On this day in 1675, Englands King Charles II commissioned the Royal Greenwich Observatory, the center of time and space on Earth. He also created the position of the Astronomer Royal at the same time, to apply himself with the most exact care and diligence to the rectifying of the tables of the motions of the heavens, and the places of the fixed stars, so as to find out the so much desired longitude of places for the perfecting of the art of navigation. The building was designed by Sir Christopher Wren, and it was the first structure in Britain that was built specifically for a scientific purpose. The prime meridian marks the boundary between the Eastern and Western hemispheres just as the equator marks the boundary between north and south, and it was established at the Observatory in 1851. The prime meridian was originally marked by a brass strip, then stainless steel, and now its marked by a green laser. The laser actually marks the historical location of the prime meridian; old methods of calculating geographical coordinates involved using measurement of local sea level, and since sea level can vary worldwide, the coordinates werent consistent. Once an Earth-centered — rather than local — system was used, the prime meridian shifted about 103 meters to the east. Greenwich Mean Time was also calculated at the Observatory, when it was still active; before the establishment of GMT, each town kept its own time, and they varied widely. Since 1833, people have been able to set their clocks by the time ball, which still drops every day at precisely one oclock p.m. The Royal Observatory was gradually decommissioned over the first half of the 20th century, and its now a museum, planetarium, and tourist attraction. Light pollution from London and electrical interference from the nearby railway system made it impossible to carry on as a working observatory, but its still the official starting point for each new day, year, and millennium.
Posted on: Sun, 04 May 2014 09:14:33 +0000
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