If your lifetime dream was to see the Northern Lights, it's time to plan your next trip. Despite still not all of the phenomena connected with it are explained, it is known to be caused by charged particles emitted by the sun during solar storms: when the solar wind reaches and hits the atmosphere of the earth and his magnetic field, the Aurora is displayed. It is a 3-D phenomenon and can be seen even from the space.
The Aurora is always different in shape, color and movement, and when it is really quiet if you listen closely you can sometimes hear the voice of the Northern Lights: a sparkling-crackling noise.
First of all it depends on luck: I saw my first Aurora Borealis in August 2007 in Lofoten Island (Norway), when it's usually very difficult to see it because there are almost 24 hours of daylight. I was so impressed that I started to cry while watching it. From that moment started my love for Northern Lights.
Of course there is no schedule to see Northern Lights, since it's a natural phenomenon, it's not like TV programs with fixed hour. But there are some rules that can help to establish the perfect moment to go and see it: if you choose a good place, it can statistically be visible every second night.
Solar activity has a cycle of 11 years, and scientists say that between 2012 and 2013 one peak was reached. This mean that also the Northern Lights reached their maximum glory in those months: now the activity will decrease again in some years to the minimum and then raise again to reach his next maximum in 2023.
Activity is classified through an index called "Kp Index" that is going from 1 to 9 and measures perturbation in the earth's magnetic field. The higher the index, the higher the possibility to see the Aurora.
Despite Northern lights are theoretically happening all year round, they are not always visible: in fact during summer in northern latitudes there are almost 24 hours of light, and since Aurora Borealis is visible only with a dark sky, there are not many chances to see it, despite still being possible. But if you want to maximize your opportunities, you better go between September and March, when there are minimum 12 hours of night. Statistically it has been observed that the activity is rising in proximity of spring and autumn equinox, so end of September - October and March are considered to be the best months. From my personal experience I would suggest to go in October, because the climate is usually milder than in March, and if you decide to extend your stay, the nights will get longer instead of shorter, and you'll have more chances to see it.
As for the weather forecast, there are services that predict the Aurora Borealis - Aurora Australis and sun activity with 2-3 days in advance, so giving a look at these websites can help to understand if it's better to go to sleep, or stay awake with the eyes at the sky.
These are two of the most famous and reliable websites:
Another nice service is the "All sky camera" a live view of the sky taken from a webcam or from a camera and continuously updated over Internet. This way if you are lazy, you can comfortablystay in your room and look at Internet to decide when to go out. These are two of them but you can find more in other cities googling for them.
Kiruna All Sky Camera
Abisko live camera
This is actually one of the main variable that will affect your choice: in fact even if you chose the best place to go in the best period, if it's cloudy you cannot see the Aurora, even if it's happening. So you better check the historical statistics of average climate, rainfall and sunny days of the place of your choice to understand if it's a good option or not. Lofoten Island in Norway in example, despite being a very good place to spot Northern Lights, are ofter very cloudy and rainy.
If you ask to some locals when is the best moment to see Northern Lights, they will tell you when it's getting really cold. This is half true: cold has only an indirect relation with Aurora. In fact it's getting really cold when the sky is clear, and there are no clouds to reflect back the heat to the earth. So basically it is more visible when it's really cold, only because it means that there are no clouds, but it has nothing to do with the temperature.
The first rule is to find a place with a dark sky. I mean a very dark sky. If you can see naked eye the Milky way, that is worth the trip itself, it means that you are in a good spot.
Once I was in Björkliden, in Swedish Lapland, a small town with just 20 permanent residents. You could think this would be a great place to see the Northern Lights: but if the sun activity is low, even a few houses can preclude your long time searched experience. So from there I decided to climb for one hour the mountain at night (I first explored the area during the day to make sure it was safe and to find a good spot) and from there I had an uninterrupted show of 6 hours of Aurora Borealis, despite the Kp index was very low at 2. I was later told that from the village they didn't see anything. So just go away from civilization.
Even the moon could affect the visibility, so you better check also the moon calendar. If the solar activity is supposed to be low, better to try without moon to have the darkest sky possible; if the activity is going to be high, it will still be ok with the moon, and actually even better with some added charm to the view.
Auroras are visible from a belt called "Auroral Oval" that is not fixed and changes according to the activity of the sun. The highest chances to lie under the oval, are obtained at about 2500km from the magnetic poles
Famous regions to see the Aurora Borealis in the Northern Hemisphere, are Alaska and Scandinavia. This not only because they are in a good location, but also because they are easy to reach and at an affordable price, and they can offer structures and entertainment to visitors. Other known destination are northern Canada, Greenland, Iceland and north of Russia.
Despite theoretically it's possible to see the Aurora also in the southern hemisphere (in this case it is called Southern Light or Aurora Australis), it is more difficult because there is not much land at the extreme south: if you look at the world map, the Antarctic Circle is only going through the sea, the only close options being Patagonia and Antarctica.
There are several places known to be good base point to hunt for Auroras.
In Europe see the Northern Lights in Norway is quite common, and Tromsø is known to be the city of Northern Lights, and despite having quite a lot of light pollution, you have good chances to spot it if you move a little bit far from civilization.
Abisko in Swedish Lapland is much smaller and known to have an Aurora show every second night, and can offer also some other activities like skiing and hiking.
A non complete list of other good places in Scandinavia is Björkliden, Kiruna, Gällivare, Kalix, Överkalix, Jokkmokk (SE), Lofoten Islands (NO), Haparanda, Tornio, Rovaniemi, Kemi (FI).
second trip to see Northern Lights in 2012, with some amazing displays of Auroras.
You can see more photos of my trip to the northin 2010 in the album of Sweden and Norway, but much more still have to be uploaded!
For photographic tips I suggest you to check the article I wrote for a Photography website wrote for a Photography website.