Astronomical Clocks - Definition and History

An astronomical clock refers to a mechanical devicehighly accurate astrological clocks. These include an
that is designed to calculate, and display, both theastrolabe built in the tenth century by Abd al-Rahman
passage of time and the movement of certainal-Sufi, an astrolabic clock made by Ibn al-Shatir in the
astrological bodies. Since the measure of time in14th century, and the castle clock built by Al-Jazari in
ancient civilizations was often associated with1206.
astrological theories, the union of these twoWhile early clock development in Europe is a bit hazy,
timekeeping devices was a natural progression whichit is generally agreed that by the thirteenth century
resulted in the creation of various astronomical clocksthey had working mechanical clocks, driven by weight
throughout human history.rather than by water. These clocks were often
The astronomical information which can be displayedattached to symbolic mechanical representations of
by one of these timepieces can include the position ofthe movement of the stars.
the sun, the moon, and various constellations, theThe development of clocks tied into astrological
phases of the moon, the date of eclipses and otherphenomenon was a natural development, since the
astronomically important events, and just aboutastrolabe was a device used by both astronomers
anything that has to do with the state and position ofand astrologers, and it was not difficult to apply simple
heavenly bodies.mechanical principles to get it to move.
It is important to note that an astronomical clock isWhile mechanical astrological clocks built during the
different from an astronomical regulator, which isMiddle Ages were impressive in scale and scope, they
designed to maintain a steady rate of time, as a unit ofwere probably highly inaccurate. This is due to the fact
measure when making astronomical measurements.that the intricate and precise gearing required to make
One of the oldest devices that could be considered anthese clocks accurate was simply beyond the means
astronomical clock is the Antikythera mechanism, builtof that days manufacturing capabilities. Further, these
in the 2nd century B.C. While this device wasn't aclocks were using a primitive verge and foliot
clock, it was a mechanical device that was used toescapement, which had errors of up to a half an hour
determine the position of certain celestial bodies.every single day. A more accurate clock was
Posidonius' orrery is a device built later on in the firstproduced by Taqi al-Din in 1559 using springs to power
century A.D. and which functioned in roughly the samethe movements.
manner.In general these astronomical clocks were built to
One of the most impressive astronomical clocks everdisplay time, and show the position of the stars, but
built was designed and executed by horologist Suthey actually had a much more subtle and philosophical
Song, during China's Song dynasty. This is was apurpose. The intricacy of the various parts, all moving
water clock, attached to a clock tower, which washarmoniously, symbolized the order of the universe,
one of the earliest known timepieces to useand helped to represent the nature of politics, and
escarpment. This clock powered an armillary sphere,society, in a way which was favorable to the current
which moved various symbols around in accordancerulers. The primal position of the sun, with smaller less
with known astrological occurrences.important symbols such as stars and constellations all
Muslim astronomers and engineers during the middlerevolving around more important structures, reinforced
ages were able to develop a series of complex andthe idea of monarchy and power by birth.