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SOHO
coronagraphs spotted a faint Earth-directed coronal mass
ejection (CME) on Sept. 25th. The eruption, which came from
the neighborhood of sunspot 9167, billowed away from the
Sun at 400 km/s (or faster) and will likely reach Earth
this Wednesday or Thursday. NOAA forecasters estimate a
10% chance of major geomagnetic storm conditions at middle
latitudes when the disturbance arrives. Although the CME
was faint, sky watchers should be alert for aurora after
local nightfall on Sept. 27th. The Moon will be new on Wednesday,
affording dark skies for aurora hunters.
SMALLER,
BUT STILL IMPRESSIVE: The largest sunspot in 9 years,
AR 9169, is gradually decaying. It now covers an area
equivalent to nine times the surface area of Earth --
down from 13 Earth-areas when the sunspot first appeared
10 days ago. Magnetic fields above the still-impressive
spot have a tangled beta-gamma-delta configuration that
likely harbors energy for powerful X-class solar flares.
Despite its potential for powerful eruptions, 9169 continues
to be remarkably quiet
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