Tuesday, 9 April 2013

Saturn- The visually unique planet









Named after the Roman God Saturn (Greek God-Cronus), the father of Zeus(Jupiter). Saturn has been known since prehistoric times. Galileo was the first to observe it with a telescope in 1610.








                   Do you know?
Saturn has at least 62 moons, of which 53 have formal names.









     When it is in the nighttime sky, Saturn is easily visible to the unaided eye. Though it is not nearly as bright as Jupiter, it is easy to identify as a planet because it doesn't "twinkle" like the stars do. The rings and the larger satellites are visible with a small astronomical telescope.

     Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is a gas giant with an average radius about nine times that of Earth. While only one-eighth the average density of Earth, with its larger volume Saturn is just over 95 times more massive than Earth.






The image here is, comparing the sizes of Saturn and Earth.














     Saturn has a prominent ring system that consists of nine continuous main rings and three discontinuous arcs, composed mostly of ice particles with a smaller amount of rocky debris and dust. The origin of the rings of Saturn (and the other Jovian planets) is unknown. Though they may have had rings since their formation, the ring systems are not stable and must be regenerated by ongoing processes, perhaps the breakup of larger satellites. The current set of rings may be only a few hundred million years old. 










         Do you know?
A persisting hexagonal wave cloud pattern around the north polar vortex in the atmosphere at about 78°N.


It was first noted in the Voyager images, North polar hexagonal cloud feature, discovered by Voyager 1 and confirmed in 2006 by Cassini.








     Saturn is termed a gas giant, but it is not entirely gaseous. The planet primarily consists of hydrogen, which becomes a non-ideal liquid when the density is above 0.01 g/cm3. This density is reached at a radius containing 99.9% of Saturn's mass. Standard planetary models suggest that the interior of Saturn is similar to that of Jupiter, having a small rocky core surrounded by hydrogen and helium with trace amounts of various volatiles. This core is similar in composition to the Earth, but more dense.

     The outer atmosphere of Saturn contains 96.3% molecular hydrogen and 3.25% helium. It takes approximately 29½ years to make a complete circuit of the ecliptic against the background constellations of the zodiac.









   The image here shows an amateur telescopic view




Most people will require optical aid (large binoculars or a telescope) magnifying at least 20× to clearly resolve Saturn's rings.





      Saturn is 9.53AU, that is, 886 million miles or 1426 million kilometers from Sun. Due to this distance, for a year to complete on Saturn (a complete revolution around Sun) it takes 29.14 earth years or 29 years, 54 days. And, similar to Jupiter, Saturn also rotates on its axis at a faster rate. The length of a day on Saturn is extremely difficult to determine. It is always harder to determine the length of a day of a gas giant than it is to determine the length of a day of a terrestrial planet, but the astronomers can find this to an approximate value of 10 hours, 47 minutes to complete a day. This makes Saturn the second fastest spinning planet in our solar system.






  Few other characteristics of Saturn:

Escape velocity                   :
35.5 km/s
Equatorial rotation velocity : 
9.87 km/s 
Equatorial radius                 : 60 268 km
Axial tilt                                 :
26.73°
Gravitational acceleration
on surface                            : 
10.44 m/s2

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