Glossary · Complication
Moonphase
A dial-train indication tracking the lunar synodic cycle, usually via a rotating disc.
Explanation
A moonphase display shows the age of the moon through an aperture, usually a disc with two moons driven by a 59-tooth wheel advancing one tooth per day, giving a cycle of 29.5 days. The true lunation is about 29.53 days, so simple moonphases drift a day in under three years; astronomical moonphases with extra gearing stay accurate for over a century.
In the object catalogue
Catalogued objects whose own source record mentions “Moonphase”. The quoted line shows where; it is the seller’s or museum’s wording, not independent verification.
Clock
Early 20th Century Continental Orrery Clock
“This early 20th-century Continental horological orrery is mounted on a blue painted hexagonal base. The instrument features a fixed outer silvered calendar dial engraved with La…”
Clock
George III mahogany longcase clock by John Wyke
“This George III mahogany longcase clock is attributed by the auctioneer to John Wyke of Liverpool and dated to circa 1770–80. The source reports an eight-day, four-pillar brass …”
Clock
Reproduction brass and enamel skeleton clock
“This reproduction skeleton clock features brass openwork framework and enamel dial elements, accompanied by a moonphase movement. The upper section is topped by a spire finial a…”
Wristwatch
Oris Stainless Steel Moonphase Calendar Wristwatch
“Oris Stainless Steel Moonphase Calendar Wristwatch”
Clock
George III mahogany eight-day longcase clock with moonphase
“George III mahogany eight-day longcase clock with moonphase”
Clock
George III mahogany eight-day longcase clock with moonphase, James De Lasalle
“George III mahogany eight-day longcase clock with moonphase, James De Lasalle”