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Saturn Saturn symbol.svg
Saturn during Equinox.jpg
Pictured in natural color approaching equinox, photographed by Cassini in July 2008. The dot in the bottom left corner is Titan.
Designations
Pronunciation/ˈsætərn/
Named after
Saturn
AdjectivesSaturnian, Cronian
Orbital characteristics
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
378.09 days
Average orbital speed
9.68 km/s (6.01 mi/s)
317.020°
Inclination
113.665°
339.392°[3]
Known satellites62 with formal designations; innumerable additional moonlets.
Physical characteristics
Mean radius
58,232 km (36,184 mi)
Equatorial radius
  • 60,268 km (37,449 mi)
  • 9.449 Earths
Polar radius
  • 54,364 km (33,780 mi)
  • 8.552 Earths
Flattening0.09796
  • 4.27×1010 km2 (1.65×1010 sq mi)
  • 83.703 Earths
Volume
  • 8.2713×1014 km3 (1.9844×1014 cu mi)
  • 763.59 Earths
Mass
  • 5.6834×1026 kg (1.2530×1027 lb)
  • 95.159 Earths
Mean density
0.687 g/cm3 (0.0248 lb/cu in) (less than water)
0.210 I/MR2 estimate
35.5 km/s (22.1 mi/s)
Sidereal rotation period
10.55 hours
(10 hr 33 min)
Equatorial rotation velocity
9.87 km/s (6.13 mi/s; 35,500 km/h)
26.73° (to orbit)
North pole right ascension
40.589°; 2h 42m 21s
North pole declination
83.537°
Albedo
Surface temp. min mean max
1 bar
134 K (−139 °C)
0.1 bar
84 K (−189 °C)
−0.55 to +1.17
14.5″ to 20.1″ (excludes rings)
Atmosphere
Surface pressure
140 kPa
59.5 km (37.0 mi)
Composition by volumeby 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
2
H
6
)
Ices:

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 about nine times that of Earth. It has only one-eighth the average density of Earth, but with its larger volume Saturn is over 95 times more massive. Saturn is named after the Roman god of agriculture; its astronomical symbol (♄) represents the god's sickle.

Saturn's interior is probably composed of a core of iron–nickel and rock (silicon and oxygen compounds). This core is surrounded by a deep layer of metallic hydrogen, an intermediate layer of liquid hydrogen and liquid helium, and finally a gaseous outer layer. Saturn has a pale yellow hue due to ammonia crystals in its upper atmosphere. Electrical current within 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 due to Saturn's larger size. Saturn's magnetic field strength is around one-twentieth of Jupiter's. The outer atmosphere is generally bland and lacking in contrast, although long-lived features can appear. Wind speeds on Saturn can reach 1,800 km/h (1,100 mph; 500 m/s), higher than on Jupiter, but not as high as those on Neptune.

The planet's most famous feature is its prominent ring system that is composed mostly of ice particles, with a smaller amount of rocky debris and dust. At least 62 moons are known to orbit Saturn, of which 53 are officially named. This does not include the hundreds of moonlets in the rings. Titan, Saturn's largest moon, and the second-largest in the Solar System, is larger than the planet Mercury, although less massive, and is the only moon in the Solar System to have a substantial atmosphere.

Physical characteristics