Apollo's Fire: A Journey Through the Extraordinary Wonders of an Ordinary Day

Morning Twilight

Gradually the dark sky paled until it looked like far away smoke.

There was no colour anywhere. . . . It felt more like dusk than dawn, but not really like any time of day or night.

—Dodie Smith, I Capture the Castle

Stephen Dedalus’s Cosmic Address

Early in James Joyce’s Portrait of the Artist as a Young Man, the youthful protagonist sits distractedly in a classroom, writing in the flyleaf of his geography text. His consciousness moves ever outward until he assigns himself a kind of cosmic address:

Stephen Dedalus

Class of Elements

Clongowes Wood College

Sallins

County Kildare

Ireland

Europe

The World

The Universe

Stephen was not the first student to indulge in such exercises. They impart a helpful perspective on our place in the scheme of things—especially when you are a child trapped in a classroom and the whole grand world beckons alluringly from outside the window. Too often organized education packages information in units that aid memorization and regurgitation. Such facts are useful, but because the brain thinks symbolically and narratively we also need examples that demonstrate the information’s relevance to our daily lives.

Like his creator, Stephen Dedalus gropes for connections that clarify meaning and significance. Whatever else he may have been missing while his mind wandered, young Stephen was at least thinking about one of the essential questions of human existence: our place in the universe. A geology text is a fitting site for such musings. Many questions about the meaning of life grapple with the idea of context. Where are we in relation to the rest of the cosmos, to other sentient creatures, even to our fellow human beings? Stephen’s own list locates him at the heart of concentric circles moving outward from the individual to the entire universe.

The child transfigured the blowsy lawns with his playing, writes Dylan Thomas in one of his stories. We all transfigure the world with our playing. Homo sapiens has been playing for longer than we can envision. We transfigure our surroundings, our individual and collective experience, with playing and knowledge and ignorance. Ptolemy and Copernicus were both correct: our universe— our physical and mental universe—is centered around both the Earth and the sun.

The cycle of the rising and setting sun, the alternation of light and dark, is the oldest story on Earth. It may well be the genesis of all linear narrative. Before our ancestors tamed the fire that lightning brought down from heaven, before they planted seeds and lingered in one place long enough to watch them magically grow into crops, before they even understood the connection between sexual intercourse and childbirth, they told the story of the day itself. This primordial cycle still determines the rhythms of our lives, our jobs, our holidays, our weather.

Mythology and science both suggest that, as far as we are concerned, the real purpose of the day is to show us our place in the cosmos. The day is an astronomical phenomenon and a unit of time, and as a frequently repeated experience it became a symbol long ago. But it is also one of our favorite ways of reinserting ourselves into a larger narrative. Every culture has conjured myths about the origin of the day and night. The sun climbing above the horizon is one of the earliest pictographic symbols in ancient history, and it reappears in most children’s first drawings. It is a milestone in each family when a child begins to understand the concept of tomorrow morning and last night. What a reassuring idea to a child that even if darkness demands a nightly surrender to monster-haunted unconsciousness, a shiny new day will greet her upon awakening. The day is a small enough unit of time to be easily comprehended by both societies and individuals. Gathered into two other natural cycles, lunar months and solar years, it forms the basis of all calendars. The story of how we learned what is actually happening in this pattern is the story of science coming of age. And, because imagination never waits until the facts are in, every culture is rich in myths about this most easily observed and most frequently occurring natural cycle on Earth—the sun’s dependable journey across the sky from dawn to dusk.

We are nature seeing nature, remarks the American writer Susan Griffin. We are nature with a concept of nature. Apparently the chief difference between Homo sapiens and our manifold kin is that for us nature is symbolic. Our mental picture of the world is more than the map of surroundings hanging over the head of an animal—a scent-based map in dogs, perhaps, and sound-based in bats. No doubt blue whales and Arctic foxes and birds of paradise all have their own concept of nature, their mental picture of the world and the interrelationships of its many parts, but presumably they do not invent for themselves a story about it as they journey through their days.

Indeed, the very word journey preserves the importance of this daily rhythm. Digging back through Middle English and Old French, we find it deriving from the Latin diurnata, for a day’s work. Over the centuries many cultures described distances as the number of days of walking or riding necessary to reach a destination, just as nowadays gadabouts on a shrinking planet refer to distances in terms of hours of driving or flying. The Latin dies, day, begat diurnus, daily, and the Late Latin diurnalis. From the last word we get journal, which as surely as diary refers to a record that is kept on a daily basis. Hidden treasure rewards even the most casual peek into such seeming trivia. For example, the beautiful word ephemeral, which we use to mean transitory or evanescent, actually comes from two Greek words meaning lasting but a day. Our daily routines and chores, our waking and sleeping hours, are literally ephemeral even though they relive the experience of the ages.

