Starship Asterisk*

A Vortex Aurora over Iceland

Explanation: No, the car was not in danger of being vacuumed into space by the big sky vortex. For one reason, the vortex was really an aurora, and since auroras are created by particles striking the Earth from space, they do not create a vacuum. This rapidly developing auroral display was caused by a Coronal Mass Ejection from the Sun that passed by the Earth closely enough to cause a ripple in Earth's magnetosphere. The upper red parts of the aurora occur over 250 kilometers high with its red glow created by atmospheric atomic oxygen directly energized by incoming particles. The lower green parts of the aurora occur over 100 kilometers high with its green glow created by atmospheric atomic oxygen energized indirectly by collisions with first-energized molecular nitrogen. Below 100 kilometers, there is little atomic oxygen, which is why auroras end abruptly. The concentric cylinders depict a dramatic auroral corona as seen from the side. The featured image was created from a single 3-second exposure taken in mid-March over Lake Myvatn in Iceland.

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A fascinating picture indeed! I have identified some of the background stars: The relatively bright one to the right is Arcturus. At top middle one can see the tail of the Great Bear - together with a small sporadic meteor trail, I presume. To the left of the aurora one can discern the W of Cassiopeia. Sadly, we also have to deal with yet another imprecise APOD description of time: "taken in mid-March".

What a beautiful and unusual aurora! I love it! Kitty a drama Queen?

Alright, so what is causing the concentric cylinders? Specifically, why cylinders, why the thin shells, and why multiple concentric ones? I've seen similar such structures in numerous auroras shown here before, but only now suddenly find these structures odd. Are these just reflections of intensity gaps in what I assume must be an otherwise smoothly continuous magnetic field?