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Just a quick look at the prophecy of the Seventy Weeks in Daniel 9:24–27 shows it involves a number of events placed in a framework of time. This requires that we understand some general background on how the early Jews kept their calendar. Having this understanding is the only way we can ground our analysis of the time factors in the real world. It will become apparent that an in-depth understanding of the passage involves discussing some complex calendar-connected matters, including how Jesus observed the Passover and its implications for the dating of the Crucifixion.

Overview of Ancient Hebrew Calendars

There were two different calendars in routine use by the ancient Hebrews. One, tied to the annual cycles of sowing and reaping, began in the seventh month in the fall, when barley was sown. This “civil” calendar was used to keep track of government and agricultural matters and provided a way to coordinate Jewish dating with that of other ancient cultures.

The other, commonly labeled the “ecclesiastical,” “religious” or “sacred” calendar, was assigned to the Israelites by God Himself and began in the spring. It began with what He simply called “the first month” in Exodus 12:2: “This month shall be the beginning of months for you; it is to be the first month of the year to you.” This was the month when the Israelites departed from Egypt in the springtime under Moses. The early Israelites also called their first month by the Canaanite term Abib, which referred to the young green-ear stage of barley ripening characteristic of spring. The rest of the months were likewise known by their number, although a few were also referred to at times by their Canaanite names, such as Zif (the second month, 1 Kgs 6:1), Ethanim (the seventh month, 1 Kgs 8:2), and Bul (the eighth month, 1 Kgs 6:38).

The Jews used lunisolar calendars, where the months were based on lunar cycles while the year and its agricultural seasons was based on the longer cycle of the sun. Because the solar year is about eleven days longer than 12 lunar months, it was necessary to periodically add an extra month to keep the lunar calendar in sync with the seasons. A thirteenth “leap month,” technically called an intercalary or embolismic month, was inserted at the end of the previous year as needed. Evidently when it was established, the first month of the year always began on or after the vernal equinox, and added an additional whole month as needed to keep the first month in the spring and the seventh in the fall. This will be discussed further below.

During the Babylonian Captivity, the Jews began to adopt Babylonian month-names. For example, the name of their first month, Nisanu, passed into routine Jewish use, where it was transliterated into Nisan and supplanted the earlier designation “first month.” The names being synonyms, here we will generally use the name Nisan, which the Jews used during the time of Christ and still use today.

Following is a list of the numbered Hebrew months and their modern equivalent names. The first number is the month according to the civil calendar beginning in the fall, the second according to the sacred calendar beginning in the spring. During leap years when a thirteenth month is needed, the original 29-day month of Adar goes to 30 days, and an extra 29-day Adar II (also called ve-Adar) is appended after it.

5/11 Sevat (Jan/Feb)
6/12 Adar (Feb/Mar)
7/1 Nisan (Mar/Apr)
8/2 Iyyar (Apr/May)
9/3 Sivan (May/Jun)
10/4 Tammuz (Jun/Jul)
11/5 Av Jul/Aug)
12/6 Elul (Aug/Sep)
1/7 Tishri (Sep/Oct)
2/8 Heshvan (Oct/Nov)
3/9 Kislev (Nov/Dec)
4/10 Tevet (Dec/Jan)

The Calendar-Keepers in the Heavens

The differences between the calendar-keeping methods of the ancient Jews and those used today go all the way back to the book of Genesis. In Genesis 1:14–15, God set forth the purpose of the heavenly bodies He created:

Then God said, “Let there be lights in the expanse of the heavens to separate the day from the night, and let them be for signs and for seasons [Heb. moedim, “appointed times” for holy convocations] and for days and years; and let them be for lights in the expanse of the heavens to give light on the earth”; and it was so.

Notice the repeated emphasis on the sun and moon as lights. God ordained not only that these heavenly bodies would provide light on the earth, but they would also provide a way to mark the passing of time. Thus, a calendar could be accurately kept using only the light of the sun and moon.

Defining the Biblical Day

The definition of a day is fundamental to any calendar. In our time a day lasts from one midnight to the next, but from the beginning it was not so. The nature of the biblical day used by the Jews can be elucidated from Exodus 12, Leviticus 23, Numbers 28 and Deuteronomy 16. These passages allow us to properly understand the sometimes ambiguous information about the Passover given later in the Gospels, ambiguous because over the centuries the Jewish leadership tinkered with their God-given calendar to make it easier to arrange Temple-centered activities without scheduling issues. Before we can use this information knowledgably, though, we must familiarize ourselves some basics about Jewish timekeeping.

“At Evening”: The Jewish Day began at Sunset

Most people are familiar with the repeated phrase in Genesis 1, “and there was evening, and there was morning,” before it states what day of Creation Week it was. As used there, “evening” was the hours of darkness, “morning” the hours of light, and the evening is listed first. This Genesis 1 pattern tells us that from the beginning of Creation, days were measured from a starting point in the evening. A day lasted from one “evening” to the next, with the term defined by the presence or absence of the sun’s light.

Not only was a biblical day measured from evening to evening, the Jewish “evening” very specifically began at sunset. This is supported by a number of passages. First consider Leviticus 23:27, 32:

On exactly the tenth day of this seventh month is the day of atonement… It is to be a sabbath of complete rest to you, and you shall humble your souls; on the ninth of the month at evening [Heb. ba erev], from evening until evening you shall keep your sabbath.

