If you’ve used a global position system (GPS) device or an online map application, you may have noticed that geographic locations on earth can be precisely described using latitude and longitude values. Latitudes range from -90 to +90 degrees, where -90 degrees is the South Pole, 0 degrees is the equator, and +90 degrees is the North Pole. Longitudes range from -180 to +180 degrees, where 0 degrees longitude is the Prime Meridian on which the Royal Observatory sits in Greenwich, England.
You may have also noticed that there are 2 main systems for the communication of latitude and longitude: degrees/minutes/seconds (DMS, a.k.a. “sexagesimal degrees”) and decimal degrees (DD). In DMS notation, each degree is divided into 60 minutes, and each minute is divided into 60 seconds, just like a clock. Fractions of sections can be represented by decimals. In DD notation, the latitude and longitude coordinates are simply expressed as decimals, with a greater number of decimal places conferring greater geographic precision.
To complicate matters, in both DMS and DD notations, locations relative to the equator and Prime Meridian can be expressed using either positive/negative values or north (N), east (E), south (S), and west (W) designations. Positive latitudes are N of the equator, while negative latitudes are S of the equator. Positive longitudes are E of the Prime Meridian, while negative longitudes are W of the Prime Meridian.
There may be times when you may need to interconvert between DMS and DD notations. For example, if you need to navigate to a certain location and are provided with DMS coordinates, it may be easier (or possibly your only option) to enter DD coordinates into your GPS device. A free DMS-DD converter is provided by the Federal Communications Commission, and there are numerous other free options available.
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