On October 25th, the UK received an astonishing early Christmas present.
At 17:48 UTC (18:48 BST), AuroraWatch UK issued an extremely rare red alert, indicating that it may have been possible to see the aurora from the entirety of the UK. There were in fact two distinct periods where geomagnetic activity went above red alert thresholds:
Although the weather, once again, wasn’t favourable for many of our followers, some great pictures were shared with us from a wide variety of locations.
Cause of Activity
At the time of the red alerts, all of our magnetometers were in agreement about sharp jumps in the magnetic field indicated by the areas between the two pairs of blue lines.
More info on our stackplots can be found on our website.
This activity was caused by yet another coronal hole coming into the view of Earth. This cool, dark patch on the Sun outputs solar material at much higher speeds than normal (around 700km/s instead of 300-400km/s). This is all happening inside of the corona, the outer atmosphere of the Sun. The light from this layer is too dim to see with a normal solar telescope, when compared to the rest of the Sun, so we need the use of a specific type of filter which only shows light with frequencies from that layer. For this, we take a look at the 193 angstroms camera aboard NASA’s SDO spacecraft. This coronal hole was absolutely enormous.:
A red alert is no common occurrence. It was the first time we’ve issued one this year. Even some southern areas of the UK managed a great view of the aurora:
— Matthew Usher (@MatthewUsher) October 27, 2016
— Maple23 (@map1e23) October 27, 2016
We also recieved quite a few photos of airglow. It’s another beautiful night-sky phenomenon that we are sometimes lucky enough to capture, but isn’t the same as the aurora.
— Andrew Sweeny (@Ramy1963) October 27, 2016
Activity is expected to remain elevated over today (28th) as the coronal hole passes us by. It is unlikely to produce a red alert again but we may see some yellow or ambers popping up – so keep an eye out.
That’s all for this roundup of the red alert activity. Remember you can follow us on Facebook and Twitter for up to date alerts on auroral activity in the UK. We also have a Flickr group where some of our favourite photographers share their images with us!