Here's why the northern lights have been illuminating Alberta skies

Emerald green, royal blue, bright violet, even some red and fuchsia they're all colours that many Albertans saw illuminate the night on Thursday as the aurora borealis became visible from many people's homes.

It was part of a particularly special stint of northern lights that have been illuminating Alberta's skies over the past week, and one scientist says a light show like this is rare.

"Twice in one week, that's really amazing," said David Knudsen, a professor and the head of the physics and astronomy department at the University of Calgary.

But why have the northern lights been so visible across the province this week?

This week's lights have been reported as far as Arizona and even parts of Italy as of Friday, and Knudsen said Thursday's display is thanks to an "extreme" magnetic storm that occurred in the Earth's atmosphere.

"Normally the aurora forms in rings around the north and south magnetic poles, and those rings are much higher latitude than Calgary," he said.

"But when things become active, the rings broaden and they push southward. That's where the electric currents that caused the aurora to thread through our upper atmosphere, and its electricity in our upper atmosphere that is what the aurora is really all about."

According to Knudsen, the sun typically goes through an 11-year cycle of activity at the moment, the sun is also particularly active.

It's because the sun is approaching the peak of its cycle. It's producing solar particles that are hurled toward the Earth by an explosion of energy onthe sun known as a coronal mass ejection.

The scientist explained that when these charged particles meet the Earth's magnetic field, electric currents that circulate through space are then generated.

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He says there's "something very fascinating that's happening not too far above our heads in the upper atmosphere," but the science behind what makes the northern lights dance and streak colours across the sky is still being explored.

"That part of it is the one that's not really understood yet, and that's why we still have research in this area. We don't know what's actually forming these characteristic shapes."

As for the colours, there is an answer for what's producing those intense hues, and Knudsen says it's about the chemistry of gases mixing with electrons in Earth's upper atmosphere the intense red and green streaks many Albertans saw are actually caused by oxygen.

"All the oxygen in our atmosphere actually comes from life on Earth. So in a way, the aurora is lighting up the breath of life on Earth," said Knudsen.

"It's a signature of the fact that there's life on Earth, but it doesn't hold true for all planets other planets have auroras from different gases, that doesn't mean that there's life there, but on Earth it's really showing us the oxygen."

Displays could continue into next year, says professor

While there are certain aspects of the northern lights that haven't yet been fully explained, scientists are still able to predict these enhanced northern lights events in advance.

Because of that, aurora borealis watchers and local photographers in Alberta have been excited for a while to get the chance to see this week's show in the sky.

Calgary-based photographer Matt Melnyk told CBC Radio's The Homestretch that the northern lights he saw earlier this week were a once in a lifetime experience.

"I saw stuff I never thought I'd ever see in my life. It was absolutely incredible," said Melnyk.

"The first thing that I noticed that blew my mind was these dark [but] bright reds that were visible to the naked eye. I've been shooting aurora for 17 years and the camera picks it up, but I'm never able to see it with my naked eye like that."

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For those hoping to get into northern lights photography, Melnyk said usually it's easiest to leave the city and find a dark place perhaps near the mountains to get a good view of the night sky.

However, if you're someone who missed the northern lights this past week, don't worry according to Knudsen, the peak of this extra sun activity could extend into next year.

"You're in luck because we don't know that we've reached the peak yet," he said.

"There's still more to come, and even if we're at the peak, it's kind of a slow decline there's always a chance of aurora because there's always a chance of some enhanced activity at the sun."