Wednesday, December 23, 2009

Solar Tsunami
The solar system is passing through an interstellar cloud that physics says should not exist. In the Dec. 24th issue of Nature, a team of scientists reveal how NASA's Voyager spacecraft have solved the mystery. Get the full story from Science@NASA.

SOLAR ACTIVITY: Yesterday, Dec. 22nd at approximately 0455 UT, magnetic fields around sunspot 1036 erupted, producing a C7-class solar flare. NASA's STEREO-A spacecraft was almost directly above the sunspot at the time of the blast and recorded this extreme ultraviolet movie:

The shadowy wave racing away from the blast site is a "solar tsunami"--a swell of hot, magnetized plasma about 100,000 km high packing as much energy as a million megatons of TNT. The tsunami petered out before it went more than halfway around the sun, but another manifestation of the blast is still going. The eruption hurled a faint coronal mass ejection (CME) into space and the billion-ton cloud should cross Earth's orbit on or about Dec. 25th. A glancing blow to Earth's magnetic field could spark polar auroras for Christmas.

more images: from Pete Lawrence of Selsey, West Sussex, UK; from C. Swiger and J. Stetson of South Portland, Maine; from Robert Arnold of Isle of Skye, Scotland

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