What a night! All that activity finally came crashing into Earth – and boy it didn’t hold back! With it, came beautiful auroras and lots of UK sightings.
Science first – photos later
If you’re here just for the photos (and I wouldn’t blame you if you are!) scroll down a little further 😉
Below is the DSCOVR satellite’s real-time solar wind and interplanetary magnetic field (IMF) data. The top panel shows the total magnetic field strength (black) and the z-component (up-down) of the magnetic field, known as Bz (red). As we can see, the Bz went very negative last night at just the right time for UK aurora hunters. Negative Bz, also known as southward Bz, is very important for transfering energy into our magnetic field (known as the magnetosphere) and generating the aurora.
DSCOVR real-time solar wind/magnetic field data for 07-08 Sept 2017.
In the fourth panel, we also have the solar wind speed (purple), this really ramped up at the same time too. Although not as important as Bz, a fast solar wind speed always helps move things along!
We started registering this solar wind activity in our magnetometers quickly. Issuing a yellow alert at 23:06 BST (07 Sept 2017), amber at 00:12 BST (08 Sept 2017) and then red at 00:24 BST. We stayed at red alert status for three hours.
The AuroraWatch UK alert status was red during the first three hours of 08 Sept 2017 (BST).
The modeled auroral oval looked pretty impressive too!
SWPC’s run of the OVATION Prime model for 0130 (BST) 08 Sept 2017
But which CME is this? There were two right?
There were! You might recall that there was a coronal mass ejection (CME) associated with the M4-class flare produced on 04 Sept 2017 (let’s call that CME1) and there was another associated with the X9-class flare produced on 06 Sept 2017 (CME2).
So which one was responsible? Well it appears that we can thank both of them actually. It seems as though CME1 cleared the way for CME2 and CME2 was able to catch up with CME1. The “shock” of CME2 (basically the front of it) actually mixed into CME1, which massively enhanced the solar wind and produced the conditions we saw.
by "pre-conditioning the solar wind", so CME1 cleared the way for CME2.
— Christian Möstl (@chrisoutofspace) September 8, 2017
(2) the shock wave of CME2 traveled through the magnetic core of CME1, thereby intensifying the Bz field which lead to #aurora lighten up!
— Christian Möstl (@chrisoutofspace) September 8, 2017
Almost there with the photos…
It’s also interesting to note that we started off getting confusing signals. ACE and DSCOVR were showing completely different orientations for Bz (ACE positive whilst DSCOVR negative).
ACE and DSCOVR giving very different solar wind/IMF readings atm. DSCOVR seems to match geomag conditions best? pic.twitter.com/brffl6O8TP
— Nathan Case (@na_case) September 7, 2017
We think it may be due to callibration issues or perhaps just that the two spacecraft were indeed seeing different things – space is pretty big! As it turns out DSCOVR was much more representative of what we saw here at Earth. But it goes to show how difficult space weather prediction can be – especially with just a couple of satellites to help us.
Oh and one more thing… we recently installed a magnetometer in Shetland (more details on that soon!). Have a look at this for activity…
Activity from the AWUK Sumburgh Head magnetometer.
Yes that scale is correct! We registered a disturbance of nearly 2000nT (compared to just under 500nT at Aberdeen) which goes to show that the auroral oval must have been almost directly overhead Shetland at that time. Well south of its usual position. The red alert status lasted into another hour in Shetland as well.
Photos – enjoy!
Though clouds were an issue for some, others still managed to sneak a peak of the beautiful aurora.
So excited to see the #Aurora for the first time! thanks @aurorawatchuk pic.twitter.com/EFuC4nR6NY
— Mike Walters (@assortedhackery) September 8, 2017
#Aurora taken on my camera and edited on my phone from #BerwickUponTweed @metoffice @spaceweather @aurorawatchuk pic.twitter.com/al05r2aGyB
— Danny Spring (@strangequark77) September 8, 2017
#Auroraborealis as seen from #newtongrange #midlothian @aurorawatchuk @WindyWilson88 @Mid_Advertiser pic.twitter.com/Ohvd3u3cEu
— Fiona Horne (@Feehster) September 8, 2017
Few mins ago back of camera just outside Dundee #aurora pic.twitter.com/bKniytNohv
— ross day (@rosscday) September 8, 2017
Just north of Dundee pic.twitter.com/SIcmA3CL6n
— philzee (@philzee72) September 8, 2017
The #Aurora is faint but visible over Edinburgh @aurorawatchuk pic.twitter.com/HPT0tYbU0g
— I am Jean-Loup 🎸 (@jean_loup) September 8, 2017
Aurora 8/9/2017 00:57 BST by Eric Pollock. All rights reserved.
Northern Lights from Bamburgh, Northumberland by Paul Taylor. All rights reserved.
Aurora 8/9/2017 01:36BST by Eric Pollock. All rights reserved.
The Bridge by D3RX. CC BY 2.0
2017_09_08_Aurora (ex CME AR12673 X-class 9.3) 2 by john.purvis. CC BY 2.0
Did you see the aurora?
If so, we’d love for you to share any photos or stories. Post here, on Twitter, Facebook, or Flickr. Also, we’d encourage you to report your sightings to the Aurorasaurus project to help space scientists (like me) understand more about the aurora and improve future predictions.
More to come?
Maybe! It’s possible that CME2 will give us another display of aurora tonight. Fingers crossed and keep an eye on our alerts.
