Solar Lunar

The Jewish calendar is a lunisolar calendar, or "fixed lunar year," based on twelve lunar months of twenty-nine or thirty days, with an intercalary lunar month added seven times every nineteen years (once every two to three years) to synchronize the twelve lunar cycles with the slightly longer solar year. Each Jewish lunar month starts with the new moon. Although originally the new lunar crescent had to be observed and certified by witnesses, the timing of the new moon is now determined mathematically.

Concurrently there is a weekly cycle of seven days, mirroring the seven-day period of the Book of Genesis in which the world is created. The names for the days of the week, like those in the Creation story, are simply the day number within the week, with Shabbat being the seventh day. The Jewish day always runs from sunset to the next sunset.

Modern practice follows the scheme described in the Mishnah: - Rosh Hashanah, which means "the head of the year", and is celebrated in the month of Tishrei, is "the new year for years." This is when the numbered year changes, and most Jews today view Tishrei as the de facto beginning of the year. The 15th of Shevat, the New Year of the Trees, has become a popular minor holiday in recent decades.

The calendar rules have been designed to ensure that Rosh Hashanah does not fall on a Sunday, Wednesday or Friday. This is to ensure that Yom Kippur does not directly precede or follow Shabbat, which would create practical difficulties, and that Hoshana Rabbah is not on a Shabbat, in which case certain ceremonies would be lost for a year.

During leap years, a month, Adar II is added before Nisan. During leap years Adar I (or Adar Aleph — "first Adar") is actually considered to be the extra month, and has 30 days. Adar II (or Adar Bet — "second Adar") is the "real" Adar, and has the usual 29 days. For this reason, during a leap year, holidays such as Purim are observed in Adar II, not Adar I.

For Karaites, the beginning of each month, the Rosh Chodesh, can be calculated, but is confirmed by the observation in Israel of the first sightings of the new moon. This may result in an occasional variation of a maximum of one day, depending on the inability to observe the new moon. The day is usually "picked up" in the next month.

Between 70 CE and 1178 CE, the observation based calendar was replaced by a mathematically calculated one. Except for the epoch year number, the calendar rules reached their current form before 820 or 921.

A synodic month is the period between two lunar conjunctions, such as between two new moons. Since the actual length of a synodic month varies by several hours from month to month, the calendar is based on a long-term average length called the mean synodic month. The virtual lunar conjunctions at the start of each mean synodic month are called molads.

The modern molad moments match the mean solar times of the lunar conjunction moments near the meridian of Kandahar, Afghanistan, more than 30° east of Jerusalem. A "new moon" is the day on which the first visible crescent of the moon is observed. It occurs 29 or 30 days after the preceding visible crescent and traditionally signaled the start of a Jewish lunar month.

In the present era actual lunar conjunction intervals can be as short as 29 days 6 hours and 30 minutes to as long as 29 days and 20 hours, a variation range of about 13 hours and 30 minutes. Furthermore, due to the eccentricity of Earth's orbit, series of shorter lunations alternate with series of longer lunations. Consequently the actual lunar conjunction moments can range from 12 hours earlier than to 16 hours later than the molad moment, in terms of Jerusalem mean solar time.


Furthermore, the discrepancy between the molad interval and the mean synodic month is accumulating at an accelerating rate, since the mean synodic month is progressively shortening due to gravitational tidal effects. Measured on a strictly uniform time scale, such as that provided by an atomic clock, the mean synodic month is becoming gradually longer, but since the tides slow Earth's rotation rate even more, the mean synodic month is becoming gradually shorter in terms of mean solar time.

Genesis 1:14, Psalm 104:19 gives us the two witnesses we need to make this a truth established by YHVH, but it does not tell us how the time piece works. That the sun was the timepiece ordained to rule the day (Gen. 1:3-5) and the year (spring to spring, Ex. 12:2). A day is one circuit of the sun about the earth, as a man running a race (Psalm 19:4-6). A year is one cycle from spring to spring which is a relationship between the earth and the sun.

Let’s see what else Genesis 1:14 says. The lights in the heavens were also given for signs and seasons. The word seasons is translated from the Hebrew word mo’ed, which means appointed times. In order to arrive at these appointed times, one must ascertain when the new moon takes place because the appointed times fall on specific days of the month. The new moon is always the first day of each month. So we can easily conclude that the moon is the timepiece that rules the lunar month.

New moon days are not Sabbaths, the Sabbath and new moon are non-commerce days. (A commerce day (work day) not a worship day.) The Sabbath and new moon are worship days. Scripture also records that every Sabbath in Scripture that is given an exact lunar date is always the 8th, 15th, 22nd, or 29th day of a month.

New Moon

When the moon breaks the plane between the earth and sun it is called conjunction. If the moon passes through the LINE between earth and sun it is a conjunction, but also causes an eclipse of the sun. We can’t see the moon at its conjunction, it is between the earth and the sun, but at that moment it enters its rebuilding phase, it becomes new.

There are 29 and 30 day months in calendar. In the deficient (29 day) months the conjunction takes place on the 29th day, meaning that the next day is new moon (day 1 of the subsequent month). Thus, there is only a one day new moon celebration (day 1). Conjunction day is the day the sun rises without the moon being seen first.

In the whole (30 day) months, conjunction takes place on day 30 rather than day 29 as in the Deficient (29 day) month. After the last Sabbath (the 29th) in a 30 day month, there is a two day new moon celebration (day 30 of the old month followed by day 1 of the new month). New moon proper is always day one. There will be no visible moon on either night.

