Monday, September 17, 2012

Sept 17th, Sun and Earth Fairly Quiet...

The above X-ray image of the sun was taken September 17th at 03:24:00 UTC by the Solar X-ray Imager (SXI) aboard the GOES-15 satellite. Note the coronal hole just to the left (east) of center. The high-speed stream from this hole should begin to affect Earth's magnetic field around September 19th. Image Credit: NOAA

For the end of September 15th and most of the 16th, the solar activity was very low. The new Active Region 1573 (AR 1573) produced occasional B-class flares as it rotated into view. AR 1566 produced a B-class flare as it approached the west limb. AR 1569 showed gradual spot and penumbral decay in its intermediate and trailer portions. New AR 1574, a small reverse-polarity group, was also designated. The was no Earth-directed coronal mass ejection (CME) activity. The forecast through September 19th: The solar activity is expected to be very low with a chance for a C-class flare.

Here at home, the geomagnetic field activity was at quiet to unsettled levels. An increase to unsettled levels occurred late in the period, associated with the onset of a solar sector boundary crossing (SSBC). Intermittent periods of weakly-southward IMF Bz along with minor increases in solar wind speeds and IMF Bt were associated with the SSBC. The forecast through September 19th: The geomagnetic field activity is expected to remain at quiet to unsettled levels on the 17th due to minor changes in the solar wind. A decrease to quiet levels is expected on the 18th. Activity is expected to increase to quiet to unsettled levels on the 19th, with a slight chance for active levels, as a coronal hole high-speed stream begins to disturb the field. Stay tuned...

To monitor solar flare activity minute by minute, visit the "Today's Space Weather" page of NOAA's Space Weather Prediction Center (

To learn more about the sun and to stay current on solar activity, visit the mission home pages of the Solar Dynamics Observatory (SDO) (, the Solar and Heliospheric Observatory (SOHO) (, the Advanced Composition Explorer (ACE) (, and the Solar Terrestrial Relations Observatory (STEREO) (


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