Powerful X-Class Solar Flare Creates Strong Space Storm
2005 01 18
By Sky & Telescope
A powerful X-class solar flare 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-rays remained above M-class levels 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.
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