When the sun reaches its highest point in the sky at a specific meridian, it is "noon" local solar time for every location on that line. The Challenge of Measuring Longitude
Every time you tap a destination into your GPS, unfold a paper map, or watch a hurricane track across a weather report, you are relying on a quiet, invisible framework invented thousands of years ago. That framework is the system of . meridian longitude
Before Greenwich, every country used its own prime meridian (Paris, Rome, even Washington D.C.). That made global navigation chaos. At the 1884 International Meridian Conference, 25 nations voted for Greenwich as the global standard—partly because of Britain’s maritime dominance and the popularity of Greenwich-based nautical charts. When the sun reaches its highest point in
In 1884, the International Meridian Conference in Washington, D.C., established the Greenwich Meridian in London as the world’s official Prime Meridian (0°). This decision was largely pragmatic; at the time, the vast majority of the world’s shipping charts already utilized Greenwich as their reference point. This standardization created the Universal Time (UT) system and the International Date Line, effectively synchronizing the planet’s clocks and maps for the first time in history. Before Greenwich, every country used its own prime
These extraterrestrial meridians allow planetary scientists to map rover locations, plan landings, and coordinate interplanetary missions.