Solar System / Saturn
 Saturn
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Saturn

Object Description:    (Object description credit, with thanks, goes to: www.seds.org)

Saturn is the sixth planet from the Sun and is the second largest:

   orbit:    1,429,400,000 km (9.54 AU) from Sun
   diameter: 120,536 km (equatorial)
   mass:     5.68e26 kg

In Roman mythology, Saturn is the god of agriculture. The associated Greek god, Cronus, was the son of Uranus and Gaia and the father of Zeus (Jupiter). Saturn is the root of the English word "Saturday".
Saturn has been known since prehistoric times.  Galileo was the first to observe it with a telescope in 1610; he noted its odd appearance but was confused by it.  Early observations of Saturn were complicated by the fact that the Earth passes through the plane of Saturn's rings every few years as Saturn moves in its orbit. A low resolution image of Saturn therefore changes drastically.  It was not until 1659 that Christiaan Huygens correctly inferred the geometry of the rings.  Saturn's rings remained unique in the known solar system until 1977 when very faint rings were discovered around Uranus (and shortly thereafter around Jupiter and Neptune).

Saturn is visibly flattened (oblate) when viewed through a small telescope; its equatorial and polar diameters vary by almost 10% (120,536 km vs. 108,728 km). This is the result of its rapid rotation and fluid state. The other gas planets are also oblate, but not so much so.

Saturn is the least dense of the planets; its specific gravity (0.7) is less than that of water.

Saturn's interior is hot (12,000 K at the core) and Saturn radiates more energy into space than it receives from the Sun. Most of the extra energy is generated by the Kelvin-Helmholtz mechanism as in Jupiter.  But this may not be sufficient to explain Saturn's luminosity; some additional mechanism may be at work, perhaps the "raining out" of helium deep in Saturn's interior.

Saturn's Rings:

                  Radius   Radius             approx.   approx.
Name               inner    outer     width  position  mass (kg)
----              ------   ------     -----  --------  --------
D-Ring            67,000   74,500     7,500    (ring)
Guerin Division  
C-Ring            74,500   92,000    17,500    (ring)  1.1e18
Maxwell Division  87,500   88,000       500  (divide)
B-Ring            92,000  117,500    25,500    (ring)  2.8e19
Cassini Division 115,800  120,600     4,800  (divide)
Huygens Gap      117,680    (n/a)   285-440  (subdiv)
A-Ring           122,200  136,800    14,600    (ring)  6.2e18
Encke Minima     126,430  129,940     3,500   29%-53%
Encke Division   133,410  133,740
Keeler Gap       136,510  136,550
F-Ring           140,210             30-500   (ring)
G-Ring           165,800  173,800     8,000    (ring)  1e7?
E-Ring           180,000  480,000   300,000    (ring)

Notes:
  * distance is kilometers from Saturn's center
  * the "Encke Minima" is a slang term used by amateur astronomers, not an official IAU designation

This categorization is actually somewhat misleading as the density of particles varies in a complex way not indicated by a division into neat regions: there are variations within the rings; the gaps are not entirely empty; the rings are not perfectly circular.

Two prominent rings (A and B) and one faint ring (C) can be seen from the Earth. The gap between the A and B rings is known as the Cassini division. The much fainter gap in the outer part of the A ring is known as the Encke Division (but this is somewhat of a misnomer since it was very likely never seen by Encke).

Though they look continuous from the Earth, the rings are actually composed of innumerable small particles each in an independent orbit. They range in size from a centimeter or so to several meters. A few kilometer-sized objects are also likely.

Saturn's rings are extraordinarily thin: though they're 250,000 km or more in diameter they're less than one kilometer thick.  Despite their impressive appearance, there's really very little material in the rings -- if the rings were compressed into a single body it would be no more than 100 km across.  The ring particles seem to be composed primarily of water ice, but they may also include rocky particles with icy coatings.

Saturn's Satellites:

           Distance  Radius    Mass
Satellite  (000 km)   (km)     (kg)   Discoverer   Date
---------  --------  ------  -------  ----------  -----
Pan             134      10     ?     Showalter    1990
Atlas           138      14     ?     Terrile      1980
Prometheus      139      46  2.70e17  Collins      1980
Pandora         142      46  2.20e17  Collins      1980
Epimetheus      151      57  5.60e17  Walker       1980
Janus           151      89  2.01e18  Dollfus      1966
Mimas           186     196  3.80e19  Herschel     1789
Enceladus       238     260  8.40e19  Herschel     1789
Tethys          295     530  7.55e20  Cassini      1684
Telesto         295      15     ?     Reitsema     1980
Calypso         295      13     ?     Pascu        1980
Dione           377     560  1.05e21  Cassini      1684
Helene          377      16     ?     Laques       1980
Rhea            527     765  2.49e21  Cassini      1672
Titan          1222    2575  1.35e23  Huygens      1655
Hyperion       1481     143  1.77e19  Bond         1848
Iapetus        3561     730  1.88e21  Cassini      1671
Phoebe        12952     110  4.00e18  Pickering    1898

Equipment & Exposure:
- Televue NP-127 (F 5.2)
- Televue PowerMate 5x (F 26 effective)
- TAK NJP Mount- Philips ToUcam Pro II (webcam)
- Avi format
- 1800 frames
- Taken 4/13/05

Processing Details:
Registax:
- Avi frames aligned and registered, result saved as TIF
Photoshop-CS:
- Sharpening with NIK Sharpener Pro
- Noise reduction in NeatImage
- Manual gradient removal
- Separate tuning of the three color layers
- Final leves, curves