Warning, /education/kstars/doc/horizon.docbook is written in an unsupported language. File is not indexed.

0001 <sect1 id="ai-horizon">
0002 <sect1info>
0003 <author>
0004 <firstname>Jason</firstname>
0005 <surname>Harris</surname>
0006 </author>
0007 </sect1info>
0008 <title>The Horizon</title>
0009 <indexterm><primary>Horizon</primary>
0010 <seealso>Horizontal Coordinates</seealso>
0011 </indexterm>
0012 <para>
0013 The <firstterm>Horizon</firstterm> is the line that separates Earth from Sky.
0014 More precisely, it is the line that divides all of the directions you can
0015 possibly look into two categories: those which intersect the Earth,
0016 and those which do not.  At many locations, the Horizon is
0017 obscured by trees, buildings, mountains, &etc;  However, if you are on
0018 a ship at sea, the Horizon is strikingly apparent.
0019 </para><para>
0020 The horizon is the <firstterm>Fundamental Plane</firstterm> of the <link
0021 linkend="horizontal">Horizontal Coordinate System</link>.  In other
0022 words, it is the locus of points which have an <firstterm>Altitude</firstterm>
0023 of zero degrees.
0024 </para>
0025 </sect1>