March 5, 2025 Early Morning Airglow

Tonight there was a filament CME passing by causing some geomagnetic unrest. Nothing major, Kp 4 at most. There was a strong glow to the northwest in the direction of G.J. and as usual I thought it was just light pollution reflecting off of water vapor. Pointing the camera revealed a nice green patch. This was unusual because I usually see the “Green Lantern’s light” in every direction except to the west! What was it doing over there? I could easily see it unaided once I knew it was there.

I think it is interesting to notice the interplay between the city lights in the distance and the airglow in the photo. I imagined living in a time before light pollution and then you wouldn’t dismiss the natural glow so easily.

The philosopher Seneca talks about glowage in the sky in the book Natural Questions:

The “depiction comes to us from Seneca, also captive to the lower latitudes his whole life, who described the northern lights [and airglow] in his Natural Questions, calling them Chasmata — chasms, rifts, gapings — of the sky:

Like a crown encircling the inner part of the fiery sky, there is a recess like the open mouth of a cave… A stretch of the sky seems to have receded and, gaping open, displays flames deep down. These all come in many colors: some are a very intense red; some have a weak, pale flame; some have a bright light; some pulsate; some are a uniform yellow with no discharges or rays emerging… The sky is seen to burn, the glow of which is occasionally so high it may be seen amongst the stars themselves, sometimes so near the ground that it assumes the form of distant fire.” - excerpt from The Poetic Science of the Aurora Borealis By Maria Popova