Saturn (planet)

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Saturn as the sixth planet from the sun in the solar system has been known since ancient times and makes it perhaps the last well known and obvious planets during those ancient times.  

Once telescopes were developed it was noticed to have a rather unusual appearance, as if it had ears, then realised later that it was a set of enormous rings in orbit around it. Hence the nick name "The ringed planet"

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Image of Saturn from the Cassini -Huygens space craft. image: JPL/NASA

Orbit basics:

  • Distance from sun: between 1,353, 572, 956 and 1, 513, 325, 783 km 
  • Orbital period (it's year):  29.447498 years
  • Moons (Natural Satellites): Saturn has 62 known moons, 53 of which have formal names. In addition, there is evidence of dozens to hundreds of moonlets with diameters of 40–500 meters in Saturn's rings.
    • The largest is Titan,  then further discovered Mimas and Enceladus followed by  Hyperion (1848) and Phoebe (1898).


  • Rings: 
    • The rings extend from 6,630 km to 120,700 km outward from Saturn's equator, average approximately 20 meters in thickness 


PIA17172_Saturn_eclipse_mosaic_bright_crop

The full set of rings, imaged as Saturn eclipsed the Sun from the vantage of the Cassini orbiter, 1.2 Million km distant, on 19 July 2013 (brightness is exaggerated). Earth appears as a dot at 4 o'clock, between the G and E rings. image: NASA/JPL


  • composed of 93% water ice with traces of tholin impurities and 7% amorphous carbon.
  • Origin of the rings. 
    • One hypothesis is that the rings are remnants of a destroyed moon of Saturn. 
    • The second hypothesis is that the rings are left over from the original nebular material from which Saturn formed. 
    • Some ice in the E ring comes from the moon Enceladus's geysers


Planet basics:

  • Type of planet: Gaseous giant
  • Length of day: 10h 39m 22.4s
  • Average radius: 60,268±4 km
  • Mass: 5.68319 x 1026 kg
  • Gravity near cloud tops at equator: 10.44 m/s2  1.06458 g
  • Temperature of cloud tops: -139.15°C (134±4 K), also quoted as -178 °C
  • Atmosphere: Thickness varies with depth to core, extreme wind speeds and planetary scale cyclonic storms.
  • Pressure: varies according to depth to core.
  • Atmospheric composition: 
    • Hydrogen H2
    • Helium He
    • Traces of ammonia, ethane, methane, propane (traces here means actually quite a lot compared with Earth given the size of the planet)



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