These verses reinforce that a biblical day lasted from one evening to the next, and add further detail. The Day of Atonement is defined here as extending from the evening of the ninth to the evening of the tenth, with severe consequences to any who violated its ban against any work within its time span (Lev 23:30, “As for any person who does any work on this same day, that person I will destroy from among his people”). Since this is a day lasting for twenty-four hours, it must have had precise start and end times. But “evening” is not a precise term as we use it today. What exactly is meant by “evening” in Scripture? The key Hebrew expression which clarifies the biblical meaning of “evening” is ba erev1, בָּעָרֶב. Usually translated “at evening,” it is used in a number of places, including Leviticus 23:32. A precise idiomatic rendering of the phrase is “at sunset”—the moment when the solar disk sinks completely below the horizon. Leviticus 22:6–7 states that it is when the sun is “down” or has “gone in” (Heb.’, בּוֹא). This is also seen in Deuteronomy 16:5–6:

You are not allowed to sacrifice the Passover in any of your towns which the LORD your God is giving you; but at the place where the LORD your God chooses to establish His name, you shall sacrifice the Passover in the evening at sunset [ba erev], at the time that you came out of Egypt.

The KJV similarly renders verse 6 with, “Thou shalt sacrifice the passover at even, at the going down of the sun.” The Everett Fox translation in The Schocken Bible is as literal as one can find: “... you are to slaughter the Passover-offering, at setting-time, when the sun comes in, at the appointed time of your going-out from Egypt.”

The expression ba erev means “sunset” wherever it is found. The Leviticus 23 account of the Day of Atonement confirms this, for that day was very precisely defined as “from sunset to sunset,” as The Schocken Bible renders it. As far as Scripture is concerned, then, a Jewish day as ordained by God was to be measured from when the sun passed completely below the horizon at sunset, to sunset of the next day. It was not measured from midnight to midnight, or from dawn to dawn.

“Between the Evenings”: From Sunset to Full Darkness

Exodus 12:6 builds upon this understanding of ba erev and takes it a bit further. It speaks of keeping a Paschal lamb in a household for several days before the Passover: “You shall keep it until (Heb. ‘ad, עַד) the fourteenth day of the same month, then the whole assembly of the congregation of Israel is to kill it at twilight” (Heb. beyn ha-arbayim, בֵּין הָעַרְבָּֽיִם). This expression is a Hebrew idiom that literally says “between the evenings.” The time it covered began at sunset (ba erev), at the moment the sun passed below the horizon, the moment the Jews understood the next day began, but then encompassed a little bit more time. Grammatically, ha-arbayim is what is known as a dual noun, one featuring a plural ending (-im) because, though used in a singular sense, it has two aspects, a beginning and an ending. Together they delineate a range of time.

The perceived ambiguity of “between the evenings” results in the Jews being inconsistent in how they interpret it, in how they decide how narrow a range of time it covers. It is found in eleven OT passages,2  and its seemingly imprecise nature has resulted in controversy that pits different groups of Jews against each other, whose opinions in turn influence Christian understandings.

The Karaites are a Jewish minority “characterized by the recognition of the written Torah [the first five books of the Bible] alone as its supreme authority in halakha (Jewish religious law) and theology.”3  They refer back to the early Exodus instances of the phrase beyn ha-arbayim to hold that it refers to the interval between sunset and full darkness—in other words, the period of twilight or dusk, as most English translations of the Bible render the idiom.4  They reject the oral traditions recorded in the Midrash and Talmud as binding, whereas most rabbinic Jews regard such oral interpretations as authoritative.

The Interpreter’s Bible under Exodus 12:6 contrasts the approach of rabbinic Judaism with that of other sects:

In Jewish orthodoxy the time of the slaughter, between the two evenings, is specified as in the afternoon, before sunset;  especially, the time approaching sunset.5 The Mishnah implies that any time after noon was valid for the slaying (Pesahim 5:3).6  Samaritans, Karaites, and Sadducees specify the time as after sunset and before darkness. The latter probably designates the more archaic practice.

Curiously conflicting with present rabbinic practice, in The Jewish Encyclopedia the Jewish Publication Society of America translates beyn ha-arbayim in every place where it is used as “dusk.” And in their Tanakh (the Jewish term for the Old Testament), they translate Exodus 12:6 and 16:12 as “at twilight.” By no stretch of the imagination can these translations be understood as beginning either just after 12 noon or in the afternoon. So we see that mainstream Jewish traditions and their modern Scripture translations are at odds with each other.

In their massive, highly regarded though older commentary on the Old Testament, Keil and Delitzsch similarly wrote:

Different opinions have prevailed among the Jews from a very early date as to the precise time intended [by beyn ha-arbayim]. Aben Ezra agrees with the Karaites and Samaritans in taking the first evening to be the time when the sun sinks below the horizon, and the second the time of total darkness; in which case, “between the two evenings” would be from 6 o’clock to 7:20... According to the rabbinical idea, the time when the sun began to descend, viz., from 3 to 5 o’clock, was the first evening, and sunset the second; so that “between the two evenings” was from 3 to 6 o’clock. Modern expositors have very properly decided in favor of the view held by Aben Ezra and the custom adopted by the Karaites and Samaritans...7

These observations indicate that we can set aside the rabbinic Jewish teachings based on oral tradition and accept that “between the evenings” refers to the twilight or dusk interval between sunset and full darkness. This period accommodated matters that took a bit of time to complete, in particular the slaying of the Passover lamb.

