Minor solar wind stream could spark auroras tonight

 Earth is entering a minor solar wind stream that could spark auroras around the Arctic Circle. High-latitude sky watchers should be alert for Northern Lights tonight.

Solar wind
speed: 452.2 km/sec
density: 1.5 protons/cm³

The Radio Sun
10.7 cm flux: 140 sfu

Planetary K-index
Now: Kp= 2 quiet
24-hr max: Kp= 2 quiet

Interplanetary Mag. Field
B_total: 5.0 nT
B_z: 2.9 nT south 

A very large solar filament channel that measures longer than 300,000 miles, is currently visible across the entire northeast quadrant. Click on the image below to view.

Joint USAF/NOAA Report of Solar and Geophysical Activity (11 Dec 2011)

Solar activity was at very low levels with only B-class activity observed. Two filament eruptions were observed during the period. A 40 degree long filament, centered near N25E25, was first observed erupting at about 11/0600Z. Shortly after, a 10 degree long filament, centered near N30W17, was first observed lifting off at about 11/0900Z. Stereo-A COR2 imagery observed a pair of CMEs off the NE limb at 11/0754Z and 11/1024Z as a result of the filament activity. At this time, neither of these CMEs are expected to be geoeffective. Solar activity is expected to be at low levels with a slight chance for M-class activity all three days of the period (12 – 14 December).

The geomagnetic field was at quiet to unsettled levels. Solar wind velocities generally varied between 450 to 500 km/s while the Bz component of the interplanetary magnetic field did not vary much beyond +/- 5 nT. The geomagnetic field is expected to be at mostly quiet levels all three days of the period (12 – 14 December).