The Importance of the Hebrew Calendar
In order to understand the events of the Passover, we must know the Hebrew Calendar. Our method of calculation of Biblical events will be very off if we do not utilize and understand the Hebrew Calendar. Therefore, we will first go over the Hebrew Calendar and how it compares to our modern calendar.
The following information comes from a Jewish website, Chabad.org.
Since Biblical times, various astronomical phenomena have been used to establish uniquely Jewish definitions for the day and its hours, the months and the year.
The length of days and hours vary by the season, controlled by the times of sunset, nightfall, dawn and sunrise. The months and years of the Jewish calendar are established by the cycles of the moon and the sun.
Though the months follow the lunar cycle, the lunar months must always align themselves with the seasons of the year, which are governed by the sun. Thus, the Jewish calendar is "Luni-Solar." The discrepancy between the solar year (365 days) and the lunar year (354 days) was resolved by every so often adding a thirteenth month to the year, to form a "leap year."
In the early times of our [Jewish] history, the High Court (Sanhedrin) in Jerusalem was assigned the tasks of determining the beginning of each month and the balancing of the solar with the lunar years. They relied on direct observation of the New Moon, astronomical data, and other considerations.
In the fourth century after the Temple's destruction, however, when oppression and persecution threatened the continued existence of the Court, a fixed calendar was instituted — based on the Sanhedrin's closely guarded secrets of calendric calculation. This is the permanent calendar according to which the New Moons and festivals are calculated and celebrated today by Jews all over the world.
Like the original system of observation, it is based on the Luni-Solar principle. It also applies certain rules by which complex astronomical calculations are combined with the religious requirements into an amazingly precise system.
Not only is the calculation of the Jewish months important, but also the calculation of the days is important. Without this understanding, we will tend to calculate events according to our modern reckoning of time. We would get hopelessly confused if we did that and deeply miss out on the truths the Word of God is attempting to reveal to us.
Again, the following is from the website, Chabad.org.
Jewish Calendar Date
When G-d [God] created time, He first created night and then day.
Therefore, a Jewish calendar date begins with the night beforehand. While a day in the secular calendar begins and ends at midnight, a Jewish day goes from nightfall to nightfall. Shabbat [Sabbath] begins on Friday night, and
a yahrtzeit lamp
is
kindled
the
evening
before
the yahrtzeit (anniversary of a person's passing), before nightfall. If the 10th of Iyar falls on a Wednesday, and a child is born Wednesday night after dark, the child's birthday is the 11th of Iyar.
On those dates wherein certain activities are restricted — such as working on Shabbat or major holidays — the restrictions go into effect the night beforehand.
(Most fast days begin at dawn ("alot hashachar"), and as such are an exception to this rule. Yom Kippur and Tisha b'Av, however, do begin at nightfall of the previous night.)
Though the day and its restrictions begin the night beforehand, many obligations associated with specific calendar dates — such as hearing the shofar on Rosh Hashanah, taking the Four Species on Sukkot, or hearing the daytime reading of the Megillah on Purim — must be performed during daylight hours only.1
Definition of Nightfall
While a day starts and ends at nightfall, the exact moment when night —
and the next calendar date — begins is not clear.
The twilight period, from sunset ("shekiah") until three stars are visible in the sky ("tzeit hakochavim"), is an "iffy" time period, known as "bein hashmashot." Shabbat and all the holidays begin at sunset, the earliest possible definition of nightfall, and end when three stars appear in the sky the next evening, the latest definition of nightfall.
A rabbi should be consulted if a boy is born during bein hashmashot (to determine when the circumcision should be scheduled), or if a person passes away during this time (to determine the date when the yahrtzeit should be observed).
Footnote
1. According to biblical law, dawn marks the beginning of the daytime, and all mitzvot associated with daytime hours can then be performed. For various reasons, however, the Sages instituted that the observance of many of these mitzvot should be delayed until sunrise ("hanetz hachamah"), or the moment when "one can recognize a familiar acquaintance."
One last quote from Chabad.org.
The Lunar Cycle
The Jewish calendar is based on lunar cycles.1 Towards the beginning of the moon’s cycle, it appears as a thin crescent. That is the signal for a new Jewish month. The moon grows until it is full, the middle of the month, and then it begins to wane until it cannot be seen. It remains invisible for approximately two days2—and then the thin crescent reappears, and the cycle begins again.
The entire cycle takes approximately 29½ days.3 Since a month needs to consist of complete days, a month is sometimes twenty-nine days long (such a month is known as chaser, “missing”), and sometimes thirty (malei,
“full”).
