The 2016 Transit of Mercury   
       
   May 3, 2016:  Solar Scientists are accustomed to seeing spots on the   
   sun--irregular islands of magnetism that sometimes erupt, producing strong   
   solar flares.   
       
   On May 9, 2016, they will see a spot of a very different kind--a dark circle   
   moving across the solar disk.   
       
   This spot is no ordinary sunspot. It's the planet Mercury, making a rare   
   transit of the sun.   
       
   Mercury passes directly between the sun and Earth about 13 times every   
   century. The last time it happened was ten years ago in 2006, and the next   
   time will be Nov. 11, 2019.   
       
   This year's transit will be widely visible from most of Earth, including the   
   Americas, the Atlantic and Pacific Oceans, Europe, Africa and much of Asia.   
       
   https://www.youtube.com/watch?v=wbkrlHDKvgE   
       
   In the USA it begins on the morning of Monday, May 9, around 7:15 AM EDT. This   
   means it begins before sunrise on the west coast, but that's no problem. The   
   transit lasts for more than seven hours, so Mercury will still be gliding   
   across the solar disk when the sun comes up over places like California and   
   Alaska. Everyone in the USA can experience the event.   
       
   Caution: Take care when viewing the transit. Mercury's tiny disk-jet black and   
   perfectly round-covers only a tiny fraction of the sun's blinding surface.   
   Looking at the sun with unprotected eyes on May 9 is as dangerous as ever.   
       
   With a proper filter, however, viewing the transit of Mercury can be a   
   marvelous experience. A telescope with a safe solar filter will be required to   
   see the tiny disk of Mercury crawling across the face of the sun. Mercury is   
   too small to be seen without magnification.   
       
   You may wish to call your local astronomy club and ask if they have a solar   
   telescope. Amateur astronomers love to show off the heavens. The event will   
   provide volunteers the opportunity to bring their 'scopes to classrooms for   
   the transit.   
       
   If you can't find access to a good telescope, NASA's Solar Dynamics   
   Observatory will also witness the entire transit and make it available in real   
   time on its website.   
       
   NASA scientist Rosemary Killen and colleagues plan to use the transit to study   
   Mercury's ultra-thin atmosphere or exosphere. The atoms in Mercury's exosphere   
   come from the surface of Mercury itself. They are blasted into space by solar   
   radiation, solar wind bombardment and meteoroids. This gives Mercury a   
   comet-like tail stretched out as long as 1.2 million miles. You cannot see   
   this tail during the transit, however.   
       
   Killen says, "When Mercury is in front of the sun, we can study the exosphere   
   close to the planet. Sodium in the exosphere absorbs and re-emits a   
   yellow-orange color from sunlight, and by measuring that absorption we can   
   learn about the density of gas there."   
       
   She says, "We will be observing the transit from the National Solar   
   Observatory, or NSO, in Sunspot, New Mexico." Killen, Carl Schmidt of LATMOS   
   at the French National Research Agency, and Kevin Reardon of the NSO will be   
   on site making observations.   
       
   The Transit of Mercury offers something to professional astronomers and   
   backyard sky watchers alike-from scientific discovery to simple wonder. Mark   
   your calendar for May 9 and enjoy the show.   
       
   For more news about rare events in the heavens, stay tuned to science.nasa.gov.   
       
   See more coverage of the 2016 transit of Mercury at http://mercu   
   ytransit.gsfc.nasa.gov   
       
       
   Regards,   
       
   Roger   
      
   --- DB 3.99 + Windows 10   
    * Origin: NCS BBS - Houma, LoUiSiAna (1:3828/7)