Читать книгу The End of Night: Searching for Natural Darkness in an Age of Artificial Light - Paul Bogard - Страница 6

Have you ever experienced Darkness, young man?

—ISAAC ASIMOV (1941)

At least when it comes to light pollution, what happens in Vegas does not stay in Vegas. What happens here seeps across the surrounding desert so that national parks in Nevada, California, Utah, and Arizona, tasked with conserving their features “unimpaired for the enjoyment of future generations,” report their horizons aglow, their dark skies tainted. It’s to one of those parks, Great Basin, that I am headed—two hundred fifty miles north on Nevada’s US Route 93, two lanes rising from I-15 toward Ely—to see for myself what’s left of the dark.

The story is the same all over the country—dark places disappearing from the map. Computer images based on NASA photos show—from the 1950s to the 1970s to the 1990s—a steady spread of light across the land, and the projected view of 2025 imagines the entire country east of the Mississippi as one great rash of yellows and reds, the most intensely populated areas blisters of white; even west of the great river only scraps of black remain, each surrounded by a civilization gnawing at its ragged edges. Still, the eastern Nevada desert is some of the darkest geography left in the United States, and Great Basin National Park lies at its heart. So here I am, charging out of Las Vegas toward maybe the darkest spot in the nation.

It’s the early evening, and all around the racing car the earth is changing, temperatures falling, animals and insects beginning to stretch and move, night-blooming plants feeling life surge again. All day the desert rocks have been gathering heat, expanding in sunlight, sending thermals skyward to soar hawks and bump descending planes. But at night the direction of energy flow reverses, the temperature drops thirty or forty degrees, and the desert rocks glow with warmth like a winter’s woodstove. In the natural rhythm of day and night, whole mountains swell and fall like the chest of a sleeper.

To the east the mountain ranges still hold the rose color of the setting sun, while to the west already they are losing their definition, dissolving into silhouettes, the darkness sloping to the desert floor, long drapes hanging from mountainsides. We call this time “twilight,” and officially, there are three stages—civil, nautical, and astronomical—that correspond to the gradual gathering of darkness and fading of the sun’s light. In this twentieth-century classification, civil means the time when cars should use their headlights, nautical means dark enough that the stars needed for navigational purposes are visible, and astronomical means when the sky darkens nearly enough for the faintest stars. Unofficially, I love biologist Robin Wall Kimmerer’s name for twilight: “that long blue moment.”

We like to think that darkness “falls,” as though it were like snow, but as the earth turns its back to the sun darkness actually rises from the east to wash and flood over land and sea. If you’ve ever stood at dusk and seen a gloaming on the eastern horizon, as though clouds were gathering, a thunderstorm brewing, that’s what you’re seeing—the earth’s shadow as we rotate into it. What we call “night” is the time when we are caught in that shadow, a shadow that extends into space like the cone to earth’s ice cream, a hundred times taller than it is wide, its vertex 860,000 miles above the earth. Dawn comes as we rotate out of that shadow into the edges of direct sunlight.

Driving northeast away from what’s left of this light, I look to the darkening sky and wonder what will be revealed. Venus, the Evening Star, emerges in the driver’s-side window just over a silhouetted range, and then the first few actual stars, those of the Big Dipper, maybe the most well-known pattern of stars in the history of the world. One of these stars, Mizar, the second from the end of the Dipper’s handle, is actually a double star, a visual binary, confirmed by telescope in 1650 but known to stargazers for millennia. In fact, the ability to see Mizar’s faint twin, Alcor, with the naked eye has long been a traditional test of vision, one I admit I’m failing as the first bright town appears down the road.

The name of the town doesn’t matter, for at least when it comes to light pollution this town is the same as ten thousand others: while its lights contribute only a little to the pollution blanketing the nation, all the different threads of the problem are here. The lights are all unshielded, for one thing, and so glare shoots this way and that, cast into the dark with little reason. Wood and chain link fences mark the boundaries between neighbors, but each neighbor’s lights here, as all across America, are allowed to roam far beyond their boundaries—a perfect example of what dark sky advocates call “light trespass.” The lights from these unshielded fixtures not only trespass onto the yards of neighbors and into the eyes of drivers passing through but straight into the sky, their energy wasted. The solitary gas station is lit beyond daylight, that light too floating from under the gas pump canopy to wipe stars from over the town. Drop-lens “cobrahead” streetlights are strung down every street, glaring into bedrooms and living rooms, the surrounding desert, and up toward the stars. Toward the edge of town come a smattering of “security lights,” those ubiquitous white lamps hovering over backyards, barnyards, and driveways across the country, and then one final billboard lit from below, the upward-pointing light skipping from the ad into space without pause.

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 pollution is evident along the horizon”) or 2 (a “truly dark site”). As for Bortle’s Class 1, which he describes as a sky so dark that “the Milky Way casts obvious diffuse shadows on the ground,” many question if such darkness still exists in the Lower 48. While rumors arrive from the deserts of eastern Oregon and southern Utah, the Nebraska prairie and the Texas-Mexico border, there’s no denying that Bortle has described a level of darkness that for most of human history was common but for the modern Western world has become unreal.

