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THE MYSTERY OF PHOBOS:
Something is wrong with Phobos.
The martian moon looks like a solid, but it is not as dense
as a rocky solid should be. Some researchers think Phobos
might be riddled with vast caverns; others say it is just
a "rubble pile" masquerading as a solid body. To
solve the
mystery, Europe's Mars Express spacecraft is making a
series of close Phobos-flybys this month. March
10th update: According to gravity-field data
just beamed back from Mars Express, mass is not evenly
distributed throughout the moon’s interior. A detailed analysis
is underway by ESA researchers. Stay
tuned!
SOLAR ERUPTION:
Magnetic fields around the corpse of old sunspot 1045 erupted
this morning, March 10th, at 0745 UT. SOHO's extreme ultraviolet
telescope recorded the action, which you can see by clicking
on the image below:
The eruption did not produce a lot of X-rays
(the corresponding flare registered only B1),
but it did hurl a billion-ton coronal mass ejection (CME)
into space. The cloud is not aimed directly at Earth, but
it could deliver a glancing blow to our planet's magnetic
field on or about March 13th. High-latitude sky watchers should
be alert for auroras around that date.
IDITAROD SKIES: This
week, hundreds of the world's finest athletes are racing 1,150+
miles across some of most extreme and beautiful terrain in
the world--the Iditarod trail of Alaska. If any of those
sled dogs raise their blue eyes to the sky, they might
see something like this:
Daryl Peterson took the picture on March 21,
2009. "I went to Nome last year to shoot the finish of
the Iditarod," he recalls. "During the race you
can almost bank on seeing some Northern Lights, even when
solar activity is low."
He's right. On average, March is the most geomagnetically
active month of the year; October is a close second (histogram).
The reason is not fully understood, but it has something to
do with the orientation of Earth's axes and the sun's magnetic
field around the time of the equinoxes. The Iditarod takes
place smack-dog in the middle of aurora
season.
Now, if only huskies could operate a camera....
March
Northern Lights Gallery
[previous Marches: 2009,
2008, 2007,
2006, 2005,
2004, 2003]
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