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
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
Marine sandglass MMM
IERS Reference Meridian
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The IERS Reference Meridian, also called the International Reference Meridian, is the prime meridian maintained by the International Earth Rotation and Reference Systems Service. It passes about 5.3 a
Prime meridian
…history, but none (unlike the prime meridian of Mars) have a basis in physical geography. Earth's current international standard prime meridian is the IERS Reference Meridian. It is derived, but differs slightly, from the Greenwich Meridian, the previous standard. Longitudes for the Earth and Moon are measured from their…
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