The Northern Lights

In his 1814 edition of the Lewis and Clark journals, Nicholas Biddle expanded upon the journalists’ brief, breathless description of the night-sky phenomenon they observed from Fort Mandan on the night of 5 November 1804:^[1]Nicholas Biddle, History of the Expedition Under the Command of Captains Lewis and Clark. (2 vols., 1814; reprint, with an introduction by John Bakeless, New York: Heritage Press, 1962), I:78.

Late at night we were awaked by the sergeant on guard to see the beautiful phenomenon called the northern light: along the northern sky was a large space occupied by a light of a pale but brilliant white colour: which rising from the horizon, extended itself to nearly twenty degrees above it. After glittering for some time its colours would be overcast, and almost obscured, but again it would burst out with renewed beauty; the uniform colour was pale light, but its shapes were various and fantastic: at times the sky was lined with light coloured streaks rising perpendicularly from the horizon, and gradually expanding into a body of light in which we could trace the floating columns sometimes advancing, sometimes retreating and shaping into infinite forms, the space in which they moved. It all faded away before the morning.

They saw them the next night too, “very brilliant in perpendiculer collums frequently changing position,” Clark wrote. In mid-August 1806, coincidentally again at the Mandan villages, they saw them. They had first seen them at Camp Dubois, on the 1 April 1804.

Since humans first had looked into the night sky, people in high northern and southern latitudes had tried to explain these dazzling curtains, spears, and arches of light. Appearing above the magnetic poles, near the North Pole and South Pole, the lights have been seen as far away as 40° north or south latitude. At Fort Mandan, the captains were at 47° north latitude.

The northern lights were portents of trouble or signs of celestial joy in different cultures. The phenomenon’s modern name, aurora borealis, combines the name of Aurora, the Roman goddess of dawn, with a word meaning north derived from the name of Boreas, the Greek god of the north wind. (In the southern hemisphere, the phenomenon is called southern lights or, scientifically, aurora australis-from the Latin for southern.

What did Meriwether Lewis and William Clark understand about the aurora borealis–literally, “Dawn of the North”? Even though the captains were well past mythological explanations, scientific theories of their time may sound a bit fanciful today. Yet, scientists of the early 21st century still cannot completely explain what causes the northern lights.

Jefferson ordered for Meriwether Lewis a two-volume reference work commonly called Owen’s Dictionary. It wasn’t the latest, and it was British, but it was the best available.^[2]Donald Jackson, “Some Books Carried by Lewis and Clark,” Missouri Historical Society Bulletin, Vo. XVI, No. 1 (October, 1959), 4-13. Beginning with “Aurora borealis is an extraordinary meteor, shewing itself in the night-time, in the northern parts of the heavens,” Owen’s went on to describe the northern lights’ appearance as:

an apparent, though not real cloud . . . terminated with one or more lucid arches, and sometimes by a long bright streak of light, lying parallel to the horizon. . . .

Out of these arches proceed streams of light generally perpendicular to the horizon, but sometimes a little inclined to it, and very much resembling the tail of comets. . . .

The upper ends of the streams appear and vanish incessantly, which causes such a seeming trembling in the air, that you would think the upper part of the heavens to be as it were in convulsions.^[3]A New and Complete Dictionary of Arts and Sciences; comprehending all the branches of useful knowledge, with accurate descriptions as well of the various Machines, instruments, tools, figures, and … Continue reading

The writer summarized four current theories, beginning with that of astronomer Edmond Halley,^[4]Edmond Halley (1656-1742), English astronomer and mathematician, who in 1705 calculated the orbit of the comet that still bears his name—Halley’s Comet, which last was visible from earth … Continue reading who thought that the Northern Lights came from a type of friction in the atmosphere:

. . . magnetic effluvia which he supposes enter the earth near the south pole, and pervading its pores, pass out again at the same distance from the northern; and thinks, that . . . they may be capable of producing a small degree of light, either from the greater density of the matter, or from the greater velocity of its motion . . . .

