Creation of the Sun, Moon and Stars, Johann Sadeler, after Maerten de Vos, 1639. Rijkmuseum
What Is the Bible’s Calendar?
The Torah prescribes the observance of festivals on very specific dates, but does not explain how the calendar must be reckoned: Is it lunar? Is it solar? Does it follow some other scheme? And why is the Torah silent on this?
Published April 3, 2019
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Last Updated September 7, 2026
He may have been associated with the early Karaites, although the Karaites generally followed the lunar calendar. See the calendars section in, Daniel Lasker, “Biblical Exegesis as a Source of Jewish Pluralism: The Case of the Karaites,” TheTorah (2017).
See also, in Zech 7:1, Esth 2:16, and others.
Editor’s note: For more on the Passover Papyrus, see Michael Satlow, “Passover and the Festival of Matzot,” TheTorah (2014); Idan Dershowitz, “Darius II Delays the Festival of Matzot in 418 B.C.E.,” TheTorah (2017).
Editor’s note: For more on this calendar, see Michael Segal, “The Jewish Calendar in Jubilees: A 364-Day Solar Year,” TheTorah (2014).
Trans. James C. VanderKam, The Book of Jubilees: A Critical Text (Leuven: Peeters, 1989), 2:42–43.
Sacha Stern, “Qumran Calendars and Sectarianism,” in The Oxford Handbook of the Dead Sea Scrolls, ed. Timothy Lim and John J. Collins (Oxford: Oxford University Press, 2010), 232–253.
Moreover, even he notes, in his introduction, that it is impossible to say for certain to what this term refers:
מי יתן לנו אות שהם מועדי השם המוקדשים? כי יש מועדים רבים בתורה ובמקרא ובכתובים.
Who can demonstrate that [moadim in Gen 1:14] is referring to the holy festivals of God? For there are many moadim in the Torah, Scriptures, and Writings.
Jonathan Ben-Dov, “Psalm 104:19, Ben-Sirah and the history of calendars in ancient Israel,” Journal of Jewish Studies 62 (2011): 7–20.
This term is sometimes used for a calendar month, e.g. in 1 Kgs 8:2, although in most cases it just means an indeterminate thirty-day period, e.g. Deut. 21:13.
Sacha Stern, Calendar and Community: A History of the Jewish Calendar, Second Century BCE–Tenth Century CE (Oxford: Oxford University Press, 2001).
Edited by Filipowski (London 1851); a new edition is in preparation by an AHRC team at UCL.
The translation here is mine in collaboration with my colleague Dr. Israel Sandman, who is preparing a new edition and translation of Abraham bar Chayya’s work. Abraham bar Chayya explains the mechanics of this reading elsewhere in this section:
ועוד כתי’ זכור את היום הזה אשר יצאתם ממצרים מבית עבדים כי בחזק יד הוציא י”י אתכם מזה ולא יאכל חמץ. וראים אנו מן הכת’ הזה עבור השנה מפני שכת’ בו אחר זכור את היום הזה ולא יאכל חמץ כלומ’ מן היום הזה והלאה לא יאכל חמץ אבל קודם היום הזה אין אתם חייבים בו. ומטעם הכת’ הזה אנו חייבים שלא נעשה פסח אלא ביום שיצאו בו ישראל ממצרים או לאחר היום הזה ונצטרך אם יהיה ט’ו’ מניסן נופל קודם יום יציאת מצרים לעבר את השנה ההיא
It is furthermore written, “Remember this day that you went forth from Egypt, from the house of slaves; that the Lord brought you out of here (lit. this) with strength of hand. Anything leavened shall not be eaten” (Exodus 13:3). From this verse we see {the requirement of} the intercalation of the year, because in it is written, after “remember this day,” “anything leavened shall not be eaten.” {This is} as if to say from “this day” and onward “anything leavened shall not be eaten,” but before “this day” you are not culpable for {eating} it. On the basis of the meaning of [this] verse, we are obligated to make Passover only on the day [on which] the Israelites exited Egypt or after [this] day. If the 15th of Nīsān falls before [the day of] the exodus from Egypt, then we will be obliged to intercalate that year.
In short, bar Chayya argues, on the basis of Exodus 13:3, that Passover can never occur before the (solar) date of the first Passover that was, according to his calculation, the earliest possible Passover in the 19-year cycle.
Sacha Stern, “Counting Time with Peg Holes,” in Conversation Pieces: Inspirational Objects in UCL’s Historic Collections, ed. M. Carnall (Oxford: Shire Publications, 2013), 68–69. Nili Fox, “A Bone-Carved Calendar,” in Tel ‘Aroer: The Iron Age II Caravan Town and the Hellenistic-Early Roman Settlement; The Avraham Biran (1975-1982) and Rudolph Cohen (1975-1976) Excavations, Annual of the Nelson Glueck School of Biblical Archaeology 8, ed. Yifat Thareani (Jerusalem: Hebrew Union College, 2011), 255–58.
In ancient times, all lunar calendars used intercalation to adjust the lunar calendar to the seasons and stars. Purely lunar calendars (i.e., without intercalation) are not attested in antiquity before the institution of the Islamic calendar in the seventh century C.E.
Sacha Stern, Calendars in Antiquity (Oxford: Oxford University Press, 2012).
