Sunday, June 17, 2012

AR 1504 Update for June 17th

A geomagnetic storm is in progress in the wake of the "double CME" impact on June 16th. The hit, which strongly compressed Earth's magnetic field, lit up both poles with bright auroras. The impact was the result of two recent coronal mass ejections (CMEs) from the sun's Active Region 1504 (AR 1504).

Beautiful displays of the Southern Lights were seen in New Zealand. In North America, Northern Lights descended as far south as Wisconsin, Minnesota, Iowa, Washington and the Dakotas.

Geomagnetic Storm Primer

A geomagnetic storm is a temporary disturbance of Earth's magnetosphere caused by a disturbance in the interplanetary medium. A geomagnetic storm is caused by a solar wind shock wave and/or cloud of magnetic field which interacts with Earth's magnetic field. The increase in the solar wind pressure initially compresses the magnetosphere and the solar wind's magnetic field will interact with Earth’s magnetic field and transfer an increased amount of energy into the magnetosphere. Both interactions cause an increase in movement of plasma through the magnetosphere (driven by increased electric fields inside the magnetosphere) and an increase in electric current in the magnetosphere and ionosphere. During the main phase of a geomagnetic storm, electric current in the magnetosphere create magnetic force which pushes out the boundary between the magnetosphere and the solar wind. The disturbance in the interplanetary medium which drives the geomagnetic storm may be due to a CME or a high speed stream (co-rotating interaction region or CIR) of the solar wind originating from a region of weak magnetic field on the Sun’s surface. The frequency of geomagnetic storms increases and decreases with the sunspot cycle. CME driven storms are more common during the maximum of the solar cycle and CIR driven storms are more common during the minimum of the solar cycle.

More AR 1504-Related Activity Likely

Solar wind conditions in the wake of the CME favor continued disturbances. Forecasters for the National Oceanic and Atmospheric Administration (NOAA) estimate a 55% chance of more high-latitude geomagnetic storms during the next 24 hours.

And NOAA forecasters are still estimating a 65% chance of M-flares and a 5% chance of X-flares from AR 1504 during the next 24 hours. To visit NOAA online, follow this link, . Please stay tuned...

To learn more about the sun and to stay current on solar activity, visit the mission home page of Solar Dynamics Observatory (SDO), .

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