Quite often when you are heading to northern lattitudes, places like Norway, Canada or Iceland you will come across a lot of pictures of Aurora Borealis. You will see postcards with night skies filled up with amazing green lights.
But what is it? And what does it really look like to naked eye?
To keep it simple I will just say that this phenomenon is caused by particles blown away from the sun, which we call solar wind. When it reaches the Earth’s magnetic field it can set the sky ablaze! However it does not happen every night. Even if you go as far north as Tromsø in Norway 70°N.
Lady Aurora – will “she” be visable?
There are quite a few factors that can determin if you will be able to see the show.
We can divide them into 2 groups: sun raleted and Earth related.
The brightness and speed of Aurora moving throughout the sky depends on speed, dencity and velocity of solar wind. Earths magnetic field can have northern and southern spin, when it doesn not match it will push solar wind away from the atmosphere.
The last one is probaly the most annoying one. Even if the rest of the factors point to astral firework show your view can be obstructed by clouds.
When does it happen?
Does it happen only in winter, or only in the night? Hell no, it happens all year round, but we can observe it only in winter because we need the night to be dark. In summer beyond the arctic circle the sun does not go down at all.
This is why Aurora Hunters venture into cold winter darkness.
So now that you now how many different criteria need to be fulfilled you know it is not that easy, even if you are in the right place. Speaking of which, if the sun is very active and the solar wind is really strong you can see The Lights as far south as The Yellowstone NP 44°N. This is quite a rare event, for example in winter 2014/15 it happened just few times. Aurora can be just a faint green light or a pale rainbow moving through the sky, or sometimes it can dance all around the sky. The color of the lights depends on which element of the Astmosphere was affected by the solar wind. Neons works the same way. Different gases shine in different colors.
Aurora Australis which illuminates the southern sky tends to be more pink, while Northern Lights are mostly green. Don’t take it as a rule tho!
Aurora-service and a KP index
If you want to find out which night is the night I would suggest observing this webside. Aurora-service provides you with viral info about current conditions. However we still do not know how to predict sun’s activity in the future so you can only catch a glimps for 3 days ahead. You can see there current kp index. The higher it is, the stonger the solar wind, therefore you can see brighter lights and they can be observed further south.
Check the weather conditions first!
Before you leave your cosy, warm apartment and venture to cold, winter night don’t forget to check the cloud coverage in the region. When you are in tourist destinations there will most likely be companies providing some sort of “Aurora Experience”. Prices may vary due to locations and group sizes but they are usually quite high. You can rely on the experience of your guide or try your own luck. It is entirely up to you. Good luck hunthing the Lights!