Around the twentieth of March there is a morning when the sun comes up across the water at Bayland Park exactly due east. Not roughly east. Due east, straight down the compass, the same as it does that morning in Galveston and in Anchorage and on the equator. If you are on the pier before six with a coffee and you know which way east is, you can watch it happen. The sun clears the far shore as a flattened orange thing, and then it rounds out and gets too bright to look at and the day starts. The next morning it comes up a little to the left of that. By June it will be well to the north, and by December well to the south, and then it will come back to the same spot on the same morning, because it always does.
That morning has a name and most people learn it in fifth grade and never use it again. It is the equinox, and the name means equal night, and it is the day when the sun, seen from anywhere on earth, stands directly over the equator. Day and night come out about the same length everywhere. On the bay it works out to a few minutes more than twelve hours of daylight, because the air bends the light a little and lets us see the sun before it has really risen and after it has really set, but close enough. Equal is the word for it.
The reason there is such a day at all is that the earth is crooked.
Hold a ball in your hand and put it in orbit around a lamp. If the ball's axis stood straight up, at right angles to the path, there would be no seasons. Every place would have the same day length forever, and the sun would rise in the same spot on the horizon every morning of every year. But the earth does not stand straight. Its axis leans about twenty-three and a half degrees off the vertical, and it holds that lean, pointed at the same distant spot among the stars, all the way around the sun. So for half the year the northern half of the planet is tipped toward the light and for the other half it is tipped away. Twice a year, in between, the lean is sideways to the sun, neither toward nor away, and on those two mornings the sun sits over the equator and rises due east for everybody. Out of that lean, and nothing else, come summer and winter and the birds and the harvest and the football schedule. Twenty-three degrees on a rock going around a fire.
It is not distance. People assume it must be, and it is not. The earth's path is very nearly a circle, and the small amount it is off puts us closest to the sun in the first days of January, in the cold, and farthest in the first days of July, in the heat. The difference is about three percent, and it is swamped by the tilt. What matters is not how far away the fire is but how squarely you face it.
You can feel that from the pier. On the equinox morning the sun climbs to a high point at what the clock calls a little after one in the afternoon, and at that high point it stands about sixty degrees above the horizon, two-thirds of the way to straight up. In June, on the longest day, it will stand at about eighty-four degrees, nearly overhead, and it will be almost impossible to find your own shadow at noon. In December it will make it to only about thirty-seven degrees, and the shadow of the pier railing will lie long across the boards all day. Same sun. Same distance, near enough. The difference is angle, and angle is everything, because a beam of light that comes in at a slant is spread over more ground than one that comes in straight down. The same sunlight that heats a square yard of the parking lot in June has to cover more than a yard and a half of it in December, and so each yard gets less. That is winter. The light is no weaker in December; there is simply more ground for it to cover.
Nobody knows for certain why the earth leans. The best account, and most of the people who study it hold to it, is that very early on, before there was a crust to stand on, something the size of a small planet struck the earth a glancing blow, knocked it askew, and threw off the cloud of rock that gathered into the moon. If that is right, the seasons and the moon are the same accident. And the moon has been holding the lean steady ever since; its pull keeps the axis from wandering the way it otherwise would. The lean is not quite fixed. The axis wobbles in a slow circle, like the top of a spinning top, once every twenty-six thousand years, and the tilt itself nods a couple of degrees either way over forty thousand. Those slow nods change how much sun the far north gets in summer, and they are what paced the ice ages: less summer sun, the snow stops melting, the ice walks south. The whole climate of the planet has swung, again and again, on a change of angle smaller than the one between the sun at the equinox and the sun a week later.
The plant on the far shore does not have seasons in the way the town does. The furnaces do not know it is March. But the plant is a creature of the tilt all the same, and in more than one way. The demand for what it makes rises and falls with the year: the gasoline for the summer drives, the fuel for the winter heat, the chemicals for the plastics for the things that get bought before the holidays. The cooling towers work harder in August because the air they are throwing heat into is hotter, and the whole complex breathes a little easier on a morning in January. And the crude that comes up the channel in the tankers is, itself, the tilt's oldest product. It is the remains of small living things that grew in a warm sea a few hundred million years ago, and they grew because the sun fell on them at an angle that suited them, in seasons that came and went then as they do now. The earth was leaning when that oil was made. It is still leaning.
The birds know the day better than we do. Somewhere south of here, in the forests of Central America and the Yucatán, small birds that weigh about as much as a couple of coins are getting restless. What sets them off is not warmth and not food but the length of the day. As the light stretches past twelve hours their bodies change; they eat more than they need and lay it down as fat under the skin, and one evening they take off over the water and fly all night and all the next day across the open Gulf, about six hundred miles of it, with nowhere to land. They burn the fat the way a turbine burns gas, steadily, at a rate they cannot change much, and if the wind is against them they arrive on this coast thin and desperate and drop into the first trees they see. The first of them are already moving in March. The big weeks come in April, when the peninsula and the coastal woods fill up overnight with color. The Nature Center on the old Brownwood land gets its share. So does any yard with a live oak in it.
Every one of those birds is running on the tilt. The equinox is the starting gun. They have no calendar and no clock and they do not need one, because the sky is the calendar, and the sky is exact.
Everything here is one thing. The angle of the sun on the pier, the length of the day that sends the birds north, the seasons that shape what the plant sells and how hard its cooling towers work, the ancient summers that grew the oil, the ice that came and went on a wobble: all of it is the same lean of the same rock toward the same fire. Energy is not a substance that comes out of a well or a plug. Energy is what the sun is doing to the earth, and the tilt is the dial that sets how much of it lands on any given place on any given day. The town at the head of the bay is in the business of that energy in a very old form, dug up and refined. The bird crossing the Gulf is in the business of it in a very new form, eaten and stored and burned in a night. The same light, spent at very different speeds.
Carl Sagan said once that we are a way for the cosmos to know itself. That is a large sentence and it can sound like something on a poster. But take it small. A person standing on a pier in Harris County before dawn, watching where the sun comes up, and knowing why it comes up there and why it will not come up there tomorrow, is a piece of the universe that has worked out its own angle. Nothing else on the bay has done that. The pelicans have not. The tide has not. The sun certainly has not; it does not know it is being watched. The knowing is ours. It is a small thing to hold on a cold pier at six in the morning, and nothing else out there is holding it.
The morning after the equinox the sun comes up a fraction to the north of where it did the day before. You would need a mark on the railing to tell. Put one there. Come back in a week and it has moved about the width of two fingers held out at arm's length. Come back in June and it is far off to the left, and the day is long and the air is thick and the flare is faint in the glare. Then it starts back. It crosses the mark again in September, the same spot, headed the other way, and the first birds of the fall are on the flats, and the whole business begins over. The railing stays where it is. The mark stays. It is only the earth that moves, slowly, leaning into the light and out of it, and the town rides along, and the pier, and whoever is on it.
