Harrison’s H-4 chronometer (1761) was accurate enough to win the British Longitude Prize. This mechanical breakthrough turned meridian longitude from a theoretical abstraction into a practical tool.
In 1884, the International Meridian Conference convened in Washington, D.C., to standardize time and navigation. They established the Prime Meridian (0° longitude) at the Royal Observatory in Greenwich, London. This decision was pragmatic; at the time, over two-thirds of the world's shipping already used Greenwich charts. meridian longitude
However, unlike latitude, where 1° equals roughly 111 km everywhere, the distance between meridians shrinks as you move toward the poles. Harrison’s H-4 chronometer (1761) was accurate enough to
is an imaginary vertical line that runs from the North Pole to the South Pole. These lines are used to measure They established the Prime Meridian (0° longitude) at
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.
But what exactly is a meridian longitude? How is it different from a parallel of latitude? And why does the choice of a "Prime Meridian" matter? This article will take you on a deep dive from the Greenwich Observatory to the depths of the International Date Line.
: The distance between meridians is greatest at the equator (roughly 111 km per degree) and decreases to zero at the poles. Great Circles