Aurora Borealis

 Here is my experience with the Aurora Borealis: I chose to go to the south end of Caesar Pond to set up my tripod as the trees blocked most of the light from many neighbors who leave their outside lights on all night long. This allowed me a northward facing view up the length of the pond. I went out at around 9pm to start the photography as you never know when the aurora will arrive.  

Nothing much showed up in the early photos except that I thought I saw the faintest green glow. This photo was taken at 9:38pm, and you can see a hint of purple and green. Here were the camera settings that I used for all the photos:

•Canon 70-D camera with a 17-40 lens. I removed my lens UV filter so that I didn't get any strange concentric circles on my images.

•Manual lens focus/Single point focus (preferably the center one).

•Move focus to Infinity (then back off until a bright object in the distance is in focus)

•Iso 1600 to 2000

•F/stop 5.6

•Temperature 3500 Kelvin

•Shutter speed of 5 to 10 seconds

•A lens hood may help reduce condensation.

After 45 minutes of standing in the dark, I was surprised when it seemed as if a spotlight was suddenly illuminating the sky to the south. At 9:50pm, I looked up and saw my telltale sign of aurora...a whitish looking cloud that was moving rapidly to the north. I started shooting photos, and even though I could not see any color, the camera picked up bright green. The green color of an aurora is caused by atmospheric oxygen atoms getting excited by electrically charged particles from the Sun that slam into our upper atmosphere at millions of miles per hour. Green is the most common aurora color.

After the initial display of green, other colors emerged. This photo was taken at 9:53pm. The yellow near the bottom of the display is also created by excitation of oxygen atoms and molecules, while the purple color occurs due to excitation of nitrogen atoms. Both the purple and yellow colors form during intense solar activity.

At 9:55pm, rays and veils were really changing rapidly, and purple was the predominant color. Do you see the black, horizontal line at the bottom of the aurora? It is in many of the photos I took. I think it is what is called a black aurora. The European Space Agency defines black auroras as anti-auroras where electrons shoot upwards into space and creates a hole in the aurora that is visible. See https://www.esa.int/Science_Exploration/Space_Science/Cluster/Black_Auroras

By 9:58pm, a pink aurora color was evident. The pink color is formed from a combination of red auroras with blue or green ones. Again, pink only forms in high or extreme solar activity.

This photo was taken at 10:24pm as the cloud cover was becoming more dense. It created some dramatic light compositions.

At 10:42pm, as the cloud cover was starting to clear out, the red auroras were starting to form. They occur at high altitudes, of up to 250 miles above Earth's surface, by the interaction of oxygen atoms with solar particles that cause the oxygen atoms to vibrate at a higher frequency / wavelength.

Check out the red aurora coloration here at 10:58pm. WOW, it was so intense.

By 11:03pm, the aurora storm was starting to weaken and even though I stayed outside until 11:45pm, this was typical of the rest of the photos that I took. I like that every aurora color was represented in this photo.

What did I miss by hanging out at the pond the entire time? I missed the dramatic corona displays that occurred straight up into the sky. I couldn't see it from my vantage point. Next time, I will set up a camera in the front yard and use an intervalometer set to automatically take photos ever 5 or 10 seconds, while I am over at the pond.