X-FLARE THREAT CONTINUES

POSSIBLE CME IMPACT ON MAY 17: A coronal mass ejection (CME) hurled into space by the X1-flare of May 15th might deliver a glancing blow to Earth's magnetic field on May 17th. NOAA forecasters estimate a 40% chance of polar geomagnetic storms when the cloud arrives. High-latitude sky watchers should be alert for auroras. Aurora alerts: text, voice.

X-FLARE THREAT CONTINUES: Sunspot AR1748 has already unleashed four X-class solar flares, but it might not be finished. The active region continues to grow beneath a delta-class magnetic field that harbors energy for powerful eruptions. NOAA puts the odds of another X-flare today at 60%. Solar flare alerts: text, voice.

NASA's Solar Dynamics Observatory took this picture of AR1748 during the early hours of May 16th:

The sunspot is not particularly large, but it is complex, with many dark cores scattered through its zone of influence. This is a sign of a complicated overlying magnetic field. Magnetic complexity is the source of AR1748's explosiveness: when tangled lines of magnetic force cross and reconnect--bang! A flare occurs.

All by itself, AR1748 has produced more X-flares than every other sunspot of the past year combined. In summary, AR1748 has given us an X1.7-class flare (0217 UT on May 13), an X2.8-class flare (1609 UT on May 13), an X3.2-class flare (0117 UT on May 14), and an X1-class flare (0152 on May 15). More could be in the offing. Solar flare alerts: text, voice.

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