Saturn

Saturn

Pictured in natural color approaching equinox, photographed by Cassini in July 2008; the dot in the bottom left corner is Titan
Designations
Pronunciation	/ˈsætərn/ (listen)[1]
Named after	Saturn
Adjectives	Saturnian /səˈtɜːrniən/,[2] Cronian[3] / Kronian[4] /ˈkroʊniən/[5]
Orbital characteristics[10]
Epoch J2000.0
Aphelion	1,514.50 million km (10.1238 AU)
Perihelion	1,352.55 million km (9.0412 AU)
Semi-major axis	1,433.53 million km (9.5826 AU)
Eccentricity	0.0565
Orbital period	29.4571 yr 10,759.22 d 24,491.07 Saturnian solar days[6]
Synodic period	378.09 days
Average orbital speed	9.68 km/s (6.01 mi/s)
Mean anomaly	317.020°[7]
Inclination	2.485° to ecliptic[7] 5.51° to Sun's equator[7] 0.93° to invariable plane[8]
Longitude of ascending node	113.665°
Time of periastron	2032-Nov-29[9]
Argument of perihelion	339.392°[7]
Known satellites	145 in total moonlets.[10]
Physical characteristics[10]
Mean radius	58,232 km (36,184 mi)[a]
Equatorial radius	60,268 km (37,449 mi)[a] 9.449 Earths
Polar radius	54,364 km (33,780 mi)[a] 8.552 Earths
Flattening	0.09796
Circumference	365882.4 km equatorial (227348.8 mi)[11]
Surface area	4.27×1010 km2 (1.65×1010 sq mi)[12][a] 83.703 Earths
Volume	8.2713×1014 km3 (1.9844×1014 cu mi)[a] 763.59 Earths
Mass	5.6834×1026 kg 95.159 Earths
Mean density	0.687 g/cm3 (0.0248 lb/cu in)[b] (less than water)
Surface gravity	10.44 m/s2 (34.3 ft/s2)[a] 1.065 g
Moment of inertia factor	0.22[13]
Escape velocity	35.5 km/s (22.1 mi/s)[a]
Rotation period	10 h 32 m 36 s (synodic; solar day)[6]
Sidereal rotation period	10h 33m 38s + 1m 52s − 1m 19s [14][15]
Equatorial rotation velocity	9.87 km/s (6.13 mi/s; 35,500 km/h)[a]
Axial tilt	26.73° (to orbit)
North pole right ascension	40.589°;  2h 42m 21s
North pole declination	83.537°
Albedo	0.342 (Bond)[16] 0.499 (geometric)[17]
Surface temp. min mean max 1 bar 134 K 0.1 bar 88 K[19] 97 K[20] 151 K[19]
Apparent magnitude	−0.55[18] to +1.17[18]
Angular diameter	14.5″ to 20.1″ (excludes rings)
Atmosphere[10]
Surface pressure	140 kPa[21]
Scale height	59.5 km (37.0 mi)
Composition by volume	96.3%±2.4% hydrogen (H 2) 3.25%±2.4% helium (He) 0.45%±0.2% methane (CH 4) 0.0125%±0.0075% ammonia (NH 3) 0.0110%±0.0058% hydrogen deuteride (HD) 0.0007%±0.00015% ethane (C 2H 6) Ices: ammonia (NH 3) water (H 2O) ammonium hydrosulfide (NH 4SH)

Saturn is the sixth planet from the Sun in the Solar System. Saturn takes about 29.5 Earth years to complete one orbit around the Sun. A day on Saturn is much shorter than an Earth day, lasting only about 10.7 hours. This means that Saturn spins much faster than Earth, completing more than two rotations in the same time it takes Earth to complete just one. ^[22]

Saturn is one of the four gas giant planets in the Solar System, with Jupiter, Uranus, and Neptune. It is the second largest planet in the Solar System (Jupiter is the largest).^[23]

