Brilliant: The Evolution of Artificial Light

by Jane Brox

  Here we have a fine and elegant argument for quieting the doubts of those who, while accepting with tranquil mind the revolutions of the planets about the sun in the Copernican system, are mightily disturbed to have the moon alone revolve around the earth.... But now we have not just one planet rotating about another.... Our own eyes show us four stars which wander around Jupiter as does the moon about the earth, while all together trace out a grand revolution about the sun.

  Galileo also observed that the moon Aristotle had perceived as perfect "is not robed in a smooth and polished surface, but is in fact rough and uneven, covered everywhere, just like the earth's surface, with huge prominences, deep valleys, and chasms." As for the Milky Way, he said: "With the aid of the telescope this has been scrutinized so directly and with such ocular certainty that all the disputes which have vexed philosophers through so many ages have been resolved, and we are at last freed from wordy debates about it. The galaxy is, in fact, nothing but a congeries of innumerable stars grouped together in clusters."

  In the centuries following Galileo, as telescopes became more powerful and refined, astronomers increasingly saw farther back in space, and farther back in time—to Andromeda, to quasars and black holes—and among the optimum places for observing the stars were the higher elevations of southern California. The nights are generally clear there, and the mountains are not so high that their summits are lost in clouds or snow squalls, yet they rise above the dense atmosphere and fog of the coastal plain. The air is usually calm on the peaks as well: the prevailing onshore winds of the Pacific flow smoothly over them. This stability makes for what astronomers call "good seeing," for it is the movement of air flowing over the earth that distorts the light and causes the stars to twinkle. (By contrast, stars viewed by astronauts in orbit appear steady, while human lights on earth glitter.)

  So exceptional was the seeing atop the peaks of southern California that during the first half of the twentieth century, the area became home to some of the most important observatories in the world. The first was the Mount Wilson Observatory, built in 1904 in the San Gabriel Mountains of Los Angeles County. "Many astronomers thought that on a good night the atmosphere over Mount Wilson was so still, the images of the stars so well defined, that it was perhaps the best seeing in the world," wrote historian Ronald Florence. But by the late 1920s, when George Ellery Hale began searching for an appropriate site to situate the 200-inch telescope he was to build, the city of Los Angeles and its suburbs had spread right to the base of Mount Wilson, and urban light was already compromising dark-sky work there. Consequently, Hale decided to house his telescope farther away from the cities, in a fern meadow on Mount Palomar, 5,600 feet above sea level. Palomar was still accessible, yet at forty-five miles from San Diego and one hundred miles from the Los Angeles basin—the 1930 census put the population of San Diego County at about 210,000 and that of Los Angeles and Orange counties at less than 250,000—it seemed safe from the effects of light pollution.

  Hale and his backers decided where to situate the telescope in 1930, but it took almost two decades for the lens to be completed—several years alone for it to be successfully cast of Pyrex at the Corning glass factory in New York and another year for it to slowly cool in an annealing oven, after which it journeyed by train across the country, moving at 25 miles per hour during the daylight hours and stopping after dark. Sixteen days after leaving the Corning factory, it arrived in a Pasadena, California, optics lab, where it remained for more than a decade as technicians, working with slurries of abrasives and with polishing rouge, ground away ten thousand pounds of glass and shaped the lens into a paraboloid. Meanwhile, crews improved the road to the summit of Mount Palomar, ran water and electric lines up the mountain, and built a dome to house the telescope. The Japanese attack on Pearl Harbor in 1941 put a stop to all work there, while almost everyone involved with the project was taken up by the war. The lens was finally trucked up the mountain in 1947. Although the population of southern California had grown markedly and New Deal electrification initiatives had increased the amount of light in homes and on the streets, Palomar remained a remote mountain rising out of the desert. Cattle grazed in the high meadows, and no appreciable light affected the observatory.

