2016 Ends with Three Supermoons   
       
   Step outside on October 16, and take a look at the moon. Not only will the   
   moon be full, but on that day, the moon will be at it's closest point to our   
   planet as it orbits Earth. This makes the October full moon a supermoon.   
       
   The term supermoon has entered popular consciousness in recent years.   
   Originally a term from modern astrology for a new or full moon that occurs   
   with the moon is within 90% of its closest approach to Earth in a given orbit,   
   supermoon now refers more broadly to a full moon that is closer to Earth than   
   average. But why is the moon closer to Earth at some times but not others?   
       
   http://tinyurl.com/gqftfrr   
       
   Since the moon's orbit is elliptical, one side (perigee) is about 30,000 miles   
   closer to Earth than the other (apogee). The word syzygy, in addition to being   
   useful in word games, is the scientific name for when the Earth, sun, and moon   
   line up as the moon orbits Earth. When perigee-syzygy of the Earth-moon-sun   
   system occurs and the moon is on the opposite side of the Earth from the sun,   
   we get a perigee moon or more commonly, a supermoon!   
       
   This coincidence happens three times in 2016. On October 16 and December 14,   
   the moon becomes full on the same day as perigee. On November 14, it becomes   
   full within about two hours of perigee-arguably making it an extra-super moon.   
       
   The full moon of November 14 is not only the closest full moon of 2016 but   
   also the closest full moon to date in the 21st century. The full moon won't   
   come this close to Earth again until November 25, 2034.   
       
   The supermoon of December 14 is remarkable for a different reason: it's going   
   to wipe out the view of the Geminid meteor shower. Bright moonlight will   
   reduce the visibility of faint meteors five to ten fold, transforming the   
   usually fantastic Geminids into an astronomical footnote. Sky watchers will be   
   lucky to see a dozen Geminids per hour when the shower peaks. Oh well, at   
   least the moon will be remarkable.   
       
   How remarkable?   
       
   A supermoon, or perigee full moon can be as much as 14% bigger and 30%   
   brighter than an apogee full moon. However it's not always easy to tell the   
   difference. A 30% difference in brightness can easily be masked by clouds or   
   the competing glare of urban lights. Also, there are no rulers floating in the   
   sky to measure lunar diameters. Hanging high overhead with no reference points   
   to provide a sense of scale, one full moon looks much like any other.   
       
   Low-hanging moons, on the other hand, can create what's called a "moon   
   illusion." When the moon is near the horizon it can look unnaturally large   
   when viewed through trees, buildings, or other foreground objects. The effect   
   is an optical illusion, but that fact doesn't take away from the experience.   
       
   A supermoon is undeniably beautiful. And we can multiply that beauty by three   
   as 2016 comes to a close.   
       
   October 16, November 14, and December 14: mark your calendar and enjoy the   
   super moonlight.   
       
   For more on beautiful views in the night's sky, stay tuned to science.nasa.gov.   
       
       
   Regards,   
       
   Roger   
      
   --- DB 3.99 + W10 (1607)   
    * Origin: NCS BBS - Houma, LoUiSiAna (1:3828/7)