doc/kstars/horizon.docbook

   1 <sect1 id="ai-horizon">
   2 <sect1info>
   3 <author>
   4 <firstname>Jason</firstname>
   5 <surname>Harris</surname>
   6 </author>
   7 </sect1info>
   8 <title>The Horizon</title>
   9 <indexterm><primary>Horizon</primary>
  10 <seealso>Horizontal Coordinates</seealso>
  11 </indexterm>
  12 <para>
  13 The <firstterm>Horizon</firstterm> is the line that separates Earth from Sky.
  14 More precisely, it is the line that divides all of the directions you can
  15 possibly look into two categories: those which intersect the Earth,
  16 and those which do not.  At many locations, the Horizon is
  17 obscured by trees, buildings, mountains, &etc;.  However, if you are on
  18 a ship at sea, the Horizon is strikingly apparent.
  19 </para><para>
  20 The horizon is the <firstterm>Fundamental Plane</firstterm> of the <link
  21 linkend="horizontal">Horizontal Coordinate System</link>.  In other
  22 words, it is the locus of points which have an <firstterm>Altitude</firstterm>
  23 of zero degrees.
  24 </para>
  25 </sect1>