A category S2 proton storm is underway
following an M-class solar flare that
erupted at 1213 UT (8:13 am EDT) on Sept.
12. Soon after the flare, SOHO coronagraphs
recorded a spectacular full-halo coronal
mass ejection, pictured right. The fast-
moving CME billowed away from the Sun at
986 km/s. Forecasters expect its leading
edge to strike our planet's magnetosphere on
Thursday. The impact could produce major
geomagnetic activity, including displays of
aurora at middle-latitudes.

The geomagnetic storm is likely to begin
less than a day after the full Harvest Moon
of Sept. 13. Bright moonlight could render
faint aurora invisible, but Northern Lights
are sometimes seen in spite of lunar
interference. So be on the lookout for unusual
lights in the sky this Thursday night!

Space Weather

-- spider (spider0@usa.net), September 13, 2000