The sun in the west

     
L>Why does the Sun rise in the east and set in the west? Question:Why does the Sun rise in the east and set in the west? Answer:The Sun, the Moon, the planets, and the stars all rise in the east andset in the west. And that"s because Earth spins -- toward the east.For a moment, let us ignore Earth"s orbit around the Sun (as well as theSun"s and solar system"s revolution around the center of the Galaxy, andeven the Galaxy"s journey through the universe). For the moment, let usjust think about one motion - - Earth"s spin (or rotation) on its axis.Earth rotates or spins toward the east, and that"s why the Sun, Moon,planets, and stars all rise in the east and make their way westward acrossthe sky. Suppose you are facing east - the planet carries you eastward asit turns, so whatever lies beyond that eastern horizon eventually comes upover the horizon and you see it! People at Earth"s equator are moving at a speed of about 1,600kilometers an hour -- about a thousand miles an hour -- thanks to Earth"srotation. That speed decreases as you go in either direction toward Earth"spoles. In the state of Texas, you"d moving at about 1,400 kilometers anhour due to rotation. If you"re in southern Canada, you"re moving at onlyabout a thousand kilometers an hour. Now think about what would happen ifyou stood exactly at the North Pole. You"d still be moving, but you"d beturning in a circle as Earth spins on its axis.You may wonder why you don"t feel this speed: it"s because human beingshave no "speed organs" which can sense absolute speed. You can only tellhow fast you are going relative to something else, and you can sensechanges in velocity as you either speed up or slow down. But we cannotreally tell whether or not we are just moving at a constant speed unlesssomething else tips us off!Think about this: Suppose you are in a car traveling down the road.


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How can you tell howfast you are going? The speedometer tells you how fast your wheels areturning, but you could be standing dead still, spinning your wheels tryingto get off a patch of ice, so let"s remove the speedometer from the car.As you go faster, your car may vibrate more because it"s working hard, butthese vibrations only tell you the car is working hard, not what velocityyou are moving at. So get a good car and some cushions to remove thevibrations you feel. Then get some good earplugs so any misleading soundswon"t distract you. And paint your car windows black so that the motion ofobjects relative to you don"t throw you off. Remember that when it comes tothe rotation of the Earth, everything around you is moving at the samespeed - you, the trees, the houses, your pet dog, everything. OK, now, howfast are you going? You have no way to tell. You don"t feel like you"removing. You feel just as you would if you were standing still! Human beingshave no ability to tell absolute motion.


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