International Prime Meridian Conference

The International Prime Meridian Conference, held in 1884, established a global standard for longitude. This conference designated the meridian passing through the Royal Observatory in Greenwich, London, as the prime meridian, representing 0° longitude. Before this, various countries used their own prime meridians, often through their capital cities.12

The Greenwich meridian became the internationally recognized reference point for longitude and served as the basis for the world's time zone system. It divides the Earth into the Eastern and Western hemispheres. While the Greenwich meridian was the standard from 1884 to 1984, it has since been superseded by the International Reference Meridian (IRM), which is defined by satellite data and differs only slightly.13