A prime meridian is a meridian, i.e. a line of longitude, at which longitude is defined to be 0°. A prime meridian and its opposite in a 360°-system, the 180th meridian (at 180° longitude), form a great circle.
This great circle divides the sphere, e.g. the Earth, into two hemispheres. If one uses directions of East and West from a defined prime meridian, then they can be called Eastern Hemisphere and Western Hemisphere.
An international conference in 1884 decided the prime meridian passes through the Royal Observatory, Greenwich in southeast London, United Kingdom, known simply as the prime meridian but also sometimes referred to as the International Meridian or Greenwich meridian.
Read more about Prime Meridian: General Concept, Earth, Other Planetary Bodies
Famous quotes containing the words prime and/or meridian:
“What was lost in the European cataclysm was not only the Jewish past—the whole life of a civilization—but also a major share of the Jewish future.... [ellipsis in source] It was not only the intellect of a people in its prime that was excised, but the treasure of a people in its potential.”
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