Friday, March 23, 2018

AURORA Taken by Steve Cullen on March 22, 2018 @ Yellowknife, Northwest Territories, Canada

Cosmic Virga 🌧️

What do you do after spending 6+ hours outside all night doing aurora photography in -25°F temperatures? You take a selfie, of course. For those of you not familiar with virga it is the meteorological term for an observable streak of precipitation falling from a cloud that evaporates or sublimates before reaching the ground. The aurora in this image looks very similar to what you might see in the southwestern U.S. skies on a summer afternoon. Except this definitely is not the southwest. Oh, and, virga doesnt come in green and violet colors either!

Some other things I figured out while creating this photograph. 1. I didnt realize that at this latitude the Andromeda Galaxy never sets. It is the glowing slanted oval just to the left of center in my photograph. 2. This is the Milky Way season for folks this far north. By late April the sky will be bright enough all night long to wash out the Milky Way. 3. You cant get those big arching Milky Way shots here in Yellowknife. Youve seen those images where the galactic core is blazing away above the horizon with the stars in the disc of the galaxy arching across the sky. What you see in my photograph is really about as arching as it is going to get. 4. At -25°F the luminance noise in photographs is pretty darn low.

As for the photograph, this isnt a normal one-shot and done selfie. It is a special technique pioneered by my Facebook friend Michael Goh that I like to use on occassion. It involves taking a single image of yours truly holding a light. Then, I take a panoramic of the entire foreground scene with the light placed on a light stand or tripod. Then, I take another panoramic of the entire scene, exposing especially for the sky. The individual images for the foreground and sky and merged to create panoramas and then those are composited together, along with the single image of me, to make the final photograph. It is a lot more involved than pulling out your iPhone and snapping an image. But, it really is the best way to shoot this type of photograph under low-light conditions and I think the results are pretty awesome.

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