A Natural History of the Senses (36 page)

At Big Sur, the hawks are working the thermals like barnstormers, swooping and banking as they ride invisible towers of warm, rising air above the sun-heated ground. Birds are so nimble and adroit. Each species has its own architecture, flight habits, and talents to make the most of the sky, which they sometimes reveal in their silhouettes. On some owls, for instance, the leading edge of the primary feathers is softly fringed to muffle the sound of their approach. Finches flap hard a few beats, then close their wings and rest a little. Turtledoves flap continuously when they’re flying. Peregrine falcons fold in their wings when they dive. Swifts, which average about twenty-five mph, have very pointy wings that make them sleeker by cutting down on drag as they dart and glide. At the Grand Canyon, you can see them working the canyon walls like small aerobats.

Our sky is also filled with “passive flyers.” Female ash trees loose their winged “keys,” and aspens and others produce long catkins that drop and blizzard across the ground. Maples launch tadpole-shaped seeds that fall whirlygig down, all blade, all propeller, like small autogyros. Thanks to the wind, the sex lives of many plants
have changed. Dandelions, milkweed, thistles, cottonwoods, and others have evolved wind-riders in the shape of parachutes or sails. Pine, spruce, hemlock, maple, oak, and ragweed don’t have flamboyant flowers, but they don’t need them to divert a bird or bee. The wind is go-between enough. Plants can’t court, or run away from a threat, so they’ve devised ingenious ways to exploit their environment and animals. Pollen grains may be as small as one ten-thousandth of an inch in diameter, yet they must travel uncertain winds and strike home. Using a wind tunnel, Karl Niklas, a Cornell scientist, recently discovered that plants aren’t just hobos, hoping their pollen will catch a passing breeze and get off at the right stop. Niklas found that the pine cone has evolved an architecture perfect for capturing wind from any direction: a turbine shape, with petal-blades that spin the air all around it. Like a planet, the pine cone wraps itself in an atmosphere of rapidly moving air, with, just below the upper, swirling layer, a still and vacant layer. When pollen falls from the rapid layer to the still layer, it cascades right down into the cone. Niklas also tested the air-flow dynamics of the jojoba plant, which uses two rabbit-ear-shaped leaves to direct air, with results that show similar finesse.

In allergy season, pollen makes me (and millions of others) sneeze a little, and my eyes sometimes itch so that I can’t wear my contact lenses. But I like knowing that all this mischief happens just because of shape. Tiny Sputniks traveling through the lower sky, some pollen looks like balls covered with spikes. Others are as football-shaped as the pupils of alligators. Pine pollen is round, with what looks like a pair of ears attached to each side. Their shapes make them move or fly at different speeds and in different patterns, and there’s little danger of the wrong pollen swamping the wrong plant. It’s odd to think of the sky having niches, but it does; even the wind has niches.

As night falls on Big Sur, all the soot of the world seems to pour down into the sunset. A swollen yellow doubloon drops slowly into the ocean, shimmer by shimmer, as if swallowed whole. Then, at the horizon, a tiny green ingot hovers for a second, and vanishes. The “green flash” people call it, with mystical solemnity. But it is the briefest flash of green, and this is the first time in all my sunset-watching
that I’ve seen it. Green, azure, purple, red: How lucky we are to live on a planet with colored skies. Why is the sky blue? The sun’s white light is really a bouquet of colored rays, which we classify into a spectrum of six colors. When white light collides with atoms of gases that make up the atmosphere—primarily oxygen and nitrogen—as well as with dust particles and moisture in the air, blue light, the most energetic light of the visible spectrum, is scattered. The sky seems to be full of blue. This is particularly true when the sun is overhead, because the light rays have a shorter distance to travel. The red rays are longer, and penetrate the atmosphere better. By the time the sun sets, one side of the Earth is turning away from the sun; the light has to travel farther, at an angle, through even more dust, water vapor, and air molecules; the blue rays scatter even more and the red rays remain, still traveling. The sun may appear magnified into a swollen ghost, or slightly elliptical, or even above the horizon when it’s really below it, thanks to refraction, the bending of light waves. What we see is a glorious red sunset, especially if prowling clouds reflect the changing colors. The last color that plows through the atmosphere without being scattered is green, so sometimes we see a green flash right after the sun disappears. In space, the air appears to be black because there is no dust to scatter the blue light.

