polar area—A stereographic grid extending to 79°30′ N from the South Pole and to 79°30′ S from the North Pole, thus providing a 30′ overlap on the Universal Transverse Mercator grid.

polar axis—The primary axis of direction in a system of polar or spherical coordinates.

polar bearing—In a system of polar or spherical coordinates, the angle formed by the intersection of the reference meridional plane and the meridional plane containing the point.

polar coordinates—See coordinates, polar.

polar distance-¹ The astronomical coordinate (0° to 180°) measured from the pole of a planet or a star to a point along an hour circle; usually limited in actual use to mean codeclination. ² The complement of the declination (co-declination) or 90° minus the declination. Polar distance forms one side of the astronomical triangle.

polar map projection—See map projection, polar

polar motion—¹ The irregularly varying motion of the Earth’s pole of rotation with respect to the Earth’s crust. ² The movement of the Earth’s instantaneous axis or rotation with respect to the axis of the figure of the Earth; wobble, wander.

polar planimeter—See planimeter; polar.

polar symmetry—Symmetry in which parts are equal and interchangeable in all directions in planes perpendicular to a central axis but not in both directions from these planes.

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Source: NSPS “Definitions of Surveying and Related Terms“, used with permission.

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