Colorful Lunar Eclipse
 
Sept. 18, 2014:  On Wednesday morning, Oct. 8th, not long before sunrise,
the bright full Moon over North America will turn a lovely shade of
celestial red.  It's a lunar eclipse-visible from all parts of the USA.
 
"It promises to be a stunning sight, even from the most light polluted
cities," says NASA's longtime eclipse expert Fred Espenak. "I
encourage everyone, especially families with curious children, to go out
and enjoy the event."
 
 http://www.youtube.com/watch?v=wmCK2Pfsh0Y&feature=youtu.be
 
A new ScienceCast video examines the red and turquoise colors sky watchers
can expect to see during the Oct. 8, 2014, total lunar eclipse. Play it
 
From the east coast of North America, totality begins at 6:25 am EDT.  The
Moon will be hanging low over the western horizon, probably swollen by the
famous Moon illusion into a seemingly-giant red orb, briefly visible before
daybreak. West-coast observers are even better positioned. The Moon will be
high in the sky as totality slowly plays out between 3:25 am and 4:24 am
PDT.  
During a lunar eclipse, the Moon passes deep inside the shadow of our
planet, a location that bathes the the face of the Moon in a coppery light.
 
A quick trip to the Moon explains the color: 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.
 
However, red is not the only color.  Many observers of lunar eclipses also
report seeing a band of turquoise.
 
http://eclipse.gsfc.nasa.gov/OH/OHfigures/OH2014-Fig03.pdf
 
Click to see a worldwide eclipse visibility map
 
The source of the turquoise is ozone. Atmospheric scientist Richard Keen of
the University of Colorado explains: "During a lunar eclipse, most of
the light illuminating the moon passes through the stratosphere where it is
reddened by scattering. However, light passing through the upper
stratosphere penetrates the ozone layer, which absorbs red light and
actually makes the passing light ray bluer." This can be seen, he
says, as a soft blue fringe around the red core of Earth's shadow.
 
To catch the turquoise on Oct. 8th, he advises, "look during the first
and last minutes of totality. The turquoise rim is best seen in binoculars
or a small telescope."
 
The depth and hue of lunar eclipse colors depends a lot on the dustiness of
the stratosphere.  When volcanoes erupt and chock the stratosphere with
aerosols, lunar eclipses can turn such a deep red that the Moon looks
almost black.  That's not the case this time, however:
 
"Despite some recent eruptions that look spectacular from the ground,
there have been no large injections of volcanic gases into the
stratosphere," says Keen. "In the absence of volcanic effects, I
expect a rather normal reddish-orange lunar eclipse similar in appearance
to last April's eclipse."
 
In other words, this is going to be good.
 
Espenak notes that "the total lunar eclipse of Oct. 8 is the second of
four consecutive total lunar eclipses. Such a set of total eclipses is
known as a tetrad." The next eclipse in the tetrad is six months from
now, in April 2015.
 
"Don't wait," he urges. Mark your calendar for October 8th, wake
up early, and enjoy the show.
 
Credits:
Author: Dr. Tony Phillips |  Production editor: Dr. Tony Phillips | Credit:
Science{at}NASA
 
More information:
 
NASA's Eclipse home page
 
 
Regards,
 
Roger

--- D'Bridge 3.99