Aurora Borealis: Why the UK?

Over the past few days, people across northern parts of the UK have been treated to spectacular views of the Aurora borealis. Scientists predict this incredible phenomenon may well continue to appear throughout the coming week, eventually making its way down to the midlands. But why is this spectacular light show, usually confined to skies above the Arctic, so visible to us now?

• The aurora is caused by solar (geomagnetic) storms hitting the Earth’s atmosphere. When the sun throws out plasma and solar radiation in a process called coronal mass ejection, it interacts with the Earth’s magnetic field causing it to glow.

• The strength of these storms is measured by something called the Kp index. This index runs from 0-9, with nine being the most powerful. The further north you are, the more likely it is you will see the lights when the Kp index is low, for example in the Arctic it is possible to see the Aurora Borealis when the Kp index is between just 0-3. The reason we have been experiencing the aurora in the UK is because recent solar storms have been particularly strong, reaching a Kp index of 5.67 (a Kp index of five is normally high enough to view the lights in the far north of Scotland). Scientists are predicting even more activity over the coming days, which is why it has been suggested that stargazers further south might also get the chance to view the spectacle.

• Atmospheric conditions also play an important part in generating the correct circumstances to view the aurora. Clear night skies have made it possible for many people to enjoy the show, but the phase of the Moon is important too. A full moon makes it difficult to view the lights, but thankfully in the UK we have been heading toward a new moon, the darkest phase, making the threat of light pollution far less likely.