September in Alaska #3 - Girdwood Aurora

Back at the Alyeska Resort, we didn’t feel there were any prospects for aurora viewing because of the overcast skies. But, we asked the desk to call us if anything popped up. In many areas with frequent aurora, hotels are happy to provide a wake-up call if the skies spark.

We depend heavily upon Spaceweather.com, a website that provides up-to-the –hour auroral maps and forecasts, plus posts a gallery of photos that make you wish you had been there. Spaceweather.com was predicting good stuff, so we went to bed hoping against hope for a hole in the sky.

Map: Spaceweather.com

Sure enough, at 2:00 a.m., we got a call. They were faint, but happening, so we grabbed our gear and jumped in the car to find a dark spot. (Just fyi: it can be hard to tell if you are seeing the beginning of aurora or just clouds because they are often very pale as they start up. The trick is to take a photograph. If you see green in the photo, get out there; something is happening.) 

Misty aurora

The Seward Highway in Girdwood has few roads off of it, so we settled for a wide turn-off. There was some passing traffic, but, fortunately, it was behind us as we faced the aurora.

Not great, but aurora

Although not spectacular, it was pretty good stuff. Lots of fuzzy pale green arcs, with a tiny bit of pink and purple showing through.

Some purple

We spent about two hours photographing – noting that a benefit of September aurora is relatively balmy temperatures. It was in the high 30s to low 40s – way better than the -40 you can get in Fairbanks in February.

One thing that is important to know when viewing aurora photos is that, as I mentioned, the camera detects the green better than the eye. So, these pictures are a bit more impressive than the actual display.

Multiple colors

Also, Scott has taught me how to shoot aurora (and bought me a decent lens for doing so). You need a fast wide-angle lens (low F-stop; my is a 2.8 50mm), a tripod and a remote switch). You have to pre-focus your lens on almost infinity, switch it to manual focus (it will not work if it tries to autofocus) and tape it in place with gaffer's tape so you won't accidentally move it. Then, you set the camera on manual. ISO and shutter speed depend on how bright the lights are. I shot most of mine at 8-15 seconds on ISO 1600-6400. If it looks good on your camera screen, it is probably underexposed; bump up the ISO or increase the exposure until it looks too bright, but still has definition. You can also fix issues with i-Photo, Lightroom or Photoshop after the fact. 

Some bright green

Still, aurora is such a rare treat because it depends on so many factors – actual solar activity, full dark, clear skies. Any display is a thrill.

The aurora is cause by collisions among electrically charged gaseous particles from the sun that enter the earth's atmosphere, blown here by “solar winds.” The charged particles are largely deflected by the earth's magnetic field, but, because the earth's magnetic field is weaker at the poles, some particles enter the atmosphere and collide with gas particles. These collisions emit light that we perceive as the dancing lights of the north (aurora borealis) and the south (aurora australis).

Auroral displays appear in many colors with pale green and pink the most common. Green is produced by oxygen molecules about 60 miles above the earth. Red auroras are produced by oxygen at heights of up to 200 miles. Nitrogen produces blue or purplish-red aurora The lights of the Aurora generally extend from 50 miles to as high as 400 miles above the earth's surface. We saw green, pink and violet at Girdwood. The lights appear in many forms from patches or scattered clouds of light to streamers, arcs, rippling curtains or shooting rays that light up the sky with an eerie glow.

Green is most common

We were up from 2:00 to 4:00 a.m., sacrificing our night’s sleep. But, it was worth it.

Trip date: September 10-21, 2015