Qumran Sect Used 364-Day Calendar Before Abandoning It, Study Says

A Tel Aviv University study proposes that the Qumran sect actively used its 364-day calendar during its formative second-century BCE period, rather than treating it only as a theoretical ideal. The calendar's 52 exact weeks kept every festival on the same weekday, but its roughly one-and-a-quarter-day annual shortfall gradually pulled observances away from the seasons. Prof. Eshbal Ratzon argues that the drift made the system impractical. She says warmer relations with Hasmonean king Alexander Jannaeus then enabled the community to adopt the Temple calendar while retaining its original system as a religious ideal and symbol of identity.