Science & Nature audiobook scripts

Stand on a beach long enough and the water will leave you, and then it will come back. It is not the wind doing that. It is the moon. Its gravity tugs on the oceans as the Earth turns beneath it, and the sea rises and falls in answer. The sun pulls too, more gently. So the next time a wave reaches your shoes, look up. Something very far away just touched your feet.

When you look at a star, you are not seeing it as it is tonight. You are seeing light that left it long ago. Light is fast, but space is very large. Even from the nearest stars beyond our sun, the journey takes years. From most of the ones you can see, far longer. So the night sky is not a picture. It is a pile of old letters, all arriving at once.

I pick up a handful of garden soil and it looks like nothing. Brown crumbs. A root hair. One annoyed beetle. But I know what I cannot see. This handful is crowded with living things, bacteria and fungi and creatures too small for my eyes, all busy turning dead leaves back into food for plants. I used to call this dirt. Now I put it down carefully, the way you would set down something that is asleep.

We call her the queen, but she does not rule anything. She lays eggs. That is her job. Nobody in an ant colony gives orders. Each ant follows simple cues, a scent on the ground, a touch from a neighbor, and out of thousands of small choices comes a trail, a nest, a rescued crumb. It looks like a plan. It is not. It is a crowd that somehow knows what to do.

Every autumn, without a map, billions of birds leave the places where they were born and fly toward warmer country. Some travel by day. Many of the small songbirds travel at night, and they pass over sleeping towns in the dark, calling softly to one another. How do they find the way? Not by one trick, but by several. They read the position of the sun and the stars. They can sense the Earth's magnetic field. They remember rivers and coastlines. And then, in spring, many of them come back. Not just to the same country. Often to the same patch of woods.

My grandfather taught me to read a stump before he taught me to read a clock. You count out from the middle, he said. In a place with real seasons, a tree lays down a new ring of wood every year, pale wood in spring, darker wood late in summer. One pale band and one dark band make a year. But he wanted me to notice more than the number. Here, the rings were wide. Good years, plenty of rain. Here they were pinched thin as thread. A dry spell, or a crowded one. That oak never moved an inch in its whole life. It still managed to keep a diary.

A cloud looks like a solid thing, a great white island, but you could walk straight through one. You have done, if you have ever been out in fog. It is made of water. Countless tiny droplets, or ice crystals higher up, each so light that the moving air holds it aloft. Here is the part I like. Water vapour needs something to gather on. A speck of dust, a grain of sea salt, a bit of smoke. Each droplet forms around one. Then the droplets bump together and grow. When they are too heavy for the air to carry, they fall. So every shower you have ever been caught in began with a speck.

Sunlight does not go very far into the ocean. Near the surface the water is bright and blue. A little deeper it dims to twilight. Below that, there is no sunlight at all, and most of the sea is like this. Dark, cold, and under enormous pressure. For a long time people assumed nothing much could live there. They were wrong. There are fish down in that blackness, and squid, and jellies, and many of them make their own light. A glow along the belly. A lure that dangles in front of a mouth. A sudden flash to startle a hunter. It is the largest living space on the planet. We have seen very little of it.

Find a road that has been cut through a hill, and look at the rock on either side. Chances are you will see stripes. Those are layers of sediment. Mud, sand, bits of shell, settling at the bottom of some long-gone sea or lake, and slowly, over a very long time, pressed into stone. The rule for reading them is simple. Unless something has turned them over, the oldest layer is at the bottom and the youngest is at the top. You are looking at time, stacked. And if the stripes are tilted, or folded like a rug that has been pushed, then you know something else. Once, very slowly, the ground itself moved.

Field notes, the back porch, a little after nine. I left the light on and sat still, and within ten minutes I had company. Small brown moths first, then a big pale green one with long tails on its wings, which I believe was a luna moth. It was nearly as wide as my palm. Butterflies get all the attention. But there are far more kinds of moth than kinds of butterfly, and most of them are out working while we sleep. Many visit flowers in the dark, the same as bees do by day. I turned the light off, so they could get back to it. I had only wanted to see who was on the night shift.

If you live near the coast, you may have noticed that not every high tide is the same. Some weeks the water climbs right up the sea wall. Other weeks it hardly seems to try. The reason is overhead. The moon does most of the work of the tides, and the sun helps. What changes is whether the two of them are pulling together. Around the full moon and the new moon, the sun, the Earth, and the moon fall roughly into a line. Their pulls add up. High tides run higher, and low tides run lower. These are called spring tides, which has nothing to do with the season. About a week later, at the half moon, the sun and moon pull at right angles to each other. They partly cancel out. The tides are gentler. Those are neap tides. A big round moon, or no moon at all, means the water has plans.

