Photo courtesy of Jim Brandenburg. This article was originally published in the 1999-2000 Ely Winter Times.
One of the northwoods’ winter wonders is the night sky. Away from artificial light sources, the view of the stars and planets is dazzling. The sheer number is awe-inspiring, especially to urban dwellers who have become so accustomed to a night sky awash with city lights that they never expect to see more than a few stars.
But the impressive abundance and intense beauty of the stars becomes little more than a sideshow on nights when the main attraction is the northern lights. Varying from a dim glow in the north to a shimmering, pulsing, radiant show filling the sky, the spectacle is worth bundling up and going outside to see even on the frostiest evenings. The light show, also called aurora borealis in the northern hemisphere, is awe-inspiring. And it also inspires curiosity. Here are answers to some of the most commonly asked northern lights questions:
What causes the northern lights?
Activity on the sun creates solar winds that blow out from the sun, flowing toward the earth in the form of electrically charged particles. When the solar winds reach the magnetic forces of Earth, most of these particles are forced out and around our planet similar to the way water flows around a rock in a rapids. But some particles make it into Earth’s magnetic sphere. These are guided toward the poles by magnetic forces in the same way iron filings are pulled by a bar magnet. Here they enter the earth’s upper atmosphere and strike the atoms and molecules of atmosphere gases. These atoms and molecules then have extra energy, which they give off as flashes of light. This process is always happening to some degree, but when there are enough charged particles penetrating the atmosphere to create so much light that it’s visible from Earth, we experience a display of northern lights. This happens when the solar winds are stronger due to extra activity on the sun’s surface.
When is the most likely time of year to see the northern lights?
Since the energy that creates the aurora originates with the sun, northern lights ebb and flow with solar activity rather than with the earth’s seasons. But because northern summer nights are so short, and because the afterglow of sunset is far to the north during summer, there is more opportunity to see auroral displays in fall, winter, and spring when the northern sky is dark longer. Auroral activity may be going on all day, but like the stars, it’s not visible to our eyes until after sunset.
Can auroral display be predicted?
When solar activity is high, there will be northern lights. The solar activity also creates interference with radio reception and telecommunication. If you’ve noticed abnormal static heard on the news, that radio interference is being caused by sun spots or solar storms. Check out the sky that night. The night following a good show of northern lights is likely to have more of them, because solar winds can be strong for several days in a row. Also, 27 days after a good display is a likely time to have an occurrence. This is because the sun’s rotation takes 27 days. So if an active sun spot creates strong solar winds blowing toward Earth, that spot will turn away from us as the sun revolves, returning to blow winds toward us again in 27 days.
What makes the colors in the northern lights?
Colors are caused by a variety of factors, including the kind of gases that are being activated by the charged particles, how deep into the atmosphere the particles penetrate, how close to the horizon the aurora is seen, what atmospheric conditions the light travels through (consider the orange rising moon and the colors at sunset), and whether the display is bright enough to activate the color sensors in our eyes. Seeing a good northern lights show depends not just on the aurora phenomenon, but on our ability to perceive it.
Is there ever sound associated with the aurora?
This is a subject of ongoing research. Although the idea was discounted by some scientists in the past, the persistent reports of this phenomenon, even by trained scientists, have led to its further examination in recent years. So far the answer seems to be yes, but we don’t know why. We know that humans could not possibly hear a relatively quiet electrical process going on at least 40 and as much as 200 miles above our heads. If you are ever able to get a recording of the sound associated with a bright aurora, carefully observe and record the experience and contact the University of Alaska at Fairbanks, where most of the land-based research on the aurora is being done. You could make a significant contribution to our understanding of this phenomenon.
What did people think caused northern lights before modern scientific explanation?
As few as 30 years ago some well educated people were explaining the aurora as reflections off ice fields in the far north, although scientists had begun attributing the displays to solar activity in the early 1900’s.
Legends and myths about the northern lights are plentiful among all people who lived in areas where they could be seen. These often involve departed spirits, the souls of dead loved ones. Some say the lights are the trails of child spirits playing ball, or lanterns lit by guides to help lost souls find their way to the afterlife. Middle Europeans tend more to legends about gods battling in the sky or dragons and other scary animals. Fire is a common theme among aurora stories told by Native Americans, including Minnesota Menominee who told of enormous torches used by friendly giants to help people spear fish at night. In Scandinavian Lapland, one belief was that the aurora was a winter thunderstorm.
Neil Davis, author of The Aurora Watcher’s Handbook, recalls his first experience seeing the aurora. It was a red display that was visible far tot he south, and many people, believing the end of the world to be at hand, panicked and ran into the streets to pray and confess past sins. His strongest memory of that night was a neighbor lady who loudly confessed “what to my youthful ears were some highly interesting social activities.” He reports that she remained in her house for several days afterwards.
What do the northern lights look like?
Certainly on nights when there is a dramatic show, nobody gazing at the night sky will miss them. But more subtle displays take the form of a softly glowing arc, usually toward the north. This arc may begin to break into streaks of light that move across the sky. In the Ely area, northern lights are most often colorless, or a light green. Occasionally, red is also present.
There is plenty to learn about the aurora, some of it more easily understood if you have a working knowledge of physics. The book mentioned above is excellent, and readable by those of us with less science aptitude than some. Published by the University of Alaska Press at Fairbanks, it has a companion video that’s a great way to see the aurora if you miss them on your visit.