This week, for the first time in quite a while, I stood in the rear garden of my home in Canada in anticipation of an approaching solar storm, and it promised to be a good one, however, very often the promised aurora can fall flat or not show at all, but as you can see in the image below, not this evening.
This evening as waves of electrified gases raced through space on the solar wind, some of that energy was captured by earths magnetic shield and pulled down magnetic field lines at the poles. Once funnelled into the polar regions these charged particles excite oxygen and nitrogen to produce the incredible phenomena that fills our night skies with otherworldly illumination.
The most familiar green light comes from oxygen between 100 to 300 km above the earth, pink and dark red is produced by nitrogen molecules at around 100 km. Very bright red auroras come from oxygen at altitudes above 300 km and the blue and purple come from hydrogen and helium though these are much easier for the camera to catch than for the eye to see.
Monday evening was a stunning aurora, bringing to life the usually invisible magnetic field lines with vivid greens, reds and purples that encircled the city of Cochrane below. As always when watching the aurora I thought of those times years ago, when I dreamed of seeing it without ever daring to hope I actually would. I crawled into bed in the early hours, freezing cold and wonderfully happy to have been able to stand beneath such an awe inspiring sight once more.
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