You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
26 lines
920 B
26 lines
920 B
15 years ago
|
<sect1 id="ai-horizon">
|
||
|
|
<sect1info>
|
||
|
|
<author>
|
||
|
|
<firstname>Jason</firstname>
|
||
|
|
<surname>Harris</surname>
|
||
|
|
</author>
|
||
|
|
</sect1info>
|
||
|
|
<title>The Horizon</title>
|
||
|
|
<indexterm><primary>Horizon</primary>
|
||
|
|
<seealso>Horizontal Coordinates</seealso>
|
||
|
|
</indexterm>
|
||
|
|
<para>
|
||
|
|
The <firstterm>Horizon</firstterm> 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><para>
|
||
|
|
The horizon is the <firstterm>Fundamental Plane</firstterm> of the <link
|
||
|
|
linkend="horizontal">Horizontal Coordinate System</link>. In other
|
||
|
|
words, it is the locus of points which have an <firstterm>Altitude</firstterm>
|
||
|
|
of zero degrees.
|
||
|
|
</para>
|
||
|
|
</sect1>
|