Tag Archives: Ocean

Ocean Biolumination and the Aurora Borealis

Although late April in Alaska typically spells the end of the “dark days” of winter and hence the aurora borealis, we were fortunate to have an active aurora forecast (KP6) and clear skies on April 23rd. Perhaps the fates were aligning without my knowing it as spring in Southeast Alaska is known for its clouds and rain, but as  I drove out to The Cannery at Icy Strait Point I was greeted by stars and a moonless night.  From the parking lot my feet crunched on the gravel of the rocky beach. I walked along with the water lapping near my feet and the sea-air filled my nostrils from the swelling waters of a high tide. I was not alone out there. My headlamp lit up only a small portion of the inky-dark night, but up ahead a mink’s eyes showed brightly like two opals in the dark. Another mustelid, a River Otter, swam in the waters just offshore. He got closer to me several times, obviously trying to figure out what I was up to. All of these wonders were the precursor to the amazing show that was only be beginning.

At 12:30 AM The aurora began to intensify over the waters of Port Frederick. Soon the pulsing green, pink, and white lights turned the ocean fluorescent green and my eyes wide. I had never seen a display this active in Southeast! I worked with my camera to tether together the sea and the Northern Lights. I was fortunate enough to have the Alaska Marine Highway Ferry add some scale at about 1AM.

Icy Strait Point, Northern Lights, Hoonah, Alaska, Southeast Alaska
Sea shells accent the Northern Lights from the Cannery in Hoonah.

Icy Strait Point, Northern Lights, Hoonah, Alaska, Southeast Alaska

At 1:30 AM the adrenaline of the incredible show finally started to wear off. I set off down the shore to go home,  staring at my feet to avoid tripping. That’s when the first small blue light in the water caught my eye. I splashed a rock into the water and blue waves of biolumintation echoed out from its crater. I stepped into the water, and my footprints erupted with light. All around me in the waters of Port Frederick, small, bio-luminescent creatures swarmed and let off burst of cerulean blue light like underwater fireflies at the slightest disturbance. It was then that I knew what I had to do! My camera began clicking 6 inches from the water’s surface as I sought together bond together the lights of the sea and the lights of the sky as its unlikely I will ever have this unique experience ever again!

Icy Strait Point, Northern Lights, Hoonah, Alaska, Southeast Alaska, Phytoplankton, Biolumination, Bioluminescence
A huge bloom of bio-luminescent creatures provides a blue glow to the foreground of this image. You can see their streaks in the water in this long exposure.
Icy Strait Point, Northern Lights, Hoonah, Alaska, Southeast Alaska
Bio-luminescent creatures in the waters of Port Frederick and under the Northern Lights.

 

Icy Strait Point, Northern Lights, Hoonah, Alaska, Southeast Alaska
The aurora borealis arches over all of Hoonah, Alaska.
The incredible dark skies of Hoonah are offset by the Aurora Borealis.

Did You Just See A Proton Arc?

A proton arc is oftentimes described as a broad band of diffuse aurora. If you do a Google Image search for “Proton Arc” a plethora of beautiful images depicting a purple, red, green, or pale band of aurora will greet your eyes. Go ahead, really, search it, I can wait. Or, you can visit this website at Spaceweathergallery.com.

I had the pleasure of seeing this pale phenomenon in Juneau on September 20th, 2016 for the first time ever. In the scene, the aurora swirled to the north in front of me over mountains.  However, a  pale, confined, band of aurora ran perpendicular to the northern display, and stretched far to the south past a large, brilliant moon. In my camera it was cool blue/white in color and was in stark contrast to the green aurora that played on the northern horizon over the mountains of Juneau.  I posted the image to an aurora group on Facebook and labeled it a “proton arc” as so many before me had done. However, I received an interesting response from renowned aurora researcher Neal Brown – a true “proton aurora” is nearly undetectable by the human eye and the concept of a “proton arc” is a widespread misconception. The disagreement between the science and the public perception set my wheels turning, and even though I am not an aurora scientist, I would like to dissect why proton arcs are not truly visible.

Proton Arc, Hoonah, Alaska, Aurora Borealis
On September 20th, 2016 I thought I saw a “proton arc” in Juneau, however, it seems my misunderstanding of this auroral phenomenon is the same of many non-scientists.

There are two ways that auroras may be formed. Most auroras are formed when excited electrons collide with oxygen or nitrogen or if protons collide with nitrogen or oxygen. Electrons which are lighter and have a lot of energy result in the traditional, dancing auroras. Electron auroras emit light at many wavelengths including 630nm (red) and 427.9nm (blue). The second way that auroras can form is when protons collide with nitrogen and oxygen. The proton collisions result in emissions of 656.3nm (red) and 486.1nm (blue) (Lummerzheim et al. 2001).  Separation of these light bands are difficult because at 656.3 the emissions require a precise instrument to differentiate them from the electron aurora. The same can be said of the emissions at 486.1 which are nearly indiscernible from the electron emissions.  To quote Neal Brown’s response in the aurora group, “To prove it is a true proton arc one would have to use some sort of spectral discrimination to see if it contained only 656.3 and 486.1 nm emissions”. Aurora researcher Jason Ahrms had this to say in a detailed Facebook post – “We don’t use color, location in the sky, how long it’s been there, or anything like that to identify a proton aurora.”. This means that simply looking at an aurora with your eyes is not enough to determine if it is a proton arc – so why is it so commonly mislabeled. The mistake is likely an innocent use of scientific jargon; those posting the images (like me) simply did a brief search to confirm what they saw before spreading the lie themselves.

A chart of the light spectrum. Copyright : http://techlib.com/images/optical.jpg
A chart of the light spectrum. Copyright : http://techlib.com/images/optical.jpg

 

The Aurora Borealis shows off a pale display in Hoonah, Alaska which is often identified a "Proton Arc"
The Aurora Borealis shows off a pale display in Hoonah, Alaska which is often identified a “Proton Arc”

Although it is impossible to detect a proton aurora with your eyes, they have been successfully photographed once identified with instrumentation. Tony Phillips of Spaceweather.com discussed the phenomena with University of Alaska Fairbanks Researcher Jason Arhns.  His image below shows how difficult true differentiation between electron and proton aurora is. Where the proton arc has been identified is barely discernible from the aurora.

This proton arc was captured by Jason Ahrns of the University of Alaska, Fairbanks. The region fo the proton arc was determined from spectral instruments, but as you can see it is very similiar in form to electron auroras. Image copy right to Spaceweather.com

It was interesting to realize that my perception of what a proton arc was had been so wrongfully influenced by what I saw online. However, if the pale auroras being captured by photographers (like the photos below) are not truly proton arcs, what are they? Incredibly, as Jason Ahrns explains, to date there are is no known explanation for these pale, elusive aurora displays! They are a new opportunity for scientific exploration in the aurora research arena. I hope they keep us posted.

 

Citations:

http://pluto.space.swri.edu/image/glossary/aurora2.html

Lummerzheim, D., M. Galand, and M. Kubota. “Optical emissions from proton aurora.” Proc. of Atmospheric Studies by Optical Methods 1 (2001): 6.

news.spaceweather.com/protonarc/