Saturn was named after the Roman god Saturn. He was the Roman equivalent of the Greek god Kronos.^[24] Saturn's symbol is ♄ which is the symbol of Saturnus' sickle.^[25]

Inside Saturn is probably a core of iron, nickel, silicon and oxygen compounds, surrounded by a deep layer of metallic hydrogen, then a layer of liquid hydrogen and liquid helium and finally, an outer gaseous layer.^[26]

Saturn has 146 known moons orbiting the planet.^[27] The largest moon is Titan. Titan is larger in volume than the planet Mercury. It is the second-largest moon in the Solar System. The largest moon is a moon of Jupiter, Ganymede. There are also many rings around Saturn. These rings are made of ice with some rocks and dust. Some people think that that the rings were made by a moon impact or other event. Saturn is about 1,433,000,000 km (870,000,000 mi) on average from the Sun. Saturn takes 29.4 Earth years in order to complete a revolution around the Sun.^[28]

1. ↑ Cite error: The named reference walter2003 was used but no text was provided for refs named (see the help page).
2. ↑ "Saturnian". Oxford English Dictionary. Oxford University Press. 2nd ed. 1989.
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): A08203. Bibcode:2010JGRA..115.8203M. doi:10.1029/2009ja015122. ISSN 0148-0227.
5. ↑ "Cronian". Oxford English Dictionary. Oxford University Press. 2nd ed. 1989.
6. ↑ ^{6.0 6.1} Cite error: The named reference CSeligman was used but no text was provided for refs named (see the help page).
7. ↑ ^{7.0 7.1 7.2 7.3} Cite error: The named reference VSOP87 was used but no text was provided for refs named (see the help page).
8. ↑ Cite error: The named reference Souami_Souchay_2012 was used but no text was provided for refs named (see the help page).
9. ↑ "HORIZONS Web-Interface". ssd.jpl.nasa.gov.
10. ↑ ^{10.0 10.1 10.2 10.3} Cite error: The named reference fact was used but no text was provided for refs named (see the help page).
11. ↑ "By the Numbers – Saturn". NASA Solar System Exploration. NASA. Retrieved 5 August 2020.
12. ↑ Cite error: The named reference nasafact was used but no text was provided for refs named (see the help page).
13. ↑ 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.
14. ↑ McCartney, Gretchen; Wendel, JoAnna (18 January 2019). "Scientists Finally Know What Time It Is on Saturn". NASA. Archived from the original on 29 August 2019. Retrieved 18 January 2019.
15. ↑ 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.
16. ↑ Cite error: The named reference Hanel_et_al was used but no text was provided for refs named (see the help page).
17. ↑ Cite error: The named reference Mallama_et_al was used but no text was provided for refs named (see the help page).
18. ↑ ^{18.0 18.1} Cite error: The named reference Mallama_and_Hilton was used but no text was provided for refs named (see the help page).
19. ↑ ^{19.0 19.1} "Saturn's Temperature Ranges". Sciencing.
20. ↑ "The Planet Saturn". National Weather Service.
21. ↑ 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.
22. ↑ "Saturn: Facts - NASA Science". science.nasa.gov. Retrieved 2024-07-08.
23. ↑ "Saturn: Facts". NASA. Retrieved 9 November 2023.
24. ↑ "Cronia (Kronia)". Holidays, Festivals, and Celebrations of the World Dictionary. 2010. Retrieved July 11, 2011.
25. ↑ Crystal, Ellie. "Saturn Mythology". Crystalinks.com. Retrieved February 28, 2007.
26. ↑ Brainerd, Jerome James 2004. "Giant gaseous planets". The Astrophysics Spectator. Retrieved July 5, 2010.{{cite web}}: CS1 maint: numeric names: authors list (link)
27. ↑ "Planetary Satellite Discovery Circumstances". NASA. Retrieved December 28, 2019.
28. ↑ "Saturn: Facts - NASA Science". science.nasa.gov. Retrieved 2024-01-11.