Aurora Is More Than Just a Name

Contrary to what most people think, the phenomenon of the northern lights is not solely related to winter. Clearly, if you go to certain parts of the world (Tromsø to give a well-known example) you are very likely to see them almost every night during the winter. But it is also true that it is a manifestation that reaches its peak power during autumn and spring. And since the aurora season in Finland is just around the corner, I decided to do a little guide for the uninitiated on how to see them, when to see them and where to see them.

Let's start with some scientific background: what are auroras borealis? In a nutshell, it is a phenomenon caused by the so-called 'solar winds' (i.e. emissions of protons and electrons by the Sun) interacting with the gases of our atmosphere and agitating them until they emit light; but that is not all, it has also been shown that on rare occasions a sound, audible to humans, can be heard. The causes and conditions for which are still being studied.

Predicting the phenomenon is rather complicated in the long term, one can make a statistical estimate based on past years and predict the 'probability' of the phenomenon occurring again, otherwise, another type of prediction that can be made is based on solar activity, but this has a range of about 2-3 days, also because it is still not entirely clear what is behind this complicated phenomenon. Everything is based on how active the outermost layer of the Sun, or Corona, is; the more active it is, the more likely there is of a geomagnetic storm and thus the manifestation of the aurora borealis.

As I said at the beginning, although it is an event associated with winter, its peak intensity and probability of occurrence is during autumn and spring; while during winter and summer, it is weaker or simply not visible due to the long Finnish days.

The best times are between September and October and between March and April; and depending on where you are, you are more or less likely to see it happen.

Clearly, if you are in the north (from Rovaniemi upwards, and thus in Lapland) the probability of the sky being lit up by this spectacle of nature is 3 nights out of 4; whereas if you are in the south (Helsinki or Turku) the probability is roughly 1 in 20 nights, so more or less once a month if the sky is perfectly clear.

As I said before, there is about a 2-3 day range for forecasting the phenomenon, a bit like a weather forecast, and there are several sites and organisations that offer this service.

• https://rwc-finland.fmi.fi/ The space weather centre offers real-time data and information on solar activity and the probability of seeing the aurora in different areas, marked by the observatories located in different areas.

• https://en.ilmatieteenlaitos.fi/auroras-and-space-weather the Finnish Meteorological Institute is less specialised but offers the same service albeit with less depth.

• Finally, the free My Aurora Forecast app, available on both iOS and Android, offers the same data as the space weather centre but with the addition of customised statistics given by location.

Great, now we know when they will happen, but where can I go to enjoy them at their best?

Let's take Helsinki as a reference because it is where I live, but as a discourse applies to all big cities: the further away from the lights the better, it would be even more ideal if there was no snow because it reflects light pollution and makes the sky less clear. Our aim is to see the stars as clearly as possible. A rather good solution would be, for example, to go to the Helsinki Observatory (Kaivopuiston tähtitorni), which is located in a park and being an astronomical observatory is designed with the precise aim of seeing the stars as clearly as possible, so it is an ideal candidate.

If the observatory is too far away for you, keep in mind the first thing I said: the more clearly you can see the stars, the better.

I suggest to bring a mattress to make the most of this incredible spectacle and dress warm enough. Also keep in mind that the forecasts are not absolute and you may be disappointed, but don't lose heart, always keep an eye on the solar wind data, and you will find a clear day with a strong aurora.

More detailed information can however be found on the two sites I mentioned, in case you have any questions after reading.

Good hunt!