The Northern Lights are the stunning beams of light that dance across the arctic skies in winter. From vivid greens, to deep purples, vibrant pinks and the occasional yellow lining, the northern lights really do inspire the viewer when they are at their best! But, have you ever wondered what these magical lights actually are? This post is here to explain the science in an easy to understand way.

Lets first get into what the Northern Lights are. The short answer:

The Northern lights, or Aurora Borealis, are the result of electrically charged particles being sent from the sun, called solar winds.  These solar winds then interact with oxygen and nitrogen in our atmosphere, creating (mostly) green light.

Simple, right?

Maybe not. So let’s delve deeper into the mysteries of this winter light show.


Where do the northern lights begin?

Let’s start with the electrically charged particles. You may have heard that it takes just a few days for solar winds to get from the sun to earth. Well, sort of. It takes that amount of time for them to get from the sun’s surface to earth. However, the story began long before that. Up to a million years before that in fact.

So, a million years ago or so, the massive nuclear fusion reactor, that we happen to call our Sun, condensed a few basic elements. The sun managed to smash them together and in the process created a vast amount of by-product. This by-product was mainly energy and fast moving particles.

Iceland Northern Lights and Starry Sky | Hidden Iceland | Photo by Brendan Bannister

The particles escape the sun

These by-products were really excited about their new existence and wanted to share it with the universe. The only problem was that it was at the center of an incredibly dense star. So, just like being late for work and trying to get your train in a crowded station the particles started pushing their way out banging into everything it could at lightning speed. Eventually the particles make their way to the surface. Now it’s time for them to escape. Despite the huge amount of gravitational pull on these particles some manage to escape the surface.

The particles that escape are mainly electrons and protons. These particles make up what is commonly referred to as solar winds. Which eventually become the northern lights. When it is accompanied with light and heat on the surface of the sun it can also be called a solar flare, though these are a little different.

These solar winds can vary in their density and speed. But generally they will make it to earth’s atmosphere in around 2 days. A high speed and high density solar wind is called a solar storm. So, the next time someone tells you that it takes only a few days to get to us you can say, “well yeah, a million years and a few days actually.”

The solar winds reach our atmosphere

Earth impact! After the two days of travel the electrically charged particles (or solar winds) reach us. Or more accurately, our atmosphere.

Interesting fact about our atmosphere. If you squeezed all the particles together to the density of concrete it would be a 15ft thick wall all around the world. It’s our invisible force field. Our shield from everything the sun and solar system throws at us. Without it life would not exist. It is also what creates the northern lights effect.

The magnet field (magnetosphere) is our protective coating around the atmosphere and is able to redirect or repel a lot of the cosmic radiation. Without this shield satellites wouldn’t function, electrical grids would be disrupted, and things like air transit would be impossible.

So when a particularly strong solar flare or solar wind hits us it could potentially be quite damaging. Luckily the majority of these particles are redirected back out into space and around us. The small remainder that enters our atmosphere create what we call the northern lights or aurora borealis

Northern Lights over Jökulsárlón Glacier Lagoon | Winter Lights photo tour with Tom Archer & Wahyu Mahendra | Hidden Iceland | Photo by Tom Archer

The northern lights are formed

The northern lights occur around the poles of the earth (yes, North and South Pole) because the magnetosphere is less strong around those areas and absorbs more of the cosmic radiation.

Finally, the colours are produced because the electrically charged particles react with, mainly, oxygen and nitrogen in the atmosphere. Though there are reportedly many different colours, the majority of light shows are green or pink. The green light is from the reaction with oxygen and nitrogen. The pink is from the reaction with oxygen much higher up in the atmosphere, and is a lot less common.

Seljalandsfoss Northern Lights | Winter Lights photo tour with Tom Archer & Wahyu Mahendra | Hidden Iceland | Photo by Tom Archer

That’s it!

Next time you are lucky enough to see the northern lights try to think about how this glimmer of light is a stark reminder that our little planet is always being bombarded, and affected by everything in space. And thanks to our amazing atmosphere we are always protected.

Now that you know all about this wonder of nature, I bet you want to to know how you can see them? You can read all about that here, or have a look at this tour, which has a chance to see them in winter. Or if you are out on your own you can check out the most up to date forecast here.


Ryan (1)

Hi I’m Ryan Connolly, I’ve guided in multiple countries and spent the last three years travelling across the globe. I have spent the past 2 years studying everything related to glaciers, climate change, and Iceland in my spare time.


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