At Big Sur lighthouse, perched on a distant promontory, a beacon flashes to warn ships away from the coast and sandbanks, its light zooming out to them at 186,000 miles per second. The searchlight of the sun takes about eight minutes to reach Earth. And the light we see from the North Star set sail in the days of Shakespeare. Just think how straight the path of light is. Pass sunlight through a prism, though, and the light bends. Because each ray bends a different amount, the colors separate into a band. Many things catch the light prismatically—fish scales, the mother-of-pearl inside a limpet shell, oil on a slippery road, a dragonfly’s wings, opals, soap bubbles, peacock feathers, the grooves in gramophone records, metal that’s lightly tarnished, the neck of a hummingbird, the wing cases of beetles, spiders’ webs smeared with dew—but perhaps the best known is water vapor. When it’s raining but the sun is shining, or at a misty waterfall, sunlight hits the prismlike drops of water and
is split into what we call a “rainbow.” On such a day, rainbows are always about, hidden somewhere behind the skirts of the rain; but to see one best, you have to be positioned just right, with the sun behind you and low in the sky.

It is nighttime on the planet Earth. But that is only a whim of nature, a result of our planet rolling in space at 1,000 miles per minute. What we call “night” is the time we spend facing the secret reaches of space, where other solar systems and, perhaps, other planetarians dwell. Don’t think of night as the absence of day; think of it as a kind of freedom. Turned away from our sun, we see the dawning of far-flung galaxies. We are no longer sun-blind to the star-coated universe we inhabit. The endless black, which seems to stretch forever between the stars and even backwards in time to the Big Bang, we call “infinity,” from the French
in-fini
, meaning unfinished or incomplete. Night is a shadow world. The only shadows we see at night are cast by the moonlight, or by artificial light, but night itself is a shadow.

In the country, you can see more stars, and the night looks like an upside-down well that deepens forever. If you’re patient and wait until your eyes adjust to the darkness, you can see the Milky Way as a creamy smudge across the sky. Just as different cultures have connected the stars into different constellations, they’ve seen their own private dramas in the Milky Way. The “backbone of night” the Bushmen of the Kalahari call it. To the Swedes, it is the “winter street” leading to heaven. To the Hebridean islanders, the “pathway of the secret people.” To the Norse, the “path of ghosts.” To the Patagonians, obsessed with their flightless birds, “the White pampas where ghosts hunt rheas.” But in the city you can see the major constellations more easily because there are fewer stars visible to distract you.

Wherever you are, the best way to watch stars is lying on your back. Tonight the half-moon has a Mayan profile. It looks luminous and shimmery, a true beacon in the night, and yet I know its brilliance is all borrowed light. By day, if I held a mirror and bounced a spot of sunlight around the trees, I would be mimicking how the
moon reflects light, having none of its own to give. Above me, between Sagittarius and Aquarius, the constellation Capricorn ambles across the sky. The Aztecs pictured it as a whale
(cipactli)
, the East Indians saw an antelope
(makaram)
, the Greeks labeled it “the gate of the gods,” and to the Assyrians it was a goat-fish
(munaxa)
. Perhaps the best-known star in the world is the North Star, or Polaris, though of course it has many other names; to the Navaho, it is “The Star That Does Not Move,” to the Chinese, the “Great Imperial Ruler of Heaven.”

