How Do Latitudes and Longitudes Work?
• Geo-coordinates are the X and Y values that we use to locate a position on the earth surface, just like locating a point on a Cartesian graph. The figure below shows the standard system most widely used today. • The center of the system (0,0) is a point in the Gulf of Guinea, offshore west Africa. The maximum and minimum values of the longitude and latitude are shown. Latitude +90 is the North Pole; latitude -90 is the South Pole. The maximum and minimum longitudes (+180 and -180) are along the same north-south line through the middle of the Pacific Ocean, because the earth is round. • The north-south line where longitude = 0 is called the Greenwich Meridian or Prime Meridian. • The units of measurement are DEGREES of longitude and latitude, symbolized by a small raised circle (°). • Geo-coordinates should always be written as “signed decimal degrees”, meaning: • Fractional parts of a degree must be written as decimals. • The sign of the longitude or latitude should be specified, but