Darkness

To fully appreciate the arrival of daylight, we need to imagine the darkness that, until recent centuries, only dawn could banish. No one in the industrialized world can remember so far back, but let’s try to envision it. Even recollections of wilderness camping or a nighttime power failure will aid this mental effort. Tonight we will look more closely at our experience of darkness, but for now let us try to conjure what life was like for human beings before the flick of a switch illuminated a room, before sentry lights guarded homes, before headlights ran ahead of vehicles like torch-bearing heralds. Go back before your great-grandparents electrified their homes. Picture a time when no artificial lights erased the lesser stars of every constellation and no glow of cities could be seen from space by astronauts circling the Earth. Rewind the film of history and watch nighttime lights winking out around the globe.

There was a time when Jack the Ripper lurked in the flickering shadows of gaslit London streets, when frightened citizens thought twice before plunging into the darkness between two oases of light. A century earlier a group of Englishmen—including Josiah Wedgwood, founder of the pottery dynasty, and Erasmus Darwin, grandfather of Charles—called themselves the Lunar Society, because to provide illumination for their tipsy progress homeward they timed their meetings to coincide with the full moon. The arrival date of Easter varies each year for the same reason: because pilgrims needed light to travel by. Ever since the Council of Nicaea in the fourth century, Easter occurs on the first Sunday after the full moon following the vernal equinox. But the moon is unreliable illumination; it wanes, hides behind clouds, even disappears for a few nights each month. Its borrowed light is feeble compared with the sun’s.

For centuries in Europe, the time between midnight and cock-crow was considered dead time, and apparently this period inspired the phrase dead of night. According to Horatio, the watchmen saw the ghost of Hamlet’s father during the dead vast and middle of the night. It was said to be the likeliest time for an attack by demons, rogues, or werewolves. The last few hours of darkness before daylight really do seem the slowest. During a night of pain, the aggrieved and the lonely and the desperately ill wonder if they can survive until dawn. In ancient rituals of symbolic death that led to rebirth, darkness often represented not annihilation but latent being, the period of waiting before the light of birth.

But we heirs of linear rather than cyclical myths imagine death as a final darkness. For us, darkness is the time before creation, the godless time. Go back before we banished it.

Imagine the eons of nightly obscurity before our protohuman ancestors dared to carry back to the cave a tree branch that had been ignited by fire from heaven. Think of the conceptual landmark that our ancestors reached when terror of fire was replaced by the idea of taming it.

Darkness is upon the face of the Earth. It is dark now and it will remain dark until morning and there is nothing that we can do about it. The darkness seems unending and impenetrable. We know from bloody experience that it is full of predators who find our flesh tasty, beasts that can see in the dark and smell our fear. This danger is not a projection of our imagination into the mysterious darkness. The danger is real. Can you imagine that you and your family are huddled together in a cave, reassuringly holding hands in the darkness? Are you looking up anxiously at every rustle of leaves?

Only if we can imagine their fear can we begin to understand how grateful our ancestors were for the dawn.

The Threat of Dawn

In 1923, in the early morning of his own life and that of the twentieth century, the already brilliant Argentine writer Jorge Luis Borges wrote a poem entitled Amanecer (Break of Day). Just before sunrise, daunted by the threat of dawn, he recalls the frightful conjecture of such philosophers as Arthur Schopenhauer and Bishop Berkeley—that the world doesn’t really exist, that all we imagine we see and hear around us is a dream, a projection, a common delusion. (To which philosophical dead end Samuel Johnson famously replied by kicking a stone and snarling to Boswell, Thus I refute Berkeley!) As the sky lightens and the sun finally arrives, Borges speculates that, if the teeming streets of Buenos Aires are no more solid than a dream, there is a moment when their airy existence is in grave danger, the shuddering instant of daybreak. This is the time of day when fewer and fewer people are left asleep to keep dreaming the world. Only those who remember its outlines from yesterday can be assured that they are facing the same reality. As the sun comes up, Borges begs his house to continue existing, and somewhere out in the shared delusion a bird begins to sing. But the now banished night, writes Borges, lingers on in the eyes of the blind. He had not yet succumbed to the increasing difficulties and eventual blindness that would darken his later years. Eventually the sun stopped rising for him and only the night remained.

A Light in the East

More than 70 percent of our planet is covered in water, and hundreds of millions of people around the world experience the arrival of each day along the boundary between earth and sea. So let us begin our experience of the day at a shoreline.

