 July 2019.
  16. ^ Cite error: The named reference CSeligman was invoked but never defined (see the help page).
  17. ^ McCartney, Gretchen; Wendel, JoAnna (18 January 2019). "Scientists Finally Know What Time It Is on Saturn". NASA. Retrieved 3 January 2025.
  18. ^ Mankovich, Christopher; et al. (17 January 2019). "Cassini Ring Seismology as a Probe of Saturn's Interior. I. Rigid Rotation". The Astrophysical Journal. 871 (1): 1. arXiv:1805.10286. Bibcode:2019ApJ...871....1M. doi:10.3847/1538-4357/aaf798. S2CID 67840660.
  19. ^ a b Archinal, B. A.; Acton, C. H.; A'Hearn, M. F.; Conrad, A.; Consolmagno, G. J.; Duxbury, T.; Hestroffer, D.; Hilton, J. L.; Kirk, R. L.; Klioner, S. A.; McCarthy, D.; Meech, K.; Oberst, J.; Ping, J.; Seidelmann, P. K. (2018). "Report of the IAU Working Group on Cartographic Coordinates and Rotational Elements: 2015". Celestial Mechanics and Dynamical Astronomy. 130 (3): 22. Bibcode:2018CeMDA.130...22A. doi:10.1007/s10569-017-9805-5. ISSN 0923-2958.
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  22. ^ a b "Saturn's Temperature Ranges". Sciencing. 20 April 2018. Archived from the original on 26 May 2021. Retrieved 26 May 2021.
  23. ^ "The Planet Saturn". National Weather Service. Archived from the original on 26 May 2021. Retrieved 26 May 2021.
  24. ^ a b Cite error: The named reference Mallama_and_Hilton was invoked but never defined (see the help page).
  25. ^ "Encyclopedia - the brightest bodies". IMCCE. Retrieved 29 May 2023.
  26. ^ Knecht, Robin (24 October 2005). "On The Atmospheres Of Different Planets" (PDF). Archived from the original (PDF) on 14 October 2017. Retrieved 14 October 2017.
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  28. ^ Munsell, Kirk (6 April 2005). "The Story of Saturn". NASA Jet Propulsion Laboratory; California Institute of Technology. Archived from the original on 16 August 2008. Retrieved 7 July 2007.
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