Babylonian Lunisolar Calendar
c. 2100 BCE · Ancient World
The Babylonian lunisolar calendar system emerged in ancient Mesopotamia around 2100 BCE. The calendar used a 12-month lunar year of approximately 354 days and incorporated intercalary months (iti dirig) to align with the solar year of about 365 days. Months began with the first crescent moon sighting and lasted 29 or 30 days. Authorities initially added intercalary months irregularly based on agricultural and social needs. This calendar system influenced the development of the Hebrew, traditional Arabic, and Persian calendars and contributed to ancient astronomical science.
Locations
Mesopotamia
Topics
astronomycalendartimelunisolar
Connected Events — 3 Connections
Established the foundational lunisolar calendar principles that spread eastward via trade routes, providing the conceptual framework that Shang astronomers adapted with their own intercalation methods Shang Dynasty Lunisolar Calendar
Provided foundational understanding of lunisolar calendar challenges that Meton mathematically refined with his 19-year cycle, building on Mesopotamian astronomical observations and intercalation techniques Metonic Cycle Discovery
Directly inherited and refined the Sumerian sexagesimal system and lunisolar calendar structure, preserving the base-60 mathematical framework that underlies modern timekeeping Sumerian Calendar and Time Division System
The Time Detectives® · Cadet Mission
Investigate This Event
Place it on the timeline. Earn points. Master the connections.
New to The Time Detectives?
Learn what it is →