same here...we call this Northern Lights, or Aurora, or locally most commonly "the lights", as in "Did you catch the lights last night"? Say that to anyone in town and they will know exactly what you mean and not hesitate to say yea or nea. But this image was a somewhat of a unique thing. I shoot a -lot- of Northern Lights.
http://www.pbase.com/santa/aurora (are just a few examples) . These were "invisible" Northern Lights. I see that I didn't explain the entire situation in my brief post with the original "Mask" image. Here's the back-story to that image.
I traveled South into the Alaska Range ( I live in North Pole, Alaska) so I could be in the mountains for some Aurora photography. It was getting late and absolutely nothing was happening. I decided to do a long exposure - 10 minutes, pointed somewhat West to get the star streaks I wanted, and kept low enough to catch a truck or car that might go by during the exposure. There was NO Aurora visible. During the exposure a truck or two did go by and leave orange streaks. After the in camera noise reduction was finally done, I was surprised to find the long exposure allowed the energy from the Aurora to be visible, reflected off the clouds. It also made the very obvious shape of a face on it's side. Yet there was no color or Aurora visible to the naked eye. I've since used long exposures literally thousands of times to capture feint Aurora, but never so interestingly as the "Mask" shot, above.