Defining the Biblical Month

Since the length of the week is self-evident—a count of seven days beginning with the first day of Creation, ending with the Sabbath day of complete rest from all labor—we can move immediately to the next main category of calendrical significance, the biblical month. This is when the moon plays the crucial role.

The First Day of Each Month

The dates set aside for the important Jewish festivals, God’s “appointed times” detailed in Leviticus 23, were based on using the moon to set the first day of each month. Psalm 104:19 affirms this role of the moon: “He appointed the moon for seasons” (moedim, the same word used in Genesis 1:14). The English translation of moedim as “seasons” tends to confuse matters, because it makes us think of the four seasons of spring, summer, autumn and winter. That, however, was not how the Hebrews understood the term. For them it referred to when the mandated festival seasons were to be observed.

One thing that stands out about these “appointments” is that their observance depended on accurately counting days. For example, Leviticus 23:5 says Passover was to be observed on the fourteenth day from the start of the first month, while the Day of Atonement would be on the tenth day from the start of the seventh month.

The first days of months were set by noting when the first visible crescent moon appeared after the previous waning moon vanished from the sky. According to the Mishnah Rosh Hashanah8 —a compilation of oral tradition of the Jews dating to about AD 200—two or three believable eyewitnesses were required for the priests to declare a new month had begun:

In reality, in ancient times the beginning of months in the Holy Land was determined (weather permitting) by the actual observation of the first visible lunar crescent. With two or three reliable witnesses, the day of the new moon was “sanctified” by the Jewish leaders so that the appropriate animal sacrifices and other offerings could be made at the temple. The message of the sanctification of the day was sent far and wide by signal fires and runners to keep all of the Jews in sync with Jerusalem—so that all could worship on the days that were sanctified and proclaimed based on the sighting of the new moons in Israel—so that all would gather for worship on the actual days on which the special holy day offerings at the temple were offered.9

This information gives us a reliable historical anchor for saying that up to the destruction of the Temple in AD 70, the Jewish calendar’s reckoning of months depended primarily on eyewitness reports of seeing the first visible crescent moon.

The Length of Each Month

Using the principle that it was by observation of the heavenly bodies that the biblical calendar could be determined, it would not have taken long for people to notice that there was not a perfectly fixed amount of time from one first observed lunar crescent to the next. The month consisted of a single lunar cycle, or lunation. Some months completed in 29 days, the rest in 30. Consistent with this, modern measurements have determined the length of the average lunar cycle is about 29.53 days.

Since observation of the moon’s light was key, the so-called conjunction, when the moon cannot be seen for two to three days, was ignored by the Jews. Use of the conjunction—the modern definition of a new moon—in geometry-based calendar calculations is first seen in the work of the Greek astronomer Meton in the fifth century BC. Although this knowledge apparently became known by the Jewish leaders later and allowed them to get a fairly accurate estimate when the next month would begin, prediction did not consistently replace sighting reports until about the fourth century AD, when the foundations of the modern Jewish calculated calendar were laid.10

In short, the biblical month had 29 or 30 days, no more, no less. If the first visible lunar crescent was seen low in the western sky after sunset on the 30th day after the previous month’s first crescent moon, the previous month was determined to have been 29 days long. Otherwise, on the following evening the new month was deemed to have begun whether or not the moon was seen, so the previous month was 30 days long by default.

Defining the Biblical Year

At different times in their history the Jews have used a variety of criteria for setting the start and end points of their year. This makes defining the biblical year an immensely complex undertaking.

Jewish leaders throughout history have displayed a propensity for “improving” on the minimal requirements God revealed in the Old Testament. By the time of Christ, they had diverged in important ways from original Old Testament teachings in a number of areas, developing oral traditions which guided how they interpreted Scripture. Jesus bluntly condemned this in Matthew 15 and Mark 7, when He criticized the scribes and Pharisees of His day as more concerned with keeping the “traditions of men” than following the words of God. This tendency extended to how they managed their calendar, for they began to value optimized Temple worship over the simple principles given in the Torah.

The Testimony of Scripture

Although the moon determined the months, it did not precisely define which month came first in the Hebrew calendar. There are two main Scriptures which shed some light on this:

Exodus 12:1–3: Now the LORD said to Moses and Aaron in the land of Egypt, “This month shall be the beginning of months for you; it is to be the first month of the year to you.”

Deuteronomy 16:1: “Observe the month of Abib and celebrate the Passover to the LORD your God, for in the month of Abib the LORD your God brought you out of Egypt by night.”

Recall that a month in ancient Israel was determined by lunar cycles. These cycles, also called lunations, originally had no names attached to them, just numbers. In Exodus 12:3 God simply called the first month “the first month.” He did not call it “Abib” as a month-name, nor did the Egyptians have such a month-name in their calendar. The term abib, as used in Scripture, refers to a descriptive characteristic of the lunation that marked the start of the year. That characteristic was the greenness of new vegetation generally, not of barley specifically; barley only comes into the picture in terms of the food crop spring was known for. The Jewish website recognizes this when it says that the Hebrew word abib translates as “spring".11  A footnote adds that abib comes from the Hebrew word eebeha (Heb. איבה), literally translated as “greenness.” It means “the month in which the grain fills out in its ‘greenness.’” Consistent with this, the Brown-Driver-Briggs lexicon gives one meaning of abib as “the month of ear-forming, or of growing green” (emphasis added). To go beyond this is to attach a narrower interpretation to the words than the text demands.

