New Mexico Aurora
June 27, 2013
Science Alert!!! On May 31st, 2013, at approximately 16:18 UTC, an interplanetary shock wave arrived at our planet starting a fierce 15 hours of non-stop geomagnetic storming. No one knows quite what the cause was, however scientists seem to believe that it was a corotating interaction region in the solar wind stream. Basically, the upper atmosphere of the sun is constantly releasing a stream of charged particles that varies in speed and temperature and when there is a transition zone between high (typically 750 km/s) and low (typically 400 km/s) speeds, a shock wave can occur. Earth's magnetic field does a pretty good job of deflecting these particles away from us, however some of them manage to get through and travel through our upper atmosphere in a small 3 to 6 degree wide band called the auroral zone which is typically 10 to 20 degrees from the north or south pole.
When the charged particles interact with the nitrogen and oxygen in the upper atmosphere, the nitrogen and oxygen become ionized (excited) by gaining an electron from the arriving solar wind. In return, they release a photon (light) so they can return to a non-excited state. The photons that are released is what causes the aurora to be visible. Sometimes, during extremely high periods of solar activity, and assuming you are in the right place on the planet, you can see these with the naked eye. Other times you need a camera with a high enough sensitivity and capability to capture long exposures to see it. On this night, I was driving through New Mexico and stopped at the Very Large Array Observatory (see movie: Contact) to shoot some photos of the Milky Way. It had been 3 solid hours since I last had cell phone coverage so I had no idea what was going on around me.
Since it was still early in the night, the Milky Way was still mostly to the east and hadn't quite rotated through the sky to be over the observatory yet. But I had some ideas for images, so I got to work. The observatory is actually composed of 27 independent antennas, 25 meters in diameter and weighing in at 209 metric tons each. These antennas are free to move along a Y-shaped railroad track, with three tracks extending out 13 miles in each direction. The freedom of movement allows the operators to configure the antennas in a number of positions that are suitable for different types of imaging. The north-south(ish) track actually crosses over the US-60, and this was my main subject since there is a convenient parking area right there.
After I finished shooting this composition, I was reviewing the images on the back of the camera and thought that it looked a little stranger than usual. Normally, in a really dark area, you can see a little bit of airglow (hazy green glaze in the sky) in a long exposure, but this was looking much stronger than usual. At this point I dismissed it with a shrug of the shoulders. Anything to make an image more interesting.
I hung around a little longer and shot some other compositions and was able to replicate my very first successful Milky Way image. Last July I was doing the same drive and decided to stop at the same spot. I had my old Canon T2i and 16-35mm f/2.8 II lens with me and applied everything I had learned up to that point. I was so excited to get it processed and printed out, in fact it's still on my wall. But once I got my Canon 5D Mk III and a better lens for astrophotography (Samyang 14mm f/2.8, although at a quarter of the price) I knew I wanted another shot at it.
I was very happy with the results and had pretty much decided to pack up and drive off to find a place to sleep when I realized that the Milky Way was almost perfectly aligned as an arch across US-60. I figured it would be a perfect composition for a panorama where I could capture the whole arch, the US-60, and the VLA Observatory all in one image. By this point in the night, traffic had slowed to about one car every 15 minutes or so, and since the US-60 is very long and very straight and very flat, I had at least 8 minutes between seeing the headlights and having them arrive on scene. So I set up in the middle of the road and composed to the north to start the panorama. I took a test shot to verify my settings and focus were good, and... I was flummoxed.
I took another one. I had never heard of an aurora this far south. I have no cell phone coverage to check on what's going on. Naturally the thought of government conspiracy came to mind, but it was quickly dismissed. I wasn't going to complain, and I decided to shoot first and ask questions later. Only in America! Kidding. I finished my first pass of the sky and started to get some higher detailed shots of the ground when I saw a headlight appear on the horizon. Uh oh. 8 minutes. That's exactly how long I needed for one good shot. I knew once he got there I was going to have to move the tripod, and finding the exact same spot would be tricky, so I figured one shot was all I was going to get. I decided to get a good image of the road and then get out of the way. In post-processing, I was able to blend it in rather nicely.
The aurora continued to burn bright, although I noticed that it was quickly vanishing. So I had to act fast to get some more shots in. I hopped on the railroad tracks again, this time facing north, and recomposed for the aurora. Within minutes it was almost gone.
Luckily I was fast enough to get one good one in and then let the camera shoot away for an hour so I could add in some star trails. This one took awhile to process - initially I wasn't quite sure how it would turn out and I had to do some fancy layer work to get the aurora to shine through properly. But it has turned into one of my favorites.
So what lessons did I learn... it's better to be lucky than good... when you think you're done, think again... it never hurts to take one more shot... and definitely always be flexible. I had intended to drive down the road another 45 minutes and up a mountain to do some star trails and catch some sleep, but by the time this was done I decided to just unstuff my sleeping bag and sleep in the back of my car in the parking lot. It was a little awkward waking up the next morning and climbing out of my car next to a family of four that had pulled over to take in the view. But at least I was fully clothed.
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