Solar Eclipse over the USA   
       
   Jan. 27, 2012: Mark your calendar.  On Sunday, May 20th, the sun is going to   
   turn into a ring of fire.  It's an annular solar eclipse--the first one in the   
   USA in almost 18 years.   
       
   An annular eclipse occurs when the Moon passes directly in front of the sun,   
   but the lunar disk is not quite wide enough to cover the entire star.  At   
   maximum, the Moon forms a "black hole" in the center of the sun.   
       
   http://apod.nasa.gov/apod/ap090125.html   
       
   "The ring of fire:" Astrophotographer Dennis L. Mammana photographed this   
   annular eclipse behind palm trees in January 1994. Copyright D. L. Mammana.   
   [more] [video]   
       
   The "path of annularity" is a strip about 300 km wide and thousands of km   
   long. It stretches from China and Japan, across the Pacific Ocean, to the   
   middle of North America.  In the United States, the afternoon sun will become   
   a luminous ring in places such as Medford, Oregon; Chico, California; Reno,   
   Nevada; St. George, Utah; Albuquerque, New Mexico, and Lubbock, Texas.   
       
   Outside of this relatively narrow zone, the eclipse will be partial. Observers   
   almost everywhere west of the Mississippi will see a crescent-shaped sun as   
   the Moon passes by off-center.   
       
   "I like to compare different types of eclipses on a scale of 1 to 10 as visual   
   spectacles," says NASA's leading eclipse expert, Fred Espenak of the Goddard   
   Space Flight Center. "If a partial eclipse is a 5 then an annular eclipse is a   
   9."   
       
   This event should not be confused with a total eclipse.  In a total eclipse,   
   the Moon covers the entire surface of the sun, bringing an eerie twilight to   
   observers in the path of totality and revealing the sun's ghostly corona.   
       
   "On that scale of 1 to 10," he adds, "a total eclipse is 'a million!' It's   
   completely off the charts compared to any other astronomical event." The next   
   total eclipse in the USA is in the year 2017.   
       
   Until then, May 20th of this year will have to do.   
       
   Annular eclipses have a special charm all their own. During an annular   
   eclipse, sunbeams turn into little rings of light.  The best place to see this   
   is on the sun-dappled ground beneath a leafy tree. Hundreds of circular   
   shadows can be found there.   
       
   You can also make a handy solar projector by criss-crossing your fingers   
   waffle-style. Rays of light beaming through the gaps will have the same shape   
   as the eclipsed sun.   
       
   http://www.youtube.com/watch?v=7YX2blo1eRk   
       
   The path of annularity cuts across the continental United States at sunset on   
   May 20, 2012. A global map is also available: click here.See also the   
   ScienceCast video.   
       
   Be careful when looking directly at the eclipsed sun, cautions Espenak. "The   
   ring of sunlight during annularity is blindingly bright.  Even though as much   
   as 94% of the Sun's disk will be covered, you still need to use a solar filter   
   or some type of projection technique. A #14 welder's glass is a good choice.   
   There are also many commercially-available solar filters."   
       
   "One of the unique things about this eclipse for watchers in the USA is that   
   the Sun will still be in deep partial eclipse at sunset, making for some great   
   photographic opportunities," he continues. "In western Texas around Lubbock,   
   the sun actually sets during the annular phase."   
       
   A swollen red sun with a black hole in the middle?  Maybe 9 out of 10 isn't so   
   bad, after all.   
       
   For more information about this eclipse, including maps and timetables, please   
   visit eclipse.gsfc.nasa.gov.   
       
       
   Author:Dr. Tony Phillips| Production editor: Dr. Tony Phillips | Credit:   
   Science@NASA   
       
   More Information   
   Solar Eclipse over the USA -- ScienceCast video   
       
   NASA's Solar Eclipse Home Page   
       
   Maps and Timetables for the May 20th annular eclipse   
       
   Annular eclipse photo gallery --- from spaceweather.com   
       
       
   Regards,   
       
   Roger   
      
   --- D'Bridge 3.73   
    * Origin: NCS BBS (1:3828/7)