Fireworks in the sky!
posted: January 9, 2015

Well, maybe it was a bit late to spectacularly launch the New Year, but at least in the northern part of the Netherlands some faint but colorful polar light could be seen low above the northern horizon on 4 January around 18:00UT. The aurora didn't last long, barely 10 minutes, but Vincent van Leijen still managed to snap this great picture.


The source of the geomagnetic field disturbance was the high speed stream of a coronal hole that transited the south-central part of the solar disk just a few days before (see SDO-images underneath). Interestingly, this coronal hole was also responsible for a similar disturbance ("minor geomagnetic storm") during its previous transit early December.


There are several reasons why the polar light in this picture seems rather faint, for example when comparing to a similar display on 12 September 2014 (see this news item). At that time, it concerned a major geomagnetic storm (one of the strongest of 2014), so significantly more intense than the 4 January display. More importantly, the 4 January picture was taken early evening, when it was not yet completely dark. Last but not least, there was a Full Moon around those days, resulting in even more unwanted bleach on the picture.