Meaning of astronomical clock

as'tronom'ical clock'

Pronunciation: [key]
  1. a clock indicating or representing the movements of the sun or planets, the phases of the moon, or the sky visible at a given time, used as a means of establishing time or for additional information, as locating celestial bodies or timing their movement.
  2. a clock used for observing the apparent time of the meridian passages of heavenly bodies.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.