Lecture gives insights on science behind aurora


If you grew up an aurora watcher, there is a good chance that much of the science of how the dancing lights function are above your head.

In fact, much of the origin of the curtains of green, and streaks of reds and purples that light up northern skies still baffle leading scientists.

Dr. David Knutsen, an auroral scientist from the University of Calgary spoke to about 40 people at the Prince of Wales Northern Heritage Centre March 3 as part of the second annual Naka Festival. He also visited students at St. Patrick High School earlier in the day.

The festival, which runs from March 2 to 7 in Yellowknife, celebrates the culture around the aurora and is named after the Willideh Yati word for the dancing lights.

Dr. David Knutsen, an auroral scientist from the University of Calgary.
Simon Whitehouse/NNSL photo

Knutsen gave an overview of Canada’s space history.

He explained how the history of imaging of auroras has evolved over the latter part of the 20th Century and how the advancement of instruments like charge-coupled device (CCD cameras) and e-pop (enhanced Polar Outflow Probe) satellites along with rocketry have helped understand what is accelerating the charged electrons that make up auroras.

He noted that aurora research is still an active area of research in science.

“Certainly with all of this richness and structure, it is still an active area of research to find out how (aurora) patterns are made,” he said, noting there are many misconceptions about the aurora and and areas that have to be better explained.

Knutsen called into question basic textbook definitions of the aurora and said they are often oversimplified.

The Encyclopedia Britannica, he noted, for example, states that “auroras are caused by an interaction of energetic particles of solar wind with atoms of the upper atmosphere” and that “particles are driven by the solar wind and captured by Earth’s magnetic field and conducted downward toward the magnetic pole.”

In fact the process is much more complicated.

Among the highlights of the presentation included the definition of solar winds and how the aurora source replicates a battery with super charged particles that travel downward into the Earth’s atmosphere.

“I believe there is an analogy between these waves and what is happening inside those huge electrical currents flowing through space,” he said. “I think the aurora is ripples in those currents just like these waves are ripples in a flowing river. ”

Knutsen made note of Canada’s contribution to rocketry since the Space Age, including the Alouette satellites of the sixties and the development of the Black Brant rockets first designed in that same decade.

Part of the presentation also showed how raw data of ions in the ionosphere are pulled from 20 minute rocket launches and examined. This ultimately helps scientists understand what it is that accelerates electrons into the ionosphere to create auroras.

Citizen science and STEVE

Knutsen also commended citizen scientists, such as the Alberta Aurora Chasers who advance questions in the field in coordination with satellite imagery. In 2018, the group, which now numbers 20,000 discovered the atmospheric phenomenon STEVE (Strong Thermal Emissions Velocity Enhancement) which is believed to be streaks of hot purple plasma travelling in the opposite direction of how electrons or ions precipitate to earth.

A photo of STEVE, which is characterized by its pinkish/purplish glow. The phenomenon is considered almost an anti-aurora because unlike the green ones that are common, electrons don’t precipitate into the ionosphere from space.
photo sourced from Wikipedia.org

“As I have said, the aurora is part of an electric circuit and we are seeing the electric current,” he said in reference of a photograph of the purple aurora. “But here is the problem – that current  is pointed in the wrong direction.

“Whereas the aurora is caused by electrons shooting down into our atmosphere, these electrons to make that current have to be going the other way. So it is like anti-aurora or opposite aurora and it makes that purple glow.

“The thinking is that it is so hot inside there that it is causing a very characteristic purplish glow but it is still the case here that the theory can’t exactly describe what is going on.”

The identification of STEVE as a phenomnen different from a typical aurroa was made by the Alberta Aurora Chasers in 2018. The identification was commemorated by a commemorative coin by the Royal Canadian Mint.
photo sourced from the Royal Canadian Mint website

Bill Braden, a Yellowknife-based photographer who hosted a photography session involving aurora at the heritage centre earlier in the week attended the lecture. He said he thought Knutsen added a simple explanation to a complex subject and provided an important highlight for the festival.

“He’s one of the world top guys looking at phenomenon of solar energy and not just aurroa but the whole field of solar behaviour and how it works with the Earth,” he said. “He is taking extraordinary complex piece of physics and making it quite understandable.”

Braden, a longtime Yellowknifer, said locals can take the aurora for granted and it is iti s a great benefit to have a festival around it to appreciate the unique phenomenon.

“I think the idea of having a festival is great and something to bring a focus to because the locals we tend to sometimes take it for granted,” he said. “The appreciation of it as an industry makes a big difference in town. it is worth celebrating and bringing some knowledge and appreciation.”

Knutsen’s presentation was supported by the Astronomy North Society and the Canadian Space Agency.


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