Brilliant (33 page)

She then covers the nest and returns to the sea. The eggs take months to develop, during which time, if the female has not been able to nest in the best of places, they are all the more vulnerable to extreme high tides, storms, and predators. If they survive their incubation period, the hatchlings then extricate themselves and dig their way—en masse—to the surface. If the surface sand is hot, they know it to be daylight, and they burrow back down and wait until the sand cools after sunset. Then they begin their trek to the sea. They are keyed to move toward the lightest horizon, and for thousands of years this meant they crawled away from dark dunes and vegetation and toward the ocean, whose surface, glinting and sparkling with reflecting starlight and moonlight, was brighter than the interior land. In a dark landscape, the baby turtles usually have no more than a two-minute trip to the beach.

But on developed beachsides, lit with condominiums, streetlights, and commercial districts, the turtles are confused by the brilliance of the built landscape at night. They crawl toward high land instead of the sea; crawl into roadways, where they are killed by cars; or crawl so far that they die of exhaustion. If they manage to reorient themselves and somehow reach the water, their mortality rate—already considerable, for they have to breach a surf rife with predators and then swim for at least a full day to reach their dwelling grounds—is much higher.

Amid the brilliance, it seems almost nothing remains unaltered by light. It affects the foraging and schooling patterns of fish and the timing of migrations. It alters the drift stream of insects on water and the vertical migration of zooplankton and fish. It diminishes the effectiveness of bioluminescent creatures. Fireflies were once bright enough to light up a village night. Now human light washes out their glow, which makes it harder for them to attract mates. And plant life is not immune. Measured light and darkness signal plants that the right pollinators are available and that competition is minimal. The coarse and prickly cocklebur
(Xanthium pensylvanicum)
—thriving in vacant lots and dumps, catching on clothes, riding on fur—flowers nevertheless and is keyed to its optimum bloom time by the length of the night. But the dark needs to be continuous: "A light break as short as one minute in the middle of a long night would prevent [it] from flowering."

Even when our lights are meant to be their most heartening and consoling, they have consequences for wildlife. In 2004, during the annual Towers of Light tribute to commemorate those killed on September 11, 2001, spectators in New York City wondered at "the thousands of little stars ... suspended in the air." It was a calm, moonless night during the fall migration. The upward flow of warm air in the columns of light induced moths to circle in the lights for fifteen stories or more, and thousands of birds, also drawn to the columns, circled above the moths. Few people understood what they were seeing. "Some people thought they were specks of dust," reported the
New York Times.
Others, perhaps remembering the rain of debris on that clear day three years before, concluded otherwise: "Some people saw ashes. Some thought there were fireworks in the light columns. Some saw spirits."

What they could not see, of course, were the actual stars, most of which were obliterated by the brilliance of the city night.

At the second match the wick caught flame. The light was both livid and shifting; but it cut me off from the universe, and doubled the darkness of the surrounding night.

—
ROBERT LOUIS STEVENSON
,
Travels with a Donkey in the Cevennes

D
URING THE LATE NINETEENTH CENTURY,
Vincent van Gogh saw countless subtleties in the dark skies of southern France: "One night I went for a walk by the sea along the empty shore," he wrote to his brother, Theo, in 1888. "The deep blue sky was flecked with clouds of a deeper blue than the fundamental blue of intense cobalt, and others of a clearer blue, like the blue whiteness of the Milky Way. In the blue depth the stars were sparkling, greenish, yellow, white, pink, more brilliant, more sparklingly gemlike than at home—even in Paris: opals you might call them, emeralds, lapis lazuli, rubies, sapphires." As van Gogh—aided by gaslight—painted that sky, he also painted myriad relations between the celestial and the human. In
Starry Night,
the illuminated village appears intimate—and inconsequential—against the roil of stars and the quarter moon above it, while in
Starry Night over the Rhône,
the human light and starlight are in conversation with each other: a couple stand at the lower right of the painting, and all around them the world is alive with light. Just beyond them, the river is ribboned with the reflection of the streetlights of Arles in the distance. And beyond the river, the town itself spangles the horizon. But it isn't too bright to stop the stars overhead or the sense of night as enormous and other. The night sky, defined by the brilliance of the stars, occupies almost half of the canvas.