Knowing exactly when the month begins has always been important in Jewish practice, because the Torah schedules the Jewish festivals according to the days of the month.
The first day of the month, as well as the thirtieth day of a malei (full) month, is called Rosh Chodesh, the “Head of the Month,” and has semi-festive status….
The Jewish Months
Nissan is the first month on the Jewish calendar. Before the Jews left Egypt, on the first day of the month of Nissan, G-d told Moses and Aaron:
“This chodesh (new moon, or month) shall be to you the head of months. ”4 Thus the peculiarity of the Jewish calendar: the year begins on Rosh Hashanah, the first day of the month of Tishrei (the anniversary of the creation of Adam and Eve), but Tishrei is not the first month. Rosh
Hashanah is actually referred to in the Torah as “the first day of the seventh month. ”5
The Jewish Months and their Special Dates
Jewish Month
Approximate
This
Month’s
Secular Date
Special Dates
Nissan
March–April
Passover
Iyar
April–May
Lag B’Omer
Sivan
May–June
Shavuot
Tammuz
June–July
Menachem Av
July–August
Tisha B’Av
Elul
August–
September
Tishrei
September–
The
High
October
Holidays
(Rosh
Hashanah
and Yom
Kippur), Sukkot,
Shmini
Atzeret,
and Simchat
Torah
Marcheshvan
October–
November
Kislev
November–
Chanukah
December
Tevet
December–
Conclusion
of
January
Chanukah
Shevat
January–
Tu B’Shvat
February
Adar
February–
Purim
March
Sanctifying the Month
“The L-rd spoke to Moses and to Aaron in the land of Egypt, saying,
‘This chodesh shall be to you the head of months.’” (Exodus 12:1–2) From the wording of this verse, “shall be to you,” the sages deduced that the responsibility of pinpointing and consecrating the chodesh, the crescent new moon, was entrusted to the leaders of our nation, the Sanhedrin, the rabbinical supreme court of every generation.
Originally, there was no fixed calendar. There was no way to determine in advance the exact day of a coming holiday or bar mitzvah because there was no way to determine in advance when the month would begin. Each month anew, the Sanhedrin would determine whether the month would be 29 or 30 days long—depending on when the following month’s new moon was first sighted—and would sanctify the new month.
Nowadays
In the 4th century CE, the sage Hillel II foresaw the disbandment of the Sanhedrin, and understood that we would no longer be able to follow a Sanhedrin-based calendar. So, Hillel and his rabbinical court established the perpetual calendar which is followed today.
According to this calendar, every month of the year, except for three, has a set number of days:
Nissan—30
Iyar—29
Sivan—30
Tamuz—29
Menachem Av—30
Elul—29
Tishrei—30
Mar Cheshvan—29 or 30
Kislev—29 or 30
Tevet—29
Shevat—30
Adar—29 (in leap years, Adar I has 30 days)
Regarding the variable months of Kislev and Cheshvan, there are three options: 1) Both can be 29 days (the year is chaser), 2) both are 30 (the year is malei), or 3) Cheshvan is 29 and Kislev is 30 (the year is k’sidran, meaning these two months follow the alternating pattern of the rest of the months). Hillel also established the rules that are used to determine whether a year is chaser, malei, or k’sidran.
The rules of the perpetual calendar also ensure that the first day of Rosh Hashanah will never take place on Sunday, Wednesday or Friday.6
When Hillel established the perpetual calendar, he sanctified every Rosh Chodesh until Moshiach [Messiah] will come and reestablish the Sanhedrin.
Footnotes
1. The lunar cycle which the Jewish calendar follows is called a synodic month—not to be confused with the sidereal month, the amount of time it takes for the moon to complete an orbit around the earth, which is a bit more than 27⅓ days. The synodic month is longer because after completing its orbit, the moon must move a little farther to reach the new position of the earth with respect to the sun.
2. For about one day before and one day after it is closest to the sun.
3. To be more precise, 29.5306 days.
6. This guarantees that Yom Kippur will not fall on a Friday or Sunday, which would result in two consecutive days when preparing food and burying the dead is prohibited; and that Hoshana Rabbah will not occur on Shabbat, which would interfere with the custom of taking the willows on this day.
Conclusion to Chapter 2
If we fail to understand the Biblical method of the calculation of time, we will not be able to completely understand what the Bible is revealing to us. When Jesus
died is particularly important because of the fulfilling of prophecy. With the knowledge of the Biblical method of calculation of time, we can then fully understand what the Bible gives us concerning the Passover events.
Chapter 3