Sparks of light

Did you know that the Northern Lights also occur in the summertime but, as it’s so bright in Northern Norway in summer, they’re invisible? Or that the Northern Lights are produced by millions upon millions of atoms lighting up at the same time?

Tromsø is situated directly beneath the Auroral Oval. Even the smallest appearance of the Northern Lights is visible here, making Tromsø an ideal place to observe them – as scientists have from day to day for a century. But what exactly are auroras? Where do they come from? And where’s the best place to see them? 

We sat down with Per Helge Nylund of The Arctic University Museum of Norway to learn more about the fascinating phenomenon of the Aurora Borealis.

Luminous atoms

“Many have thought that the Northern Lights are produced through refracted sunlight, like rainbows are,” explains Nylund. “But they’re not – they’re formed by energy from the sun. Simply put, the Northern Lights appear when gases in the Earth’s atmosphere are bombarded with particles – electrons – from the sun and begin to glow as a result. The Northern Lights we see are simply illuminated gas. And that gas is part of the Earth’s atmosphere.”

A mass of tiny electrons flows from the sun in all directions into the cosmos, he explains, adding that some collide with the Earth. As the Earth has a magnetic field, the electrons are directed towards the polar areas and strike in a circle around the geomagnetic north and south poles. This is the reason why there are no Northern Lights at the equator.
“The particles from the sun arrive at very high speed and crash into the layer of gases in the upper atmosphere. When a particle smashes into an atom, the atom’s surplus energy makes it unstable. It develops ‘existential problems’. An atom has few means to get rid of energy but it can emit a small flash of light. So, to rid themselves of their energy, atmospheric atoms begin to glow. When millions upon millions of atoms shine at the same time, we can see the light from the ground,” Nylund says with a smile.

During many years as a communication consultant, Nylund has told countless children, adults and (not least) journalists what the Northern Lights are, with great enthusiasm. He has a unique ability to explain the phenomenon in an easily understandable way.

"The Northern Lights occur because the Sun blows kisses to Earth"

“Once I was interviewed for Japanese children’s TV and had three seconds to explain what they are. I said that the Northern Lights occur because the Sun blows kisses to Earth.”

Different gases produce different colours

Nylund says that the process of an atom producing light after being struck by an electron takes less than a second – a long time in the atomic world. And since there are many millions of atoms illuminating together, it looks like the light is moving.

“When the Northern Lights dance across the sky, what we are seeing, simply, is a huge number of atoms coming alight, one after another. It’s totally crazy when you think about it,” says Nylund.

- Why do the Northern Lights have different colours? 
“Different elements of gas burn with a different colour. The green light results from oxygen atoms burning with a green colour. And if the Northern Lights are green with a little pink below, there’s nitrogen burning pink and purple. The Northern Lights change colours where two different elements meet. It’s interesting that the colour says something about how high the Northern Lights are, too. The border between green and pink light is 100 km above the ground.”

Northern Lights research

At the turn of the last century, Norway’s leading researcher of the Aurora Borealis was Kristian Birkeland (1867–1917). The founder of the first Northern Lights observatory in Alta in 1899, Birkeland discovered, among other things, how the Northern Lights are associated with magnetic currents in the upper atmosphere. In 1918, a geophysical observatory opened at Prestvannet in Tromsø and, 12 years later, the Northern Lights Observatory opened in the same place.

In 1928, some small buildings for housing instruments were erected as a part of the observatory – without nails, since metal can affect the measurements. Constituting a completely unique environment for scientific research in Norway, these protected buildings remain at Prestvannet, just like they were when they were erected. “If something from Tromsø were to be inscribed on the UNESCO World Heritage List, it would be this place,” says Nylund. 

Research into the Northern Lights still continues in Tromsø, and UiT Norway’s Arctic University is at the forefront of knowledge.

“While we know how the Northern Lights are formed, now we’re investigating how they affect other things, such as space weather, and whether they create sound. There are people who say they have heard the Northern Lights while standing on the Finnmarksvidda plateau. Science can’t explain it yet, but there are many theories. Pretty cool!” says Nylund.

If you want to see the Northern Lights, Nylund has no doubt where you should head to. “Prestvannet is the place to be. That’s the spot in Northern Norway specifically chosen for the study of the Aurora Borealis. There are a few more buildings and a bit more light up there now, but the top of Tromsøya is a good place to see the Northern Lights. There’s nowhere else in the world where they’ve been studied more than they have up there!”