The Sunís Apparent Diurnal Motion
by Charlie Williams
Observed from above the north pole, the earth rotates counterclockwise, from west to east in a period of 23 hours, 56 minutes, 4 seconds. The observer on earth shares this motion and sees the objects in the heavens cross the sky from east to west. The exception will be to an observer at the north and south poles, where the celestial objects turn in concentric circles above the horizon.
In the middle latitudes of the northern and southern hemispheres, the sun and stars seem to rise and set. These terms reflect the old belief that the sky is in motion. What is actually taking place is the lowering of the eastern horizon revealing new objects in the east while the western horizon moves up to cover those in the west.
The rising and setting sun became a convenient timekeeper to regulate activities on earth. On the eastern horizon at dawn, the sun climbs to itís highest altitude by midday and reaches the western horizon at dusk. In the northern hemisphere the diurnal arc (daily path) of the sun is to the south; in the southern hemisphere the sun will be north at midday. Between the Tropics of Cancer and Capricorn, the position of the sun at noon will depend upon the time of year and the latitude from which it is observed.
Another of my 50 year old class work...Bill
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