Natural Connections: Aurora Magic

"The light-gathering powers of a camera lens can pick up on the greens, reds, and purples that are actually being emitted and show us just how vivid the lights truly are."

Natural Connections: Aurora Magic

My snowshoes sank into drifts softened by the warm day. At the frozen lakeshore, the view opened up to a curtain of lights.

Sometimes I’ve gone out to look for the northern lights and have squinted and wondered if that faint glow was really them. Last night there was no question. Vertical rays of light rose from an invisible line a hand’s width above the horizon. They formed a curtain that rippled as if in a breeze. Now and then a particular ray would brighten and reach higher, and the activity shifted from due north across the lake, to west down the channel, and back east toward a little resort on the point.

I imagined the solar winds out there, rushing toward Earth, transferring energy into our magnetosphere, and pushing electrons there down the magnetic field toward us. As those electrons encountered nitrogen and different forms of oxygen, the excited molecules emitted light like a neon sign.

Although the auroras are always made of colored light, I saw only white…or maybe it was pale green? That’s just a function of my night vision and the sensitive rod cells around the outsides of my retinas picking up light but not color. Cameras, especially with long exposure times, can gather more light than our eyes and help us see the greens, reds, and purples of the aurora more vividly.

Standing out on the cold snow, I texted a few friends about the aurora and soaked it in. Soon there was a lull, and I headed inside.

While rinsing out my toothbrush, my phone buzzed. “The sky is dancing!” wrote my friend. I threw on a warmer coat and headed back outside. In just an hour, the temperature had dropped enough that the snow crust supported me firmly. And yes, the sky was dancing.

Pillars, curtains, and swirls of light danced along the horizon. As the beams strengthened and the flashing increased, the display shifted from the Little Dipper into Cassiopeia. This “Westward Traveling Surge” is a phenomenon associated with sudden brightening and activity in the aurora called a substorm. Substorms happen when a plasma flow short-circuits and is suddenly flung toward Earth causing a surge of activity.

My jaw dropped as the pillars shot upward, and then overhead and behind me. Light danced across even the southern sky. And directly above me, the curtains turned to curving bands that flashed, wiggled, and swirled. After almost losing my balance, I gave in and lay down on the snow to look straight up.

Substorms were first described in the International Geophysical Year of 1957-58 when scientists from all over the world coordinated their efforts to observe the aurora simultaneously. That same effort also led to the discovery of the Auroral Oval—imagine the northern lights originating from crowns sitting on top of the North Pole...and the South Pole, too!

When we are south of the Auroral Oval, we only see the sides of those faint curtains of light on the northern horizon. When the oval widens or shifts far enough south, the light curtains appear straight above us, and you can look up at the bottom of the curtains instead of at their side. Then, the corona appears. This psychedelic, converging pattern at the top of the sky is rare to see and highly sought after by aurora chasers.

I’ve long thought that auroras were most visible at night just because we can only see them when it’s otherwise dark, and most visible in winter for the same reason. As it turns out, the best northern lights occur around midnight, when the Sun is on the far side of the Earth. You may have seen a diagram of the solar winds hitting the Earth’s magnetic field, then curving around the planet and creating a tail on the far side. The best auroras come from that tail, and thus are visible around midnight. In addition, cracks that form in our magnetosphere near the equinoxes make impressive auroras more common in March and September.

I also thought that northern lights were always caused by coronal mass ejections (CME) of plasma, but this event came from a hole in the Sun’s corona where the magnetic field is open to space, allowing high-speed solar wind streams to escape. The coronal hole that caused this storm is reportedly thirty times the size of Earth. Luckily, the solar winds from coronal holes are less likely to interrupt radio communication, disrupt power stations, and damage satellites.

“The best of my life!” “An unbelievable experience!” “The sky was alive!” “Magia!” “Taika!” “Magic!” This was the most spectacular auroral display in many peoples’ experience. Thanks to social media, I could see photos and exclamations from Iowa, Indiana, Alaska, Canada, Poland, Denmark, Finland, Australia, Tasmania, and more.

The same Sun gives us all the energy we need to live, and the Earth’s magnetic field protects us when that energy becomes intense. Together, they make magic.

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at www.cablemuseum.org/books and at your local independent bookstore, too.

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is closed for construction of our new exhibit: The Northwoods ROCKS! It will open on May 2, 2023. Follow us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.

Last Update: Mar 29, 2023 6:54 am CDT

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