what is another name for the prime meridian
Prime meridian A prime meridian is ultimately arbitrary, unlike an equator, which is determined by the axis of rotationâ€”and various conventions have been used or advocated in different regions and throughout history.[1] The most widely used modern meridian is the IERS Reference Meridian. It is derived but deviates slightly from the Greenwich Meridian, which was selected as an international standard in 1884.