How did the Jewish calendar come to be? Why are there sometimes two days of Rosh Chodesh and sometimes not? Who keeps Yom Tov for two days? Why are some parshiyos read together? What do Chazal have to say about the International Date Line? Which halachos apply when there is an eclipse? Does the “Magen Avraham’s z’man for k’rias Shema” really exist? Why do we wait for Rabbeinu Tam (and why is he always late)?

While all of us are familiar with and use the Jewish calendar, there is much about it that lies beneath the surface. Explorations in the Jewish Calendar is the culmination of twenty years of research in the mechanics of the Jewish calendar and the halachos of the daily z’manim. For the first time, these complicated topics are presented to inquisitive readers in clear, easy-to-understand English.

Rabbi Moshe Ze'ev Granek is the author of four books, including a multi-volume commentary on the Sefer Hamitzvos of the Rambam. In addition to researching the topic of the Jewish calendar for over twenty years, he is, at present, a member of the kollel of the Bais Havaad of Lakewood, NJ, which specializes in topics of Choshen Mishpat. He lives in Jackson, NJ.