Defining “Spring”

By referring to abib “greenness,” God thus defined spring in very practical terms. In particular, it must be said that He did not define abib in terms of the vernal equinox. This is an erroneous association adopted by many commentators, especially Messianic Jewish believers steeped in rabbinical traditions. Apparently sometime in the first century AD, the leaders of the Sanhedrin found the Greek calculated methods of astronomy popularized by Meton to be useful in evaluating the truthfulness of eyewitness reports of the first lunar crescent of a month. This fixation on astronomical mathematics also led to the vernal equinox being used to determine the intercalations that defined when Passover was celebrated. This “tradition of men” was in time enshrined in the Mishnah, and still holds considerable sway over the thinking of many.

The resultant ambiguity in the definition of “spring” contributes to the confusion in defining the biblical year. Some Messianic Jewish interpreters insist that only a first crescent “on or after the vernal equinox” could start a new year, suggesting the equinox was observationally determined via the shadow cast by a post.12  Others, notably the Karaites, say that it is the state of the barley crop in Israel that is key, narrowly defining the required “greening” as only applying to barley.13 But from the Scriptures just given it appears that, if the first crescent of a new lunation happened when spring-like conditions already existed, then in principle not just Passover, but the entire first month could begin a few days before the vernal equinox. There was no apparent scriptural prohibition to starting the month of Nisan before the equinox; those who have problems doing this are using their own definition of “the month of abib” to forbid it.

It is interesting that in our day, the Karaites keep a close watch on the status of barley in Israel. In 2021 one website14  reported that greening barley was observed before the lunation that began on March 14 that year, making that date Nisan 1. The vernal equinox did not arrive until six days later on March 20. This illustrates that starting a Jewish year prior to the vernal equinox is quite possible, and it is wrong to legalistically decree that Nisan 1 could never fall before the vernal equinox.

Thus, the lunation that started the year was set within the season of spring, of greening up as the winter faded away. First springtime came, ushered in by the “latter rains” that made the hills bloom abundantly with wildflowers in March.15  After this came the first visible crescent moon of the springtime, which marked the start of the Jewish year. The oft-made association of “abib” with immature, still-green barley is a derived one, not the primary meaning of the word. It is not about barley per se, but about the season of spring in which the crop’s heads green up and fill out.

That this practical definition of spring is the right way to view it is also indicated by considering that agriculture is closely tied to growing zones. In the northern hemisphere, as one moves south things start growing generally earlier in the year. This is true entirely apart from the vernal equinox date. Though associated with the manifesting of spring, the equinox doesn’t cause it. The greening up that characterizes spring is due to several factors; increasing day-length alone doesn’t do it, as rainfall and proximity to the ocean are also involved. The equinox is a measure of how high the sun is in the sky at the midpoint in its celestial journey between the solstices, and is just one of several factors which triggers the renewed growth of vegetation in springtime. It is only an arbitrary, modern scientific definition of convenience that equates the vernal equinox with “spring,” and it is highly debatable that the ancients, prior to developing knowledge of astronomical mathematics, would have used the equinoxes to define spring and fall. Their calendars were keyed to the rhythms of growing things and how to keep their lunar cycles in sync with them.

Connecting these clues with the function of the sun and moon as the signposts for calendar transitions, we can say that the first month of each year was meant by God to begin with the first lunation of spring.16

Observe the Spring New Moon, then Count to Passover

Deuteronomy 16:1 ties in with this way of looking at the relationship between spring and the first month/lunation of the Jewish year. It says the Hebrews were to “observe” (Heb. šāmar, שָׁמַר) the “month” (Heb. chodesh, חֹדֶשׁ, the lunation) of abib (spring). Although chodesh is often equivalent to our word “month,” it also can refer specifically to the crescent new moon that starts a month. The verse can thus be read, “take note of the new moon at the time of spring greening.” The lunar crescent that marked the start of the Jewish year had to be that which fell in the spring.

The most obvious meaning of this phrase is that the Jews were to note the first crescent moon after greening vegetation indicated spring had arrived. Then they were to count days from this crescent moon—not from the date of the vernal equinox—to determine when to celebrate the Passover. Chodesh indicates this signal was tied primarily to the crescent moon, not the sun-dependent vernal equinox or the status of the barley crop.

Besides, during the forty years of wilderness wanderings the growth of a barley crop could never have served as an anchor for counting days; during the exodus the Hebrews were nowhere near cultivated fields of barley, but dependent on manna (Ex 16:35) for food. Yet they were still obliged to celebrate the Passover at the right time. The readily observable thing to watch for was the first crescent moon after vegetation in general had begun greening up.

The Testimony of History: The Babylonian Calendar

Like the Hebrews, the Babylonians used a lunisolar calendar of 12 months, and like the Jewish calendar it had to deal with the challenge of synchronizing the lunar year with the longer solar year. It likewise used the earliest sighting of a visible lunar crescent to set the first days of its months, and its year began in the spring, in the month they called Nisanu.