Monsieur de Marain^[5]Jean Jacques Dortous de Mairan (1678-1771), French astronomer and author of Dissertation sur les variations du barometre, Beziers: E. Barbut, 1715. endeavours to prove that it is owing to the zodiacal light, or the atmosphere of the sun, which mixing with our atmosphere, and being of an heterogeneous nature, produces the several appearances of the aurora borealis.

Mr. Maier,^[6]Mr. Maier is not identifiable. The Academy of Sciences, St. Petersburg, Russia, was founded by Peter the Great in 1724 and opened the following year; today it is The Russian Academy of Sciences. … Continue reading of the academy at Petersburg, accounts for it from exhalations fermenting and taking fire in the atmosphere of the sun, which mixing with our atmosphere, and being of an heterogeneous nature, produces the several appearances of the aurora borealis.

Mr. Rowning^[7]Rowning may be John Rowning (1701-1771), author of A Compendious System of Natural Philosophy, London: S. Harding, 1744; 8th edition, 2 vols. London: Printed for J.F. and C. Rivington, 1779. gives a very ingenious and natural solution of all the above phaenomena, from such effluvia as are continually exhaled from the surface and bowels of the earth.

Comet-predictor Halley was furthest from the truth, in this case, since the “effluvia” don’t go into one side of earth”s atmosphere and out the other. Marain came closest to what we now understand.

It seems that the writer thought that the aurora borealis was a new heavenly phenomenon, but that’s only because climate had intervened for some years before their time, in the form of the Little Ice Age.

Owen’s Dictionary stated that “. . . the aurora borealis is a very common phaenomenon in countries near the pole; but there are not many upon record, as having appeared in England before that of March 1715.” Since that time, however, they have been and still continue very frequent. Apparently no one had noticed that the auroras, like so many other natural phenomena, appeared in cycles. When the Owen’s was published our sun was just entering a cycle of activity that warmed earth up from the “Little Ice Age.” As described by geologist Robert Bergantino,

The term “Little Ice Age” applies to a period of cooler and wetter weather in parts of the northern hemisphere. The date of onset depends largely on location. The Norse colonies on Greenland had already succumbed to increasing cold by the early 1300s, but glacial studies in the Rockies and Pacific Northwest suggest that glacial increase did not begin there until the early 1400s, and then the increase was quite slow.

The “cold maximum” occurred in the mid-1700s (picture George Washington crossing the Delaware River amid ice floes—now non-existent—or hauling his cannons across the ice of rivers that haven’t frozen over since). Many glaciers in the Northwest, however, did not reach their maximum extent in the early 1800s. The main cold period had ended in most places by the mid-1800s, but temperature graphs show a slight increase in some areas until the early 1900s, then the temperature dropped again, only to begin rising again after the 1940s.^[8]Robert Bergantino to Joseph Mussulman, 2 October 1998.

In terms of sunspot activity, the Little Ice Age era is called the “Maunder Minimum,” for the twentieth-century British astronomer who discovered it. Written records and carbon-14^[9]Carbon-14, radioactive carbon, is present in all living things, and is replenished while they live. After death, carbon-14 decays at a fixed rate. By testing the amount of carbon-14 in organic … Continue reading both show that minimal sunspot eras occurred in the seventh and fifteenth centuries A.D., while the first century B.C. (“Roman Maximum”) was a time of frequent sunspots, as was the 12th century A.D. (“Medieval Maximum”). Carbon-14 testing also indicates that the sunspot cycle may have lasted about ten years in the past, shorter than today’s eleven-year cycle.^[10]T. Neil Davis, “Historical Auroras,” at http://www.gi.alaska.edu/ScienceForum/ASF4/448.html/ Alaska Science Forum, 7 January 1981. An earlier study of sunspot activity between 1750 and … Continue reading

Other than sunspot activity, some scientists believe, the sun undergoes much longer cycles of overall activity that cause slow heating and cooling in earth’s climate. The earth .s magnetic fields also experience long-term alterations, with their uneven circles expanding, contracting, and changing shape.^[11]Davis, “Historical Auroras.”

