The Great Aurora of 2014 February 27/28

2014 March 27

Ken Kennedy

On February 25 a returning active area on the Sun which had previously been designated AR1967 reappeared on the solar limb and was re-designated AR1990. This still active area promptly released an X4.9 flare with a Coronal Mass Ejection (CME), the third most powerful so far of solar cycle 24.
Because of the proximity of AR1990 to the solar limb it was at first thought that the associated CME would not interact with Earth, but at about 17:30 on February 27 an impact occurred. At about the same time the Bz turned sharply southwards and the Kp jumped to 4 then quickly to 6. Conditions for magnetic interaction and aurora over UK were almost perfect on Feb 27 despite the position of the active area which was the origin of the CME.
By unusually good fortune, the skies over much of the British Isles were clear on the evening of February 27/28 and reports and images of the auroral display quickly spread over social media allowing many to go out and see this bright and lively display. Green bands and arcs with rapidly changing rays which rose from the bands, changing colour from green to red as they rose to almost the zenith, were seen. Reports have been sent to the BAA from many locations and some include sightings of the rare corona and auroral pulsation.
It will be worth keeping an eye on AR1990 to see if it continues to produce flares. The Sun has quite a number of spots at the moment and it may be that we are experiencing the predicted second solar cycle peak following a first peak in 2012. After a number of years when the aurora seemed to be confined to the most northerly regions of the UK this may well herald a return to more widespread sightings.

Ken Kennedy, Director, Aurora Section
Photo above: Nick Turner