From the moment I first encountered Bortle’s scale, I wondered about the places I had visited and lived and loved, like the lake in northern Minnesota where as a child I first experienced real darkness and began to learn about night. I wondered as well if there were any Bortle Class 1 places left in my country. Another way to phrase that question is this: In the Lower 48 states, are there any places left with natural darkness? Or, yet another way, Is every place in my country now tarnished by light?

I decided to find out. I would travel from our brightest nights to our darkest, from the intensely lit cities where public lighting as we know it began to the sites where darkness ranking a 1 might still remain. Along the way, I would chronicle how night has changed, what that means, what we might do about it, and whether we should do anything at all. I wanted to understand especially how artificial light can be both undeniably wonderful, beautiful even, and still pose a long list of costs and concerns. I would start in cities such as Las Vegas—in NASA photographs the brightest pixel in the world—and in Paris, the City of Light. I would travel to Spain to explore “the dark night of the soul” and to Walden Pond to check in with Thoreau. I would meet with scientists, physicians, activists, and writers working to raise awareness of the value of darkness and the threats from light pollution: the epidemiologist who first connected artificial light at night with increased rates of cancer, and the retired astronomer who founded the world’s first “dark sky” organization; the minister who preaches the necessity of the unknown, and the man whose work has saved countless nocturnal migrating songbirds in several major cities—it’s through people like these that I would tell this story.

My first move was to contact Chad Moore, a founder of the National Park Service’s Night Sky Team. For over a decade, Moore has been chronicling levels of darkness in the U.S. national parks, and I wanted to know what he thought I would find.

“Well,” he explained, “as you slide down this ramp from nine to one into darkness it’s not a smooth slide. It’s … bumpy.” Moore explained that with the Bortle scale, while the difference between 9 and 5, or between 5 and 2 would be obvious to anyone, the difference between 9 and 8 or between 2 and 1 can be difficult to discern. “There’s so much fuzziness that it’s prone to misinterpretation, and so if you’re grumpy you’ll give yourself a five, and if you’re optimistic you’ll give yourself a three … and it’s really a four,” he laughed.

That made sense, but are there still any Class 1 places left in the United States?

“There are rare places and rare moments where places in the U.S. compare with the rest of the world,” he said. “I would like to think that I’ve seen that, that I’ve glimpsed Class One. But it takes some diligence. It’s easier to get a plane ticket to Australia and drive out past Alice Springs … It could take a while before you find that combination here in the United States.”

Satellite photographs of the earth at night tell of two worlds—the illuminated civilization of developed (and developing) countries and the darkness of poor or uninhabited areas—and in some ways Moore is right; it would be easier to fly somewhere exotic and remote. But I wanted to know night closer to home. I wanted to know the darkness we experience in our daily life.

I decided to focus my journey on North America and western Europe. First, this is where the artificial lighting now sprawling over the world began and where it continues to evolve: It is Western thinking about darkness and light—and Western technology—that shapes the developed world’s night. Second, few of us will ever fly to Australia and drive out past Alice Springs, but we all experience night where we live and work and love.

And most of us, if we wanted, could get ourselves out to real darkness closer to home, like the darkness of a rural highway in eastern Nevada.

“Our sun is one star in a disk-shaped swarm of several hundred billion stars,” writes astronomer Chet Raymo. That disk-shaped swarm is our Milky Way Galaxy, and what arcs in three dimensions above this dark Nevada desert is the outer arm of that spiral, toward which we look from our inner-galaxy location. Raymo continues:

I have often constructed a model of the Milky Way Galaxy on a classroom floor by pouring a box of salt into a pinwheel pattern. The demonstration is impressive, but the scale is wrong. If a grain of salt were to accurately represent a typical star, then the separate grains should be thousands of feet apart; a numerically and dimensionally precise model of the Galaxy would require 10,000 boxes of salt scattered in a flat circle larger than the cross-section of the Earth.

This means that every star in our night sky, every individual star any human has ever seen with his or her naked eye, is part of our galaxy and its “several hundred billion stars.” Outside our galaxy exist innumerable other galaxies—one recent estimate put the number at 500 billion. At some quick point the size of the universe becomes overwhelming, its distances and numbers bending our brains as we try to comprehend the incomprehensible—that our night sky is but one tiny plot in a glowing garden too big to imagine.

But of course, for all of human history we have indeed imagined. Ancient civilizations from North America to Australia and Peru created constellations not only from groups of individual stars but even from the black shapes made by the gas and dust that lie between Earth and our view of the Milky Way’s smokelike stream. And for ages we imagined it might well be smoke, or steam, or even milk—not until 1609 did Galileo’s telescope confirm what he suspected, that the Milky Way’s glow was the gathered light of countless stars.

In these countless stars, in their clusters and colors and constellations, in the “shooting” showers of blazing dust and ice, we have always found beauty. And in this beauty, the overwhelming size of the universe has seemed less ominous, Earth’s own beauty more incredible. If indeed the numbers and distances of the night sky are so large that they become nearly meaningless, then let us find the meaning under our feet. There is no other place to go, the night sky makes this clear.

So let us go dark.