A few nights ago (March 23rd), I was fortunate enough to be able to witness the most spectacular auroral display I’d ever seen. Granted, I’d only ever seen the aurora once before this, but this experience blew that one out of the water. I’m not going to bury the lede on this one (like I usually do), since you’ve all surely seen the image I put at the top of this post. You might be thinking “Peter, is this just an excuse to share your cool aurora pictures with your audience?” And yes, that is partially true. But if you think that is the only reason, well, you underestimate my ability to turn anything into trivia. You see, the image at the beginning of this post was not actually the aurora. Confused? Read on.
Most of the time when people picture the aurora, they think of it something more like this (also photographed by me on March 23rd):
The green and pink glow you see in this picture is caused by oxygen and nitrogen (respectively) being ionized high in the Earth’s upper atmosphere. Particles from the solar wind are captured by the Earth’s magnetic field, which carries them to areas near the poles. When they run into gasses in the thermosphere (one of the Earth’s atmospheric layers), anywhere from 50 miles to 400 miles above the surface. Certain events, such as coronal mass ejections, can change the shape of the Earth’s magnetic field, bringing aurora to locations they do not normally reach. That’s what happened on the night I photographed these.
However, the brilliant beam of light you see below is not actually aurora. It’s STEVE. The pink glow to the right of the beam is aurora. While STEVE often with aurora, it is not actually a part of the aurora.
STEVE stands for “Strong Thermal Emission Velocity Enhancement”. And for any of you thinking that that is a rather silly acronym, you’d only be partially correct. You see, STEVE is not really an acronym. It’s actually a “backronym“. Citizen scientists documenting aurora first identified it in 2016. While this effect is not rare, it had not been independently identified prior to this. Someone in the group decided to call it “Steve”, after this scene from the movie Over the Hedge. Scientists decided they needed a more serious name for this phenomenon, but the nickname had already taken off.
In comparison to normal aurora, STEVE takes the form of an stream of plasma about 250 miles up. In 2018, scientists determined that STEVE is caused by electrons in the Earth’s ionosphere heating up other particles, causing them to turn into plasma.
Ultimately, this is a technical distinction, which is usually only of interest to astronomers and other scientists. To most other people, STEVE is just a funny name for a fantastic light show. If you are interested in viewing the aurora, you should travel as far north as you can get. It is rare for them to come to this latitude (southern Washington), and this display was actually the best aurora seen in six years. As we get closer to solar maximum (a whole different topic I’m not going to get into now), we should expect to see even better aurora in 2024 and 2025. So make your travel plans now.
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The title of this post was a reference to this clip from the BBC.