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July
29, 2008: On Friday, August 1st, millions of people
in Greenland, Siberia, Mongolia and China—especially China—are
going to witness a total eclipse of the sun. The Moon's cool
shadow will sweep across the landscape, silencing wildlife
with sudden darkness, filling the sky with the sun's ghostly
corona, transforming ordinary folks into life-long eclipse
chasers. Mainstream media gives this sort of thing saturation
coverage.
Totality
is a big event, but its not the only event on August 1st.
Don't forget the partial eclipse!
Right:
A partial eclipse over Texas, photographed June 10, 2002,
by Science@NASA reader David Guerra.
While
millions of people experience totality, billions
will experience a fractional coverage of the sun with many
delights of its own. The partial eclipse can be seen from
about a quarter of Earth's surface, including all of Asia,
most of Europe, the Middle East, India, and the Maine corner
of North America. If you live in one of those areas, get ready
for fun.
The
first thing to remember about a partial eclipse is don't
look at it. Even the tiniest sliver of sun left uncovered
by the Moon can badly hurt your eyes. They don't call it "blinding
sunlight" for nothing.
Instead,
look at the ground.
Beneath
a leafy tree, you might be surprised to find hundreds of crescent-shaped
sunbeams dappling the grass. Overlapping leaves create a myriad
of natural little pinhole cameras, each one casting an image
of the crescent-sun onto the ground beneath the canopy.
Above:
Crescent sunbeams photographed during a partial eclipse in
June 2002. [more]
No
trees? Try this trick: Criss-cross your fingers waffle-style
and let the sun shine through the matrix of holes. You can
cast crescent suns on sidewalks, driveways, friends, cats
and dogs—you name it. This opens up a seldom-tapped well of
possibilities for hand shadows, like the crescent-eyed turkey
shown above.
Unlike
the total eclipse, which lasts no more than a few minutes
while the sun and Moon are perfectly aligned, the partial
eclipse goes on for more than an hour--plenty of time for
shadow play. The fun begins at sunrise in Quebec, mid-morning
in Europe, after lunch in Iraq and late afternoon in India.
Graphic artist Larry Koehn has created five animated maps
that show when to look: North
America, Europe,
Middle
East, India
and Asia.
Above:
An animated eclipse map of Europe created by graphic artist
Larry Koehn. Global and additional regional maps can be found
on his web site ShadowandSubstance.com.
Copyright 2008, all rights reserved.
Of
particular interest is a broad line stretching roughly from
Nova Scotia, through Quebec and diagonally across the Hudson
Bay. There, on Friday morning, August 1st, observers may witness
a fiery crescent rising from the waters of the Bay or the
Atlantic, dimmed to human visibility by low-hanging clouds
and mist. Don't stare. Even "dim suns" are perilous.
At
such a time, the temptation to use a telescope or binoculars
can be powerful. Again, care is required. Sunlight focused
through optics is hot and dangerous to the eyes. Direct viewing
should only be attempted with the aid of a safe solar filter.
(These are found easily enough by typing "solar filter"
or "eclipse glasses" into your favorite search engine.)
Or, to be on the safe side, use the 'scope as a projection
device, shining a bright crescent on a wall or sidewalk for
everyone to see.
When
all is said and done, setting all fun aside, it must be admitted
that there is no substitute for totality. So NASA, in partnership
with UC Berkeley and the Exploratorium, will broadcast the
August 1st eclipse from a remote location in China, deep inside
the path of totality. Tune into NASA TV this Friday at 6 am
EDT for complete
coverage.
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Author: Dr.
Tony Phillips | Credit: Science@NASA
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