Northern Lights Now – A widespread aurora display delighted viewers across northern Europe and North America on September 1st and 2nd. Kp values, a global measure of aurora activity, reached G2 storm levels. Northern lights were visible in Denmark, Maine, New Hampshire, Wisconsin, and across Canada.
Here are some highlights from Twitter, check back tomorrow for a more detailed storm recap:
Northern Lights Now – SWPC has posted a G2 storm watch for August 2nd and a G1 storm watch for August 3rd. NLN will keep a live blog of the storm as it unfolds here.
Update 8/4 2:30 UTC (10:30pm EST)
A quick recap: The big winners for aurora photography in this storm were the Northern states west of the Great Lakes and Canada, New Zealand and Tasmania. Denmark was also in the sweet spot at the very beginning of the storm when the initial CME arrived. There were a couple pictures of faint pillars in ME, NH and VT as well.
Solar wind never quite reached the high levels expected in the prediction. The helps explain why the storming started a little later than predicted also – if the wind is moving slower, it takes longer to travel from the Sun to Earth. In the end there were four periods of G1 storming recorded.
Thanks for following along for this storm!
Update 8/3 16:30 UTC (12:30pm EST)
The storm seem be dying down. Solar wind speeds have picked up, but they did not reach the predicted 600+ km/s. Here’s a create timelapse video from overnight from Robert Snache (@spirithands)
Update 8/3 11:00 UTC (7:00am EST)
So many wonderful pictures overnight. There were 3 periods of G1 recorded, and it appears there is a 4th happening now. There is an outside chance that the current period will reach G2. Here are a couple tweet with aurora pictures the we’ve seen overnight:
Starting about an hour ago, Bz dipped back south. Bt is still very strong, so this may be enough to produce some more pillars in the mid-latitudes. Aurora hunters will still probably need long exposures to get a good view. KP=5.33 (G1) in 20 minutes. Here’s a look at the boulder KP 3-hour averages so far – notice that storming didn’t technically reach G2 levels during the last substorm:
Update 8/2 23:00 UTC (7:00pm EST)
G2 storming is now predicted by the Wing-KP model. KP=6 shortly! This is almost exactly when the initial forecasts indicated we might see G2 storming. The strong solar wind hasn’t really picked up yet – wind speeds have only just touched 450 km/s.
Bz shifted to the north, so NLN is expecting this storm to be short lived. Good luck. Hopefully there will be more later tonight
Update 8/2 22:30 UTC (6:30pm EST)
First aurora picture of the night! This tweet shows a photo from Denmark by Twitter follower @ADphotography24
Around 8:00am UTC Bz made a decisive shift to the south. This should be good for aurora hunters and we expect to see some pictures coming in soon. We also expect the wing-KP models to reflect this aurora within the next 2-3 hrs.
The first hints of the expected solar storm from the filament eruption appear to be arriving. Solar wind, density and Bt/Bz all reflected the shocks impact. The shock was weaker than expected, but also a little earlier than expected. We’re not really expecting any aurora yet, still plenty of hours ahead for a show.
Northern Lights Now – SWPC has issued two geomagnetic storm watches for G2 storming (KP=6+) on August 2nd and G1 storming (KP=5+) on August 3rd. These watches are the result of a pair of solar features that will impact Earth starting midday UTC on August 2nd. The NLN AuroraCast shows the current predicted timing for the timing. As always, these can be within +/- 6 hours:
Please visit NLN’s live blog of this storm and follow out Twitter feed for the most up-to-date information.
The first solar event that will impact Earth is the arrival of a very slow moving CME (Coronal Mass Ejection) that was launched during the July 28th filament eruption. The eruption happened almost dead center (near N01E06) on the solar disk. The associated CME was estimated to be travelling at 125-150 km/s. At that speed, it could take as many as 7 days for the CME to arrive at Earth, but it should be pushed by the ambient solar wind to 350 km/s or so. Then, an even higher wind from a coronal hole high speed wind stream should push it even faster to 600-650 km/s. There are several factors making the timing on this forecast complex – current models show the CME arriving midday to late August 2nd, 5 days after it’s launch.
In the animated GIF below watch the filament eruption in a composite of AIA 211, 193 and 171 wavelengths. These frames are about 14 hours of images taken by the Solar Dynamic Observatory (SDO) cameras. Note that just to the east (left) of the eruption, the coronal hole rotating into center disk is visible as a darker area:
The second feature is a large coronal hole that rotated into geoeffective position on July 31. The high speed stream from this CH measured at STEREO Ahead indicated that winds could reach 650-750 km/s at L1. This very strong wind will likely start impacting Earth either with or just after the CME arrives. If it “pushes” the particles in the CME, they will arrive at the leading edge of the shock. Due to the elongated shape of the CH, the period of elevated winds could be extended in duration. Here is an image of the coronal hole from SDO in AIA 211 from July 31 as it rotated toward Earth:
Together these storms have the potential to arrive with a strong shock and an extended period of high solar wind and active geomagnetic conditions. If they do, it should be a very good couple of nights for aurora hunters worldwide. As an added bonus, the Moon will be waxing just past new, so skies should be dark.