On the eastern coast of the United States, light creeps across the Atlantic from Africa and Europe. The sun wakes pelicans and jellyfish before wading ashore to warm the foot-printed sand. In the few coastal areas where an early riser can escape some percentage of the omnipresent light pollution, clouds may not reflect enough illumination from the surface to reveal their presence. Dark clouds stealing across an equally dark sky generate a new mythology as they erase part of Orion or the Scorpion. In this situation, arriving well ahead of color, dawn begins as the slow resolution of the sky into dark masses of shadow against the gradually lightening heavens behind them.

Now it is light enough that cloud shapes are visible all across the sky, even in the west, above the curving earth where people and animals still slumber. Often at the seashore clouds can be so wind-tossed that their shadowy dawn shapes fade out at the edges into a charcoal sketchiness. As they float grandly toward you and then over your head, they look like torn shreds of dark cotton. The military procession of this army of giants would feel ominous at dusk. But dawn seldom feels ominous; we have been too long conditioned. There is no knowledge more closely woven into the fractaling neurological pathways of the brain than the knowledge that dawn will be here soon to change everything about the world. The boundaries of our daytime world are being restored—intact, freshened.

Dawn cloud shows are some of the most dramatic of the day. The lowest level of clouds, those just coming over the horizon, remain dark, finally purpling along their top edges. Swaths—areas still too vague to be called bands—are salmon-colored, and farther up rise washes of white and pink and purple. Above them blue is quickly pouring into the formerly black sky, diluting from indigo through cobalt and cerulean. The dark forms of the clouds—constantly changing shape over a coastal area where differing degrees of warmth keep air moving—merge and twist, expand like amoebae, and chase each other overhead.

The increasing red hues in the east, fading to the lighter end of the impressive range of celestial blues, remind us that as the planet turns your particular neighborhood toward the sun, light rays are angling through a great mass of atmosphere. It is easy to forget that sunrise is not a solar phenomenon but instead purely terrestrial. Our local star interacts no more with the parade of excitable clouds heralding its arrival than do the headlights of a distant car with the rain that blurs them on your windshield.

The atmosphere’s effect on light rays will be a topic that recurs throughout this book, even after dark, so we ought to begin at the beginning. People often ask why sunrise and sunset colors are so dramatic, but we forget to ask why the midday sun seems yellow to us although astronauts and space cameras report it as white. The atmosphere cushions us too well to permit light rays to sneak through without alteration; there is a great deal of invisible substance floating around up there. Even without the larger particles suspended in it, air consists of molecules of oxygen, nitrogen, hydrogen, and other elements. The wavelength of light is at least a thousand times larger than any individual molecule, however, so their tiny atoms alone are not the primary obstacle to incoming photons. (Wavelength refers to the distance between crests as the wave moves through space or through some medium such as air.)

The larger culprit is the air’s dense population of dust and pollen and floating microorganisms. To visualize how strong this mass can be, remember that air blurs distant views like a screened window, that it buoys up jets and albatrosses, that it is capable of incinerating a meteor through friction or of stirring enough speed to toss a yacht like a bathtub toy. Textbooks often compare our planet’s atmosphere to the peel of an orange, to give us some idea how relatively thin it is. A suit of armor might be a better representation—with dangerous chinks in it growing ever larger as the ozonosphere depletes and tears gaping holes over various parts of the body. (We’ll look at this terrifying scenario later, when we examine a completely different process involving ozone—the day’s usual buildup that results from increasing heat.)

Other than at noon in the tropics, light rays are always entering the atmosphere at an angle, greater or lesser depending upon latitude, season, and time of day. After a ray of light from the sun hits the outer stratum of air, what we see of it down here at the surface depends upon the physical attributes of each color of the spectrum. Visible light, as every rainbow demonstrates—and as recorded in the mnemonic abbreviation Roy G. Biv that schoolchildren learn—ranges from the red end of the spectrum, through gradations of orange, yellow, green, and blue, that indefinable dark blue called indigo, to the violet that arbitrates between blue and red and completes the circle on artists’ palettes. The words infrared and ultraviolet indicate that these forms of radiation are below (have longer wavelengths than) red and above (have shorter wavelengths than) violet.

Painters, or even children with crayons, quickly learn the frustrating quirk of physics that, while all the colors of light combine to produce white, all the opaque pigments combine to produce black. It is important to keep in mind, although difficult to remember when facing a coastal sunrise or a Paul Gauguin painting, that color is merely the animal brain’s interpretation of variable wavelengths of electromagnetic radiation. And not even all animals see this way; moths perceive on flowers infrared images that are invisible to us. As Carl Sagan once remarked, We might just as reasonably translate wavelengths of light into, say, heard tones rather than seen colors—but that’s not how our senses evolved.

