Noun
meridian at zero degree longitude from which east and west are reckoned (usually the Greenwich longitude in England)
Source: WordNetIn Indian astronomy, the prime meridian is the great circle of the Earth passing through the north and south poles, Ujjayinī and Laṅkā, where Laṅkā was assumed to be on the Earth's equator. Aryabhata
Europa's prime meridian is the line intersecting this point. citation Research suggests the tidal locking may not be full, as a non-synchronous rotation has been proposed: Europa spins faster than it orbits, or at least did so in the past. Source: Internet
For that reason we have to define another type of north, called "grid north," which points along the longitude line called the Prime Meridian. Source: Internet
The requirement that satellite-based geodetic reference systems be centred on the centre of mass of the earth caused the modern prime meridian to be 5.3" east of the astronomic Greenwich prime meridian through the Airy Transit Circle. Source: Internet
It was recommended for adoption as the international Prime Meridian in 1884. Source: Internet
Noting and calculating longitude Longitude is given as an angular measurement ranging from 0° at the Prime Meridian to +180° eastward and −180° westward. Source: Internet