We know much more than Lewis and Clark did about what causes the northern lights, but questions remain. In short, scientists believe they have figured out what happens to cause the beautiful sight, but they still are studying the mechanics of how it occurs.^[12]Sources for this page include multiple articles in Encyclopaedia Britannica and World Book Encyclopedia.

Most importantly, we at least understand that the northern lights are a natural, regular function of our solar system.

From the sun, a continuous flow of charged atomic particles—the solar wind—travels throughout our solar system. The sun itself undergoes a cycle of activity that spreads over more than 22 earth years. At the beginning of the cycle, there are fewer sunspots—darker and cooler places on the sun’s surface (which may be caused by alterations in the sun ‘s magnetic field). Then, over the next 11.1 years on average, more and more sunspots appear until they reach peak activity. Sunspots become fewer and fewer during the rest of the approximately 22-year cycle.

Associated with sunspots are solar flares, which are brief but strong eruptions of radiation. Carried by the solar wind, the radiation reaches the edge of earth’s atmosphere about two days after the solar flare can be observed by telescope. When the radiation enters earth’s ionosphere, it interrupts radio signals sent by people around the earth. Our planet’s ionosphere is an outer layer of atmosphere, holding very few molecules and subatomic particles, which reaches from about 49 to 310 miles above earth’s surface. At about 50 to 60 miles up, cosmic rays and solar radiation regularly split oxygen molecules into ions and free electrons—subatomic particles that carry electric charges. Because it reflects radio rays, the ionosphere is what makes radios work, most of the time. Solar flares interrupt radio transmission.

Also around any astronomical body is a magnetosphere, a field whose own magnetic force, rather than the planet’s, is in control. When radiation from a solar flare reaches earth, the magnetosphere captures the charged particles and somehow directs them down through the ionosphere toward the magnetic pole. In the northern hemisphere, the magnetic north pole is over the southern tip of Greenland, not at the geographical North Pole.

As Lewis and Clark and their sergeant stood outdoors at Fort Mandan watching the northern lights, they were seeing a solar flare’s radiation pass through the ionosphere, flowing toward magnetic north. When this concentrated burst of solar radiation hit still-whole oxygen and nitrogen molecules, it split masses of them all at once. The subatomic particles . energy escaped in wavelengths that caused certain colors to appear as light moving in its .infinite forms . far up in the cold November sky.^[13]Red, blue, and yellowish-green are the colors seen in earth’s aurora borealis.

But part of the energy that causes auroras may come from earth itself. Research published in January 2003 suggests that movements in earth’s magnetic field also may send electrons into our atmosphere.^[14]Published in Science, reported by Scientific American at http://sciam.com/ Andreas Keiling of the University of Minnesota, and the Center for Space Research on Radition, at Toulouse, France, published an analysis of a year’s worth of data collected by NASA’s POLAR satellite.

Looking at ripples in the Alfven waves (movements in the magnetic field) at 15,500 to 23,560 miles altitude, the group concluded that those waves created enough energy to throw electrons into earth’s atmosphere. Keiling wrote that, “One third of the energy [of auroras] could be driven by these waves.” Scientists still don’t know why the Alfvén waves occur, though.

As research continues, it is worthwhile to look back to Norway in about 1230 A.D. A book called The King’s Mirror collected current knowledge—just as Owen did five hundred years later—written in the form of a father answering his son’s questions about the physical world, governments, and how to live. Beginning an explanation of the aurora borealis, the author wrote:

. . . it is the same with the northern lights as with anything else we know nothing about, that wise men put forward ideas and simple guesswork, and believe that [which] is most common and probable.

