Definition:Meridian/Terrestrial/Prime
Definition
A prime meridian is a terrestrial meridian which is determined by history and circumstance to be the international reference meridian with respect to which terrestrial longitude is defined.
Also defined as
Many sources take it for granted that the prime meridian is also the Greenwich meridian.
However, the Greenwich meridian has since been superseded as the international reference meridian by the IERS reference meridian.
Also known as
A prime meridian is also known as a standard meridian.
Some sources refer to it as the principal meridian, but this has a subtly different definition on $\mathsf{Pr} \infty \mathsf{fWiki}$.
Also see
- Results about prime meridians can be found here.
Historical Note
From $1884$ to $1974$, the prime meridian was the Greenwich meridian.
In $1974$ this was superseded, and the prime meridian is now taken to be the IERS reference meridian.
Sources
- 1976: W.M. Smart: Textbook on Spherical Astronomy (6th ed.) ... (previous) ... (next): Chapter $\text I$. Spherical Trigonometry: $4$. Terrestrial latitude and longitude.
- 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): meridian: 1.
- 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): meridian: 1.