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HARVEST MOON: This
weekend's full Moon (Sept. 14/15) has a special name--the Harvest
Moon. It's the full moon closest to the northern autumnal equinox
(Sept. 22). In years past, farmers depended on the light of the
Harvest Moon to gather ripening crops late into the night. Post-Edison,
we appreciate it mainly for its beauty. Be alert in the nights ahead
for Harvest Moon halos,
coronas
and 'dogs.
MARTIAN DEVILS: Dust
devils are dancing around Phoenix. On Sept. 9th, the Mars lander
photographed no fewer than five red whirlwinds, including this one:
The whirlwind measured about 5 meters in diameter. It was 1 km
from the lander at the start of the movie and 1.7 km away at the
end, two and a half minutes later, putting its speed at greater
than 18 km/h. Phoenix not only saw but also felt the devils; air
pressure around the lander dipped sharply during the flurry, according
to a
NASA report.
So many dust devils in a single day may signal a change in the
weather, perhaps related to the onset
of winter at Phoenix's landing site. "It will be very interesting
to watch over the next days and weeks to see if there are lots of
dust devils or if this was an isolated event," says Phoenix
mission scientist Mark Lemmon of Texas A&M University. Stay
tuned.
KASATOCHI UPDATE:
When a massive cloud of volcanic ash and
sulfur dioxide hits the stratosphere, where does it go next? Click
here for the answer. The movie you just saw, prepared
by atmospheric scientists at the University of Bremen in Germany,
shows how a plume of SO2 from the eruption of Alaska's
Kasatochi volcano swirled, twirled and spread throughout Earth's
northern stratosphere during the month of August 2008. Click on
the image to watch it again:
People lucky enough to look up when the plumes passed by witnessed
spectacular sunsets and sunrises. The display has subsided as the
clouds have disipated--but the show is not over yet. Look carefully
at the last frame
of the movie. Subtle tendrils of ash and sulfate aerosols are still
cross-crossing the stratosphere putting on a nice show for attentive
sky watchers.
Kasatochi continues. Keep an eye on the sunset!
recent photos: from
Vincent Phillips near Liverpool, England; from
Linda Neilsen of Seattle, Washington; from
Matt Champlin of Skaneateles, New York; from
Tomas Trzicky of Prague, Czech Republic; from
Marek Nikodem of Szubin, Poland; from
Doug Zubenel of Cedar Creek, Kansas.
Sept.
2008 Aurora Gallery
[Aurora Alerts] [Night
Sky Cameras]
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