If you've seen James Cameron's Titanic (that is to say, if you're a participating member of contemporary Western Civilization), you'll remember the "I'm the King of the World", and the consonant "I'm Flying" moments. They were quintessential declarations of liberty. One, a thriving poor man refusing to think himself needy, the other, a destitute rich girl escaping her chattel’s pen. These declarations, made on the bow of a Great Ship crossing the Atlantic, are self-evidently imitable. The Great Ship being the Titanic; imitable conjugates with irresistible tragedy. The same claims might be made anywhere. They surely have been. Jack and Rose might have shouted these words from the grand staircase, the stern of the ship, or the port rails. It wouldn’t have captured the same effect would it? Climbing onto the rail at the bow of the ship, each, in their turn, stood at the front of the world and refused to be defined by circumstance. The predicaments, the castes, the schemes of others, were put behind them and they faced the boundless expanse with courage and hope. Anyway, that’s the way I saw it. And, that made me think that a ship moving through the ocean is a kind of model of the Earth moving through space, and that made me wonder if you might not be able to stand on the “bow of the greater ship” and wave your arms and yell something declarative, meaningful, poignant. Well, of course it has to be possible. But what would that look like? The questions to answer are; where on the spaceship Earth am I now, and, if I am determined to stand on the bow, where, on the surface of the Earth, do I have to be, and, is there one place that is “out front”? It will be readily apparent that the Earth’s motion through space complicates the picture. Spinning on it’s axis, I am rotating at a rate of 360 degrees per day. That means that just standing still, my head is pointing at a constantly changing place relative to the sky (as measured by the stars). Its like asking “where do you sit to be on the front of a merry-go-round?” There’s more. Moving in a great arc around the Sun, we travel nearly a billion kilometers in a year. Here again, we are constantly changing our direction, giving us a cycle of astronomical seasons evidenced by the constellations we can and cannot view through the course of the year. For my purposes, it seems reasonable to limit ourselves to those motions measured by the day and the year. There is no need (beyond awe) to consider your motion relative to the center of the Milky Way or to introduce your motion relative to other galaxies. Those motions are staggering, precisely because the scale of motion compared to this life’s short ride doesn’t begin to tease your hair. Choosing simplicity, let’s think of our Earth like an ocean liner, the Earth’s orbital plane as the ocean, and ourselves as passengers scurrying toward the bow. Jack and Rose had a simpler system to interpret. The same part of the boat was always moving first through the water. Because of its rotation, the Earth is not like that. If you consider a race car that has lost its grip on the track, you’ll have a crude idea of our predicament. The car continues on a path mostly the same direction along the pavement, but as it spins and tumbles, the driver will one moment be facing the direction his body is moving and the next moment he may be facing in exactly the opposite direction that he is moving. We are like that, only our motions are slow and orderly in comparison to the hapless driver. We have only to wait patiently, and note that moment when our rotation brings us to an intersection with the arc of the Earth’s revolution. At that moment, once a day, we are faced in precisely the same direction that we are moving. The moment occurs at sunrise each day. Many of my students find this difficult to grasp. I find it difficult to clarify without a model.* Here is my evolving attempt. You know that the shadow of the Earth is on that side of the planet that is away from the Sun. Our shadow is always on the outside of the Earth’s orbital path. The terminator is the edge of that shadow. It divides night from day and we, rotating on the surface of the Earth are always moving from daylight across the terminator into night and then back across the terminator into sunlight again. You could refer (in all places except the poles) to the sunrise terminator, and the sunset terminator. If the Earth's path around the Sun were a highway, the terminator would lay parallel to the center-line. When you are crossing the sunrise terminator, your position on Earth is located on the front of the planet, in that, this location faces the exact direction that the Earth is moving in its arc around the Sun. With just one more complication. When Jack and Rose stood at the front of the Titanic, their bodies were perpendicular to the surface of the Atlantic, through which we measure their motion. Picture this. Had they been laying on the deck, going head first toward the western horizon, their proclamations would not have sounded nearly as cool. Children don’t generally play like they are birds by laying on their bellies. Jack and Rose stood on a surface that was itself parallel to their motion. We are on a surface, unless you're at the poles, that is essentially perpendicular to our motion. Gravity fools us into thinking we are on top of the world. We know better and need to factor this in as it pertains to our voyage. Unless I am standing on the poles, I am nothing like perpendicular to the motion of the Earth around the Sun.** Standing then, actually puts me moving head first into space at sunrise. The better effect is produced if you lay on the ground with your head to the north. Your left hand will be to the east and the rising sun. Here, you are plastered against the "front" of the planet, you will look straight into the sky, the direction you and the Earth are moving at that moment. Spread your arms and yell, “I’m Flying!” if that suits you. You certainly are. Or, just contemplate the circumstance and your relation to it at that moment. Far away someone is relaxing under a darkening sky. They are on the stern of a very large vessel looking out into the galactic wake. *Actually, I do use an evolving model in my classroom. I've included a couple of photos which may be helpful in making my point. **The tilt of the Earth’s axis in relation to the “plane of the ecliptic” is a relevant detail here, but, for pity's sake, models that are perfect representations take up just as much room as the real thing. |
1 Comment
12/2/2017 05:17:59 am
Scientist search and giving the new and unique information about this world. It tell us the world change day by day and smokes is not good for world. So It change the in air and its risky for breath.
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