Meridiaane

Meridiaane are imaginary lines that traverse the globe from the North Pole to the South Pole. In geography, they define longitude and form part of the coordinate grid used for navigation, mapmaking, and timekeeping. The Prime Meridian, designated at 0 degrees longitude, passes through Greenwich and serves as a reference point for measuring east and west. Meridians are angular, with one degree of longitude representing a smaller ground distance toward the poles than at the equator.

Geographically, meridians work together with parallels (lines of latitude) to create a graticule, a network that enables precise positioning on maps and globes. The system also underpins time zones, since local solar time varies with longitude. The International Date Line, which roughly follows the 180th meridian, marks the boundary where the calendar date changes.

In traditional East Asian medicine, the term meridians also refers to energy channels believed to conduct qi, or vital energy, between organs and body surfaces. From this perspective, acupuncture points lie along these meridians and are stimulated to restore balance and health. The scientific status of meridians in this context remains a topic of debate; explanations vary, and Western medical consensus does not universally recognize an anatomical basis for these pathways.

Historically, the concept of meridians in geography emerged from the needs of navigation and cartography, while analogous ideas appeared in various cultures. The word meridian itself derives from Latin, meaning mid-day or noon, reflecting historical ways of describing the sun’s position.

See also: longitude, prime meridian, time zones, acupuncture, qi.