Imagine these light waves marching in a phalanx toward a ring of guards defending a castle, and it is not difficult to envision how some are likely to be repulsed and some to get through. Which are deflected and which permitted to continue moving forward depends upon the angle at which they enter the atmosphere—in other words, on how much air they must traverse between space and our eyes. One end of the color phalanx is less stubborn than the other. The blue end of the spectrum is scattered sooner than the red. As light makes its way downward through the atmosphere, the blue is deflected first, creating the effect of a blue sky surrounding the sun. Even the relatively thin layer of air directly above our heads is enough to scatter blue, so that it becomes the color we see overhead all day. Mars, in contrast, with under one percent of Earth’s atmosphere at sea level, would normally have during its daylight hours a deep indigo sky.

Although this phenomenon is often just called scattering, physicists know it as Rayleigh scattering, after the English physicist John William Strutt, Lord Rayleigh, who first understood the process (and who also won the 1904 Nobel Prize for the discovery of argon). Scattering differs from absorption. As mentioned before, light waves are larger than the individual hundred-millionth-of-a-centimeter size of the simple molecules that compose most of the atmosphere. Such molecules, along with dust and other particulates, scatter light, but they don’t actually absorb it. Absorption, the blocking of light waves, is caused by larger compounds such as nitrous oxides, those dangerous by-products of combustion engines and industrial manufacture. Smog is brownish partially because it is genuinely absorbing sunlight.

Nor is our beloved blue sky an optical effect that you can observe only from the surface of Earth. It is visible from space. In 1961, Yuri Alekseyevich Gagarin, the pioneer Russian cosmonaut, became the first human being to see his native planet in its entirety. During his 108-minute flight, he was in orbit for less than an hour and a half, looking down from a height of 203 miles. But it was enough time and enough distance to leave Gagarin dazzled with the view. And one of the first experiences he later wrote about was the way that he could actually see the blue sky of Earth against the black of space: The Earth has a very characteristic, very beautiful blue halo, which is seen well when you observe the horizon. There is a smooth color transition from tender blue, to blue, to dark blue and purple, and then to the completely black color of the sky. Only four years earlier, a retired American air force pilot, David Simons, had piloted a balloon through steadily thinning atmosphere to an altitude of more than nineteen miles, where he became the first eyewitness to report a dark purple sky. What a long and winding road from the footprints at Laetoli to the adventurous naked apes who climbed high enough—with the complex and long-term assistance of their fellows—to look down on home.

You don’t have to be a cosmonaut to at least glimpse the sky’s fade to darkness in space. Aboard an airplane at the usual cruising altitude of only a few miles, you can look out the window and see the lighter blue below, the darker blue beside you, and above you a slow fade toward an unfriendly-looking indigo. After this eerie moment, you may decide that the in-flight movie looks nicely distracting. No wonder blue is the color of most sky deities. As late as the mid-seventeenth century, in his Art of Painting, the Spanish artist Francisco Pacheco was insisting that Mary’s cloak must always be portrayed as a celestial blue because no other color would do her justice. (Later, godless Nietzsche simply maintained that the lush blue afternoon skies in Turin helped him collect his thoughts.)

Red, in contrast, has a lower wavelength and moves more lazily, plodding its slow way between obstructions. Only now at sunrise, and later at sunset, does it move through enough air, slicing horizontally through the atmosphere, to scatter and turn clouds into banks of red and orange. Physicists like to point out that you can witness this scattering effect with a simple experiment at home. Fill a fishbowl, or even a large glass pitcher, with water that contains just enough milk to slightly cloud it. Then shine a flashlight through it. The light by itself will appear yellow, like the sun, but observed through the milky water it looks reddish. Stay in the same position and have someone else move the flashlight around the back of the bowl, keeping its light aimed toward you. You will observe that the light changes all the way through the spectrum from reddish to bluish and back to reddish, as it angles through varying amounts of milky-water atmosphere. (Naturally, different solutions will result in different colors and intensities.) Sky colors are created in the same way, by light bouncing off particles suspended in air instead of water. It makes sense that the more particles a beam of light encounters in its lower-angled flight through dense air at this time of day, the more dramatic the changes from midday’s blue. The light is no more red upon its arrival at our atmosphere than it is blue at other times of day; it is produced by the milky air’s filtering out of other colors.

Incidentally, without this scattering effect—these barriers to light shipping directly from its source to our eyes—even at sunrise the sky above us would be as black as the sky over the airless moon, blacker than Earth’s darkest moonless night atop a mountain in the wilderness. Why a universe populated