Sun spots on the sun cause solar winds which, when they come into contact with the Earth’s magnetic field, create the phenomenon. Because of the magnetic element this is stongest nearest the poles, however in some less frequent cases they can be seen much further south. Scientists have created a method for predicting their likelihood and measuring their strength.
Whilst in Alta we saw them on our first afternoon (by our lodge) and then on the next night during a “Northern Lights hunt”. Frustratingly for our guide we then saw them again, very brightly, on our return to the lodge having just spent 3 hours outside at minus 12 !
Shilli-Fully Travels 