The Goddess of Dawn

Aurora in New Jersey, May 11, 2024

The word "Aurora" comes from Latin. In Roman mythology and Latin poetry it is the name of the goddess of dawn. It was first used by Gallileo in the context of the atmospheric phenomemon. The word pairs “Aurora Borealis”, or “Northern Lights”, conjures up imagery of colorful, curled flows of light tucked away in the high northern latitudes, somewhere in the Nordics or Iceland. Rarely does this phenomenon descend from the earth's poles to the lower latitudes. In the contiental United States, that means it does not extend beyond northern states like Minnesota or Alaska.  Viewing the Northern lights has been on the bucket list of low latitiude dwellers like myself.

Spring of 2024, May 11th was one of those very rare occassions when the "goddess of dawn" visited us right here in my New Jersey backyard at the lowly 40 degrees north latitude. 

Night Mode

First hint of an aurora shot on iPhone
(night mode) through a window

On the predicted night of the event, the weather forecast showed heavy cloud cover for most of the night, but a clearing at 4 a.m. I happened to wake up at around 3:30 a.m. by chance, remembered the prediction - and decided to take a look out of a north facing window in an adjacent room. The sky was clear. However I could not see any auroras by naked eye. There was what looked like a long vertical patch of faint cloud slightly west of north extending high up towards the zenith. It was like the contrail of a jet, but a much wider band. I went back and grabbed my glasses - the slanting "cloud" was still there. At this point on a hunch, I placed my phone against the window glass, put it in night mode and took a shot. That decision would end up adding an item from my bucket list to my astronomical “seeing” repertoire.

The phone image "developed" over 3 seconds. I could see strange vertical streaks of colors in the scene which looked unusual. Having no prior experience of this, I wasn’t sure if it was the real thing or how long this would last. To investigate some more, I grabbed my SLR and a tripod, and went down to the backyard. 

The next hour was a journey of discovery. While visually I could not see much, I pointed the camera north and took a wide angle view at 18 mm focal length. What I could see on my camera screen was clearly auroras, a first for me, but also something I never expected to see of all places, from my own backyard. As I experimented with different exposure durations starting at 3 seconds, beautiful slanting shimmer of light clearly stood out in all long exposure shots. They appeared like slowly changing curtains of light, fading, brightening and shifting almost slowly from shot to shot a few seconds apart. I later put together a time lapse of several images captured over about 2 minutes of elapsed time, compressed to 6 seconds - that shows the slow lateral shifting movement. The video is included below. 

Nature’s Neon Signs

Auroras are caused by events in the sun. Coronal Mass Ejections (CME) - which is plasma ejected from the solar flares or Coronal Hole - solar winds carrying electrons that race towards the earth. These charged particles and their associated interplanetary magnetic fields interact with the earth's magnetic field and the particles stream down from the north and south poles. They collide with gas molecules in the earth's atmosphere energizing them. As the excited molecules fall back to stable states, the energy is released as photons. This is similar to what electric current does to gases sealed inside the tubes of neon signs. Just as the colors in neon tubes are determined by the gases in it (usually a noble gas like neon from where it gets the name), the aurora colors are based on the gas they interact with - usually blue for nitrogen and green for oxygen in the atmosphere.

A Rare Aurora

Space weather can lead to pretty outcomes like auroras but also dangerous ones that affect life on earth. One such event was the Carrington Event caused by geomagnetic storms in 1859. The damage included telegraph lines catching fire. The impact today of a similar event would be significantly more since there are more power installations, satellite communication and aircraft at play.  Since then, a system of prediction was put in place in the United States in 1961, in the form of the national Space Weather Prediction Center, a divsion of the NOAA (National Oceanic and Atmospheric Administration). This event was predicted with great precision three days ahead by the agency. 

  

The agency issued a media warning for Friday, May 11 based on observing a sunspot cluster labelled AR 3664 producing several moderate to strong solar flares on Wednesday May 8, 5:00 a.m. ET.  Of these solar flares detected, at least five flares were associated with CMEs that were directed towards the earth. 

Coincidentally, I happened to catch a picture of this sun spot a day before the warning was issued. This particular sun spot was facing the earth positioned at the center of the sun's disc.  

The expected geomagnetic storm impacts was expected to be a G5, the highest on the NOAA scale for the event. 

Space weather prediction on May 11, 2024 shows G5 category Geomagnetic Storms

On a NOAA scale of 1-5, a G5 level event is expected to happen only 4 times (4 days) in an 11 year solar cycle and is visible on more southern latitudes.

In other words, this event was very rare. So much so that it was reported as “historic” and was front page news on top American news outlets as sightings were reported as far south as Florida and Texas.  

The NOAA/SWPC geo-storm warnings continue into the weekend, on slightly diminished scale. Lacking another CME, the aurora event is now perhaps on the decline. However after a fully clouded Saturday, we are expecting clear skies on Sunday night.  Will the goddess of dawn visit again? 

We will surely find out!