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Saturn

Saturn Astronomical symbol for Saturn
Saturn during Equinox.jpg
Saturn in natural color, photographed by
Cassini in July 2008, approaching equinox. The little white dot in the bottom left corner is Titan.
Designations
Pronunciation Listeni/ˈsætərn/
Adjectives Saturnian, Cronian
Orbital characteristics
Epoch J2000.0
Aphelion 10.086 AU
(1,509 Gm)
Perihelion 9.024 AU
(1,350 Gm)
9.554909 AU
(1,429.39 Gm)
Eccentricity 0.05555
  • 29.4571 yr
  • 10,759.22 d
  • 24,491.07 Saturnian solar days
378.09 days
Average orbital speed
9.69 km/s
317.020°
Inclination
113.665°
339.392°
Known satellites 62 with formal designations; innumerable additional moonlets.
Physical characteristics
Mean radius
58,232±6 km
Equatorial radius
  • 60,268±4 km
  • 9.4492 Earths
Polar radius
  • 54,364±10 km
  • 8.5521 Earths
Flattening 0.09796±0.00018
  • 4.27×1010 km2
  • 83.703 Earths
Volume
  • 8.2713×1014 km3
  • 763.59 Earths
Mass
  • 5.6836×1026 kg
  • 95.159 Earths
Mean density
0.687 g/cm3
(less than water)
0.210
35.5 km/s
Sidereal rotation period
10.55 hours
(10 hr 33 min)
Equatorial rotation velocity
  • 9.87 km/s
  • 35,500 km/h
26.73° (to orbit)
North pole right ascension
  • 2h 42m 21s
  • 40.589°
North pole declination
83.537°
Albedo
Surface temp. min mean max
1 bar level 134 K (−139°C)
0.1 bar 84 K
+1.47 to −0.24
14.5″ to 20.1″
(excludes rings)
Atmosphere
59.5 km
Composition by volume

by volume:

≈ 96% hydrogen (H2)
≈ 3% helium (He)
≈ 0.4% methane (CH4)
≈ 0.01% ammonia (NH3)
≈ 0.01% hydrogen deuteride (HD)
0.0007% ethane (C2H6)
Ices:

by volume:

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. Although it has only one-eighth the average density of Earth, with its larger volume Saturn is just 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 outside the Frenkel line 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 (500 m/s), higher than on Jupiter, but not as high as those on Neptune.


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