Severe geomagnetic storm subsiding
Image credit: SpaceWeather
A severe geomagnetic storm (Kp=7 to 8) that began yesterday when a CME hit Earth's magnetic field is subsiding.
At the peak of the disturbance, auroras were sighted around both poles and in more than six US states including Michigan, New York, South Dakota, Maine, Massachusetts and Minnesota. Sky watchers at the highest latitudes should remain alert for auroras as Earth's magnetic field continues to reverberate from the CME impact.
Solar wind
speed: 539.7 km/sec
density: 0.1 protons/cm3
The Radio Sun
10.7 cm flux: 148 sfu
Planetary K-index
Now: Kp= 2 quiet
24-hr max: Kp= 7 strong
Interplanetary Mag. Field
Btotal: 7.9 nT
Bz: 3.6 nT north
The source of all this solar and geomagnetic activity is sunspot AR1302. Measuring more than 150,000 km from end to end, the sprawling active region is visible even without a solar telescope.
The sunspot has quieted down since unleashing dual X-flares on September 22nd and 24th. Nevertheless, NOAA forecasters estimate a 40% chance of more X-flares during the next 24 hours. Any such eruptions would be Earth-directed as the sunspot crosses the center of the solar disk. (SpaceWeather)
The northern lights were seen last night as far south as Michigan, New York, South Dakota and Maine in the United States, and also from Europe and New Zealand. It was the strongest geomagnetic storm since October 2003.
A HD video of what the northern lights look like during a strong geomagnetic storm as we had yesterday can be seen at http://www.vimeo.com/27315234