Tag Archives: G2

December 2015 Aurora Among Best of Solar Cycle 24

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Northern Lights Now – A solar storm resulting from a pair of CMEs arrived at Earth on December 19, 2015 and induced 30 hours of G1-G2 aurora activity. It proved to be one of the strongest geomagnetic storms of solar cycle 24. Aurora hunters around the world were able to capture stunning photographs of green, red, pink, and purple swirling through the sky. NLN will be writing a complete recap post, but here is a teaser of amazing tweets that has been in the NLN feed over the last two days.

Rob Write Photos – based in Maine from the evening of Dec 20 just after sunset:

Peter Caltner share this, showing the Aurora as far south as the Austrian Alps:

In Ireland, reports came in from Waterford. Here’s a picture from Waterford of the aurora with purple mixed in by Rónán McLaughlin:

Jake Stehli caputured this set of pictures in Wisconsin on the first night of the storm, just as it was really kicking up.

And one of our favorites of this storm so far by KW photography:

Happy Hunting

G2 Aurora Storming Predicted for Oct 8 2015

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SWPC has issued a G2 geomagnetic storm watch for October 7th and 8th and a G1 geomagnetic storm watch for October 9th. A positive polarity equatorial coronal hole will be producing a high speed solar wind that should be arriving late on Wednesday October 7th. On the previous rotation (Sept 8) this coronal hole produced a 2 day period of G1 and G2 storming. Here’s an image of the coronal hole on the previous rotation, and on the current rotation (Click for larger view):

Coronal hole images from last rotation and this rotation
Comparison of Sept 8 Coronal hole rotation to Oct 6

Coronal holes on the equator of the sun take roughly 27 days to make a full rotation. During that time they are constantly changing and evolving. It is clear this coronal hole – the dark areas on the AIA 211 images above – has become larger. It is generaly a safe bet that if the previous rotation created a strong solar stream, the current rotation will as well.

Like on the last rotation, the predicted storm is coming at a good time for aurora hunters. The Moon will be in a waning crescent phase, so there shouldn’t be much light pollution from the moon. For viewers in the northern hemisphere there is between 30 and 90 minutes of additional dark hours as the nights are longer and days are shorter since the last rotation. This is what the phase of the moon should look like:

Moon phases during predicted Aurora period
MoonPhases for Oct 7-9

Predicting the timing of Aurora that come from a coronal holes is a little easier than that from CMEs. It is hard to determine the speed and orientation of a CME, but with a coronal hole there is a narrower window. That said, predicting the exact timing of any geomagetic storm is difficult, and predictions can be off by as much as 6-12 hours. As of this writing, the current timeline calls for a peak of the G2 storming to happen starting at the end of October 7 and continuing through the early hours of Oct 8 – with G1 storming continuing for up to 6 more hours. For the East Coast Time zone, this means Wednesday evening from sunset through 3:00-6:00AM. NLN’s current infographic for the timing of the storm’s arrival:

NLN aurora prediction clock showing predicted storm arrival
Aurora timelines as of 10/6/2015

The predicted timelines are updated twice daily, you can always find them on NLN’s three-day forecast page. You can also keep an eye on the current and near-term predicted KP and the ovation auroral oval on the NLN Current Current KP Real-Time page.

Happy Hunting!