When does the Hebrew Month begin?

This article is about how we at The Refiner's Fire, determine the 1st day of the new Hebrew month. We very strongly believe that declaring the first day of the month by the "sighted moon" is only a long-held myth (not discussed in this article) misunderstood to be "the" correct method, and we do not advocate it because it is demonstrably incorrect.

The new calendar month, as we will show, begins the first full day after conjunction of the moon with the sun, and though many argue "you can't see conjunction", we will show that "seeing" conjunction is irrelevant. All one needs to know is the day the conjunction happened which is quite easy to know by observation alone!

Also, many will argue that a "sign" must be "visible" and since "conjunction" clearly can't be "seen", conjunction can't be a sign! They argue that Genesis 1:14 declares this! We will show that conjunction is decidely a sign, and that Geneses 1:14 does not limit the signs...

All that is required to show that the "sighted moon" is a myth is to WATCH the moon through the entire month, month after month, year after year, to realize one cannot escape the conclusion that the "sighted moon" beginning of the month is terribly erred!

Just as the day ends and begins in darkness (at sunset) and the moed-year can end and begin in darkness1 - so it would follow that the month should end and begin in darkness and not by a "sighted moon".

The astute reader will note a curious lack of scripture citation in this article! That's because there are no scriptures telling us how to determine the beginning of a new month! None! Just as there are no scriptures telling us how to determine the new year, or the day! Do not believe it if someone says "Scripture tells us the month begins with the sighted moon"! That claim is simply not true.

Many will argue scripture specifies the crescent, but that myth has been around so long, it is simply "assumed" to be true! In fact, I challenge anyone to find a single scripture saying the new month is determined by a "sighted moon"! Many also say it is "obvious" that the sighted moon determines a new month because "anyone" can see the new moon and tell it is a new month! Really? To me, when we see a new crescent, it is instead rather "obvious" that the moon is already at least a day old! And it's not just "anyone's" responsibility to determine the beginning of the month! It was the responsibility of the body of Levites assigned the duty (and later the Great Sanhedrin). It matters not if "anyone" can see the crescent because most of those people have no idea what it means.

Many will argue that it is a matter of historical record that "two witnesses" came forward to declare they had seen the crescent moon and the new month was declared. Historical record or not, found in Talmud or not, that only adds to the myth that this was the method of determining the new month, it is not "proof".

"Proof", in fact, is simply in the looking - the same way the ancients did eons ago, which, for some reason, we've forgotten how to do! The method of the "sighted moon" is this: It is wrong! Anyone, in Biblical times as well as today, by simply observing the moon throughout the month, month after month, year after year, one would inescapably draw that conclusion. Just watch the moon!

Observing the Moon

The proper technique is to take advantage of all the moon's signs! We'll discuss the signs in a moment. But first, let's look at some of the problems with the "sighted moon".

The error of the "sighted moon"

While those who insist the new month begins at the sighting of the new crescent moon, it is, in actuality, without foundation because think about it: If the new month only just began when you saw the 1st crescent at sunset....then, applying the same rule, the last visible crescent of the old month (seen at sunrise) would mean that it was the last day of the old month! After all it's the same sign! That is, if you saw the last, faint old crescent of the old month at sunrise, then it must mean that that very day is the last day of the old month, after all it is the exact same rule you are applying to the visibility of the new crescent! But between the last visible crescent of the old month and the 1st visible crescent of the new month are 2-3 days! So clearly something is wrong with the method.

You really must apply the same rule to the sighting of the "new crescent" and the sighting of the "old crescent"! If sighting the "new crescent" identifies the first day of the new month, then sighting the "last crescent" of the old month must also identify the last day of the old month! Applying the same rule of "sighting the crescent" results in two different days for the "1st" of the new month. The "sighted crescent" method is busted by this very simple observation.

Some will argue, while defending the "sighted moon" new month, that scripture provides the method. They will cite Genesis 1:14 arguing that the word for "sign", which in Hebrew is "owt", insisting that it implies the sign must be "visible". Thus by demanding "owt" means "visible sign", they conclude and insist that the month can't begin at conjunction because a moon in conjunction can't be seen, thus can not be a "sign". But this is a dreadful twisting of scripture leading to a very poor conclusion. The Hebrew word "owt" is nowhere limited to mean only "visible sign". It means, depending on its context, a "signal, evidence, mark, sign, token" among other uses. Since the moon is always visible sometime during each day of the month except when it in its period of conjunction, the very fact that the moon is not visible is a very clear sign! The absence of the moon is the sign!

Genesis 1:14 says: "Let there be lights in the dome of the sky to divide the day from the night; let them be for signs, seasons, days and years". We see no one arguing that the "year" is determined by a "visible" sign! Yet no one can "see" the sun pass by the same spot in space that it passed 365.2422 days earlier, but we can still determine a new year has begun! And the day itself begins when the sun has set! The sun has disappeared! It's NOT visible! You can no longer "see it", yet the absence of the sun is the sign a new day has begun.

But we don't have anyone saying sunset can't be a "sign" because you can't see the sun! So why do they insist that the absence of a visible moon can't be a sign? They insist, apparently, because they simply have not thought about the problem and are desperate to "prove" the long-held myth that "this is the way the ancients did it".

So some will argue that Genesis 1:14 says only "light" is a sign! Really? Do we find that scripture actually says that only the "light" of the moon is the "sign"? If so, then why does Genesis 1:14 say "...to divide the day from the night"....is not darkness also a "sign"? And why would YHWH use "darkness" as one of the plagues of the exodus (Exodus 10:21-22) if it were not a "sign"?! Some things unseen are as much a "sign" as things seen2!

