An astronomical clock is a clock with special mechanisms and dials to display astronomical information. This information can include everything from the relative position of the sun and the moon to major planets to zodiacal constellations.
The term Astronomical clock is loosely used to refer to any clock that shows astronomical information. The clock could include the location of the sun and the moon, age and phase of the moon as well as other astronomical data. However, it should not be confused with an astronomical regulator which is just an ordinary pendulum clock. Most astronomical clocks are often marked in the center with a disc representing earth and a golden sphere representing the sun which rotates around the earth once a day representing a 24 hour period.
Early designs were less accurate than intended due to the lack of mechanical abilities amongst manufacturers. Although the wheelwork was advanced the timekeeping mechanisms were full of errors.
Astronomical clocks were a status symbol as much as clocks. Many were used as demonstrations or exhibition pieces. However, growing interest in astronomy in the 18th century revived interest in the astronomical clocks and many were built for actual accurate astronomical information.