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

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 * Origin: NCS BBS - Houma, LoUiSiAna (1:3828/7)