Latitude, the distance in degrees on the earth's surface measured north and south of the Equator. The Equator, which divides the earth into the Northern and Southern hemispheres, is designated as latitude 0 degrees (0°). The North Pole is 90 degrees north (90° N); the South Pole, 90 degrees south (90° S).
Lines of latitude are imaginary lines that circle the earth in a true east-west direction. They are often called parallels because they run parallel to the Equator and to each other. Viewed on a globe from either pole the lines form concentric circles, the largest circle being the Equator. On some maps lines of latitude are shown nonparallel because of distortions caused by the map projection.
Each degree of latitude spans about 69 statute miles (about 60 nautical miles or 111 kilometers) on the earth's surface. The exact distance varies slightly from the Equator to the poles because the earth is an imperfect sphere. From the Equator to 40° north and 40° south the span is slightly less than 69 statute miles; from 41° to the poles it is slightly more.
The latitude of any point on the earth is most precisely expressed in degrees, minutes, and seconds. Each degree is divided into 60 minutes (60'), and each minute into 60 seconds (60°). The latitude of the U.S. Naval Observatory in Washington, D.C., for example, is 38°55°14° N. Together, latitude and longitude (the east-west coordinate) precisely locate a point on the earth.
Celestial latitudeis used in locating heavenly bodies.
