ANNUAL MOTION - ANNUAL MOTION The positions of the stars...

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ANNUAL MOTION The positions of the stars are almost the same after 24 hours, but there is a small difference. If you have an accurate measurement of the time, and you look exactly 24 hours later, you will find that the stars have moved (the word "drifted" is often used) a small amount toward the west compared to the previous night. Casually looking at the sky you wouldn't notice this, but this east to west drift continues night after night, and after a few weeks you would notice it. In a month the motion would be about 30 degrees. At some time during the year the group of stars you are watching might disappear below the western horizon. At some time later they would reappear above the eastern horizon. And after exactly one year the stars would appear at the same point where they started. This is called annual motion. After one year the motion repeats. The speed of annual motion is about 1 degree per day. THE PLANETS
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This note was uploaded on 12/15/2011 for the course AST AST1002 taught by Professor Emilyhoward during the Fall '10 term at Broward College.

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ANNUAL MOTION - ANNUAL MOTION The positions of the stars...

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