The Metonic Cycle Made Simple

All calendars require some form of intercalation. This means that in order to keep the calendar months aligned with the correct seasons, additional time must occasionally be added. In the modern Gregorian calendar used the world over, the extra time comes in the form of a "leap" day every fourth year when an extra day, February 29, is added. The exception to this rule is the rare occurrence of a century year that is not divisible by 400. Thus, 2000 was a leap year, but 1900, 1800, and 1700 were not. In those years, there were eight years between leap years. The only other century year that had a leap day was 1600. (Prior to that time, the Julian calendar was used that did not exclude certain century years from being leap years.)

The Creator's calendar also requires intercalation. This is done by the addition of an extra month, a 13th month, in an "embolismic" year. A strictly lunar calendar, such as that used by Muslims, floats backward through the year. Thus, Ramadan sometimes occurs in the fall, but a few years later in the summer, and a few years after that in the spring, and so forth. A luni-solar calendar, on the other hand, anchors the lunar months to some event within the solar year. (For more on the Biblical New Year, refer to "Biblical Calendation: Reckoning the New Year.")

The Biblical calendar is luni-solar and begins with the New Moon nearest the vernal equinox. Because the lunar year is 11 days shorter than the solar year, it is sometimes necessary to add a 13th month to realign the lunar year with the solar year. Years containing 13 months are called "embolismic years." These embolismic years fall into a very predictable 19-year cycle. Meton, a Greek astronomer, is typically credited with being the first to discover this cycle. In actuality, he merely introduced to the West the astronomical principles discovered by Kidinnu (or Cidenas), a Babylonian astronomer from around the same time period.

There are seven embolismic years within the 19-year cycle. The pattern of common versus embolismic years is as follows. Embolismic years (years containing 13 months) are shown in red:

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

• There are never two embolismic years in a row.
• There are never more than two common years before there is another embolismic year.

Below is a chart illustrating the Metonic cycle from 1954 to 2048¹. It is very important to note that this chart is based on Jerusalem time (Jerusalem, Israel = UTC +2)². The New Moon Day Gregorian dates listed here are specific to Jerusalem and will not necessarily be applicable to other locations. You will need to check conjunction times³ and dawn (astronomical twilight) times⁴ for your specific location to ascertain the Gregorian dates on which New Moon Day will fall in your area.

In order to identify the start of a new year (Abib 1), we must locate the New Moon closest to the vernal equinox. (Using this method typically places the start of the year between March 7 and April 6.)

Note: When we have correctly identified the New Moon closest to the vernal equinox, the following criteria will be met:

1. The vernal equinox will take place before Passover (the 14th day of the lunar month).
2. The vernal equinox will take place before the full moon.

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¹ The decision to map the Metonic cycle specifically from 1954-2048 is completely arbitrary. The sole purpose of this chart is to establish the Metonic Cycle with certainty. Any group of years extensively mapped out will result in the same conclusion, confirming the constancy of the Metonic cycle, as well as our current position in the cycle. WLC is in no way suggesting that the world will end in 2048. In fact, WLC is convinced that Yahushua will return much, much sooner.
² WLC believes that Jerusalem time should be used to determine the beginning of the year, not because WLC reckons earthly Jerusalem as today holding an exalted position, but because the feast days are anniversaries of real events. Passover, for example, was the day of our lord's crucifixion in Jerusalem. Using Jerusalem time (in relation to the vernal equinox) to begin the year ensures that we are observing the feast days on the same days as Christ and his apostles 2,000 years ago.
³ http://aa.usno.navy.mil/data/docs/MoonPhase.php *
http://eclipse.gsfc.nasa.gov/phase/phasecat.html *
(Note: Conjunction is referred to as the astronomical "new moon".)
* On rare occasions, the calculated times reported by NASA and the USNO in the links above may vary slightly, i.e. by one minute. The table below is based primarily on data provided by the USNO.
⁴ http://aa.usno.navy.mil/data/docs/RS_OneYear.php (Important Note: A Biblical day begins a dawn - astronomical twilight, NOT sunrise. You will need to select "astronomical twilight" as the type of table.)
When looking up the dawn times for your area, DO NOT FORGET to take daylight saving time into consideration when applicable. UTC time is unchanging; it does not make allowances for daylight saving time.
http://www.timeanddate.com/worldclock/sunrise.html (Important Note: A Biblical day begins a dawn - astronomical twilight, NOT sunrise. You will need to select "twilight/rise/set (sun)" in the Columns section after selecting your location.)
⁵ Time and Date of Vernal Equinox, http://aom.giss.nasa.gov/srver4x3.html

3/21  3:47

3/21  9:36

3/20 15:25

3/20 21:14

3/21  3:04

3/21  8:53

3/20 14:42

3/20 20:31

3/21  2:20

3/21  8:10

3/20 13:59

3/20 19:48

3/21  1:37

3/21  7:26

3/20 13:16

3/20 19:05

3/21  0:54

3/21  6:43

3/20 12:32

3/20 18:22

3/21  0:11

3/21  6:00

3/20 11:49

3/20 17:38

3/20 23:28

3/21  5:17

3/20 16:55

3/20 22:44

3/21  4:34

3/20 10:23

3/20 16:12

3/20 22:01

3/21  3:50

3/20  9:40

3/20 15:29

3/20 21:18

3/21  3:07

3/20  8:56

3/20 14:46

3/20 20:35

3/21  2:24

3/20  8:13

3/20 14:02

3/20 19:52

3/21  1:41

3/20  7:30

3/20 13:19

3/20 19:08

3/21  0:58

3/20  6:47

3/20 12:36

3/20 18:25

3/21  0:14

3/20  6:04

3/20 11:53

3/20 17:42

3/20 23:31

3/20  5:20

3/20 11:10

3/20 16:59

3/20 22:48

3/20  4:37

3/20 10:26

3/20 16:16

3/20 22:05

3/20  3:54

3/20  9:43

3/20 15:32

3/20 21:22

3/20  3:11

3/20  9:00

3/20 14:49

3/20 20:38

3/20  2:28

3/20  8:17

3/20 14:06

3/20 19:55

3/20  1:44

3/20  7:34

3/20 13:23

3/20 19:12

3/20  1:01

3/20  6:50

3/20 12:40

3/20 18:29

3/20  0:18

3/20  6:07

3/20 11:56

3/20 17:46

3/19 23:35

3/20  5:07

3/20 10:57

3/20 16:52

3/19 22:33

*1970: Please note that while Passover would have occurred on the same date as the vernal equinox (March 21), the equinox actually took place before March 21 dawned (@2:54 AM in Jerusalem). Consequently, the Passover was actually the day after the equinox.