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How the Sun Travels
Symmetrically
Across the Sky
The sun's daily path across the sky is symmetrical. If it rises X number of degrees north of east, it will set that same number of degrees north of west. If it rises X number of degrees south of east, it will set that same number of degrees south of west.
Further, the sun rises at an approximate angle of 90 degrees minus your latitude, and also sets at that same angle.
The Northern Hemisphere
Here in the northern hemisphere--with the exception of certain times in the very low latitudes of the tropics--the sun arcs across the southern sky.
It crosses your meridian--meaning it bears due south--at local apparent noon (LAN).
Point of Interest
The clock time of 1200 likely won't coincide with LAN. The reason for the difference is that humans divide the earth into local time zones, 15 degrees of longitude wide. In Florida, for instance, Jacksonville and Tallahassee are both in the Eastern time zone, yet Jacksonville is about 156 miles east of Tallahassee so the sun passes over Jacksonville before it passes over Tallahassee. The clock time of LAN can vary throughout the year for any location. Also, changes from Standard to Daylight time affect the clock time of LAN by one hour.
It then goes on to set in a westerly direction at the same angle as it rose in the east (approximately 90 degrees minus your latitude), and the same direction (north or south) and distance (stated in degrees of arc) it rose away from east.
- Example: The date is March 31. Your latitude is 30 degrees north. The sun rose today in the direction of 086 degrees, which is 004 degrees north of east. The sun's rising angle was approximately 60 degrees (90 degrees minus your local latitude of 30 degrees). At LAN (12:28 on this day), the sun crossed your meridian, meaning it was in exactly the SOUTH at that time. In the afternoon, the sun continued its journey across the sky to the west, ultimately setting at 274 degrees, or 004 degrees north of west. Its setting angle was the same as its rising angle-- approximately 60 degrees, or 90 degrees minus your latitude.
The Southern Hemisphere
In the southern hemisphere, once again excepting certain times in the tropics' low latitudes, the sun arcs across the northern sky.
In crosses your meridian--meaning it bears due north--at local apparent noon LAN, then goes on to set in a westerly direction at the same angle as it rose in the east (approximatley 90 degrees minus your latitude), and in the same direction (north or south) and distance (stated in degrees of arc) it rose away from east.
- Example: The date is March 31. Your latitude is 30 degrees south. The sun rose today in the direction of 086 degrees, or 004 degrees north of east. The sun's rising angle was approximately 60 degrees (90 degrees minus your local latitude of 30 degrees). At LAN (12:28 on this day), the sun crossed your meridian, meaning it was in exactly the NORTH at that time. In the afternoon, the sun continued its journey across the sky to the west, ultimately setting at 274 degrees, or 004 degrees north of west. Its setting angle was the same as its rising angle-- approximately 60 degrees, or 90 degrees minus your latitude.
Because the sun's path across the sky is symmetrical, it makes our job as navigator a whole lot easier than if the path were something other than symmetrical. When using the sun to find direction, you'll rely heavily on this symmetry of the solar path.
