Watch Terminology Dictionary

A clock equipped with astronomical information, it features mechanisms for displaying the relative positions of the sun, moon, zodiac signs, and planets. While there is no clear definition, an astronomical clock can be considered one equipped with a mechanism for automatically displaying the astrolabe used to measure the positions of the sun and planets. Those made before the 15th century are believed to have been powered by water or weights. The world's first precision astronomical clock is said to be the "Dondi Clock," designed by Italian Giovanni Dondi (1318-1389). While no actual examples remain, Dr. Ludwig Oechslin faithfully recreated it from blueprints in the 1990s. The most complex astronomical clock today is "Clock No. 4" (1967), manufactured by Norwegian Rasmus Jonathan Soames (1893-67). In addition to the sun, moon, and zodiac signs, it can also display sunspots. It was auctioned at Sotheby's in 2002 and purchased by an anonymous collector.