Throughout time, people have looked up at the sky to figure out where they were. When I was a girl, I used to take an empty can, stretch a piece of tinfoil over one end and pierce pinholes in it in the outline of a constellation; then I’d shine a flashlight in the other end, and have my own private planetarium. How many wanderers, lost on land or sea, have waited till night to try and chart their way home with help from the North Star. Locating it as they did connects us across time to those early nomads. First you find the Big Dipper and extend a line through the outer two stars of its ladle. Then you’ll see that the North Star looks like a dollop of cream fallen from the upside-down Dipper. If the Big Dipper isn’t visible, you can find the North Star by looking for Cassiopeia, a constellation just below Polaris that’s shaped like a W or an M, depending on the time you see it. To me, it usually looks like a butterfly. Because the Earth revolves, the stars seem to drift from east to west across the sky, so another way to tell direction is to keep your eye on one bright star in particular; if it appears to rise, then you’re facing east. If it seems to be falling, you’re facing west. When I was a Girl Scout, we found our direction during the day by putting a straight stick in the ground. Then we’d go about our business for a few hours and return when the stick cast a shadow about six inches long. The sun would have moved west, and the shadow would be pointing east. Sometimes we used a wristwatch as a compass: Place the watch face up, with the hour hand pointing toward the sun. Pick up a pine needle or twig and hold it upright at the edge of the dial so that it casts a shadow along the hour hand. South will be halfway between the hour hand and twelve o’clock. There are many other ways to tell direction, of
course, since roaming is one of the things human beings love to do best—but only if they can count on getting home safely. If you see a tree standing out in the open, with heavy moss on one side, that side is probably north, since moss grows heaviest on the shadiest side of a tree. If you see a tree stump, its rings will probably be thicker on the sunny side, or south. You can also look up at the tops of pine trees, which mainly point east. Or, if you happen to know where the prevailing wind is coming from, you can read direction from the wind-bent grasses.

It’s November. The Leonids are due in Leo. Pieces of comet that fall mainly after sunset or before sunrise, they appear in the same constellations each year at the same time. In Antarctica, I had hoped to see auroras, veils of light caused by the solar wind bumping into the earth’s magnetic field and leaving a gorgeous shimmer behind. But our days were mainly sun-perfect, and our nights a grisly gray twilight. In the evening, the sea looked like pounded gunmetal, but there were no auroras to make glitter paths overhead. Here is how Captain Robert Scott described one display in June 1911:

Tonight Mars glows like a steady red ember. Though only a dot of light in the sky, it is in my mind a place of blustery plains, volcanoes, rift valleys, sand dunes, wind-carved arches, dry river beds, and brilliant white polar caps that wax and wane with the seasons. There may even have been a climate there once, and running water. Soon Venus will appear as a bright silvery light, as it
usually does about three hours after sunset or before sunrise. With its gauzy white face, it looks mummified in photos, but I know that impression is given by cloud banks full of acids floating above a surface where tricks of light abound and the temperatures are hot enough to melt lead. There are many kinds of vision—literal, imaginative, hallucinatory; visions of greatness or of great possibilities. Although I can’t see the steady light of other planets just yet, I know they are there all the same, along with the asteroids, comets, distant galaxies, neutron stars, black holes, and other phantoms of deep space. And I picture them with a surety Walt Whitman understood when he proclaimed: “The bright suns I see and the dark suns I cannot see are in their place.”

Sunrise. Darkness begins to wash out of the sky. A thick lager of fog sits in the valley like the chrysalis of a moth. Venus, Mercury, and Saturn burn bright silver holes in the slowly bluing sky. The stars have vanished, because by the time starlight gets to Earth it’s too dim to be seen during the daylight. Two black shapes in the fog reel into focus as cows. A calf reveals itself. Learning about the world is like this—watching and waiting for shapes to reveal themselves in the fog of our experience. A wan sky curdles with gauzy streaks of cloud. The land is veiled in mist. The highest hill looks like a train’s smokestack: Clouds trail behind it. Now the cloud world that was horizontal becomes vertical as cumulus begin to rise over the mountain. Venus throbs, a broken lighthouse in the western sky. A nation of cloud tepees rises along the top of the ridge. The first hawk of the day glides on cool air, wings arched. The dew sits in round, bluish drops on the clover-rich grass. A squadron of eighteen pelicans flies in a long check mark overhead, turns on edge and vanishes, turns again and tilts back into sight. A huge pillow of fog rolls through the valley. The cows disappear, but the sky grows bluer; Venus fades, white clouds begin to form, the fog lifts like a fever, a house and more cows appear. A lone, lightning-struck tree stands like a totem pole on a hillside, the light quickens, and birds begin their earnest songs, as the first yellow floats up like egg yolk over the ledge of the world, and then the sun is a canary singing light.