Has been quite some time since I’ve been lucky enough to shoot some aurora! There’s only been a few solar storms this year, and it’s always been cloudy in my area so I haven’t been out in a while. Last night/this morning was definitely an exception though.
When I first started shooting northern lights and witnessing the different formations that can be made, I wondered why there wasn’t different classifications to define the different structures. The more I shot, and in turn more I read about Aurorae (plural), I realized there ARE classifications for the different kinds!
it’s surprisingly difficult to research the different types. Most info is academic and written in physics jargon. I think the lack of basic and easily understandable info on the subject is due to the fact that we (science) is only beginning to understand and document/study the different types and how each one is formed. The classification of this phenomenon is still in its infancy and therefor doesn’t have tons of source material to research and rewrite in simple terms for people everywhere to understand and access.
There are two main classifications of Aurora: Diffuse and Discrete.
Diffuse is the most common type. Whether we can see it visible to the naked eye or not it is almost always present in the auroral zone. I have been training myself to see it for almost two years now of chasing aurorae so it is very obvious to me now when there’s some in the northern sky. Almost every night in the winter (if you’re far away from city lights and there’s no moon) close to the northern horizon it can be seen. I’m sure most people who live even in the northern united states have seen it and not thought anything about it. It looks like a faint haze, like a city’s lights glowing or the pre-dawn sunlight just peaking over the horizon, except to the north!
The second type is Discrete Aurora. This is the type that’s breathtaking to watch, and is further broken down into smaller classifications.
The first and most common of these sub categories are “quiet auroral arcs” which like their name suggests, are arcs of green that just kind of hang in the northern sky without any movement. They look very similar to a diffuse auroral glow, except have more defined edges that make the arc more prominent than just random glowing.
Next are “deformed auroral arcs”. I think these are the type that when most people think about Northern Lights, this is the kind they’re thinking about. They start as a quiet arc but then as they get more energized start swirling, waving, folding and in general dancing around.
There are two more types called “Auroral Bulges” and “Omega Bands” that I don’t understand enough about to try explaining to you. Another phenomenon that I’m not going to talk about because I don’t know enough about is “proton arcs”
The last type of Discrete Aurora, and the namesake of this post, is “Pulsating Aurora” I’ve only seen it three times, but is one of my favourite ones to watch. Unlike deformed arcs I think Pulsating aurora generally has a much less saturated color, sometimes almost looking glowing white instead of any color at all. What makes it so interesting to watch is the speed at which it moves, and pulsates. It’s not bubbly, it’s jagged. It looks like radiation. it’s a visible manifestation of the geomagnetic field. if our eyes could see radiation as visible light, I’m pretty sure this is what it would look like. It’s nearly impossible to explain the feeling I get when watching Pulsating Aurora. The first time I saw it I momentarily thought I took some mushrooms earlier that night and forgot about it. That’s how mind blowing these shows can be.
Last night I’m pretty sure I saw every different kind of aurora I just talked about happening at different times, or sometimes even a couple happening simultaneously to another. The most prominent features in the first picture above are caused by the Pulsating Aurora, and is one of my favourite aurora photos ever, so that’s why I named the post after it. Here’s the first picture again to look at larger and a couple more to to treat you all to something at the end of this long read. They also were taken this morning, but at times of slightly less activity.
Feel free to leave questions or comments! or go and check out my web page, there’s lots more night/aurora pictures there (and many, many other things too)