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 thisdouble-punch CME is expected to result in auroras and minor to moderate disturbances in power grids at high latitudes.

August 5 CME Update:

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 thisdouble-punch CME is expected to result in auroras and minor to moderate disturbances in power grids at high latitudes.

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.

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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.