There is a small white seabird with a black cap and a sharp red bill called the Arctic tern. You could hold one in your two hands. It makes one of the longest migrations of any animal on Earth. It nests in the far north, during the northern summer, when the days there are very long. Then, as that summer ends, it flies south. And keeps flying. Down the length of the oceans, all the way to the waters around Antarctica, where the southern summer is just beginning. A few months later, it turns around and comes back. Think about what that means. This bird lives through two summers every year. It may well see more daylight than any other creature alive. We tend to think of home as one place. The Arctic tern has two, at opposite ends of the planet, and it spends its whole life going from one to the other, chasing the light.

Under a forest floor there is a partnership most hikers never see. Dig carefully near the roots of a tree, and you may find fine pale threads running through the soil, thinner than cotton. Those are fungi. The mushrooms you notice above ground are only the fruit. The threads are the main body. Many of these fungi live joined to tree roots, and the two of them trade. The tree makes sugar from sunlight, which the fungus cannot do, and it passes some of that sugar down. The fungus, with its far-reaching threads, gathers water and minerals from the soil and passes some of those up. Neither one is being generous. It is closer to a business arrangement, and it is very old. I find that I walk differently since I learned this. A forest is not a collection of separate trees standing near each other. Underfoot, it is knotted together.

Out here you learn to count after lightning. Flash, then one Mississippi, two Mississippi, until the thunder rolls in. Here is what you are measuring. Lightning is a giant spark, and it heats the air around it so suddenly that the air bursts outward. That burst is the thunder. The two happen together, in the same place, at the same moment. But light travels so fast that the flash reaches your eyes almost instantly. Sound is a slowpoke. It takes roughly five seconds to cover a mile. So the gap is distance. Count fifteen seconds, and that strike was about three miles off. Count five, about one. And if the counts are getting shorter, the storm is walking toward you. My grandmother did not know the physics. She knew the rule. If you can hear it, she said, you had better already be in the house. She was right. If you can hear thunder at all, go indoors.

Field notes, the allotment, a damp morning in October. Turned over the first spadeful and counted six earthworms, which pleased me more than it probably should. I have come to think of them as the unpaid staff. They pull dead leaves down from the surface and eat them. They swallow soil, and what comes out the other end is finer and richer than what went in. Their burrows leave little channels, so that air and rainwater can get down to the roots. An earthworm has no eyes and no lungs. It breathes through its skin, which must stay moist, and that is why you see so many on the path after a night of rain. My neighbour digs his beds over twice a year and wonders aloud where his worms have gone. I have not had the heart to tell him. I put my six back and covered them up. They had work to be getting on with.

A lot of people believe the North Star is the brightest star in the sky. It is not. It is not even close. What makes the North Star special is not how it shines. It is where it sits. The Earth spins like a top, and the axis it spins around points, at the northern end, almost exactly at that one modest star. So as the night goes on, every other star appears to wheel slowly across the sky. That one stays put. To find it, look for the Big Dipper. The two stars on the outer edge of its bowl point the way. For centuries, sailors and travelers in the northern half of the world used it to know which way was north. Not because it was dazzling. Because it was dependable. I think about that sometimes. In a sky full of brighter things, the one people steered by was simply the one that did not move.

In the late nineteen seventies, scientists exploring the deep seafloor found something nobody had predicted. They had gone looking for hot springs on the ocean floor, places where seawater seeps down into the crust, is heated by the rock below, and comes pouring back out. They found the springs. What they did not expect was the crowd. Around the vents, in total darkness, there was life. Clams. Crabs. Tall tube worms with red tips, swaying in the warm water. This was a puzzle. Nearly every food chain people knew of began with sunlight, with plants or algae. There is no sunlight down there. The answer turned out to be bacteria. These microbes get their energy not from light but from chemicals in the vent water, and everything else in that community depends on them. For a long time we assumed life needed the sun. Down there in the dark, it had found another way to make a living.

A mountain looks like the most permanent thing there is. It is not. It is being taken apart while you look at it. Water does most of the work. Rain soaks into cracks in the rock. On a cold night that water freezes, and ice takes up more room than water does, so it pushes the crack a little wider. The next thaw, more water gets in. Do that enough times and a piece breaks off. Then gravity and streams carry the pieces downhill. Boulders knock into each other and become cobbles. Cobbles become gravel. Gravel becomes sand. A river is a conveyor belt, moving a mountain to the sea one grain at a time. It is far too slow to watch. But pick up a smooth pebble from a riverbed and hold it in your palm. It did not start out round. That is a mountain you are holding, well on its way to becoming a beach.