  The Hale Telescope saw first light in January 1949, and on that occasion the eminent astronomer Edwin Hubble claimed: "The 200-inch [telescope] opens to exploration a volume of space about eight times greater than that previously accessible for study.... The region of space that we can now observe is so substantial that it may be a fair sample of the universe as a whole." After months more of adjustments—opticians polished the last five- or six-millionths of an inch of the lens with hand-held cork tools and then their own thumbs—the telescope was officially turned over for exploration and research. Astronomers identified stars and studied their birth, evolution, and death; studied the workings of the galaxies; and searched for the age of the universe itself. "Astronomy is an incremental science," Florence wrote. "Each night adds data, fragmentary glimpses and measurements of the reaches of the universe.... Amidst that steady accumulation of knowledge, the achievements of the [Hale] telescope stand out as a history of twentieth-century astronomy."

  But by the 1960s, light pollution began to compromise the quality of dark-sky study at Palomar—as it has at many observatories throughout the world in the past fifty years. In some places where dark-sky study is severely limited or impossible, institutions such as the David Dunlap Observatory outside Toronto and the Yerkes Observatory outside Chicago have been transformed into historical sites and education centers. Even in working observatories, quite a few celestial objects simply aren't apparent anymore. "It's like I'm looking for the glitter of a little pen-ray flashlight in the glare of bright sunlight," commented one astronomer at the Kitt Peak National Observatory outside Tucson, Arizona. "That 20 percent increase in sky brightness means it takes us 40 percent longer to record the same faint, distant objects. You get less done per expensive hour of operating the telescope."

  Sometimes there isn't enough dark time in a night to record an object at all anymore. In addition, mercury vapor lamps—the most popular type of street lighting—do more than blot out the stars. They also compromise astronomers' ability to take an object's spectra—that is, split the light from the telescope into its component colors. Astronomer Dave Kornreich explains:

  When you take a spectrum of fluorescing objects like galaxies, you see that the spectrum is not smooth, but made up of a number of lines. Each line is a unique indicator of the presence of a certain chemical. By studying the strengths of these lines, astronomers can deduce the chemical composition and temperature of the objects they observe.... Mercury vapor lamps have an enormous number of these spectral lines in all parts of the spectrum [which] interfere with astronomical observations.

  By 1980, when the population of San Diego County had grown to just under 2 million, light pollution around Palomar had become so severe that in the following years, scientists at the observatory, in an effort to counter the further increase of pollution, began working with the surrounding town and county governments to try to reduce unnecessary lighting and glare in the area. Light pollution may appear to be as complex as modern lighting itself, for not only do countless individual lights contribute to it, but different kinds of artificial light—incandescent, low- or high-pressure sodium vapor, low- or high-pressure mercury vapor, tungsten-halogen, fluorescent, and LED—affect the surroundings in different ways. And no matter the kind of light, the effect of lighting in any one place is always variable because its intensity and apparent brilliance are affected by weather, by the dust and gas in the atmosphere, and by the cloudiness or clarity of the sky. The direction and path of the illumination makes a difference as well. "Light traversing a path at a shallow angle above the horizontal ... will cause more sky glow, since it will encounter more particles and droplets from which to be scattered on its way through the atmosphere," wrote astronomer Bob Mizon. The type of surface the
light eventually falls on matters as well: whether it's wet or dry, smooth or rough, dark or light determines the reflectivity of any light.

  The Palomar scientists and town and county officials attempted to mitigate the light problem at the observatory by creating zoning ordinances. For decorative lights, such as those used to illuminate advertising, and lighting at outdoor sales areas, they established strict shielding requirements, which would direct the artificial light downward. They also established an 11:00 P.M. curfew for nonessential lighting, and in the fifteen-mile radius around the observatory, ordinances forbade decorative lighting altogether. Riverside County replaced its mercury vapor streetlights with more efficient sodium vapor lamps, which don't interfere with the spectra of astronomical objects.

