Calendars and time
Callippic Cycle
Direct answer
Callippic Cycle: The Callippic Cycle is a 76-year refinement of four Metonic cycles, traditionally shortened by one day to improve lunar alignment.
The Callippic Cycle refines the Metonic pattern across 76 years.
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At a glance
- Found in
- Calendars & Timekeeping
- Related
- Metonic Cycle, Dominical Letter, Calendar, Julian Date
The Callippic Cycle refines the Metonic pattern across 76 years.
A cycle or timeline schematic for comparing the named timekeeping concept.
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The story behind Callippic Cycle
Callippus proposed the refinement in the fourth century BCE by combining four nineteen-year cycles and reducing their total length.
Why Callippic Cycle matters
Callippic Cycle illustrates how ancient astronomers corrected a useful cycle after recognizing its accumulated error.
Callippic Cycle in practice: an example
A Callippic scheme treats 940 lunar months as one day shorter than four unadjusted Metonic cycles.
Where readings of Callippic Cycle go wrong
It is a mistake to treat it as a calendar universally adopted across the ancient Mediterranean.
Sources and editorial method
Research references used for this entry include:
- U.S. Naval Observatory: Astronomical Almanac Glossary - Reference definitions for astronomical periods, coordinates, dates, and time scales.
- Source
- The Great Almanac Dictionary
- Category
- Calendars & Timekeeping
- Last updated
- 2026-09-26
See how ancient cycles were corrected
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More in Calendars & Timekeeping
- Draconic Month
- Geocentric Coordinate Time
- Intercalation
- Local Apparent Solar Time
- Ordinal Date
- Sidereal Year
- Unix Time
- Astronomical Day
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Common questions
What is the Callippic Cycle?
The Callippic Cycle is a 76-year refinement of four Metonic cycles, traditionally shortened by one day to improve lunar alignment.
What do people get wrong about the Callippic Cycle?
It is a mistake to treat it as a calendar universally adopted across the ancient Mediterranean.
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