Longitude — Meridian

Meridian longitude is the angular distance between a point on the Earth's surface and the prime meridian, measured in degrees, minutes, and seconds. The prime meridian, also known as the Greenwich Meridian, passes through Greenwich, England, and is designated as 0° longitude. Meridian longitude is a way to express a location's east-west position relative to the prime meridian.

The Earth rotates 360 degrees in approximately 24 hours. By dividing 360 by 24, we find that the Earth rotates . This relationship is why meridians are the foundation of our time zones. meridian longitude

: Every meridian is approximately the same length, stretching from pole to pole. Timekeeping and Navigation Meridian longitude is the angular distance between a

In 1884, the International Meridian Conference met in Washington, D.C., and established the (passing through the Royal Observatory in Greenwich, London) as the world's official Prime Meridian. It is designated as 0° longitude . How Longitude is Measured Longitude is measured in degrees, minutes, and seconds: The Earth rotates 360 degrees in approximately 24 hours

While the "Reference Meridian" used by modern GPS (the IERS Reference Meridian) actually sits about 100 meters east of the historic Greenwich observatory due to more precise satellite measurements, the principle remains the same. Whether you are tagging a photo on social media, navigating a commercial airliner, or tracking a shipping container across the ocean, you are utilizing the invisible grid of meridian longitude.

This convergence is why polar maps are often displayed using different projections (like the Azimuthal projection) rather than the standard Mercator projection, which grotesquely exaggerates the size of polar regions.