April 21, 2016 - SPACE - Geomagnetic activity should shift to an active state on April 23rd, when Earth enters a stream of high-speed solar wind. The solar wind is flowing out of this coronal hole on the sun.
Coronal holes are places in the sun's upper atmosphere where magnetic fields peel back, allowing solar wind to escape. In the image, above, from NASA's Solar Dynamics Observatory, the flow of solar wind is traced by arrows. The escaping material is now nearing Earth.
|Coronal hole on April 18. Credit: SDO/AIA.|
The incoming solar wind stream is filled with positive-polarity magnetic fields. This means it might not do a good job sparking auroras. Positive polarity magnetic fields from the sun do not easily link to Earth's planetary magnetic field. As a result, their effect on our magnetosphere is often muted.
UPDATE: A geomagnetic storm watch was added for April 23rd. The coronal hole will be turning into a geoeffective position and a solar wind stream flowing from this hole is expected to generate minor (G1) storming at higher latitudes.
|Coronal hole on April 21. Credit: SDO/AIA.|
Sky watchers at higher latitudes should be alert for visible aurora once the stream arrives if local daylight and weather conditions allows.
- Space Weather | Solar Ham.