The thin line between us and them.
- The great circle passing through the celestial poles, the zenith, and the nadir of an observer’s location
- Contains the horizon’s north and south points, perpendicular to the celestial equator and horizon
- Celestial meridian is coplanar with the analogous terrestrial meridian projected onto the celestial sphere; meaning the imaginary lines that divide the outward sphere projected in space to give it a 3 dimensional scope of location and relativity to oneself here on earth
- This makes the number of astronomical meridians is infinite