Eastern & Western Longitude: Measuring Position East or West of Greenwich

Defining the Grid

Lines of longitude (meridians) are great circles running pole-to-pole, intersecting the equator at right angles. They measure angular distance east or west of the Prime Meridian (0°) at Greenwich, England.

• Eastern Longitudes: 0° to 180° East (E)
• Western Longitudes: 0° to 180° West (W)

The 180th Meridian & the International Date Line

The 180° line serves as the International Date Line (with zigs to avoid splitting nations). Crossing west→east adds a day; east→west subtracts a day.

Precision

Degrees are subdivided into 60 minutes (′), each minute into 60 seconds (″), enabling pinpoint navigation and time-zone delineation worldwide.