In astronomy, a vertical circle is a great circle on the celestial sphere that is perpendicular to the horizon. Therefore it passes through the zenith and the nadir. There is a vertical circle for any given azimuth, where azimuth is the angle measured east from the north on the celestial horizon. The vertical circle which is on the east-west direction is called the prime vertical. The vertical circle which is on the north-south direction is called the Local Celestial Meridian (LCM) or Principal Vertical. Vertical circles are part of the horizontal coordinate system.
Famous quotes containing the words vertical and/or circle:
“In bourgeois society, the French and the industrial revolution transformed the authorization of political space. The political revolution put an end to the formalized hierarchy of the ancien regimé.... Concurrently, the industrial revolution subverted the social hierarchy upon which the old political space was based. It transformed the experience of society from one of vertical hierarchy to one of horizontal class stratification.”
—Donald M. Lowe, U.S. historian, educator. History of Bourgeois Perception, ch. 4, University of Chicago Press (1982)
“They will mark the stone-battlements
And the circle of them
With a bright stain.
They will cast out the dead
A sight for Priam’s queen to lament
And her frightened daughters.”
—Hilda Doolittle (1886–1961)