I am a novice surveyor learning the fundamentals behind coordinate systems and have a questions regarding geodetic north. I understand that true north is the geographic north, or the location of longitude convergence. I think of this location as referenced to the physical earth with the prime meridian passing thru the Greenwich observatory. However, with an ellipsoid horizontal datum, is the north associated with the ellipsoid or does it remain associated with the earth? So if I translate to a different ellipsoid datum, does the north remain fixed on the physical earth or is its orientation impacted by the translation to a different datum ?