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ATMOSPHERIC OPTICS
EXHIBITION: The Boyden Gallery of St.Mary's
College in Maryland is planning a major exhibition of atmospheric
optics photos during the summer of 2010. Got images? The deadline
for submissions is Nov. 30, 2009. Atmospheric optics expert
Les Cowley has the full
story.
PHOTOGRAPHIC AURORAS:
On Sunday, Nov. 8th, a minor solar wind stream
buffeted Earth's magnetic field, spawning a subtle display
of Northern Lights. "To the naked eye, the auroras were
barely visible," says Helge Mortensen of Kvaløya, Norway.
"But a 30-second exposure with my digital camera revealed
a lovely green band cutting across the sky."
This kind of aurora borealis--visible to the camera but not
to the eye--is called a "photographic aurora." The
phenomenon is more common and widespread than you might think.
In July, for instance, amateur astronomer Howard Edin recorded
photographic auroras at a star party in Valentine, Nebraska:
photo.
That's pretty far south for "Northern Lights." The
key, says Edin, was exposing the
scene for a full 30 seconds--the same exposure time Mortensen
used in Norway two nights ago.
Astrophotographers should be
alert for geomagnetic activity. The next time the solar
wind gusts, a great photo could be just half-a-minute away.
SUNSET FIREBALL:
If only photographers had faster reflexes.... On Saturday,
Nov. 7th, around 5 p.m. Pacific time, a brilliant fireball
raced4 across the sky of California's San Francisco Bay, where
tens of thousands of people saw it. So far, however, not a
single photo of the fireball has emerged. The meteor disappeared
into the sunset before anyone could raise his or her camera.
When shutters finally started clicking, all that remained
was a trail of debris:
"Pepper Dela Cruz took this picture outside the Miramar
Restaurant in Half Moon Bay on the San Francisco Peninsula
just as the sun was setting," says Doug Moore, who submitted
the photo on Pepper's behalf. "It shows debris from the
fireball, which lasted for several minutes before dissipating."
The origin of the fireball is still uncertain. Meteor expert
Peter Jenniskens of NASA's Ames Research Center believes it
was "a small, random asteroid that crashed into our atmosphere.
The remains [of the space rock] probably landed in the Pacific
Ocean," he says.
More fireballs are in the offing. Earth is passing through
a stream of debris from Comet 2P/Encke, and this is causing
the annual Taurid meteor shower, which peaks between now and
Nov. 12th. The shower only produces about 5 meteors per hour,
but what the display lacks in number, it makes up for in dazzle.
Taurids
tend to be fireballs, slow and very bright. The best time
to look is during the hours around midnight when the constellation
Taurus is high overhead: sky
map.
Note: Based on the time of day and other factors, Jenniskens
says "the Bay Area fireball was probably not a Taurid."
October
Northern Lights Gallery
[previous Octobers: 2008,
2007, 2006,
2004, 2003,
2002, 2001]
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