You know the Northern Lights are worth it when seeing them was the whole point of flying 5 hours to Iceland, even prioritized over a relaxing soak in the Blue Lagoon or dog sledding.
If you've ever watched the children's movie Inside Out, you'd be familiar with the term "core memories". In our daily lives, thousands of thoughts are processed in our minds, most of them being just meaningless debris. However, core memories are far from debris. It's a moment in time that revolutionizes your personal medium –– the way you understand the world, leaving a permanent watermark on your individuality.
I think that's part of the reason why I never forgot the moment those vibrant shades of green, smashed against the sky and spread in all sorts of abstract patterns. In that instant, huddling together with my family for body heat, I became spellbound by its mesmerizing beauty and breathtaking movements. Perhaps a core memory had just been formed.
Where do these huge majestical waves even come from?
That was most likely the first question little Eian asked himself all those years ago, and it's probably what fueled my interest in science. The questions I asked myself forced me to solve them, and as a result, my search history became full of the Northern Lights.
The activity that creates these showers of emerald glory comes from none other than the sun. Forming the sun are ions, which continuously radiate from the sun's surface (called the solar wind). Most people have the impression that particles in space fly like a bumblebee –– curving, dipping down, and all of a sudden turning directions. However, that isn't true. Particles travel in a straight line and will continue in that linear trajectory until they bump into another particle.
How does that help answer our question? Well, if the sun is constantly shooting out these ions in straight directions, some of them are obviously aimed right at Earth. In fact, as a solar wind begins encroaching near Earth, it's met with the planet's magnetic field.
Funnily enough, most people have never considered the importance of our magnetic field. Without this invisible blockade shielding Earth, solar winds would blow away Earth’s fragile atmosphere, preventing all life. Luckily, we indeed have one, which blocks most of the solar winds.
However, there's one good ol' saying that says that "nobody (or nothing) is ever perfect", right? Well, neither is the magnetic field. Although most of the ions are shielded away, some of the ions become briefly trapped in ring-shaped holding areas around the planet, which are centered around the Earth’s geomagnetic poles.
As a result, the ions of the solar wind collide with molecules of oxygen and nitrogen from the Earth’s atmosphere. The energy released during these collisions releases a glowing halo around the poles—an aurora, evoking colors that dazzled the eyes of young Eian.
Perhaps the very imperfection of the magnetic field, is actually what makes it so perfect.
Now that we know how the Northern Lights get here, why are they green? Well, they aren't always green. Referring to the image a couple of paragraphs above, we can see some shades of pink, maybe even some red as well.
Well, if you're taking high school chemistry, you're probably familiar with the usual mandatory "Flame Test" lab, where students dump metals into the flames of Bunsen burners. The result of this is a change from the normal blue color of the Bunsen burner flame to (for example) green due to the excitation of the metals from the heat leading to a release in energy.
That same concept is applied here, as the ions from the solar winds collide with molecules such as oxygen and nitrogen, those molecules will be excited as well and eventually release energy, evoking the familiar green and purple colors that we see respectively.
Moreover, since oxygen and nitrogen are the two most abundant gases in the atmosphere, it makes sense that the Aurora Borealis is often green with shades of purple, as collisions between ions will most likely happen between those two gases.
Of course, however, there are many other elements in our atmosphere that may also be struck with flying ions from the sun and excited, which gives us a more unique (possibly more picturesque) painting of the night sky.
Ultimately, the Northern Lights is something I think everybody needs to witness at least once in their lifetime. There's a reason why there are paid tours to see the Aurora. It's truly an extraordinary and unforgettable experience (perhaps a core memory for you as well?). Not only are their origins interesting, but it makes for a totally instagrammable post and a pretty neat computer wallpaper.
More than that, light shows here in New York are pricey, sometimes over $100. But nature generously offers us a sweet deal that's not 100 dollars, but 100 percent off (minus the plane flight) to see something that's probably (scratch that, definitely) more worthy of your time.
The "magic" of the shimmering iridescent light curtains may not seem real (too beautiful to be true), but the name "Aurora Bo-(REAL)-is" lets you know it's all legit.
Bibliography
“Northern Lights.” Northern Lights or Aurora Borealis Explained, 4 Jan. 2014, https://www.northernlightscentre.ca/northernlights.html.
“What Are the Northern Lights?” The Library of Congress, The Library of Congress, 19 Nov. 2019, https://www.loc.gov/everyday-mysteries/astronomy/item/what-are-the-northern-lights/.
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