A Tetrad of Lunar Eclipses   
       
   March 27, 2014:  For people in the United States, an extraordinary series of   
   lunar eclipses is about to begin.   
       
   The action starts on April 15th when the full Moon passes through the amber   
   shadow of Earth, producing a midnight eclipse visible across North America. So   
   begins a lunar eclipse tetrad-a series of 4 consecutive total eclipses   
   occurring at approximately six month intervals.  The total eclipse of April   
   15, 2014, will be followed by another on Oct. 8, 2014, and another on April 4,   
   2015, and another on Sept. 28 2015.   
       
   "The most unique thing about the 2014-2015 tetrad is that all of them are   
   visible for all or parts of the USA," says longtime NASA eclipse expert Fred   
   Espenak.   
       
   http://www.youtube.com/watch?v=5gzgSuJM5O8   
       
   A new ScienceCast video explains the lunar eclipse tetrad of 2014-2015. Play   
   it!   
       
   On average, lunar eclipses occur about twice a year, but not all of them are   
   total.  There are three types:   
       
   A penumbral eclipse is when the Moon passes through the pale outskirts of   
   Earth's shadow.  It's so subtle, sky watchers often don't notice an eclipse is   
   underway.   
       
   A partial eclipse is more dramatic.  The Moon dips into the core of Earth's   
   shadow, but not all the way, so only a fraction of Moon is darkened.   
       
   A total eclipse, when the entire Moon is shadowed, is best of all.  The face   
   of the Moon turns sunset-red for up to an hour or more as the eclipse slowly   
   unfolds.   
       
   Usually, lunar eclipses come in no particular order. A partial can be followed   
   by a total, followed by a penumbral, and so on.  Anything goes. Occasionally,   
   though, the sequence is more orderly. When four consecutive lunar eclipses are   
   all total, the series is called a tetrad.   
       
   http://preview.tinyurl.com/md5h2na   
       
   Click to view a complete visibility map of the April 15th lunar eclipse.     
   "During the 21st century, there are 9 sets of tetrads, so I would describe   
   tetrads as a frequent occurrence in the current pattern of lunar eclipses,"   
   says Espenak. "But this has not always been the case. During the three hundred   
   year interval from 1600 to 1900, for instance, there were no tetrads at all."   
       
   The April 15th eclipse begins at 2 AM Eastern time when the edge of the Moon   
   first enters the amber core of Earth's shadow.  Totality occurs during a 78   
   minute interval beginning around 3 o'clock in the morning on the east coast,   
   midnight on the west coast.  Weather permitting, the red Moon will be easy to   
   see across the entirety of North America.   
       
   Why red?   
       
   A quick trip to the Moon provides the answer: Imagine yourself standing on a   
   dusty lunar plain looking up at the sky. Overhead hangs Earth, nightside down,   
   completely hiding the sun behind it. The eclipse is underway.   
       
   You might expect Earth seen in this way to be utterly dark, but it's not. The   
   rim of the planet is on fire! As you scan your eye around Earth's   
   circumference, you're seeing every sunrise and every sunset in the world, all   
   of them, all at once. This incredible light beams into the heart of Earth's   
   shadow, filling it with a coppery glow and transforming the Moon into a great   
   red orb.   
       
   Mark your calendar for April 15th and let the tetrad begin.   
       
   More information about the lunar eclipse may be found on NASA's eclipse home   
   page   
       
   Credits:   
   Author: Dr. Tony Phillips | Production editor: Dr. Tony Phillips | Credit:   
   Science@NASA   
       
       
   Regards,   
       
   Roger   
      
   --- D'Bridge 3.99   
    * Origin: NCS BBS - Houma, LoUiSiAna (1:3828/7)