How to see the aurora in the midsummer when you shouldn't really be able to see the aurora
It's common in aurora circles to talk of aurora seasons. And in many ways this makes sense - not because the aurora actually stops happening during a few weeks in the midst of June, in the same way that the season of Spring ends and gives way to summer. Rather it's simple because it really doesn't get dark enough. As we get closer and closer to summer solstice, twilight hangs on longer and longer until eventually the northern horizon never moves beyond dusk into night proper. So even if there was an aurora happening, it would be unlikely to be able to shine through the ambient brightness, and distinguishing between it and the twilight sky would be nigh on impossible. It would have to be an aurora of unusually large size to do that. And those are not very common.
In fact, I thought I was pushing it when I caught this lovely little show at Slemish, Co Antrim on 12th May this year. An aurora? In May?!? This was taken around midnight, and even then in mid May the sunset glow and evening dusk were still there. In fact, it was only the presence of the tell tale pillars of light that really confirmed for me that the aurora was happening.
That would be it for the 2014/15 season, I thought. It was nice to fit one last aurora viewing in, but now focus would shift towards noctilucent season (which have a season in the literal sense, only being visible for a few months from mid May to Mid July).
It would take a solar storm of unusual size to change that. And on 22 June, the day after the longest day of the year - when viewing conditions for the aurora are at their worst in terms of the sky getting truly dark - the aurora delivered just that.
Thursday 18 June
On 18 June, a new sunspot region, 2371, rotated into view on the surface of the sun and it piqued the interest of space weather enthusiasts. Space Weather Live reported on it, saying than an M-class solar flare was possible in the next few days. And indeed, by the very next day, this beauty had delivered - an M3 solar flare, complete with a CME. The CME was only partially earth directed, but a glancing blow was expected in the middle of the afternoon on the longest day of the year. Not much chance of it delivering an aurora visible to us in midsummer then...
Sunday 21 June
But region 2371 was far from done. For on Sunday 21 June, summer solstice itself, it emitted a double M-class solar flare which fired out a CME. But a full halo CME, this time. And that meant one thing - this CME was coming straight towards us. As Space Weather Live reported it, 'no chance of a glancing blow here - this even won't miss our little planet.' Excitement was now beginning to build in the aurora chasing world. The CME was heading to us quickly, and expected impacts put it around 18.00 hours on Monday. Could this be the one to do it? Could this CME punch through the dusk of twilight?
Monday 22 June
Just after dinner time on Monday, I took my camera out into the garden. The skies were clear, and the sun was blazing overhead. I put my homemade Baader filter on to my zoom lens and took some images of the sun. I was keen to capture that wonderful sunspot region in all its glory. And indeed I did. But, as I was taking this very picture, the CME from 21 June was impacting our atmosphere. And amazingly this region had just fired off yet another solar flare, peaking at M 6.6. What a busy little sunspot region this was being!
The stats from the ACE satellite were responding to the arrival of the CME just before 18.00 UTC (19.00 BST). The speed of the solar wind jumped from 400 km/s to over 700 km/s. It's temperature and density jumped upwards. And the magnetic field responded too - the Bt (its density) jumped upwards and crucially the Bz (its orientation) dropped dramatically southwards to a staggeringly low value of -40. This was big. The forecasts were predicting very high storm potential during the next number of hours, even as high as Kp 7 or 8. If anything could beat these twilight skies, this bad boy could!
The hunt begins
And so it was very much game on. Although there was still a very long wait until the darkest hours around 01.00 on 23 June. The skies were clear and the forecast was good (if cold) and I headed for a favourite location back to Slemish just before sunset at around 21.00 hours. But as I was waiting there, some clouds began to close in, spoiling my sunset view. In fact, over the next few hours, the cloud thickened and the skies above and to the NW became obscured. Around 23.00 hours, my photography buddy Alistair White had arrived to join me, and we made the decision to leave Slemish and head for the coast. There was a gap just visible there, so it seemed like our best shot. Just before we left, I checked the magnetometers. They were going mad so the signs remained very positive!
Twenty minutes later we were standing on the beach at Glenarm. The wind had died down, the waves were gently lapping at our feet and the skies above were clear. The golden glow of sunset clung in a band along the north eastern horizon, and above it the deep blues of dusk stretched far up into the sky. It wasn't dark. It wasn't ever going to get fully dark. But we lived in hope that this aurora would deliver the goods. We had no 3G signal were we were, so tonight it was going to be old school - determination and patience to stick it out in the hope that something would happen!
