What are Northern Lights?

The progress of science and technology over the last century enabled us to understand the process that hides behind this spectacular show happening in the northern sky.

Solar storms & Magnetic field

At any given moment, an enormous explosion, called solar flare, takes place on the surface of the Sun and ejects into space large clouds of charged particles, called solar winds. These particles can travel millions of kilometers, and some may eventually collide with the Earth. On average, it takes about two days for these solar winds to reach our planet. When it does, most of these charged particles are deflected away, but some become captured in the Earth’s magnetic field, accelerating down towards the north and south poles into the atmosphere. This is why aurora activity is concentrated at the magnetic poles.

These particles then collide with atoms and molecules in the Earth’s atmosphere and basically heat them up. This physical process is called "excitation". Therefore, when observing the northern lights, we are seeing atoms and molecules in our atmosphere colliding with particles from the Sun. The aurora's characteristic wavy patterns of light are caused by the lines of force in the Earth’s magnetic field.

Shades and colors

The aurora's most common color is green. However, some displays of this phenomenon can sometime show hints of blue, purple, red or even white. The secret behind these different shades of colors lies in the composition of the atmosphere. As you may know, the Earth's atmosphere is divided in many layers. We live inside the Troposphere, which is the first layer (or last if you come from space) of our atmosphere. It is where clouds are formed because this is where most of the water can be found. In order, the next layers are the Stratosphere, Mesosphere, Thermosphere and Exosphere. The northern lights occur inside the Thermosphere, which lies approximately between 80 and 600 kilometers vertically. The auroras most often appear at altitudes of 100 to 300 kilometers in the atmosphere, but can reach altitudes of up to 600 kilometers from the ground.

The composition of our atmosphere consists mainly of various amounts of different gases including Nitrogen, Oxygen, Argon and Carbon dioxide, all of these being at various different levels in the atmosphere. Different gases in the Earth’s atmosphere give off different colours when they are excited. Oxygen gives off the fluorescent green color of the aurora when it collides with charged particles at about 100 to 300 kilometers up in the atmosphere. However, at higher altitudes (300 to 400 kilometers), Oxygen is less concentrated and is excited at a higher frequency, producing a red color. When solar particles collide with Nitrogen in Earth's atmosphere at an altitude of 100 kilometers or less, it causes purple colors and sometimes blue.

How to see them?

Northern Lights can occur any day of the year, any hour of the day. However, in order to see them, there are a few components that need to align.

Night sky

To be visible to our eyes, we need the dark night sky to be our background. That's the reason why winter is the best time of the year to see northern lights. Autumn and Spring can also offer beautiful display of auroras but there is a shorter time span to see them.

Clear sky

Auroras happen in the Thermosphere. Clouds happen in the Troposphere. Therefore, a cloudy sky will block our views of northern lights. As guides, we use cloud coverage forecasts to figure out where is the best location to see northern lights and is often our main concern when it comes to probability of seeing the auroras.

Solar activity

This goes without saying. As explained before, northern lights are the consequence of solar flares. There is no absolute rule regarding this, but on a general basis, the higher the solar activity, the higher the chances to see auroras.

Light pollution

Just like for gazing at the stars, the further away from light pollution, the better the view will be. Light pollution can come from either city lights, but also the moon. Would you be able to see northern lights even on a full moon, or close to a city? Short answer is yes, but only with a higher solar activity, and even then the northern lights would look dimmer than what it actually is.

Clear view

This one is also obvious. One must be able to see the sky. When hunting for northern lights, it is a good idea to have as much visibility as possible, especially facing north. Therefore, one must avoid forest areas or being inside a city where building can block the views. Lakes or swamps are great locations to see the auroras.

Myths and Legends

If you've ever been fortunate enough to witness the northern or southern lights in person, it likely won't surprise you that they have inspired countless myths and legends around the world.

Sámi

For the indigenous people of northern Scandinavia known as the Sámi, auroras are considered to be the souls of the dead. They are both feared and respected in equal measure. It is believed that if you catch the attention of the aurora, it could reach down and carry you off into the sky. Therefore, the Sámi people try to keep a low profile when the northern lights are dancing in the sky. That means no big gestures, whistling or singing. Even to this day, many Sámi stay indoors when the auroras are out.

Vikings

Contrary to the Sámi, the Vikings celebrated the northern lights. It meant that their god Odin had sent the Valkyries, described as female warriors riding on horses through the sky, to retrieve the souls of fallen warriors in order to take them to Odin's hall Valhalla. They believed that the aurora was light reflected off of the Valkyries' battle armor.

Finns

In Finnish, the name for the northern lights is "Revontulet", which means "Fox Fires." The name comes from an ancient Finnish myth, in which the lights were caused by a magical fox sweeping his tail across the snow scattering it up into the sky.

North American Tribes

Many North American tribes also have their own myths and legends when it comes to the aurora. The Cree Indians believed that the northern lights are the spirits of the dead trying to communicate with loved ones still on Earth. The Algonquins' belief was that the auroras are from a fire built by their creator Nanahbozho to remind them that he is watching over them.