How does light pollution impact seeing the Northern Lights?

To be able to see the Northern Lights, a number of factors come into play. Firstly, the season is important: you need to time your visit to the Reykjanes peninsula for some time between late August and mid April to give yourself the best chance of the aurora borealis being visible.

It’s occasionally possible slightly earlier or later in this period. However because the sun sets late in the middle of an Icelandic summer and rises very early, in midsummer the skies never truly get dark. Light isn’t your friend when it comes to the Northern Lights, which we’ll explain in more detail a little later on.

Solar activity is also crucial. The higher the levels of solar activity, the greater the chance of the Northern Lights materialising. We measure this using something called the Kp index, which scores solar activity from 0 to 9. The higher the number, the stronger the aurora is predicted to be. It’s rare to have a forecast at the top of the scale, but even if there’s only a slight chance, in northerly latitudes such as Iceland you may still catch sight of the aurora.

Clear skies are another must. The Northern Lights occur high in the earth’s atmosphere, while almost all of our weather happens much closer to the ground in the troposphere, which is the lowest level of the earth’s atmosphere. Clouds form in this layer. The thicker they are, the more they obscure what’s going on above them. So if there’s enough cloud in the way, you won’t see even the most spectacular Northern Lights displays.


The impact of light 

You can be forgiven for thinking that the aurora is a seasonal phenomenon. We read a lot about Northern Lights season, and how the aurora doesn’t materialise in summer. Yet, this is actually a misnomer, as it refers to when we typically see them rather than when they occur.

Solar activity, in the form of solar flares and coronal mass ejections, occurs throughout the year. These explosions of energy excite gases in the earth’s atmosphere such as nitrogen and oxygen; when they return to their normal state, they give off coloured light which we know as the aurora.

Even when conditions are looking promising, to be able to fully appreciate the intensity and colours of the Northern Lights we need to look at them against a dark background. So during the day, or during light summer evenings, even though it’s happening we aren’t able to see enough contrast to get a view of it.


Light pollution of whatever kind is problematic

If the sky is light, for whatever reason, our eyes cannot pick out the colours. So for instance it’s a good idea to avoid a full moon if possible when scheduling your Northern Lights trip to Iceland as the light from the moon, accompanied by stars, will make the night sky much brighter.

We’ll find a similar issue within urban areas. When we talk about light pollution we mean the alteration of outdoor light levels as a result of human action. In other words, light levels that differ from those occurring naturally. In towns and cities, there are streetlights, illuminated signs and other sources of light such as vehicle headlights.

According to estimates, more than 99% of people living in the USA and Europe do so under light-polluted skies. The impact of such light pollution extends beyond town and city limits, creating a light glow in the sky that can be seen out in the countryside, impacting the amount of darkness there as well.

 
Population distribution matters

Back in 1950, around 70% of the world’s population lived in rural areas. Over time, urbanisation has increased and by 2030, the United Nations estimates that around 60% of the world’s inhabitants will be city dwellers. Iceland’s no different; in fact, its population distribution is broadly in line with the global picture.

According to the latest figures from Statistics Iceland, 63% of the population live in the capital region (the continuous area of settlement from Hafnarfjörður to Mosfellsbær), equating to 239,733 people. No wonder that there are so many bright lights in this part of the country.

Any light, whether from natural sources or the actions of people, washes out the night sky to a greater or lesser extent. Sources of artificial light can temporarily blind us with their glare, making it difficult to see the aurora borealis. However, the good news is that it’s not impossible to see the Northern Lights, even within a city under a full moon.

If you can find a place where you’re out of direct light, for instance using a building to shield you from the source of the light, it can make things a little easier, particularly if the Northern Lights are especially intense. Move around between different spots until you find somewhere suitable and let your eyes adjust again to the darkness.

 
Reykjanes boasts many dark places suitable for glimpsing the Northern Lights

In comparison to the capital region, the Reykjanes peninsula is sparsely populated, particularly if you omit Keflavik and neighbouring Njarðvík (whose combined 2024 population is 21,847). This means it’s comparatively easy to get out of the way of manmade sources of light pollution and find a dark spot to wait for the aurora to show up.

Some of the best spots are along the peninsula’s unspoilt coastline. One favourite is at Garðskagi, close to the old lighthouse. Alternatively, the Krýsuvík geothermal area is another possibility. You also might see them above landmarks such as the Bridge between Continents. But so long as you can park safely and have an uninterrupted view of the sky, there are many suitable spots for Northern Lights viewing throughout this part of Iceland.

 
Enlist the help of technology

NASA observes all manner of things in space, and the Ultraviolet Imager of its POLAR satellite is capable of seeing the aurora even in daylight conditions. This works by screening out the sunlight. In the false colour pictures it publishes, the strongest aurora show up in red and less intense showings appear blue.

As individuals, we don’t have access to such technology of course when we set out on our Northern Lights hunt. But we can get a helping hand thanks to something much more affordable. Viewing the sky through the viewfinder of a camera or the screen of a smartphone can help enormously. In doing so, it transforms what can look like something pale and grey moving across the sky into the colourful green and purple displays that have lured us outside in the first place.

So even in our light-polluted world, there’s still a chance to experience the magic of the Northern Lights. Heading out to an uninhabited spot such as in Reykjanes is a good start. Pick a moonless night when there is a forecast of strong solar activity and of clear skies, which gives you a good chance of seeing this incredible celestial phenomenon.

If you are lucky enough, the memory will last you a lifetime, though we should probably warn you, catching sight of the Northern Lights in Iceland is addictive and you may want to return over and over again.