And it didn't take long. Just after 23.00 hours, a small but perfectly formed noctilucent cloud display developed to the east. As the skies got gradually and ever so slightly a deeper blue, the shimmering whites of these glorious clouds became evermore distinct. I set up my camera for some time lapse shots. He we were - two mates, standing on a beach in deepest midsummer, enjoying a cool (non-alcoholic!) beer, while watching a delightful NLC display. Even if the aurora didn't deliver, this was still going to be a good night.
And so the hours passed while we waited. My eyes were scouring the skies above, my mind playing tricks on me, convincing me I could see faint pillars of light. But every time I thought I saw something, I realised I was imagining it.
Until 00.50 hours, that is.
I was shooting a close up time lapse of the NLCs to the east with my zoom lens when I thought I glimpsed a ray of light to the north. Closer scrutiny confirmed my initial thoughts this time - the auroral substorm had arrived and the pillars of light were here!
I quickly fumbled around to change my lens from the 300mm zoom to the 11mm ultra wide. I knew this show was going to have to produce very tall pillars to cut through the twilight, and the 11mm was the best choice to try to fit them in. I got the lens on, fired off a test shot. And, lo and behold, there they were!
For the next half an hour or so, the rays slowly made their way across the sky, from north to east, traversing the twilight zone, cutting through in purple majesty not only the dark blues of dusk above, but mixing with the yellows of sunset to produce the most exquisite green band low in the sky.
I decided to go for some time lapse photos here too, shooting with settings I've never been able to come close to in aurora photography before: f/3.2, 10 seconds and ISO 100 (yes ISO 100!!) For the first 10 minutes, the display was clearly visible to the naked eye (although without the colour). For the remaining 20 minutes or so, it died back a bit and was just about visible if you looked hard enough. At this stage, my enthusiastic leaping around attracted the attention of four young people who were out for a night's camp on the beach. They left their fire and came over, curious as to what was going on. When I explained it to them and showe them the pictures, they were stunned. It was their first aurora - it's always a delight to share that experience with anyone.
Of course, we stayed on for about another 45 minutes or so, to see if anything else might happen. But by now it was after 02.00, and the light of dawn was building again. It was time to call it a night. We went home gorged on the experience, tired but happy at another successful night's aurora hunting.
It was a dream fulfilled. A massive aurora had arrived, when the skies were clear of cloud, and it peaked at just the time when the skies were at their darkest above us. We were living the dream - the 'out of season' midsummer's night dream no less!
Check out my time lapse video of the NLCs and midsummer's aurora here:
St Patrick's Day all over again
As a postscript, this storm proved to be indeed a big one, the biggest since St Patrick's Day 2015, which itself was the second biggest solar storm in this solar cycle. I was standing at more or less the same place I was when that storm hit, so it might be interesting to see some comparisons of the shots - and a hint of what we would have seen on 22 June if we had been in midwinter and not midsummer!
The K indices for the UK magnetometers during the CME impact. It was a big show indeed!
Sunspot region 2371 gave off multiple solar flares and CMEs and produced some great aurora displays in the southern hemisphere where they were experiencing mi-winter. As a tribute, Space Weather Live put together this awesome time lapse video of its transition across the face of the sun.
Sunspot region 2371 tribute
A quick update on the current geomagnetic conditions.We are still experiencing the effects of today's coronal mass ejection arrival but the impact has been rather insignificant compared with what was forecast.While the solar wind speed remains high around 600km/s, the strength of the IMF declined from an initial value of 12nT to 9nT right now with the direction (Bz) being mostly northward. These kind of values are really insignificant and we can unfortunately conclude that it is even unlikely that we will reach the minor G1 geomagnetic storm threshold. Auroral displays will be confined to high latitude locations. A shame as this looked like a promising coronal mass ejection on LASCO but it turned out to be a disappointment for auroral activity here on Earth.Nonetheless we thank you for following us the past few days. It was a very interesting week thanks to sunspot region 2371 which gave us the second strongest geomagnetic storm of this solar cycle.Unfortunately we have to conclude that sunspot region 2371 is decaying and it is right now only a shadow of it former self. It's delta structure is no longer there as it has ripped loose from the trailing sunspot region. The chance for even a low-level M-class solar flare is very low. To honor this sunspot region that gave us this exciting week we made a time lapse video with SDO footage showing how this sunspot region evolved from June 16 when it appeared at the limb until right now. We also show the M2.0/M2.6 solar flare that launched the full halo CME which was responsible for the severe G4 geomagnetic storm on 22 and 23 June.Thank you for your support and keep following us!Posted by SpaceWeatherLive on Wednesday, June 24, 2015