Even in the midst of Arles, in
The Café Terrace on the Place du Forum, Arles, at Night,
human life negotiates a middle distance between the cobbled street and the stars. The glow of gaslight washes the walls of the café and its canopy roof; here and there a private, ruddy luminescence shines from second- and third-floor windows, and a few shop windows glow. But beyond the terrace, the dark increases quickly, and stars glitter in the gaps between buildings. Present-day astrophysicist Charles Whitney suggests that van Gogh "has overpopulated the small patch of sky in view of the interference that might be expected from the café lights." And van Gogh himself once insisted, "I
should be desperate if my figures were correct.
...I do not want them to be academically correct.... My great longing is to learn to make those very incorrectnesses, those deviations, remodelings, changes in reality, so that they may become yes, lies if you like—but truer than the literal truth." You can imagine, in the truth of his time, that even in the midst of nightlife, contemplation of the stars was part of being at home in the world, a counterpart to earthly life.

For many people, light pollution is now so pervasive that it obliterates any chance they may have to observe the night sky. In particular, sky glow—the orangey brightness in the air around cities, towns, and industrial sites that fades to purple in the upper night sky—hinders our seeing. Although sunlight reflecting off the moon, earth, and cosmic dust, and starlight scattering through the atmosphere, make for some natural sky glow, the ubiquitous light shed from homes, businesses, and streetlamps causes most of it. In the twenty-first century, even many wide suburban backyard views of the heavens have shrunk to a sprinkling of dim stars, and most people in the developed world see the night sky as if it is always washed in moonlight, at least as bright as a first-quarter moon. To people in large modern cities, the night sky always appears brighter than on nights near the full moon in the countryside, and the Milky Way—that bridge across the sky of dust and stars and gas, "brilliant with its own brightness," Ovid once wrote—can't be seen with the naked eye by two-thirds of Americans and half of all Europeans.

The Milky Way had always been the stuff of legend, variously called the Deer Jump, the Silver River, the Straw Thief's Way, the Way of the Birds, the Way of the White Elephant, the Winter Way, and the Heavenly Nile. It guided pilgrims at night and so was known also as the River of Heaven, the Road to Santiago, and the Roman Road. Now its appearance has become so unfamiliar that when the lights went out in Los Angeles during a 1994 earthquake, "emergency organizations as well as observatories and radio stations in the L.A. area received hundreds of calls from people wondering whether the sudden brightening of the stars and the appearance of a 'silver cloud' (the Milky Way) had caused the quake."

If you can't see the Milky Way anymore, you can't see a fourth-magnitude star, magnitude being the measure of how bright a star appears from earth. The brightest objects have negative magnitudes: the magnitude of Sirius is –1.4 and that of Venus is –4.5. In moderately light-polluted skies—where the Milky Way no longer appears—about three hundred second- and third-magnitude stars are still visible, but all the lesser ones—almost seven thousand fourth-, fifth-, and sixth-magnitude stars—are lost. Also, all the stars in light-polluted skies are less apparent than they were to our ancestors because the lights we live by are often so bright they suppress the rod system of the human eye: "About one-tenth of the World population, more than 40 percent of the United States population and one sixth of the European Union population no longer view the heavens with the eye adapted to night vision, because of the sky brightness."

The disappearance of stars is most keenly felt by astronomers, the true descendants of Galileo, who turned the first telescope toward the night sky. "Surely it is a great thing to increase the numerous host of fixed stars previously visible to the unaided vision," wrote Galileo in 1610, "adding countless more which have never before been seen, exposing these plainly to the eye in numbers ten times exceeding the old and familiar stars." His first observations, which included the discovery of four moons orbiting Jupiter, reinforced his belief in a sun-centered universe:

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."