(astron.) Any great circle of the celestial sphere passing through the zenith and the nadir and perpendicular to the horizon.
A great circle on the celestial sphere that passes through the zenith and the nadir and thus is perpendicular to the horizon.
Vertical-circle Sentence Examples
Attached to the cross-arm which carries the microscopes used to observe the ends of the dipping needle is a clamp, which will hold the needle b in such a way that its plane is parallel to the vertical circle and its axis is at right angles to the line joining the two microscopes.
A vertical circle passing through the sun may also be seen.
Reflection from an excess of horizontal prisms gives rise to a vertical circle passing through the sun.
To the telescope the vertical circle for reading angles in This word has been a puzzle to etymologists.