| AURORA ALERTS:
Did you miss the Northern Lights of June 25th? Next time get
a wake-up call from Space
This summer, NASA engineers will try to realize a dream older than
the Space Age itself--the deployment of a working solar sail in
Earth orbit. NanoSail-D is scheduled for launch onboard a SpaceX
Falcon 1 rocket on July 29, 2008: full
California is on fire. Hundreds
of wildfires in the northern half of the state are filling the
air with smoke
and filling the sky with ... lavender suns? Christopher Calubaquib
saw one on June 26th when he looked through the haze over El Sobrante,
"Because of the smoke, the sun was not very bright,
and I didn't need to use a filter to take the picture," says
Calubaquib. The colors are genuine. A day later, another lavender
sun appeared over Arcata, California: "This
photo was not processed or retouched; it's how the sun really
looked," says photographer Mike Kelly.
What makes the sun lavender? It happens when the air is filled
with particles measuring about 1 micron (10-6 m) across,
a little larger than the wavelength of red light. Micron-sized particles
scatter red light strongly, while letting shades of blue pass through.
The mix of ash over El Sobrante produced a lavender hue, reminiscent
of the great
Alberta muskeg fires of September 1950. Believe it or not, the
same physics can turn the Moon blue, but that is another
Is the smoke wafting through your hometown this weekend? Be alert
for the lavender sun.
WHERE ARE THE CANADIAN
NLCs? Noctilucent cloud (NLC) activity is
intensifying. In the past two weeks, vivid electric-blue waves and
tendrils have been sighted in Russia, Poland, Latvia, Lithuania,
Denmark, Germany, the Czech republic, England, Ireland, Northern
Ireland, Scotland and Wales. Latitudes between 50o and
56o north have been favored with particularly bright
displays. And that raises a question: Where are the Canadian
NLCs? (continued below)
NLCs over Latvia
on June 26th. Photo credit: Aigar Truhin. [gallery]
NLC sightings from the same range of latitudes in Canada have been
conspicuous by their absence. "I look for NLCs every night,
and there haven't been any," reports Ed Steer of Edmonton,
Alberta. "Tonight (June 26th, the date of a big display over
Europe) has perfect viewing conditions and there isn't even a hint
of any around." Only a
pair of photos of a weak display over Calgary on June 27th bucks
NLCs in Canada are either substantially absent or going unnoticed.
One factor at work may be the low population density of Canada compared
to Europe in range of NLC activity. Fewer eyeballs means fewer sightings.
On the other hand, NLCs may be truly avoiding North America. These
clouds and their behavior is unpredictable.
Canadian readers, your observations are needed. Check the photo
gallery for observing tips and be alert for NLCs.
2008 Aurora Gallery
[Aurora Alerts] [Night-sky