When the town ends, the darkness at its edge envelops the car, and my headlights cut the lit world down to just what lies ahead. The land on either side falls away, as though the highway is a bridge with thousand-foot drops to the left and to the right. The windshield soon resembles a Van Gogh night sky with its starry smattering of bugs. A jackrabbit sits eating at the side of the road, lifting its long ears absently as the car rushes past. Not long after, a coyote steps from the highway’s other side, eyes aglow, a less fortunate jack hanging from its jaws. A barn owl lifts from a highway marker on the shoulder and flaps ahead for a few beats as though leading the way, then veers off into darkness and disappears.
In the Minneapolis suburb where I grew up lies a golf course with a road cutting through its center, white picket fence on either side. As a teenager I drove an old Volvo box that allowed me to turn off its headlights and sail a sloping, curving road lit only by parking lights, 35 miles an hour. The red wagon I own now is too smart and safe for that—the headlights remain on whether I want them or not—and I assume the same is true of my brand-new rental. But I’m wrong. The temptation is immediate and irresistible, and despite the fact that I’m not going 35 mph on this straight highway but nearly three times thirty-five, I rotate the dial.
In an instant the road disappears, my stomach drops, and I feel as though flung from the edge of the earth. The sensation is exhilarating fear, as my every fiber demands to know what I’m doing. I turn the headlights back on and feel my heart return to beating. The highway before and behind me holds no other cars, and no artificial lights shine in the black sea on the other side. I turn the lights off again and again—longer each time, long enough for my eyes to focus on what little of the highway my parking lights reveal, long enough to look ahead at the starry night flowing toward and over and past, and think of Star Trek’s starship Enterprise accelerating into space. Long enough to feel the car begin to float from the road’s surface and fall into the sky.
The temptation is to leave off the lights, to drive in the dark for more than these few moments. But while I’m happy to know the thrill of boldly going 100 mph through the desert at night, to feel catapulted from earth into space, I am also happy to be alive, and so I slow to 20 mph. It’s what seems now a trolling speed, and so I turn even the parking lights off and lean my head from the driver’s window. The warm dry air flows over, the asphalt rolls underneath, and I realize I am headed directly toward a meeting at the horizon with the Milky Way as it bends from one end to the other. As though on its own, the car slows to a stop in the middle of Route 93 in the middle of the Great Basin desert. Any car or truck coming from either direction will show long before I’d need to move. Unless, of course, they are driving with their lights off, too, staring up at this altogether other highway.
“To know the dark, go dark,” advises Wendell Berry. But seen from satellites at night, our planet’s continents burn as though on fire. Across the globe the collected glow from streetlights, parking lots, gas stations, shopping centers, sports stadiums, office buildings, and individual houses clearly details borders between land and water, sometimes spreading even into the sea on squid fishing boats, their spotlights built to mimic noonday sun. It would be one thing if all this light were beneficial. But while some does good work—guiding our way, offering a sense of security, adding beauty to our nightscape—most is waste. The light we see in photos from space, from an airplane window, from our fourteenth-floor hotel room, is light allowed to shine into the sky, into our eyes, illuminating little of what it was meant to, and costing us dearly. In ways we have long understood, in others we are just beginning to understand, night’s natural darkness has always been invaluable for our health and the health of the natural world, and every living creature suffers from its loss.
The earth at night, circa 2000. (C. Mayhew & R. Simmon (NASA/GSFC), NOAA/ NGDC, DMSP Digital Archive)
Our light-saturated age makes it difficult to imagine a time when night was actually dark, but not all that long ago it was. Until well into the twentieth century, what passed for outdoor lighting was simply one form or another of fire—torches, candles, or dim, stinking, unreliable lamps. And while these forms of lighting were an improvement on the earliest (skewering and burning oily fish or birds, gluing fireflies to your toes), how feeble this light was: A single 75-watt incandescent bulb burns one hundred times brighter than a candle. Historian E. Roger Ekirch reports that “pre-modern observers spoke sarcastically of candles that made ‘darkness visible,’” and a French proverb advised, “By candle-light a goat is lady-like.” Travelers considered moonlight to be the safest option for nighttime navigation, and lunar phases were watched far more closely than they are today. By the end of the seventeenth century, many European cities had some rudimentary form of public lighting, but not until the end of the nineteenth century did any system of electric lights—now so easily taken for granted—come into use. The darkness of our nights has been fading steadily ever since.
No continents burn brighter than North America and Europe. Already, some two-thirds of Americans and Europeans no longer experience real night—that is, real darkness—and nearly all of us live in areas considered polluted by light. In the United States, Henry Beston’s warning of “lights and ever more lights” from Cape Cod in 1928 may have seemed extreme for many of the 120 million Americans alive at the time, most of whom lived in rural areas without electricity, but fewer than ten years later he was well on his way to being proven right. With FDR’s signing into existence the Rural Electrification Administration in 1935, the old geography of night in the United States was certain to change. By the mid-1950s, whether in the city, the suburb, or the country, most Americans lived with electric light. In the half-century since, as the American population has risen past 300 million, those lights have continued their steady spread unabated and, for the most part, unnoticed. Could we jump from the dark of the 1930s (or 1950s, or even 1970s) to that of tonight, few of us would fail to be impressed by the dramatic increase in artificial light. But that increase has been gradual enough that it would be easy to imagine our nights are still as dark, or nearly so, as they ever were.
With this in mind, and knowing, as he says, “the extent to which ever-growing light pollution has sullied the heavens,” amateur astronomer John Bortle created in 2001 a scale on which he described various levels of dark skies, ranking them 9 to 1, brightest to darkest. He hoped his scale would “prove both enlightening and useful to observers,” though he knew it might stun or even horrify some. While Bortle’s distinctions can seem overly subtle, or inconsistent, they offer a language to help define what we mean when we talk about different shades of darkness, about what we have lost, what we still have, what we might regain.
Most of us are all too familiar with the brighter end of Bortle’s scale—his Class 9: Inner-city Sky, or Class 7: Suburban/Urban transition, or Class 5: Suburban Sky—for these are the levels most of us call normal, what we call “dark.” But Bortle’s scale shows us what we are missing. Indeed, most Americans and Europeans, especially the youngest among us, have rarely or never experienced—and perhaps can’t even imagine—a night dark enough to register 3 (“a rural sky” where only “some indication of light