I just returned from a trip to the mountains of Alberta and British Columbia in Canada. Without a doubt the Canadian Rockies are some of the most spectacular mountains around. Honestly, I can’t say I’ve seen every mountain on the planet, but I know the Canadian Rockies must rank up there with the best. The area I visited was mostly in the province of Alberta along a stretch of highway known as the Icefields Parkway. I love that name. We have the Blue Ridge Parkway near where I live, which is no doubt a cool place, but Icefields Parkway? That is just plain exotic to me!
My plan for this trip was to see fall colors, mountains, and maybe some snow. Yes, the Canadian Rockies are already getting snow! From a photography standpoint, one of my favorite subjects is fall colors mixed with snow. There was plenty of snow in the higher elevations, but nothing that was accessible. However, even though my plans for snow didn’t materialize, I was treated to an unexpected pleasure: the aurora borealis! Yes! I was far enough north during the recent period of high auroral activity that I could see the northern lights on three different nights. If you have never seen the northern lights, you must get them on your bucket list. They are without a doubt one of the most amazing natural phenomena you’ll ever see.
This image is from Abraham Lake, which is east of the Icefields Parkway. As you can see from the reflections in the water, it was a very calm evening. Across the lake was a line of clouds that darkened the horizon. This image clearly shows the bright green and red colors from the aurora, even though my eyes could not discern the red glow while I was watching the scene unfold over a period of about ten minutes while the aurora was active. I was curious about what causes the colors in the aurora, so I studied up on it. It turns out that the aurora is caused by a complex combination of factors that is not completely understood.
One major factor is the solar wind, which is a stream of energetic atomic particles emitted by the sun. These particles continuously bathe the planets in the inner part of the solar system, including our earth. Most of the time, the particles in the solar wind are deflected around our atmosphere by the earth’s strong magnetic field (this is the same magnetic field that makes a compass point north). Occasionally, though, the solar wind is very intense due to solar flares and is strong enough to partially penetrate our earth’s magnetic field. When this happens, the solar wind particles interact with atoms of oxygen and nitrogen high above the earth near the edge of outer space. As a result, the oxygen and nitrogen become energized and emit light. (Think about this the next time you see a neon sign glowing in the dark…the phenomenon that makes the sign work is the same as the one that causes the glow in the aurora!) It turns out that the emitted light in an aurora is predominantly green, with smaller amounts of reds and rarely some blues. The red color is frequently higher in altitude than the green color, which is clearly evident in my photograph.
A second major factor in the appearance of the aurora is the earth’s magnetic field, which defines the shape of the aurora. This is due to the fact that the energized oxygen and nitrogen atoms have an electric charge, which means they align with the magnetic field lines of the earth. It reminds me of the way iron filings on a piece of paper form arcs when you place a magnet beneath the paper. If you have never seen this, it is a simple experiment. Try it sometime! Ultimately, the magnetic field lines of the earth create the vertical streaks in the aurora that you can see so well in my photograph.
Whew! See? I told you the aurora was complex! It is interesting to me that one of the most beautiful sights in nature is also one the most complex from a scientific standpoint. All complexities aside, I hope you enjoy this image as much as I do!