Prime meridian (Greenwich)
A prime meridian, based at the Royal Observatory, Greenwich, in London, was established by
Sir George Airy in 1851. By 1884, over two-thirds of all ships and tonnage used it as the
reference meridian on their charts and maps. In October of that year, at the behest of U.S.
President Chester A. Arthur, 41 delegates from 25 nations met in Washington, D.C., USA, for
the International Meridian Conference. This conference selected the meridian passing
through Greenwich as the official prime meridian due to its popularity. However, France
abstained from the vote and French maps continued to use the Paris meridian for several
decades. In the 18th century, London lexicographer,Malachy Postlethwayt published his
African maps showing the 'Meridian of London' intersecting the Equator a few degrees west
of the later meridian and Accra,Ghana.
The prime meridian passes through the Airy transit circle (51°28′40.1247″N 0°0′5.3101″W[3])
of the Greenwich observatory. It was long marked by a brass strip in the courtyard, now
upgraded to stainless steel, and, since 16 December 1999, has been marked by a powerful
green laser shining north across the London night sky.
The Greenwich meridian passes through:
United Kingdom,
France,
Spain,
Algeria,
Mali,
Burkina Faso,
Togo,
Ghana,
Flag of Norway.svg Queen Maud Land in Antarctica.