Meridian Longitude [top] Instant

Unlike the Equator, which is a natural midpoint for latitude, there is no "natural" starting point for longitude. Throughout history, different cultures used their own "prime" meridians, such as the Paris Meridian or lines through the Canary Islands. What is longitude? - NOAA's National Ocean Service

| Meridian | Longitude | Significance | |----------|-----------|---------------| | Prime Meridian | 0° | Greenwich, London. Base for GPS and UTC. | | Antimeridian | 180° | Opposite Greenwich; near International Date Line. | | Tropic of Cancer/Capricorn | – | Not meridians (they are lines of latitude). | | Central European Meridian | 15°E | Basis for Central European Time (UTC+1). | | 90th Meridian West | 90°W | Runs through central North America (New Orleans, Winnipeg). | meridian longitude