Halo CME

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