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Reference.org
Position of the Sun
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<p>The position of the Sun in the <a href="/facts/Sky/wwvQ84J1">sky</a> is a function of both the <a href="/facts/Time/HceJKUGB">time</a> and the <a href="/facts/Geographic_coordinate_system/RkjfcY6k">geographic location</a> of observation on <a href="/facts/Earth/HLLmDfj0">Earth</a>'s surface. As <a href="/facts/Earth%2527s_orbit/BGGCdFag">Earth orbits</a> the <a href="/facts/Sun/CadPCVHh">Sun</a> over the course of a <a href="/facts/Year/51V242hh">year</a>, the Sun appears to move with respect to the <a href="/facts/Fixed_stars/grlDbIPX">fixed stars</a> on the <a href="/facts/Celestial_sphere/TYAtXgor">celestial sphere</a>, along a circular path called the <a href="/facts/Ecliptic/cJxXDDDW">ecliptic</a>. </p><p><a href="/facts/Earth%2527s_rotation/mDbXcKUx">Earth's rotation</a> about its axis causes <a href="/facts/Diurnal_motion/WXqqYtES">diurnal motion</a>, so that the Sun appears to move across the sky in a <a href="/facts/Sun_path/CSFAAsms">Sun path</a> that depends on the observer's geographic <a href="/facts/Latitude/IBYqkjhU">latitude</a>. The time when the Sun <a href="/facts/Culmination/qGHPjMRs">transits</a> the observer's <a href="/facts/Meridian_(astronomy)/rpbtsv5R">meridian</a> depends on the geographic <a href="/facts/Longitude/HsC61ML9">longitude</a>. </p><p>To find the Sun's position for a given location at a given time, one may therefore proceed in three steps as follows: </p> <ol><li>calculate the Sun's position in the <a href="/facts/Ecliptic_coordinate_system/28zkWwVa">ecliptic coordinate system</a>,</li> <li>convert to the <a href="/facts/Equatorial_coordinate_system/dn5W4Eoo">equatorial coordinate system</a>, and</li> <li>convert to the <a href="/facts/Horizontal_coordinate_system/msJQPYg0">horizontal coordinate system</a>, for the observer's local time and location. This is the coordinate system normally used to calculate the position of the Sun in terms of <a href="/facts/Solar_zenith_angle/mwzmcUW6">solar zenith angle</a> and <a href="/facts/Solar_azimuth_angle/3NKskdCW">solar azimuth angle</a>, and the two parameters can be used to depict the <a href="/facts/Sun_path/CSFAAsms">Sun path</a>.</li></ol> <p>This calculation is useful in <a href="/facts/Astronomy/0ArJVM1p">astronomy</a>, <a href="/facts/Navigation/sGGAJ0AQ">navigation</a>, <a href="/facts/Surveying/qchGcnRC">surveying</a>, <a href="/facts/Meteorology/xblFr28q">meteorology</a>, <a href="/facts/Climatology/bYS7FktY">climatology</a>, <a href="/facts/Solar_energy/YBSajyN4">solar energy</a>, and <a href="/facts/Sundial/RWM823m2">sundial</a> design. </p>