Scientists continue to study the phenomenon of the aurora borealis not only on our own planet but throughout our solar system,^[15]Auroras have been observed on Jupiter, Saturn, Uranus, and Neptune, planets that have low atmospheric densities compared to earth’s, and are composed mostly of helium and hydrogen. hoping to replace the old somehows and maybes with a more believable explanation.

World Views

Long before scientists started trying to figure out the northern lights, people around the world had watched their spectacular displays, and come up with their own explanations. Look at these from northern hemisphere people, and note the great range from positive to negative.

Joyful Events

Algonquin people believed that the god who created earth and people afterward moved to the far north. Keeping a promise made to the first people, he sometimes kindled giant bonfires in the sky to remind his creations that he still looked after them.^[16]Introduction to 1998 art exhibit “Aurora Universalis” at InterAccess Electronic Media Arts Centre, Toronto, by curator Nina Czegledy, http://www.interacess.com/aurora/

Inuit people of Alaska and Canada thought the lights came from joyful dancing by the dead in the highest level of the afterlife.

The warlike Scandinavians of the Middle Ages described a heavenly place where heroes slain in battle spent eternity in a banqueting hall called Valhalla. Daily they went out to battle, but when they returned their wounds miraculously healed. The northern lights were the reflection of Valhalla’s ceiling, made entirely of battle shields, or of the heroe’ shields flashing in their eternal wars, or of the shields of the Valkyries, battle maidens who escorted the heroes to Valhalla then served their feasts.^[17]World Book Encyclopedia.

Estonians credited a wedding feast that was being held in the heavens.

Shetland Islanders called the aurora borealis the Merry Dancers.

Some Eskimos thought the spirits were playing a soccer-like game.^[18]See http://www.polarbearsinternational.org/news-room/scientists-and-explorers-blog/aurora-and-its-fantastic-indigenous-interpretations

Signs of Danger

Ancient Romans termed the display “blood rain.”

Fox Indians in the Wisconsin area thought the northern lights were the ghosts of enemies they had killed in battle.^[19]Ibid.

Point Barrow Eskimos tried not to go outdoors during northern lights displays, and if they had to do so, took weapons to defend themselves from the lights.^[20]Ibid.

In Northern England, James Radcliffe, Earl of Derwentwater, was a leader in the 1715 rebellion that sought to restore King James to the throne. He was beheaded in the Tower of London after the rebellion was quashed. An especially reddish display of northern lights the same day led to the aurora’s being called “Lord Derwentwater’s Lights” in his home region.

More recently, the northern lights were taken as omens of war when they were visible from London during Germany’s 1939 blitzkrieg, and on 7 December 1941, when they were seen as far south as Cleveland, Ohio, on the day that Japan attacked Pearl Harbor.

Robert Service, “Northern Lights”

Canadian poet Robert Service (1874-1958) captured both sides in his poem “The Ballad of the Northern Lights.” A gold rusher to the Yukon in 1898 sees the northern lights as good when there is hope, and evil after his party has bad luck.

When fortune seems to be smiling:

And the skies of night were alive with light, with a throbbing, thrilling flame;
Amber and rose and violet, opal and gold it came.
It swept the sky like a giant scythe, it quivered back to a wedge;
Argently bright, it cleft the night with a wavy golden edge.
Pennants of silver waved and streamed, lazy banners unfurled;
Sudden splendors of sabres gleamed, lightning javelins were hurled . . . .

When things were bad:

And the Northern Lights in the crystal nights came forth with a mystic gleam.
They danced and they danced the devil-dance over the naked snow;
And soft they rolled like a tide upshoaled with a ceaseless ebb and flow.
They rippled green with a wondrous sheen, they fluttered out like a fan;
They spread with a blaze of rose-pink rays never yet seen of man.
They writhed like a brood of angry snakes, hissing and sulphur pale;
Then swift they changed to a dragon vast, lashing a cloven tail . . . .