They can be seen from space and 5 other things you didn’t know about the northern lights

David Suzuki remembers seeing the northern lights for the first time while camping in northern Ontario as a 15-year-old, “I just lay back and enjoyed this incredible show, and I’ve been enchanted ever since.”

In the early 17th century, the Italian astronomer Galileo gave them the name aurora borealis, from the Roman goddess of the dawn and the Greek name for the north wind. But we know that they’ve been observed by Northern peoples who have oral traditions about them that go as far back as 700 AD.

Northern lights touch everybody that sees them. They exist in the south too, of course (the aurora australis), but since fewer people live near them in the Southern Hemisphere, it’s the borealis that gets most of the love. 

In the Nature of Things documentary, The Wonder of the Northern Lights, Suzuki joins an international team of aurora-chasing experts to solve its mysteries.

Here are some things we learned.

The vivid colours are caused by different gases in the atmosphere

The northern lights shine in vivid greens, reds, blues and purples. Solar wind from the sun is funnelled by our magnetic field to both poles where it collides with gases in our atmosphere. 

The particles in the solar wind stretch out like a plastic band gaining energy and when they finally snap back, they release that energy and create bright bursts of colour. Nitrogen shines as violet, hydrogen as blue and oxygen as green and red. 

In fact, the lights can occur at any time of the day, but we can’t see them unless it’s dark.

The lights appear to dance in the sky

Until recently nobody knew why the aurora shifted and danced across the sky. It wasn’t until information from a fleet of satellites, and a team of ground-based observers, was combined. They found that radio waves out in space, called "Chorus", that act like a switch, causing the lights to flicker.

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Auroras come in a random assortment of shapes

Most of the time, the aurora is happening off in the horizon and looks like a curtain of light. Other times, you’re directly underneath, and it looks like giant a crown with light spreading out in all directions or arcing over the night sky like a rainbow. The shape depends on where the person is standing — two people can look at the same Aurora, at the same time, but experience it very differently.  Scientists also believe that the strength and speed of the solar wind may have an impact too.

The lights can move south

Occasionally, auroras are visible far from the Earth’s poles. The size of the event depends on how strong the solar winds are, and during super solar storms, auroras can be seen much closer to the equator.

In 1859, the earth was hit with a very powerful solar storm and records show that people witnessed the lights as far south as the Caribbean! Today, a solar wind that strong could cause a power surge to our electrical grid, causing power loss. Of course, the upside is very dark skies which would make the lights even more visible and beautiful. 

The aurora is visible from space

At an orbit thousands of kilometres above Earth, the aurora looks like a flickering crown around the poles of our planet. NASA has a fleet of spacecraft orbiting Earth to watch and measure the aurora and astronauts on the International Space Station often see them from the same distance, observing them from the side, not just from below like as we normally experience.

Other planets have auroras

Saturn and Jupiter have beautiful auroras too, more powerful than Earth's though, because these planets have stronger magnetic fields. Auroras shine not only with light but also with radio waves, which allow scientists to detect them far away in deep space using a radio telescope. 

Since auroras are a sign that gases like oxygen are present in a planet’s atmosphere, they could be an indicator of alien life. Scientists are now scanning the stars and distant planets, compiling a list of other worlds that shine with the green glow of oxygen.

Watch The Wonder of the Northern Lights on The Nature of Things.