The space weather division of the NOAA issued a space weather advisory bulletin on the afternoon of September 26, 2011. At high latitudes there is a severe geomagnetic storm. At lower latitudes the geomagnetic storm is only at moderate levels. Auroras, also called the northern lights, are one of the effects of geomagnetic storms.
The bulletin states that observers in Asia and Europe are in the most favorable longitudes for observing aurora resulting from this geomagnetic storm. It gets dark at these longitudes earlier and therefore closer to the onset of the geomagnetic storm. If the storm lasts long enough, however, aurora may also be visible in North America, particularly at high latitudes, such as Canada and the northern half of the United States.
The geomagnetic storm results from a strong M class solar flare and an associated Coronal Mass Ejection (CME). The CME struck Earth with a glancing blow at 8:37 AM Eastern Time on September 26. Had the CME struck Earth more directly, the geomagnetic storm would have been much stronger.
The active sunspot region 1302 caused the solar flare and CME. This active region will remain well placed to produce CMEs that could strike Earth more directly for the next 3 to 5 days. It is likely that this sunspot region could produce more flares or CMEs. Hence there is a good possibility of aurora and other geomagnetic activity for the next few days.
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