  Even with concerted efforts to contain light pollution in southern California, the seeing at Palomar is becoming more and more deeply compromised. The mercury vapor lights from surrounding cities have grown so bright that astronomers can no longer observe some parts of the spectrum of celestial objects. In 1999 one astronomer noted that "the city lights can be directly seen through gaps in the mountains, meaning that city light is making its way directly into the telescopes, without first even being reflected by the sky. Many observers have given up looking at objects in the southwestern sky, because the light pollution is so bad in that direction."

  As much as light pollution obscures an understanding of deep space, it obscures an understanding of time, for seeing outward "is equivalent to looking backward in time," Richard Preston notes.

  The universe—as we see it—could be imagined as a series of concentric shells centered on the earth—shells of lookback time. The shells closest to the earth contain images of galaxies near us in time and space. Farther out are shells containing images of remote galaxies—galaxies as they existed before our time. Still farther out is the shell of the early universe. Some of the photons reaching a telescope's mirror are nearly as old as the universe itself. The quasars are brilliant pinpoints of light that seem to surround the earth on all sides, shining out of deep time. Beyond the quasars, the observable universe has a horizon, which could be imagined as the inner wall of a shell. This horizon is the limit of lookback time, which is also an image of the beginning.

  The Hubble Space Telescope—the first space-based observatory—orbits beyond the distortions of the atmosphere and the effects of light pollution, and it sends back to Earth clearer and deeper views of the universe than previously possible. But space-based telescopes—extraordinarily expensive and precarious—can't fully replace what happens when human thought meets the dark sky, whether at rarefied Palomar, where scientists gather and play cowboy pool as they wait for their precious observation time; in a remote pasture where an amateur astronomer collects starlight with a homemade telescope built of wood and mirrors; or at the back door of a farmhouse, where a child looks up and stares.

  Perhaps what we've lost with the disappearance of the night sky is more profound than we can possibly know. "Then Humankind was born," Ovid wrote in Metamorphoses.

  Either the creator god, source of a better world, seeded it from the divine, or the newborn earth just drawn from the highest heavens still contained fragments related to the skies, so that Prometheus, blending them with streams of rain, molded them into an image of the all-controlling gods. While other animals look downwards at the ground, he gave human beings an upturned aspect, commanding them to look towards the skies, and, upright, raise their face to the stars. So the earth, that had been, a moment ago, uncarved and imageless, changed and assumed the unknown shapes of human beings.

  21. The Once and Future Light

  The spiritual instant that is our life...

  —HENRI FOCILLON,

  The Life of Forms in Art

  WE IMAGINE THE FAR PAST as a world carved out of the dark, guttering flame by guttering flame, a past full of other people, and the crackle and smell of other lights: rushes, moss, spruce twigs, tallow, whale oil, and pine. Light in a world lacking it, where abundance and brilliance are a dream flaring for a moment and then gone, where light itself means one thing, the materials of it another: the rushlights of the poor, the beeswax of the church. But they aren't so far away, those people back there. We who live in a world built of light still carry the longings of those without it, still dream of abundance and brilliance even though we can have all the light we want—almost any kind—and have it in an instant.

  Given what we have, and given what we know about the power of light and the limits of our resources, about the trajectory of a changing climate, how will we choose to illuminate our future? Can we overcome the desire for ever more and brighter light? Can we think rationally about light and what it means to us? One of the first things we ask of light is that it grant us some assurance in the dark. Except during the threat of aerial bombardment or under the glare of interrogation, it has almost always made us feel safer. But whether or not it truly ensures our safety is an open question, one that has been argued since the seventeenth century, when a few European cities expressly forbade streetlights for fear that they encouraged footpads and drunks, even as other cities were installing them in hopes of bringing order to the night.

  Although criminals have historically avoided light—at least since the Middle Ages, when thieves shied away from nights of the full moon—it doesn't certainly keep them away when they sense an opportunity. British astronomer Bob Mizon notes, "The Home Office Crime Survey, published in October 2000 and based on the experience of victims of crime, suggests that premises which have security lighting are as likely to be broken into as those without it." Mizon also relates the story of "a car storage area, unoccupied at night, but not much lit up. It was near a major highway, and burglars would pull off, cut a hole in a fence, grab parts and leave, fast. The police finally caught one, and asked 'Would better lighting help?' The burglar replied: 'Sure, I could get in and out a lot faster and not get caught.'"

