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The Jewish Calendar

This article examines the Jewish calendar, which is essential for understanding the chronology of biblical events. It is part of a series exploring the prophecy of Daniel.

11 min Jewish calendar biblical chronology 1 verse 1 book

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Introduction

This study is one of the elements of our research devoted to establishing a chronology of the life of Jesus the Messiah on the basis of Daniel’s prophecy of the seventy weeks (Daniel 9.24-27). It should be understood in connection with the other studies in this series, each of which contributes complementary historical, calendrical and biblical data. Together, these works form a coherent analysis aimed at reconstructing, as precisely as possible, the sequence of events reported in the Gospels.

In our contemporary era, we tend to accept the conventions of days, months and years without question, thanks to the widespread adoption of the Gregorian calendar as an international standard, although some nations keep their traditional calendars.

Over the centuries, the different methods used to measure and define time have given rise to intense debate and reflection. The aim of this study is not to carry out an exhaustive analysis of this complex subject, but rather to shed light on the particularities of the Jewish method. This enriched understanding will enable us to better grasp the chronology of events as they are related in the biblical texts.

I. The Complexity of Drawing Up a Calendar

The question of time, and in particular the measurement of years, would have been greatly simplified if the orbital period of our planet around the sun had been a neat multiple of 12 (months) and therefore of 4 (seasons). In reality, however, things are much more complex, since the Earth completes its orbit in about 365.24219879 days. This length of time, corresponding to one year, immediately reveals the challenges inherent in establishing an accurate calendar.

This quest for a reliable calendar has deeply marked human history. Although many attempts have been made to synchronize this calculation with civil time, most ended in failure or in imperfect solutions, with the notable exception of the reform undertaken by Pope Gregory XIII.

The Gregorian calendar, which is now the worldwide reference, was first adopted in Catholic countries on October 15, 1582. It took nearly four centuries, with many twists and turns, for this system to be adopted worldwide. This gradual adoption bears witness to the sociopolitical complexities and the resistance encountered in harmonizing time across different cultures and nations.

II. The Main Reference Points

Within our year, we identify four particularly significant astronomical phenomena: the summer and winter solstices, as well as the spring and autumn equinoxes. These events mark the transitions between our four seasons, establishing a regular and predictable rhythm.

The equinoxes occur around March 21 (spring) and September 22 (autumn). On these dates, the length of day and night are approximately equal everywhere on Earth.

The solstices, for their part, correspond to the days when the day is longest, around June 21 (summer), and shortest, around December 21 (winter).

At the same time, we consider the day, defined by the period of the Earth’s rotation on its axis. The standard length is 86,400 seconds (24 hours), although this figure is in reality an average. Indeed, the length of the solar day varies slightly throughout the year, being shortest around September 16 (about 23 hours, 59 minutes and 39 seconds) and longest around December 22 (about 24 hours and 30 seconds).

We also note the lunar cycle, or lunation, which lasts about 29 days, 12 hours, 44 minutes and 2.8 seconds. This cycle corresponds to the time needed for the Moon to complete one orbit around the Earth and return to the same phase. Curiously, the Moon also makes one rotation on its own axis in this same period, which keeps the same face turned toward the Earth.

These different cycles and astronomical phenomena pose challenges for the measurement of time, particularly when one seeks to align days and months with the seasons of a solar year, underscoring the complexity and ingenuity of the calendar systems developed over the centuries.

III. The Jewish Reckoning

The Jewish calendar is a complex and sophisticated system that combines lunar and solar cycles. It is made up of lunar months alternating between 29 and 30 days. The week, made up of seven days, culminates in the , observed on Saturday.

Each Jewish month begins at the new moon. This reckoning results in an annual shortfall of about 11 days compared with the solar year. To make up for this imbalance and preserve alignment with the seasons, the calendar alternates between years of 12 and 13 months, following the Metonic cycle.

The Jewish day begins at sunset, and the division of the night into 12 equal parts means that the length of an hour varies over the course of the year, depending on the time between dusk and dawn. Consequently, an “hour” in this system may be shorter or longer than the standard 60 minutes. For example, in the month of April, the ninth hour may correspond to 3 p.m. in our system, if the day lasts approximately 12 hours beginning at 6 a.m.

