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Sun Packs a Double Punch-UPDATED
UPDATE August 8, 2011: Below is one of the many aurora images sent in from the weekend's geomagnetic storm. Not just restricted to Canada, the Northern Lights spilled across the border into the United States as far south as Utah, Colorado, and Nebraska and for European observers as far south as England, Germany and Poland.

Utah aurora on August 6, 2011 resulting from the arrival of the combined CMEs blasted from the sun on August 3, 2011.
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This faint red light image taken in Thatcher, Utah on August 6, 2011 is typical of lower-latitude auroras during major geomagnetic storms. Image Courtesy of Scott Lowther.

UPDATE August 5, 2011: The initial August 2 coronal mass ejection (CME) arrived at Earth August 4 around 5 pm EDT. The two August 3 CMEs combined, arriving at Earth August 5 around 1:20 pm EDT, resulting in a strong compression of the magnetosphere. The arrival of this double-punch CME is expected to result in auroras and minor to moderate disturbances in power grids at high latitudes.

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This video taken by SDO in extreme ultraviolet light shows the M9.3-class solar flare and cme generated by sunspot 1261 early on August 4, 2011. Credit: NASA/SDO/AIA

Following an M9.3 solar flare, sunspot 1261 release a Earth-directed coronal mass ejection. › View larger
This still from the video shows the cme lifting off from sunspot 1261. Credit: NASA/SDO
On August 3, the sun packed a double punch, emitting a M6.0-class flare at 9:43 am EDT and a slightly stronger M9.3-class flare at 11:41 pm EDT. Both flares had significant coronal mass ejections (CMEs) associated with them that will give the Earth a glancing blow.

CMEs are solar phenomenons that can send solar particles hurling into space at high rates of speed, sometimes affect electronic systems in satellites and on the ground.

Based on current solar and heliospheric modeling carried out by the Space Weather Lab at NASA’s Goddard Space Flight Center, the flares are likely to merge and their combined effects will reach Earth’s near-space environment on August 4 around 7 pm EDT.

Animated model of Aug 4, 2011 coronal mass ejection path.
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This animated model shows the expected path of the August 4, 2011 cme cloud. Credit: NASA/CCMC

The flanks of the CME could impact STEREO A, Mars and Mercury/MESSENGER spacecraft. A CME of this strength is likely to cause auroras at high latitudes and may affect some satellite operations, but is unlikely to cause any major impacts to electrical systems on Earth.

Further updates on the event will be provided as they become available.

What is a solar flare? What is a coronal mass ejection?

For answers to these and other space weather questions, please visit the Spaceweather Frequently Asked Questions page.


Susan Hendrix/Holly Zell
NASA's Goddard Space Flight Center