About fifty miles above sea level, far beyond the outer reaches of the ozone layer, there lies a huge stretch of air called the thermosphere, where temperatures soar to 2000° Centigrade. Particles in this part of the sky are so scarce that, as Lyall Watson writes, “not enough of them strike a body in orbit to transfer such awesome heat,” though there are more than enough to “combine with other charged particles thrown into the edges of our atmosphere by gusts of solar wind” and create the “awesome display of pyrotechnics” we call the Aurora Borealis and Aurora Australis, or the Northern and Southern Lights:
Such auroras concentrate around the polar circles, appearing a few hours after sunset as pale greenish glows that brighten until phantom curtains of lime green, gold, and magenta arch across the sky, as though a gigantic explosion had taken place just over the edge of the world and heaven itself was on fire.
These lights, which Louise B. Young compared to “firelight flickering on the ceiling of the world”, have been capturing the imaginations of artists and storytellers since time began. The Inuit of Hudson Bay believed they were the lanterns of demons in search of lost souls; the Norse saw them as the spears, armor, and helmets of the Valkyries leading fallen soldiers to Valhalla; Greenlanders thought they were the dancing spirits of children who had died at birth.
Death has been associated with polar auroras from the first. The Ngarrindjeri of southern Australia have referred to the lights as the campfires of the dead, while the Inuit of northern Alaska, saw them as evil. Even in the lands between these two geographical extremes, auroras have been a cause for concern. Seneca, in his Naturales Quaestiones, records that, during Tiberius’ reign (14–37 AD), an aurora above the city of Ostia, near Rome, glowed so intensely that a military unit stationed nearby, believing the town was on fire, galloped to the rescue.
In eighteenth-century Europe, the Aurora Borealis, like so many aspects of nature, was largely transformed from an object of horror into an object of wonder. The English explorer and naturalist Samuel Hearne, in his Journey from Prince of Wales’ Fort in Hudson Bay to the Northern Ocean (1795), wrote with surprise that, during the long winter nights north of the Canadian lake Athapapuskow, the Aurora Borealis provided sufficient light for him to read even “a very small print”. Hearne was also the first European to note the noise that the lights seem to make “as they vary their colours or position”. “I can positively affirm,” he wrote (in a passage that would later entrance both Wordsworth and Emerson), “that in still nights I have frequently heard them make a rustling and crackling noise, like the waving of a large flag in a fresh gale of wind.”
There have been many theories about the origins of auroras over the years. Seneca wondered whether they were formed above or below the clouds. Hearne, like many people in his time, believed they consisted of a storm of comets. Benjamin Franklin theorized they were the result of electricity gone haywire in the upper air. It was not until the twentieth century that the Norwegian scientist Kristian Birkeland (1867–1917) laid the foundations of our current understanding of the phenomena, though, in fact, there’s still a good deal about them scientists don’t understand.
Auroras remain a cause for wonder — a reminder of the strange, moving beauty of the universe, which extends so far beyond us it boggles the mind. John Steinbeck, in Travels with Charley, expresses this nicely when, on his way to Maine in a camper van, he goes out into the night to get his dog some biscuits and happens to look up:
the Aurora Borealis was out. I’ve seen it only a few times in my life. It hung and moved with majesty in folds like an infinite traveler upstage in an infinite theater. In colors of rose and lavender and purple it moved and pulsed against the night, and the frost-sharpened stars shone through it. What a thing to see at a time when I needed it so badly!