The Hebrew Calendar
by Dr. Irv Bromberg, University of Toronto, Canada 
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Image at right shows the far side of Moon:
Click on image to see a 150-second near side time-lapse movie of
13 lunar cycles.
Click here to see a 24-second lunar full rotation movie with text explanation, as seen from the Lunar Reconnaissance Orbiter (LRO).
Menu (click on desired choice):
- The Kalendis Calendar and Zmanim Calculator
( Free ) Version 11.157(1678) released Oct 8, 2020 - Hebrew Prayer for Maintenance of Good Health with English and French translations
399KB
- Weekly Torah Portions and Special Sabbaths
- The Lengths of the Seasons
- The Duration of Twilight
- Rambam and the Seasons
- The Seasonal Drift of the Hebrew Calendar (correlation with solar cycle, long-term drift)
- Request for Rain (Sh'ela) and Blessing the Sun (Birchat haChamah)
- Why Divide Hours into 1080 Parts?
- Ancient Hebrew hourly mazalot (symbolic names) and weekday names 100KB
- Exact Hebrew Calendar Full Cycle Weekday Frequencies
- The Length of the Lunar Cycle
- Moon and the Molad of the Hebrew Calendar
- Correlation with lunar cycle, reference meridian, long-term drift
- Novel fixed arithmetic cycle of "yerm eras" exactly equivalent to the traditional molad cycle
- The Rosh Hashanah Postponements
- The Rectified Hebrew Calendar (353-year leap cycle, progressive molad)
- Fixed month lengths, obeys all weekday and day counting rules of the traditional Hebrew calendar.
- Applies the traditional Rosh HaShanah postponement rules to progressively shorter molad intervals.
- Links to the web site of the Sanhedrin, re-established in 5765:
- Hebrew: Home page, a description of how the court was re-established, and the Calendar Committee page
- English: Home page, a description of how the court was re-established, and the Calendar Committee page
- An Astronomical Hebrew Calendar
- The Hebrew Calendar "Y6K"
- Links to Geographic Name Servers (for User-Defined Locales in Kalendis)
- What's new at this web site?
Acknowledgement
I would like to thank my teacher and friend, Rabbi Moshe Ginz, who helped this project progress by encouraging and by spending many hours reviewing the classical sources with me. He subsequently moved back to Israel and completed advanced rabbinic studies to qualify as a dayan (rabbinic judge).