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:
“Baltimore lay very near the immense protein factory of Chesapeake Bay, and out of the bay it ate divinely. I well recall the time when prime hard crabs of the channel species, blue in color, at least eight inches in length along the shell, and with snow-white meat almost as firm as soap, were hawked in Hollins Street of Summer mornings at ten cents a dozen.”
—H.L. (Henry Lewis)
“I knew that my vocation was found. I had received the call, and having done so, I was sure my work would be assigned me. Of some things we feel quite certain. Inside there is a click, a kind of bell that strikes, when the hands of our destiny meet at the meridian hour.”
—Amelia E. Barr (1831–1919)