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PERSEID
METEOR SHOWER: Earth is entering
a stream of debris from Comet Swift-Tuttle, source
of the annual Perseid
meteor shower. International observers are now
reporting more than a dozen Perseids per hour,
a number that will increase as the shower reaches
its peak on August 12-13. Full moonlight will reduce
visibility on peak night, but not enough to completely
spoil the show. The best time to look is Saturday
morning, Aug. 13, just before dawn when the Moon
is low, the shower is peaking, and the
ISS is flying overhead. Also, be sure to tune
into Space
Weather Radio to hear the ghostly pings of Perseids
disintegrating over the US Air Force's Space Surveillance
Radar.
What was that? Dawn is
a great time to see satellites. There are hundreds
in Earth orbit, and you're sure to see some of them
while you're watching the Perseids. This
app for Android phones can tell you what you're
seeing.
MAJOR
FLARE, NOT EARTH-DIRECTED: On August
9th at 0805 UT, sunspot 1263 produced an X7-class
solar flare--only the third X-flare of new Solar
Cycle 24 and the most powerful so far. NASA's Solar
Dynamics Observatory captured the explosion's extreme
ultraviolet flash:
The brunt of the explosion was not Earth directed.
Nevertheless, radiation from the flare created waves
of ionization in Earth's upper atmosphere, briefly
disrupting communications at some VLF and HF radio
frequencies. The blast also accelerated a mild torrent
of protons toward Earth; they can be seen speckling
the images in this
SOHO movie of a CME emerging from the blast
site. The CME will probably miss Earth. At this
time, however, we cannot rule out a glancing blow
from the flank of the cloud on August 11th or 12th.
Stay tuned for additional analysis. Solar
flare alerts: text,
voice.
X-flares of Solar Cycle 24: Feb.
15, 2011 (X2), March 9, 2011 (X1), Aug. 9, 2011
(X7). Before these three, the previous X-flare occured
on Dec.14, 2006, (X1) during old Solar Cycle 23.
WEEKEND
AURORAS: A widespread display of
auroras erupted late Friday, Aug. 5th, when a double-CME
hit Earth's magnetic field and sparked a G4-category
geomagnetic storm. Click on the image to view a
time lapse video of the event recorded by Michael
Ericsson on the shores of Tibbitt Lake in the Northwest
Territories of Canada:
"Although not the most intense auroras I've
ever seen, this one is definitely up there on my
favorites list," he says.
The show was not restricted to Canada. Northern
Lights spilled across the border into the United
States as far south as Oregon,
Utah,
Colorado,
and Nebraska.
(Note: The faint red
lights photographed in Nebraska are typical
of low-latitude auroras during major geomagnetic
storms.) Observers in Europe as far south as England,
Germany and Poland also witnessed a fine display.
Browse the
gallery for more examples.
Did you miss the show? Don't let
that happen again. Sign up for geomagnetic storm
alerts: text,
voice.
August
2011 Aurora Gallery
[previous Augusts: 2010,
2009, 2008,
2007,
2006,
2005,
2004, 2003,
2002]
2011
Noctilucent Cloud Gallery
[previous years: 2003,
2004, 2005,
2006, 2007,
2008, 2009]