It is sometimes argued that these similarities indicate that during the exile the Jews, like a number of other ancient peoples, adopted the Babylonian calendar. The roots of the Jewish calendar, however, were inextricably tied to the Torah and thus deeply ingrained in their national identity, which they steadfastly maintained throughout the exile. This makes it extremely unlikely they would have permitted Babylonian customs to change their ways of determining days, months and years. This consideration, together with the lack of any clear historical evidence of Babylonian influence on the Jewish calendar, implies that the Jews simply maintained their ancient calendar customs unchanged while living in a foreign land. After all, is that not what they still do today?

Philo of Alexandria, in the first century AD, made a pertinent remark which has general applicability to the Jewish culture and its calendars at all times, including during the Babylonian exile:

But not all (peoples) treat the months and years alike, but some in one way and some in another. Some reckon by the sun, others by the moon. And because of this the initiators of the divine festivals have expressed divergent views about the beginnings of the year, setting divergent beginnings to the revolutions of the seasons suitable to the beginnings of the cycles. Wherefore (Scripture) has added, ‘This month (shall be) to you the beginning’, making clear a determined and distinct number of seasons, lest they follow the Egyptians, with whom they are mixed, and be seduced by the customs of the land in which they dwell (Quaestiones ad Exodum 1. 1, Marcus 1953: 4–5) (emphasis and bracketed comment added).17

After many years of calendar experimentation, in 503 BC the Babylonians implemented a 19-year cycle of intercalations, where a thirteenth “leap month” was added to certain years. They settled on a fixed pattern in which years 3, 6, 8, 11, 14 and 19 of each cycle appended an extra Addaru II to the end of a year, while in year 17 an extra Ululu II was added at midyear.18

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As the tables in Parker and Dubberstein show,19  this regular 19-year cycle of intercalations resulted, from 499 BC on, in forcing the whole month of Nisanu following the intercalation to start on or after the vernal equinox. This was doubtless connected with the Babylonians’ knowledge of astronomy, something the ancient Hebrews did not have. It must be emphasized that there is no evidence the Jews adopted this intercalation pattern until after the fourth century AD; for example, they never intercalated their eighth month, later called Elul, to match the Ululu II intercalation in the Babylonians’ 17th cycle. The longstanding Hebrew approach to the calendar, which like the Babylonians started the year in the spring with its first visible crescent moon, nevertheless resulted in the start of its first month closely matching the Babylonian determination of Nisanu 1.

This similarity opened the door during the exile, under the Persian Achaemenid rulers, for Jewish adoption of Babylonian month-names. This can be seen in the books of Zechariah (1:7, 7:1) and Esther (2:16, 3:7, 3:13, 8:9, 8:12, 9:1), where months are given with both the original numbered-month designation and the adopted Babylonian name. The use of Babylonian month-names is also seen in Ezra (6:15) and Nehemiah (1:1, 2:1, 6:15).

From these shared month-names we see that at that time in history, the Babylonian and Hebrew calendars must have been quite similar, but this does not allow us to conclude they were identical. The Babylonians arrived at their 19-year cycle of intercalations by relying on astronomy and experimentation, while the ancient Jews independently kept a similar calendar based on following God’s instructions in the Torah.

The Seleucid Era

After the fall of Babylon to the Persians, its calendar was taken up unchanged by its successors, save that under the Seleucids the whole intercalation pattern was shifted a year forward so the nineteenth year of its cycle aligned with the first year of the Seleucid era (311 BC). Because the books of 1 and 2 Maccabees use Seleucid Era dating, it appears that at this time the Jews were politically constrained to use that calendar, including its regular 19-year cycle of intercalations that started Nisan after the vernal equinox.

Later, in the second century BC, the Jews threw off their Seleucid overlords when the Maccabees rebelled against them during the reign of Antiochus Epiphanes, the abominable desolator of their Temple. This marked the start of the Hasmonean era, which brought with it changes in the Jewish calendar. According to Sacha Stern, an expert on ancient calendars:

Whether the Judaean calendar of the Hasmonaean period corresponded exactly to the Babylonian reckoning cannot be known. Hasmonaean rulers are more likely to have set their own calendar independently than to have relied on moon sightings and declarations of new moons that were being made in Babylonia, a region that was now part of a foreign kingdom… It is also questionable whether the Hasmonaeans made the same intercalations as in the Babylonian calendar, thus always celebrating Passover in the Babylonian Nisan [meaning, the Jewish Nisan at times began on a different day, so it could fall in a different month depending on how intercalation was done]. Datings from the Hasmonaean and early Roman periods… suggest that Jewish and Babylonian months regularly coincided. However, this evidence is too sporadic to prove that the Babylonian calendar was consistently followed and used. In this period, Babylonian [and Seleucid] intercalations were based on a fixed cycle of 19 years; this cycle is not attested in any Jewish source prior to the institution of the fixed rabbinic calendar (fourth century CE), which may suggest that until then this cycle had never been in use [by the Jews] (emphasis in original, bracketed comments added).20

These observations indicate that the end of Seleucid influence led to calendar change in Judea, connected with the renewed spirit of Jewish national identity at that time. Judea became ruled by high priests who apparently turned aside from Seleucid customs, including the calendar they had imposed on them, and returned to the way the Jewish calendar had traditionally been reckoned. That calendar, based on following Deuteronomy 16:1, apparently held sway from the start of the Hasmonean era through the end of the reign of Herod the Great. As the Jewish calendar in the Achaemenid era was in such agreement with that of the Babylonians that they could adopt the latter’s month-names, we may extrapolate from that to conclude there was a similar large degree of agreement between the calendars of the Hasmonean Jews and the Seleucids. As Stern put it, they “regularly coincided” without being identical; they followed different principles to arrive at similar end results.

