You’ve probably heard about the northern lights. You may have even been lucky enough to see them. But you probably don’t know what causes them. The northern lights — also called aurora borealis (say "ah-ROAR-ah bore-ee-AH-lis") — are coloured lights that appear in the northern sky. Kind of like nature's fireworks.

So…what causes them?

Photo credit: Trodel via Visual hunt / CC BY

The northern lights are caused by electrons being blown out by the solar wind. Sounds technical, right? Think of it this way: it's like the sun burping out these really small particles (the electrons) into the air. These tiny electrons mix with gases in the Earth’s atmosphere, which makes them glow.

When can I see them?

Photo credit: musubk via Visual Hunt / CC BY-NC-SA

The best time to see the northern lights is when the skies are clearest. Winter and spring — or between December and April — are the best times to see them. You’ll have to stay up late, though. You can see the lights best between 10 p.m. and 2 a.m. (way past your bedtime!). And you should dress warm — the best place to see the northern lights in Canada is way up north in the Yukon Territories, so you're going to get chilly!

Aurora borealis or northern lights?

The auroral borealis in Estonia. (Wikimedia/Kristian Pikner/CC BY-SA 4.0)

They're both right! The name "aurora borealis" comes from the French astronomer and scientist Pierre Gassendi. He called it aurora for the Roman goddess of the dawn, and boreas, which is the Greek word for the north wind.

Northern lights mythology

A painting by Peter Nicolai Arbo of a Valkyrie — a female Viking warrior, 1869, National Gallery of Norway. (Wikimedia/public domain)

There are many different folktales about the northern lights. The Vikings believed that the lights were the reflection of the shields and armour of the female warriors — also known as the Valkyrie — who were immortal, or that it was the Bifröst Bridge that led those who fell in battle to their final resting place in Valhalla.
 

Photo by Joey Gannon licensed CC BY-SA 2.0

It would have been rare to see the northern lights in China, but early Chinese legends about the northern lights have to do with dragons! The lights were believed to be a celestial battle between good and evil dragons who breathed fire across the sky.
 

Photo by bm.iphone licensed CC BY 2.0

There are many Indigenous legends about the northern lights all across North America. Some spoke of them as torches of giants in the sky or the souls of animals they hunted like deer, whales or salmon. Other legends spoke of the lights as a powerful spirit who assisted shamans; a torch-lit path to help souls along their journey; or the light from the fire built by the creator.
 

Photo by Mark Dumont licensed CC BY-NC 2.0

In Finland, where the northern lights are very bright, their myth involves a sly little arctic fox. It ran so quickly across the snow that its tail made sparks fly into the night sky, creating the northern lights. Which makes sense, since the Finnish word for northern lights is revontulet — which literally means "fox fire"!

Did you know?

You can see the northern lights from space. (Photo via Visual Hunt)

• The northern lights appear 200 to 300 kilometers above the earth and are bright enough to be seen from space.
• The most common colours of the northern lights are green, pink, purple, red, yellow and blue.
• You can also see southern lights — or aurora australis (say "ah-ROAR-ah os-traw-lis") — if you’re close to the southern pole.
• Earth isn't the only planet to have auroras — scientists have found them on Neptune, Jupiter, Saturn and Uranus.
• No two northern lights will ever look the same — you will always see different patterns and colours in the lights.
• The northern lights don't just produce beautiful colours, they also make sounds like claps, crackles and static. But these are hard to hear with all the other noise around us.