With its roots in the astrolabes developed by the ancient Greek astronomers to determine the position of the sun and stars, this astrolabium clock does more than simply count off hours, minutes, months, and dates. Crowning this extraordinary precision instrument is a miniature globe of the earth that rotates and revolves around a solid brass sun. Attached to the earth's gear assembly is the moon, which maintains its synchronous rotation around the earth (always presenting the same face to land-based observers, depicted by the grey hemisphere). All orbiting bodies move in real time, perfectly synchronized with clock's skeleton quartz movement, 24 solid-brass gears, and differential, all which provide precise timekeeping. Designed by Richard Hermle of the famous German clock-making family, it is an exacting reproduction of the beautiful 18th-century "heaven machine" built by the famous clockmaker Philipp Matthaus Hahn (1739-1790). Known to antiquity as a "telurium," the astrolabium is mounted on a lacquered solid cherry base with a mouth-blown crystal dome. The miniature earth is made of a combination of four semi-precious stones, including abalone, green agate, jade, and mother of pearl, cut in detail to depict continents and oceans. Minor assembly. Includes one C battery that provides up to one year of operation. 11 1/4" H x 8 1/4" Diam. (8 lbs.)