Meridian

A meridian is an imaginary line on the Earth’s surface that runs from the North Pole to the South Pole, connecting points of equal longitude. Meridians are used in geographic coordinate systems to measure distance east or west of the Prime Meridian, which is designated at 0 degrees longitude and runs through Greenwich, England. Each meridian is defined by its angle of longitude, measured in degrees, with values ranging from 0° at the Prime Meridian up to 180° east or west. Meridians are essential for navigation and mapping, as they help to establish the geographic grid system alongside parallels of latitude. In addition to their geographical significance, the term “meridian” can also refer to specific cultural or scientific concepts, such as meridians in traditional Chinese medicine, where they are believed to be channels through which vital energy flows in the body.