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By recording the alignments of the heavenly bodies over a long period of
time (after all, there was no TV back then), periodicity and other
characteristics can be easily observed. The solstices are actually fairly
easy to predict since it is the "standstill" day of the sun,when it reaches
its greatest extreme north or south of due east on the horizon at sunrise.
For example, an observer standing at a monument and watching the movement
of the sun over a long period of weeks would see it gradually drift
northward along the eastern horizon at sunrise during the springtime. We
have just passed the summer solstice, when the sun reaches its furthest
point north on the horizon. On June 21, the sun began its slow march south
toward fall and winter, when in its furthest south position we northerners
get chilled. Any culture monumentalizing astronomy in architecture would
most certainly have some notions about planetary movements and would
eventually note the predictable arithmetic structures of these movements.
By counting the number of days it takes for the sun to complete a single
circuit from, for example, summer solstice to summer solstice, the observer
would be recording the number of days in a year. The solstices are
separated by approximately 183 days, dividing the year in half, and the
equinox falls about 91 days later. The phenomena of the solar cycle has a
handy four-part symmetry that makes for easy math.
Many of the structures with astronomical alignments were in fact observatories and are laid out with lines of sight to other monuments or significant natural formations such as mountains. The longer the line of sight, the more precise the measurements can be. Usually there is a central viewing area that houses the viewer-astronomer. This fixed datum point is then used to measure the movement of the sun and other bodies in relation to other fixed points on the ground. (For example, Stonehenge has the famous "Heel Stone", from behind which the rising sun on the equinox is seen to align when viewed from the center of the monument.) There is debate, however, about how these ancients interpreted the equinox since, without a concept of a round earth, the notion of an equator is problematic. Thus, it is questionable whether they understood the equinox as we do, as the day the earth lies directly above the terrestrial equator. For info on some of the "mysterious" places that house astronomical observatories, see http://www.mysteriousplaces.com/ For info on America's "stonehenge", see http://www.stonehengeusa.com/
Overviews of "archeoastronomy" can be found at |
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