Solar, Lunar, and Luni-solar Calendars

Next Part The Seven-Day Weekly Cycle

Back to The Truth About God’s Calendar

Solar calendars go strictly by the time of the earth’s orbit around the sun. In a solar calendar, such as the Roman calendar (that most nations now observe), the time of the beginnings of the months, in relation to the moon, have no bearing whatsoever. It is strictly solar. The moon is given no consideration in the Roman calendar!

Next we consider the lunar calendar. The Islamic calendar is an example of a strictly lunar calendar. All the months begin with the new moon. They are alternately 29 or 30 days in length, with adjustments made every 33 years. Opposite to the Roman calendar, the solar aspects have no bearing on the purely lunar calendar. Since annual corrections are not implemented, the months will have the tendency to creep forward into different seasons of the year. In fact, the months creep through the full cycle about every 33 years. Imagine January where July used to be—this is the Islamic calendar. Finally, the third type of calendar is the luni-solar calendar. This is the type that God presented to Israel, and it is based on both the solar and lunar frames of reference. The months and years are kept in balance. However, this task is somewhat complicated.

Let’s examine this.

Reconciling the Solar and Lunar Time frames

Before focusing upon calendar adjustments, we need to introduce a crucial element from astronomy—the 19-year time cycle. Precisely every 19 years, the sun, earth and moon come back to the same location relative to each other. This was understood by ancient astronomers and still stands as one of the many axioms of astronomy in relation to our solar system. The fact that the earth and the moon come back into the precise configuration with respect to the sun every 19 years serves as a continual evaluation as to the accuracy of the calendar. By implementing the adjustments built into the Hebrew calendar, it is completely unique, among calendars currently in use, in that it is kept “in sync” with this astronomical clock.

We now focus on the adjustments that keep the Hebrew calendar in harmony with the solar and lunar time frames—with the 19-year time cycle serving as a self-test of this task.

To reconcile the difference in the solar and lunar “years,” 7 years are established as leap years in every 19-year cycle. To summarize, 7 leap years contain 13 months and the other 12 years (called common years) contain 12 months, amounting to a total of 235 months in a 19-year time cycle. To see the pattern of leap years in a 19-year cycle, notice the following layout. Leap years are underlined to help clarify the pattern.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

Now that the concept of 19-year time cycles has been introduced, we can clarify other terms. We will be addressing these time cycles again, shortly. (Most authoritative references on the calendar use the term “intercalary” for the term “leap.” We will use only the term “leap” in this booklet.)

The months in a year alternate between 29 and 30 days, beginning with 30. This process of alternating between 29 and 30 days gives an average of 29 1/2 days. Below is a simple layout of the months as they occur, along with the days as they would fall in normal (common) years, followed by a leap year to the right. The month of Tishri is listed first since the start (new moon) of this month is the benchmark for calculating the entire year. This will be explained more fully below:

Common Year							Leap Year
Month Tishri Heshvan Keslev Tebet Shebat Adar V’Adar Nisan Iyar Sivan Tammuz Ab Elul		Days 30 29 30 29 30 29 — 30 29 30 29 30 29		Month # 7 8 9 10 11 12 13 1 2 3 4 5 6		Month Tishri Heshvan Keslev Tebet Shebat Adar V’Adar Nisan Iyar Sivan Tammuz Ab Elul		Days 30 29 30 29 30 30 (Becomes 30 days on leap years) 29 (Inserted 7 times every 19 years) 30 29 30 29 30 29

The month named V’Adar means Adar II. It comes at the end of the sacred year and is the extra 13th month only added to leap years.

A lunar month is 29 days, 12 hours and about 45 minutes—about 45 minutes longer than the 29 1/2 days designated for a month in the calendar. To make up for this discrepancy, adjustments were called for in the Hebrew calendar to bring the months back into balance. Two methods were used:

Heshvan (the 8th month) would be assigned 30 days in certain years, instead of the usual 29. Keslev (the 9th month) would be assigned 29 days in certain years, instead of the usual 30.

These two months are used to balance the actual lunar months, which differ by about 45 minutes from the average months as assigned to the calendar. So these two months bring the lunar times back into balance. These adjustments operate independently of each other. Time cannot be lost. It has to be accounted for, and this method has worked well for millennia.

Because of calendar adjustments, plus the combination of leap years and common years, we have the possibility of six different lengths of years. These six possibilities are:

Regular Common year = 354 days (12 months x 29 or 30 days)
Deficient Common year = 353 days (Keslev with 29 days)
Full Common year = 355 days (Heshvan with 30 days)

Regular Leap year = 384 days (13 months x 29 or 30 days)
Deficient Leap year = 383 days (Keslev with 29 days)
Full Leap year = 385 days (Heshvan with 30 days)

Some sources designate common years as normal years. They might designate the Full common year as the Excessive common year or the Perfect common year. Some authorities use the term “Defective” in place of “Deficient.” The precise names may vary, but the concepts are the same. That is why understanding the concepts is more important than memorizing terms. Don’t get confused if the terms vary in cases where the same Hebrew word can be interpreted in multiple ways, such as common or normal or ordinary, etc. Be assured that the principles that underpin the concept of the Hebrew calendar are consistent, reliable and time- proven.

These six possibilities constitute the full range of year lengths. This may seem complicated, but these adjustments are required to keep the lunar cycles in harmony with the solar cycles and the solar cycles in harmony with the seasons. This lunar-solar balance is achieved exclusively by the Hebrew calendar. No other calendars in use today achieve this balance.

The Benchmark

All calculations within the sacred calendar have a certain “benchmark” from which crucial conclusions are derived. This introduces the concept of the Molad of Tishri. Molad refers to the new moon that signals the beginning of a new month. Tishri is the seventh month of the sacred year. The Molad of Tishri is of greatest importance, as far as the calendar is concerned. This is because Tishri begins with the new moon announcing the beginning of the Feast of Trumpets. The remaining three fall Holy Days also occur during this month.

The Molad of Tishri announces not only the beginning of the seventh month, but also the beginning of the civil year. This is somewhat comparable to the fiscal year that many businesses observe, usually from July through June of the following year. The beginning of the sacred year is in the spring of the year. It begins with the month of Nisan (Abib). Passover is observed on the 14th of this month, followed by the Days of Unleavened Bread. The fact that the civil year does not coincide with the sacred year is the reason that the above chart begins with Tishri (month #7), and the beginning of the sacred year (month #1), which is Nisan, is about midway down the chart.

As the beginning of the civil year, the Molad of Tishri is counted as the focal point of the calendar year. This particular new moon is the benchmark on which the calculations are hinged. The Molad of Tishri is sometimes simply referred to as the “Molad.” As a point of interest, if someone sought to find out the length of a particular year, the procedure would be to find the Molad of Tishri for the beginning of that year, as a starter. Next, the Molad of the following year would be calculated. Then the length of the year would simply be the number of days between the two Molads. It could only be one of the six possibilities, discussed earlier. Do not worry about remembering all of these details. However, you will soon see them come into play and fit into the pattern of establishing the exact days upon which the Molad of Tishri (beginning of the Feast of Trumpets) and the other Holy Days will fall.

Next Part The Seven-Day Weekly Cycle

Back to The Truth About God’s Calendar

Back to By David C. Pack