The Herodian Period

During the Hasmonean period Rome began exerting its military might in the Near East. This led to Herod the Great coming to power over Judea in 37 BC, when with Roman aid he overthrew and put to death the last high priest/king of the Hasmonean line, Antigonus. Herod was an all-powerful despot who exercised absolute control over the high priest and the Sanhedrin, deposing or putting to death those who fell out of his favor.21  This political reality indicates that up to the time of Herod’s death in 4 BC, the priests were content with a defensive stance, preserving and conserving the heritage of past generations. This included a return to the calendar’s Deuteronomy 16:1 roots. Stern alludes to this, while also reflecting influence by the Mishnah:

It is also possible that intercalations in Judaea deviated sometimes from the Babylonian calendar because they were now governed, in accordance with biblical law, by the requirement that Passover in the first month be celebrated in the agricultural season of ’aviv, the ripeness of the crops—a requirement which might have conflicted sometimes with the Babylonian [and Seleucid] practice of beginning the year [not just Passover] after the vernal equinox (bracketed comments added).22

Significance of the Tekufah

Hence it appears that, from the Hasmonean period to the late first century BC, and probably extending somewhat into the first century AD until the political situation got settled after Herod, the Jewish calendar returned to following a straightforward understanding of Deuteronomy 16:1. As discussed earlier, this defined the first month as the first lunation after the greening up of vegetation—the distinctive characteristic of spring—commenced. Unlike with the Babylonian and Seleucid calendars, it was therefore permissible at that time for the Jewish month of Nisan to begin prior to the vernal equinox, so long as things were spring-like.

But it appears that, beginning in the first century AD, the Metonic 19-year cycle of intercalations began to exert a fresh, if subtle, influence on the Jewish leaders. In seeking greater control over the calendar which regulated Temple worship, the Sanhedrin began to use the vernal equinox as the main criterion for determining the arrival of spring. Along with this they began emphasizing the relationship of Passover, rather than the start of Nisan, to the equinox. This was also associated with an apparent tendency to depreciate the importance of eyewitness reports of the first lunar crescent, giving greater credence to the calendar priorities of the Sanhedrin.

This leads us to consider the difference in how the Hebrew term tekufah, “circuit,” was understood by the Jews before and after the first century AD. The reasoning given by a Karaite website appears sound:

The claim has been made by proponents of the equinox calendar theory that the word equinox actually appears in the Tanach. They are referring to the word Tekufah or Tequfah which appears in the Hebrew Bible four times. Tekufah is in fact the post-Biblical word for “equinox”, however, it never has the meaning of “equinox” in the Tanach. In Biblical Hebrew, Tekufah retains its literal meaning of “circuit”, that is something which returns to the same point in time or space [from the root Nun.Quf.Pe. meaning “to go around”]. To claim that Tekufah means equinox in the Tanach, just because it had this meaning in later Hebrew, is an anachronism (bracketed comments in original).23

That article presents the four instances of the biblical use of tekufah—Exodus 34:22, Psalms 19:7, 2 Chronicles 24:23, and 1 Samuel 1:20. It is clear in all of them that tekufah in Scripture has nothing to do with the equinoxes. Exodus 34:22 literally refers to the Feast of Ingathering (Tabernacles or Sukkot) at “the turning of the year” (Everett Fox translation).24  This reflects the literal lexical meaning of the term tekufah. By comparing this verse with the parallel passage in Exodus 23:16, which speaks of Sukkot as at “the end of the year,” it is readily seen that, biblically speaking, tekufah refers not to equinoxes but to the turning point of the agricultural year when one harvest is gathered in (Dt 16:13) and the next cycle of sowing and reaping commences. As the article concludes:

None of the four appearances of Tekufah in the Hebrew Scripture have anything to do with the equinox. Instead, this term is used in Biblical Hebrew in its primary sense of a “circuit”, that is a return to the same point in space or time. Only in Post-Biblical Hebrew did Tekufah come to mean “equinox” and to read this meaning into the Tanach creates an anachronism.

Stern likewise expresses skepticism that tekufah had anything to do with the equinoxes at this time: “In Exod. 34:22, the festival of Tabernacles is associated with the phrase תְּקוּפַת הַשָּׁנָֽה [circuit of the year]. Rabbinic sources interpret this phrase as meaning the (autumnal) equinox, but this is unlikely to have been its original meaning” (emphasis and bracketed comment added).25

The First Century AD

In the first century AD the power of the priesthood to regulate the calendar came into its own. With a magnificent new Temple, no dominating Herod, and Roman overlords who were content to take a largely hands-off approach as long as taxes were paid and the local authorities kept the peace, the priesthood was encouraged to break from their longstanding Scripture-based traditions in the interest of increasing the influence of the Temple over Judean society. This included tweaking intercalations to favor Passovers consistently late in the year, using strategies recorded in the Mishnah to facilitate attendance at Passover. J.B. Segal cited several rabbinic sources to show that, in the oral traditions codified by AD 200, the Sanhedrin could adjust some aspects of their calendar so it would better serve their aims:

A year may be made embolismic [intercalated] on three grounds—on account of the (state of the) green ears of corn or (that of) fruit (growing on the) trees or the (lateness of the) tekupha [the spring equinox]. Any two of these reasons may justify an embolismic year, but one of them (alone) does not justify an embolismic year. Everyone is glad when the (state of the) green ears of corn is one of them. Rabban Simeon ben Gamaliel says, On account of the (lateness of the) tekufah.” (BT Sanhedrin 11b; Tosefta Sanhedrin ii. 2; JT Sanhedrin 1. 2 (fol. 18d) (bracketed comments added).26

There are indications that the rabbinic intercalation rules cited by Segal were connected with a presumed “rule of the equinox” by which the Jews intercalated their calendar whenever the vernal equinox would have otherwise landed on Nisan 16:

Rav Huna bar Avin sent this instruction to Rava: When you see that, according to your calculations, the season of Tevet, i.e., winter, will extend to the sixteenth of Nisan, and the spring equinox will occur after the sixteenth of Nisan, add an extra month to that year, making it a leap year. And do not worry about finding an additional reason to justify making it a leap year, as it is written: “Observe the month of spring” (Deuteronomy 16:1). That is to say, see to it that the spring of the season, i.e., the spring equinox, is in the new part of Nisan, i.e., the first half, before Passover.27

The “that is to say” remarks of Rav Huna illuminate how the rabbis of his time (third century AD) interpreted Scripture. Their redefinition of the meaning of Deuteronomy 16:1 is obvious. Having somehow adopted an unbiblical understanding that tekufah referred to the spring equinox—one suspects this was related to the spread of Greek astronomical geometry knowledge—they interpreted Deuteronomy 16:1 though that lens. Rather than viewing the verse as an admonishment to keep alert for when the first visible crescent of apparent spring arrived, they saw in it permission to celebrate Passover—at the full moon—even if it started on the very day of the vernal equinox. It is no wonder the Sanhedrin had to implement various postponement rules to compensate for Nisan theoretically starting before there was even a hint of greening manifested!

If one followed this Mishnaic precept that the calendar should be intercalated without hesitation if the vernal equinox would be as late as Nisan 16, this meant that Nisan could theoretically start up to 15 days before the astronomical start of spring. With a Julian vernal equinox date of March 23, if that was Nisan 15, the month of Nisan would have started on March 9! No wonder the Sanhedrin developed supplemental postponement rules; this was unrealistically early in the year. Witness the Babylonian calendar, which from 500 BC on never started Nisanu before March 23. Stern has pointed out:

It is possible that intercalation in the Jewish calendar was based entirely, in this period, on the Babylonian system of intercalations… However, it seems strange that as late as the first century CE, Roman Judaea and (even further) Berenike were still under the sphere of Babylonian calendrical influence. E. Schwartz has suggested that in the period of the Temple, Passover was celebrated late so as to enable pilgrims to reach Jerusalem on time for the festival. This suggestion not only is plausible in its own right, but also finds support in a rabbinic tradition that the year would be especially intercalated to allow the pilgrims already on their way to reach Jerusalem for the festival.28

For these reasons, from the Hasmonean era until the first century AD the biblical “month of abib” should be understood as the lunation starting with the first crescent moon after vegetation began greening up and spring-like conditions existed. The vernal equinox date was irrelevant during this era of Jewish history. The start of the month was determined by eyewitness reports in Jerusalem that were vetted by the Sanhedrin, not first crescent sightings made at Babylon, so the Babylonian calendar was likewise irrelevant, except insofar as it bore similarities to the Jewish calendar. The observed first crescent moon of spring seen at Jerusalem, where the moon was higher in the sky at sunset and might have been seen a day earlier than at Babylon, could have resulted in the Jewish month of Nisan starting a day sooner than the Babylonian month of Nisanu; and by the magic of intercalation, if the crescent sighting at Jerusalem was on the 29th day of Adar, the Jewish year could have started a full month earlier than at Babylon. We will see later that how the date of Nisan 1 is determined plays a significant role in the conclusions we reach regarding when Christ was born and crucified.

This situation began to change in the first century AD, when the Sanhedrin changed the definition of spring to refer to the vernal equinox. This resulted in the Jewish year consistently beginning later in the spring. Apparently what eyewitnesses reported about the first observed crescent moon was no longer regarded as determinative, but was taken under advisement, as indicated by the postponement rules found in the Mishnah. The decision whether to intercalate the calendar and push the observance of Passover a month later ultimately depended on the priorities of the Sanhedrin, not Scripture.


The various aspects of the Hebrew calendar were initially defined authoritatively by God in Scripture. Under the influence of Jewish leaders some things were modified over time, including the criteria for intercalating the calendar. This is why it is important to examine calendar-related matters in the context of the period under discussion, lest we make the error of applying customs followed at a later period to an earlier one when they did not apply.