A honeybee that finds a good patch of flowers has a problem. She cannot carry it all home herself, and she cannot talk. So she dances. Inside the dark hive, she runs in a short straight line, waggling her body from side to side. Then she circles back and does it again, while other bees crowd close and follow her. The dance is a set of directions. The angle of her run tells them which way to fly, measured against the position of the sun. How long she waggles tells them how far. Think about that. An insect, in the dark, is describing a place she has been to others who have never seen it. And they understand. They leave the hive and fly to it. We like to believe that language belongs to us. But in a wooden box at the bottom of someone's garden, a bee is giving directions, and getting them right.

Every fall, people say the leaves are turning. What is actually going on is better than that. All summer, a leaf is green because it is full of chlorophyll, the pigment that lets it make food from sunlight. There is so much of it that it hides everything else. But the yellows and oranges are already in there. They have been there since spring, underneath, waiting. When the days get shorter and the nights get cool, the tree stops making chlorophyll. The green fades. And the colors that were hidden finally get their turn. The reds are a little different. Many trees make those fresh in autumn, and they tend to be brightest after sunny days and cool nights. So a maple in October is not putting on a new coat. It is taking one off. I find that oddly comforting. Some of the best colors a thing has only show up when it stops working so hard.

Field notes, a gravel road west of town, late afternoon in May. It was warm and sticky when I parked. The wind was out of the south, and the air had that heavy, soft feeling. To the northwest there was a dark line along the horizon. That was the cold front. Cold air is denser than warm air, so when a mass of it moves in, it slides underneath and shoves the warm, moist air upward. Rising air cools. The moisture in it condenses. That is how you get a wall of cloud where an hour ago there was nothing. I watched it come. Then the wind dropped to nothing. A meadowlark kept singing. And then it swung around, all at once, out of the northwest, and it was a different day. Cool and sharp. I could smell rain. I got back in the truck. You do not need a forecast when the sky tells you that plainly.

Field notes, the rock platform south of the headland, an hour before low tide. When the sea pulls back it leaves pools behind in the rock, and each one is a small, crowded town. In the first I found anemones, open like flowers, which they are not. They are animals, and those petals are tentacles waiting for something small to blunder in. I found limpets clamped to the stone, and a hermit crab wearing a shell far too grand for him. Everything that lives here has the same problem. The ocean keeps leaving. For hours they must put up with sun, wind, drying air, and the occasional gull. Then the water comes back. The limpet seals itself down to keep its moisture in. The anemones left out of the water fold up into wet blobs and wait. I kept my hands out of it. It is their town. I was only passing through, and the tide was already turning.

Okay, first thing. A shooting star is not a star. Stars are enormous and very far away, and if one actually fell on us, nobody would be making a wish. What you are seeing is much smaller. It is a bit of rock or dust from space, often no bigger than a grain of sand, hitting the Earth's atmosphere at tremendous speed. It heats up and glows, and for a second it draws a bright line across the dark. Most burn up completely, high above the ground. Some nights you can see a lot of them. That is a meteor shower. It happens when the Earth passes through a trail of dust left behind by a comet. So here is my advice. Get away from the streetlights. Lie on your back. Give your eyes twenty minutes to get used to the dark. Then just wait. The sky is about to throw sand at you, and it is beautiful.

Most birds are noisy fliers. Listen to a pigeon take off, and you will hear its wings clap and whistle. An owl is different. An owl can pass a few feet over your head, and you may hear nothing at all. The secret is in the feathers. The front edge of an owl's wing feathers has a fine fringe, like the teeth of a comb, and the surface of the feather is soft, almost like velvet. Together these break up the rush of air that makes other wings loud. This matters for two reasons. The mouse in the grass does not hear the owl coming. And the owl can still hear the mouse. Many owls hunt largely by sound, and a noisy wing would drown out the small rustle they are listening for. So the next time you hear an owl call, remember this. The call is the only part of that bird you were ever meant to hear.

The ground you are standing on is moving. The outer shell of the Earth is not one solid piece. It is broken into slabs called plates, and they drift, carrying the continents and the ocean floors with them. They move about as fast as your fingernails grow. You cannot feel it. But over millions of years, it changes everything. Where two plates pull apart, molten rock wells up and makes new crust. Where they push together, the land can crumple upward into mountains. And where they grind past each other, they stick, and strain, and then suddenly slip. That slip is an earthquake. Look at a map of the world, and you can see a clue. The east coast of South America and the west coast of Africa look as though they would fit together. They would. They once did. The map on your wall is not a portrait. It is a single frame from a very slow film.