  How complex the relation between light and street crime may be is illustrated by a study undertaken by the Illinois Criminal Justice Information Authority. In the late 1990s, researchers evaluated the impact of increased lighting in Chicago alleyways where the Department of Streets and Sanitation had replaced 90-watt lights with 250-watt lamps. In the ensuing months, violent crime at night increased by 14 percent, crimes to property increased by 20 percent, and substance abuse violations increased by 51 percent, while daytime offenses in the alleyways decreased by 7 percent. The authors of the study came to no clear conclusions as to why there was such a surge in crime, but they suggested that perhaps both citizens and police were witness to more offenses in the brightly lit alleyways, and consequently reported more of them. Perhaps, too, the greater illumination made residents feel more secure, so more people ventured out after dark, and the increased activity may have led to an increase in crime.

  The correlation between light and safety may never be fully explained, for what light can do and what we imagine light can do are not entirely separate things. Our insistence on bright night lighting is inextricably linked with our feelings of safety, but those feelings are relative to our accustomed surroundings. Michel Siffre, living with one small light deep in his glaciated cavern, felt assured by his meager illumination. "Yes, my tent became my universe," he wrote. "Its effect upon my mind was remarkable. When I left the lightbulb on and went outside, the tent glowed in the cold darkness with a redness that was singularly comforting. From the moraine I often looked back at it with a feeling of love. It represented security and shelter—no matter how specious that security and shelter, which was threatened constantly by the cave-ins of rock and ice."

  Even over the course of our own lives, the amount of light that makes us feel safe is a moving frontier: the more light we're accustomed to, the more we feel we need for security. For many of us now, abundant artificial light, not darkness, feels natural after the sun goes down. We not only walk in bright light; we also leave it behind us. Our houses are lit when we go out at
night, and in the deserted small hours, light dazzles at rural crossroads, gas stations, empty parking lots, and shut-up summer homes and hotels. We turn our lights on in the early dusk and leave exterior house lights burning while we sleep. The lamps that assured our ancestors in the gaslight era would not be enough for us today.

  Given the history of light's steady increase, nothing less than a conscientious, international effort will ensure a future in which the brilliance we live by stays the same, or—as astronomers David Crawford and Tim Hunter hope—markedly decreases. Crawford and Hunter were among the first voices calling for a return to darker nights, and in 1988 they established the International Dark-Sky Association for the express purpose of abating light pollution and increasing public awareness of the consequences of excess light. The association suggests strategies to reduce lighting—simply shutting off unnecessary lights would go a long way toward achieving this goal. (In the United States alone, wasted light costs more than $1 billion a year, and a 100-watt bulb left burning through all the dark hours in a year creates about five hundred pounds of carbon dioxide.) The group also promulgates the control of light through shielding and by directing essential light so that it illuminates only what it's intended to. For any new lighting, the association advocates extensive planning that takes into account an understanding of how illumination affects the surrounding environment.

  In twenty years, the influence of the International Dark-Sky Association has grown far beyond a circle of stargazers, having gained the support of architects, city planners, and lighting designers:

  A growing number of businesses are rethinking their attitudes toward the environment.... This shift has had some influence on the business of government, as well, including how we plan our day and night urban landscape.... Sustainability's emphasis in urban design and artificial night lighting is to improve the quality of lighting, not its quantity. [A more] holistic view of lighting design produces less environmental impact than poorly designed, more traditional approaches: it requires less energy from power plants.... And, ultimately, there is a net economic savings.... Because most of the Earth's population lives in cities or urban centers, nighttime lighting needs to be one of the key components of any city policy for urban development and for increasing the quality of life for its citizens.... While community planners remain firm in their mandate for safety, utility, and ambiance, some are beginning to examine the myths of night lighting, the meaning of utility, and the requirements necessary to create an effective and efficient ambiance.