After the fourth century AD, political opposition meant the Jewish ruling council was no longer able to effectively communicate first lunar crescent or intercalation decisions in a timely fashion to the Diaspora communities in Babylon and elsewhere. This led to the creation of the modern calculated Hebrew calendar. This calendar, built upon astronomical geometry principles initially seen in the Greek calendar of Meton in the fifth century BC and supplemented by rules developed by the Sanhedrin to avoid various scheduling inconveniences with Temple activities, provided a way for widely separated Jewish communities to follow the same calendar wherever they were. The use of eyewitness observation of lunar crescents to determine months gave way to using the invisible lunar conjunction and pure calculation. The result is that the Jewish calendar of our day often does not agree with that of biblical times.

For this reason, the modern calculated Hebrew calendar cannot be used to give conclusive answers to some dating questions. In important ways the ancient Babylonian calendar, from the Achaemenid era forward, more closely approximates what the Jews followed up to the fall of the Temple in AD 70. Lacking firm evidence the Jews of that period ever followed the 19-year intercalation pattern that undergirds the post-Achaemenid Era Babylonian calendar, the Metonic Cycle of the Greeks, and the modern calculated Hebrew calendar, we cannot simplistically equate any of these with the Jewish calendar before, and to some extent during, the first century AD.

We may summarize by saying that, although we do not know all of the details about how the ancient Jewish calendar was organized throughout its history, we have enough data culled from historical records to reach reliable conclusions most of the time. We have a high degree of reliability in Jewish chronology on a macro scale, because the dates of important historical events can be synchronized in multiple ancient calendars of the Jews, Babylonians, Greeks and Romans. In particular, we have the requisite accuracy to arrive at reliable conclusions related to the prophecy of the Seventy Weeks in Daniel 9:24–27.


1. See Coulter, Chapter 4 in The Christian Passover (online at

2. Ex 12:6; 16:12; 29:39, 41; 30:8; Lev 23:5; and Num 9:3, 5, 11; 28:4, 8.

3. Wikipedia gives a good summary at

4. In Chapter 3 of The Christian Passover (online at, Fred R. Coulter goes into great exegetical depth to demonstrate that the Hebrew expression beyn ha-arbayim can only refer to the interval between the completed passing of the sun below the horizon at sunset and full darkness. This conclusion was independently affirmed by Frank Nelte, “The Talmud Proves It... The O.T. Passover was at the Beginning of Nisan 14th,” at It is likewise upheld by the Enhanced Brown-Driver-Briggs Hebrew and English Lexicon. electronic ed. (Oak Harbor, WA: Logos Research Systems, 2000, S. 787) and Gesenius’ Hebrew and Chaldee Lexicon to the Old Testament Scriptures (Bellingham, WA: Logos Research Systems, Inc, 2003, S. 652); the latter observes that it was “according to the opinion of the Karaites and Samaritans (which is favoured by the words of Deut. 16:6), the time between sunset and deep twilight.”

5. Discussed at

6. “Rava said: The mitzva of the daily offering is from when the sun begins to descend westward so that the evening shadows slant eastward, shortly after midday. What is the reason for this? It is because the verse states: In the afternoon [bein ha’arbayim], which we understand to mean from the time that the sun begins to descend westward [ma’arav].” Online at Gesenius’ Lexicon likewise affirms this as the Jewish view: “The Pharisees, however (see Josephus Bellum Jud. vi. 9, § 3), and the Rabbinists considered the time when the sun began to descend to be called the first evening… and the second evening to be the real sunset (Gr. δείλη ὀψία).”

7. Keil, K. and Delitzsch, C.F. Biblical Commentary on the Old Testament. Exodus 12.

8. See The Mishna: Second Division: Appointed Times (Moed), Rosh Hashanah, Chapters 1 & 2.

9. Church of God Study Forum,

10. This is discussed in depth in books by Sacha Stern: Calendar and Community (Oxford: Oxford University Press, 2001) and Calendars in Antiquity (Oxford: Oxford University Press, 2012).

11. “When is the Jewish Month of Aviv?”

12. Cf. for example Derek Davies, “Determining equinoxes by observing the sun” at

13. There are helpful comments about this at and

14. “Abib Confirmed! - Yahweh's Restoration Ministry,”

15. Cf.

16. In agreement with this, see

17. Quoted in Sacha Stern, Calendar and Community (Oxford: Oxford University Press, 2001), 34.

18. Cf.

19. Richard A. Parker and Waldo H. Dubberstein, Babylonian Chronology 626 B.C.–A.D. 75. Brown University Studies XIX. Providence, RI: Brown University Press.

20. Stern, op. cit., 30–31.

21. Cf. Josephus, Antiquities 17.6.4 (Loeb 17.164): “Herod…deprived Matthias of the high priesthood, as in part an occasion of this action, and made Joazar, who was Matthias’s wife’s brother, high priest in his stead.”

22. Sacha Stern, Calenders in Antiquity (Oxford: Oxford University Press, 2012), 255.

23. Abib FAQ: Vernal Equinox and Tekufah. Karaite Korner,, accessed February 11, 2023.

24. The Five Books of Moses. The Schocken Bible, Volume 1, Trans. Everett Fox (New York: Schocken Books, 1995), 457.

25. Stern, op.cit, 52; in note 210 he suggests tekufah refered to the solstices, i.e., the endpoints of the sun’s circuit through the heavens.

26. J.B.Segal, “Intercalation and the Hebrew Calendar,” Vetus Testamentum Vol. 7, Fasc. 3 (July 1957), 250-307 (287).

27. Rosh Hashanah 21a, William Davidson Talmud (

28. Stern, op. cit., 61–62.

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