We MIGHT get a strong Aurora if they sky clears


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This Is SKY & TELESCOPE's AstroAlert for Sun-Earth Interactions
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A s t r o A l e r t
Sun-Earth Alert

Solar Terrestrial Dispatch
http://www.spacew.com

17 January 2005

POWERFUL X-CLASS SOLAR FLARE CREATES STRONG SPACE RADIATION STORM

A powerful X-class solar flare (class X3.8) erupted from active
sunspot
Region 10720 at 09:52 UTC (4:52 am EST) on 17 January. This remarkable event
involved a steady increase in solar x-ray intensities for a period of over 2
hours before beginning a slow decline.X-raysremainedaboveM-classlevels
for over five and a half hours. The solar explosion was also exceptionally
"loud." At frequencies of 10 cm (about 2800 MHz), the explosion was over 80
times louder than the background noise of the Sun, registering a burst
intensity of 12,000 sfu (the normal background level being about 150 sfu).
The solar flare and the associated high velocity coronal mass ejection
succeeded in accelerating protons to near relativistic velocities, arriving
at the Earth within tens of minutes. The huge influx of energetic particles
increased the existing space radiation storm from a category S2 to a
category
S3 event, which is sufficient to be of concern to spacecraft operators and
astronauts.

This event was associated with a high velocity Earthward-directed
coronal mass ejection. Although an analysis of the CME is not yet complete,
there is fair certainty that its arrival at the Earth will result in periods
of major to severe geomagnetic and auroral storm activity. The arrival time
is yet to be determined, but a good guess would probably be later on 18 and
into 19 January (UTC time).

Region 10720 still appears to be capable of unleashing additional
energetic solar events, which it may do (perhaps more than once) during the
next 5 to 6 days before it transits the western solar limb.


** End of Astroalert **