In the time of Jesus the Messiah, two systems coexisted: the Jewish calendar and the Julian calendar, introduced by Julius Caesar. The Julian calendar is the ancestor of our Gregorian calendar, with days beginning at midnight. In this system, the sixth hour is equivalent to 6 a.m.

The fixing of the months was a prerogative of the , the Jewish authority, which relied on observations made in Jerusalem. The difficulty of pinpointing the new moon accurately means that modern astronomical calculations may differ from ancient observations.

As for the beginning of the year, it is marked by the month of Nisan, in which the Feast of Passover falls. This feast must take place in the spring, after the March equinox. To ensure this alignment, the could order the addition of a thirteenth month, called Adar II, as needed.

This ingenious combination of lunar and solar cycles made it possible to harmonize the Jewish calendar with the rhythm of the seasons, thus ensuring that the feasts and religious rites took place at appropriate times throughout the year.

IV. The Differences in Years

The starting points for measuring time vary greatly between cultures, each system having its own reference era. For the Jewish tradition, the year of the creation of the world, according to their chronology, marks the origin of their calendar. Thus, a date such as 18 Kislev 5781 in the Jewish calendar corresponds to December 4, 2020 in our Gregorian system. Today, many Jews use both systems in parallel.

The , for their part, had established the founding of Rome as their time reference. In France, and in many other Western countries, the Gregorian calendar is based on the , whose starting point is the presumed year of the birth of Jesus.

In ancient Israel, during the period of the kings, time was often reckoned from the year of a sovereign’s accession to the throne, which was generally aligned with the following month of Nisan.

This method of dating means that interpreting biblical chronologies requires particular care and an understanding of these varied historical and cultural contexts. For an accurate study, it is therefore essential to take into account the various dating systems and their meaning within the different traditions.

V. The Origin of the Jewish Calendar

The Jewish calendar follows the instructions of the law of Moses. The day beginning the previous night comes from the creation.

The 7-day week also comes from the creation and from the institution of the .

The first month of the year stems from the deliverance from the land of Egypt.

The month of Nisan in the Jewish calendar coincides with the Feast of Passover (Pesach) as well as with the beginning of spring. For this reason, it was established that Passover must take place after the March equinox, which occurs around March 20 or 21.

Since the Jewish lunar year does not correspond exactly to the solar year, which itself is not precisely aligned with 12 lunar cycles, the month of Adar II is added roughly every three years to make up for the annual shortfall of 11 days. This procedure ensures that the Jewish feasts remain in step with the seasons.

There is still a traditional Jewish calendar, known as the Karaite calendar, which relies not on astronomical calculations but on the direct observation of the new moons and of the ripeness of the barley in Israel. This system results in a slight discrepancy with astronomical reality, but it is considered to be more faithful to the practices of the first century.

In this calendar, the dates are not predetermined. At the end of the year, in the month of Adar, Karaite observers examine the ripeness of the barley to determine the beginning of spring. If necessary, they may decide to delay the start of the following year by adding a thirteenth month, Adar II. This process underscores the importance of beginning the year in the spring, in accordance with the principles of the first century.

However, with today’s climate changes, the accuracy of the Karaite calendar could be affected, although this was not a problem at the beginning of our era. For this reason, in our calculations, we refer to the astronomical dates of the new moons and we place Passover after the spring equinox, on March 20 or 21, in order to remain faithful to the practices of the time of Jesus the Messiah, even if this implies a certain divergence from the astronomical calendar.

Conclusion

It is indeed difficult for us today to conceive of the challenges faced by the ancients in setting up a system of measuring time that would take into account days and nights, lunar cycles, and the different seasons all at once.

The Jewish calendar, which is of particular interest in the study of the sacred texts, differs markedly from our Gregorian calendar. A thorough understanding of this system is crucial for correctly interpreting the events mentioned in the Gospels.

In the Jewish calendar, the day begins at sunset, around 6 p.m., and not at midnight. Hours do not correspond to a fixed 60 minutes either, but vary according to the length of the day and the night, each period being divided into 12 equal parts. To keep the lunar months aligned with the solar year and the seasons, an additional month, Adar II, is periodically inserted. Furthermore, it is imperative that Passover (Pesach) take place in the spring, after the March equinox.

If these particularities are not well understood, they can indeed lead to errors in the interpretation of biblical chronologies. It is therefore essential for researchers, students and anyone interested in biblical history to familiarize themselves with these nuances in order to avoid any misunderstanding.