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:
“I tell you, hopeless grief is passionless;
That only men incredulous of despair,
Half-taught in anguish, through the midnight air
Beat upward to God’s throne in loud access
Of shrieking and reproach. Full desertness,
In souls as countries, lieth silent-bare
Under the blanching, vertical eye-glare
Of the absolute Heavens.”
—Elizabeth Barrett Browning (1806–1861)
“It was my heaven’s extremest sphere,
The pale which held that lovely deer;
My joy, my grief, my hope, my love,
Did all within this circle move!”
—Edmund Waller (1606–1687)