After the last Sabbath of the month, (the 29th) there is a new moon celebration until the moon is indeed considered new. If the moon conjuncts during some portion of a day, the first part of that day is in the old month and the remaining portion is new. A newly waxing moon can be seen with the naked eye and perfect atmospheric conditions about 17 hours after conjunction if you are in the right place. Granted, you cannot see the moon 17 hours before conjunction and 17 hours after conjunction from the same location. However, the moon is new at conjunction, not from the visible crescent. Just because you cannot see the moon when it becomes new (at conjunction) does not mean that it is not new.

It is true, if months were observed from the visible crescent, then depending on what point over earth the moon conjuncts, it might be from 17 to 40+ hours after conjunction before you spot the first visible crescent, which presents a problem. There is always a full moon on the first day of Unleavened Bread, the evening that separates the 14th and 15th of Abib. If we wait until the visible crescent to start counting the days of the month, we will miss having the full moon at the “appointed time” by 24-48 hours. Understanding conjunction eliminates this problem.

Exodus 12:6-10 tells us that Israel was to kill the lamb on Abib 14, at even (between the evenings actually), which means sometime in the afternoon. They were to put the blood on the doorposts that day, and they were to eat it THAT night (the night the Death Angel would pass over). That night was connected to Abib 14. They were not to leave any of the lamb remaining until the following morning (the next day). Did THAT night belong to the next day (Abib 15) or THAT day (Abib 14). Clearly the night after the evening belonged to Abib 14 because it is called THAT night, not the next night or tomorrow night.

The visible crescent may be as much as 1-2 days after the conjunction due to various factors. If we calculate the new moon from the visible crescent, our feasts days will be off by as much as 2 days. If done every month, at least you would be consistent by your own reckoning, but history tells us that the Sabbaths (the 15th) of Passover Unleavened Bread and Tabernacles always begin at the time of the full moon. If we calculate the festivals from the visible crescent, we could in essence begin these feasts by as much as 2 days after the full moon.

For the purpose of establishing the beginning of the month, using so called local visibility of the new crescent from outside Israel leads to arbitrary decisions and confusion. The first aspect of arbitrary decisions and confusion is defining local visibility. Suppose the new crescent can be seen from Fort Worth, but cannot be seen from Dallas, which is 30 miles to the east. Should people in Dallas accept the testimony of people in Fort Worth for visibility of the new crescent to start a month? What distance should be the limit for accepting someone else's testimony? Suppose the only places in the United States from which people can see the new crescent are over 8000 feet above sea level in the Rocky Mountains. Should people elsewhere in the United States accept their testimony?

If no one in the United States can see the new crescent, but some people in Baja, Mexico can see it, should their testimony be accepted in the United States? In order for local visibility of the new crescent to be applied in today's world, it must first be defined so that there is a principle to apply. In order to be practical it should be defined in some manner so that any proposed definition may be applied in different areas of the world, not merely on one small island.


Starting the Month when it comes to you Today the part of the world east of Israel always starts the Sabbath before Israel, and the part of the world west of Israel always starts the Sabbath after Israel. Thus India starts the Sabbath before Israel and the United States starts the Sabbath after Israel. To be consistent with the way we keep the Sabbath, we should also begin the start of the month according to the same principle: the people in India begin the start of the month before the people in Israel and the people in the United States begin the start of the month after the people in Israel. This principle extends to the IDL and is what mainstream Judaism uses. If one sees this for the first time in its very low position in the sky, one will be very uncertain that this is the new crescent, but if one has seen it that way all along for the previous 15 minutes, there will be no reason to doubt that it is the new crescent.

When the crescent is seen from the northern hemisphere, it looks different near the time of the vernal equinox compared to near the time of the autumnal equinox. Near the vernal equinox it looks somewhat like a bowl whose bottom is horizontal and down. Near the autumnal equinox it looks somewhat like a backwards letter C.

In the spring when it gets near the horizon, the bowl shaped crescent gets flattened to a very short horizontal straight line, and anyone seeing this who had not already been watching it before would not think this was a crescent since all the curvature would be gone. In the autumn when it gets near the horizon, the backwards C shaped crescent gets flattened to the outline of what appears to be an extremely narrow squashed tip of a cigar, but not filled internally, and anyone seeing this who had not already been watching it before could easily mistake it for the outline of a cloud.

The use of the IDL for the 24-hour day, starting with sundown as it gradually sweeps across the globe, has attained worldwide acceptance by keepers of the Sabbath, and this principle for the start of a month has been accepted by mainstream Judaism (Orthodox, Conservative, and Reformed), and the Karaites also accept it, but typically starting one or two days later than the MCJC.

This method does cause people to the east of Israel up to the IDL to begin to observe the first day of the seventh month prematurely, perhaps on some occasions causing two days of  observance. In ancient times Israel did the same thing as indicated in I Sam 20:27, 34. Hence this is not a significant fault. The sighting of the new crescent from within the boundaries of Israel should determine the day, and this day should be accepted around the world based upon the IDL with sundown as it sweeps across the globe.

The noun chodesh (meaning month as well as new moon) has the same consonants as the Hebrew adjective chadash (almost always translated new, and having the meaning new and the Hebrew verb chadash (about half the time translated renew and half the time repair). Hence the collective association of new, renew, and repair is associated with the Hebrew word chodesh, rather than the concept of old, dwindling, or thinning, which is associated with the old crescent in the sense of a continuous sequence of snapshots of the visible moon each night as it changes from first visibility to last visibility.

Hence linguistically, from the choice of the Hebrew words chodesh and chadash, it must refer to the new crescent rather than the old crescent. From these considerations (independent of Isa 47:13 and the separate evidence from Ezra and Nehemiah), the biblical month begins with the day that the Levitical priesthood approves of the sighting of the new crescent with their blowing two silver trumpets. However, no month may have more than 30 days, based on Gen 7:11 with Gen 8:3-4. 

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