Projections

A map projection transforms the Earth's spherical two-dimensional coordinate system called latitude and longitude to the plane or planimetric map surface. Throughout history, map projections have been developed to meet various mapping purposes that satisfy societal needs. Early purposes were philosophical in nature such as cosmography, where there was a spiritual need to map the relationship between the heavens and the Earth, or for the quest of geographic knowledge, where scholars and explorers attempted to illustrate the known world. Other societal needs emerged as sea-going technology improved - better ship designs facilitated ocean-going navigation and thus propelled exploration, colonization, and extended political power. Modern activities such as air travel, delineation of borders, space travel, and search and rescue operations rely upon map projections that accurately map the Earth's coordinate system. Of course, cultural differences in the way societies have viewed their geographic surroundings have led to various incarnations of projections and their applications. Moreover, societies have used projections in such a way as to advance their own ideological agendas, often with unconscionable results. Progress in both mathematics and computer technology has facilitated the development of hundreds of map projections for a variety of applications.