is a geographic coordinate that specifies the east‑west position of a point on Earth’s surface. It is measured as an angle from the prime meridian (0° longitude) to the meridian passing through the point, ranging from 0° to 180° east or west.
Stand on the Royal Observatory’s Prime Meridian line in London (or a local one in your city) and realize: you’re straddling the world’s reference point for time and space. meridian longitude