Prime meridian (Greenwich)
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The Greenwich meridian is a prime meridian, a geographical reference line that passes through the Royal Observatory, Greenwich, in London, England. From 1884 to 1974, the Greenwich meridian was the in
Laser projected from the Royal Observatory, marking the prime meridian of Greenwich
Tourists queuing to take pictures on the brass line marking the prime meridian at the Royal Observatory, Greenwich
A GPS receiver at the marking strip of the Greenwich Meridian in front of the Royal Observatory. The indicated longitude is not exactly zero because the geodetic zero meridian on a geocentric reference ellipsoid (which is what GPS positioning yields, using the IERS Reference Meridian) is 102 metres east of this strip.
Prime meridian
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A prime meridian is a meridian in a geographic coordinate system at which longitude is defined to be 0°. On a spheroid, a prime meridian and its anti-meridian form a great ellipse. This divides the bo
Gerardus Mercator in his Atlas Cosmographicae (1595) used a prime meridian somewhere close to 25°W, passing just to the west of Santa Maria Island in the Azores in the Atlantic Ocean. His 180th meridian runs along the Strait of Anián (Bering Strait)
The line of the Greenwich meridian at the Royal Observatory, Greenwich, England
The prime meridian sign in Parnay, Maine-et-Loire, France
Prime meridian sign near Somanya, Ghana