THE SOUTHWORTH PLANETARIUM
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43.6667° N                   70.2667° W
Founded January 1970
Julian date:  2457770.16

              "Life isn't about finding yourself.   Life is about creating yourself."

                            -George Bernard Shaw

THE DAILY ASTRONOMER

Wednesday, January 18, 2017

The Other Pandora

Behold Pandora

PANDORA     Image: NASA

No, this is not the troubled woman who inadvertently released the world's ills.  Nor is is it the mysterious vessel tucked away within the planetarium's star dome shadows.  Instead, this Pandora is one of the many moons that revolve around the planet Saturn.     As of the latest count, sixty two satellites revolve around the sixth world.     That places it second on the list of planets with the greatest number of known moons    Jupiter is second with 67.    (Refer to yesterday's DA  "Extra Terrestrial Solar Eclipses.")   

In December 2016, the Cassini Spacecraft passed to within 25,000 miles of Pandora, approximately equal to one-tenth the distance separating Earth and its one moon.   During this close approach, Cassini captured the clearest photo ever taken of this , highly battered  little world.      The image scale is 787 feet per pixel, a considerable improvement over the 1000 foot/pixel image Cassini captured in 2005.  Despite the higher resolution, this picture of Pandora is reminiscent of thumb indented clay.    

With a diameter extending only 52 miles, Pandora is negligibly small, even by gas planet satellite standards.     It is so small, in fact, that it went undiscovered until Voyager 1 first spotted it in October 1980.         For five years following its discovery, Pandora was known simply -and unromantically  as S/1980 S 26.   Only in 1985 did the International Astronomical Union assign it the name "Pandora."       Ironically,, this moon was once thought to have been a shepherd moon, one whose gravitational influence helps to keep Saturn's outer rings in alignment.      After all, Pandora orbits just outside of Saturn's comparatively tenuous F -ring.      Subsequent observations demonstrated that Pandora was not a shepherd moon, but just happened to be close to the rings.

​Pandora.   A rather grainy image captured by Voyager 2 in August 1981.

Image:NASA

We can expect Cassini to capture many more such images as it begins a long death spiral through the rings en route to Saturn's upper atmosphere.      On September 15, 2017, the Cassini probe will plunge into the planet it has been closely studying since its July 2004 orbital insertion.       Over the next few months, we'll re visit this probe now and then to admire the worlds its viewing for one last time during its Saturnian swan song.