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31 lines
933 B
31 lines
933 B
13 years ago
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<sect1 id="ai-horizon">
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<sect1info>
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<author
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><firstname
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>Jason</firstname
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> <surname
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>Harris</surname
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> </author>
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</sect1info>
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<title
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>The Horizon</title>
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<indexterm
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><primary
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>Horizon</primary>
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<seealso
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>Horizontal Coordinates</seealso>
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</indexterm>
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<para
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>The <firstterm
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>Horizon</firstterm
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> is the line that separates Earth from Sky. More precisely, it is the line that divides all of the directions you can possibly look into two categories: those which intersect the Earth, and those which do not. At many locations, the Horizon is obscured by trees, buildings, mountains &etc;. However, if you are on a ship at sea, the Horizon is strikingly apparent. </para
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><para
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>The horizon is the <firstterm
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>Fundamental Plane</firstterm
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> of the <link linkend="horizontal"
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>Horizontal Coordinate System</link
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>. In other words, it is the locus of points which have an <firstterm
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>Altitude</firstterm
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> of zero degrees. </para>
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</sect1>
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