In parts of the eastern United States, there is an insect that spends nearly all its life underground, waiting. It is called a periodical cicada. The young ones hatch, drop to the ground, and burrow down to the roots of trees, where they feed on sap. And there they stay. Not for a season. For thirteen years, or for seventeen, depending on the kind. Then, one spring, when the soil warms, they come up. All of them, nearly at once. They climb a tree trunk, split their skins, and unfold a pair of wings. For a few weeks the woods are loud with them. The males sing. Eggs are laid in the twigs. And then the adults die, and it goes quiet again. Folks complain about the noise, and I understand. It is considerable. But think of it from their side. If I had waited seventeen years in the dark for my one summer, I believe I would holler too.

Pour yourself a glass of water and have a look at it. I want to tell you where it has been. The water in that glass is very old. Not the glass, not the tap, the water itself. The Earth does not make much new water, and it does not lose much either. The same supply goes round and round, and has done for an unimaginably long time. Here is the circuit. The sun warms the sea, and water rises from the surface as vapour, leaving the salt behind. Up it goes, into cooler air, where it gathers into droplets and makes cloud. The wind carries the cloud over land. The droplets grow heavy and fall as rain, or as snow. And then it takes one of several roads. Some of it runs off into streams and rivers and heads back to the sea. Some soaks down into the ground and may stay there for a very long time. Some is drawn up by the roots of a tree and breathed out through its leaves. Some sits as ice on a mountain. But sooner or later it comes back to the sea, and the whole business starts again. So that glass in your hand has been a cloud. It has very likely been a river, and snow, and part of an ocean. It may have passed through a fern, or a dinosaur. Drink up. You are only borrowing it.

Ask a room full of adults why it is hot in summer and cold in winter, and most of them will say the same thing. In summer, the Earth is closer to the sun. It is a perfectly reasonable guess. It is also wrong. The Earth's path around the sun is nearly a circle. Our distance changes a little, but here is the detail that settles it. The Earth is closest to the sun in early January, in the middle of the northern winter. So it is not distance. It is tilt. The Earth spins on an axis, and that axis is not straight up and down. It leans. And it keeps leaning in the same direction all the way around its orbit. That means for part of the year, the northern half of the planet is tipped toward the sun. The sun climbs higher in the sky, its light strikes the ground more directly, and the days are longer. That is northern summer. Six months later, the north is tipped away. The sun stays low, the light arrives at a slant, and the days are short. And here is the proof you can check with a phone call. When it is summer in Chicago, it is winter in Sydney. If the seasons were about distance, the whole world would warm up and cool down together. It does not. One planet, two opposite seasons, all because of a lean.

Field notes, the fence line behind the house, twenty minutes before sunrise. I came out in the dark with a thermos and a folding chair, and for a while there was nothing to hear but my own breathing. Then one robin started. Just one, somewhere in the maple, a few clear phrases and a pause. Another answered from across the road. By the time the sky had gone from black to gray, I could not have counted them. Robins, a cardinal, a wren that seemed far too small for the noise it was making. People have a lovely idea that birds sing at dawn because they are glad of the morning. I would not want to rule out gladness. But the singing is mostly business. In many species it is the male who sings, and he is saying two things at once. To other males he is saying, this patch is taken. To females he is saying, I made it through the night, and I am strong enough to stand here and shout about it. Why so early? Nobody can say for certain, and there is probably more than one reason. The air is often still at that hour, so a song carries. By seven it had thinned out. The birds had gone to find breakfast. I folded up my chair. Every one of those songs was a fence, and I had sat through the whole neighborhood being rebuilt.

Field notes, the bottom of the garden, a cool morning in June. I pushed my hand into the middle of the compost heap, and it was warm. Properly warm, like a loaf not long out of the oven. On a morning when I could see my own breath, that is a fine thing to find. Nobody is heating it. Not me, anyway. The warmth comes from the workers. A compost heap is a feast, and the guests are mostly too small to see. Bacteria get in first, breaking down the soft stuff, the vegetable peelings and the grass clippings. There are so many of them, working so hard, that they give off heat. Fungi take on the tougher material, the stalks and the dry leaves. Later, when things cool down, the worms and the beetles move in to finish the job. They need what any workforce needs. Food. Some moisture. And air, which is why I turn it over with a fork now and then. Left packed down and soggy, a heap goes sour and smells it. Give it some months, and the pile shrinks right down and turns dark and crumbly. It smells like a forest floor after rain. That is what gets me. I put in scraps. Rubbish, really. And a crowd of creatures I will never meet hands me back the best soil on the block. I gave it a turn, and left them to it.