Then there is the problem of the age of the new crescent moon. The very fact that for it to be visible, the moon must long enough past its renewal, that is, far enough away from the sun and high enough in the dusk sky just after sunset to present a visible crescent bright enough to be seen in the bright glowing sky near the western horizon! (But if the moon is far enough away from the sun to be seen, does that not automatically mean it is already "older" than "new"? That fact alone should be sufficient to tell the observer that upon sighting a crescent, it only indicates that the month began already!)

[Sidebar: About the term "new moon". The term is sometimes mistaken as the first visible crescent of the moon. This is a myth and likely comes from a misunderstanding of the Hebrew word חדש ("chodesh"), properly derived from "to be new" and in scripture only refers to the new month, but not to how that new month is determined. Unfortunately, many Bibles translate "chodesh" as "new moon" rather than a more correct "new month". This has fueled the misconception that the new crescent "is" the determinant of a new moon. Properly, if the moon is not visible at all, then it is "new moon" for it is in the process of going from old to new or being renewed. Indeed the term "new moon" applies to the unseen moon (at conjunction) all the way to 1st quarter, a week after the moon has been renewed.]

Since the moon orbits the earth in an ellipse, with a close point (perigee), and a far point (apogee) from the earth, and the orbit itself precesses around the earth... the moon speeds up or slows down in its orbit depending on whether it is near perigee or apogee. That means that each and every month, the moon "presents" itself to us as a "new crescent" at a very different lunar "age"! That is to say, sometimes, even though the moon is actually there in the sky at at sunset, it is still too close to the sun to be seen at that sunset, and one must wait another FULL DAY before it can be sighted! That automatically means your method of determining the day of the new month is extremely flawed! If you can't reliably "sight" the new moon at the same lunar "age" each month, then it is a dreadful "sign" of the new month!

Some months in fact, from the geographical latitude of the Holy Land, you can see the new crescent when the moon is only about 1 day old, such as in the Spring, when the moon is both high enough and far enough from the sun at sunset, while some other months you can't spot it till it is over 2 days old, such as in the Fall when the moon is certainly far enough from the sun but is not high enough in the sky at sunset to be spotted! Would YHWH really expect us to use such an unreliable method to establish the month?

Still another problem! Since the calendar month is defined by the moon, and "new moon" means that the calendar month should just be beginning, that simple fact necessitates (actually requires) the "middle" of the calendar month being defined by a full moon. After all, if the moon is "new" when it is between the earth and the sun3, then it is seen as "full" when the moon is on the other side, that is, the earth is between the moon and the sun, and "full" therefore MUST mean the calendar month is half over! (The calendar must match the moon.) Simple, obvious, and you really can't get around it! When the moon rises full or nearly full - your calendar should say it has become the 15th of the month since the middle of the Hebrew calendar month averages 14.75 days! (The average lunar month is 29.5 days, so 1/2 a month is 14.75 days which means the 15th calendar day must begin when the moon is full or becoming full. Variations of the moon's orbit "broaden" the period of the full moon, so what's being described here is only intended to be generally correct. Nevertheless, the proper Hebrew calendar should contain the full moon in the right calendar day.)

But the "sighted moon" month has a serious detrimental side-effect! That side-effect is that if one has declared the new month only by the sighted moon, it means that when the middle of the calendar month comes around, when the calendar date says it's the 15th, you find that the moon is already well past full! Oops! Something is wrong! What is wrong is you chose the incorrect day to determine the first day of the month! Indeed, if you are watching for the moon on the day it does rise at or near sunset, rising full or nearly full, your "sighted crescent" calendar will say the date is only now becoming the 13th or 14th! By this simple observation, you can see, indeed prove, the "sighted moon" new month is the dreadfully wrong method to begin each month!

And finally, let me address the myth of the "two witnesses" declaring the sighting of the crescent. The great sage, Maimonides, wrote in the 12th century CE:

Each month the moon disappears and becomes invisible for about two days, or somewhat more or less - for about one day at the end of the old month, before it reaches its conjunction with the sun, and for about one day after its conjunction with the sun. Then it reappears in the evening in the west, and this night, on which it becomes visible in the west after its disappearance, is the beginning of the month. From this day on 29 days were counted, and if the new crescent appeared on the night of the 30th day, this 30th day was the first day of the new month. If, however, it did not appear on that night, the 30th day would belong to the old month and the 31st day would be the first day of the new month. And no matter whether the moon did or did not appear in the night of the 31st day, no attention was paid to it, for the lunar month never lasts longer than thirty days. (From "Sanctification of the New Moon", Maimonides, about 1175 CE)

Maimonides went on to say that it was the court which held the responsibility to establish the month and that the responsibility of the two witnesses was only to validate that the crescent was seen. The sighting of the crescent only established that the assumed 30th day of the month, just ending at that sunset, was instead the 1st day of the month. If the crescent was not seen at sunset the 30th, of course the that sunset became the 1st of the new month and the crescent would be seen at the next sunset, which began the 2nd. Therefore, the value of the witnesses was not to establish that the new month had just begun, but only to validate the new month. This was called "sanctification" of the new month. Unfortunately, the idea that the "sighting of the crescent" established the beginning of the month became mistaken as the method of establishing the new month.

Using all the signs

The solution to how to determine the month is to use all the signs as they would have in ancient days before computers. What follows is a list of these signs and how they are used:

  1. Watch the old moon
  2. Watch for "1st Quarter"
  3. Watch for the approach to full moon
  4. Watch for when the full moon rises
  5. Watch for when the full moon sets
  6. Watch for "3rd Quarter"
  7. Keep a record of the instances of 29 and 30 day months

Admit it! No one today does these 7 things, any of them, and no one you know does these things! Today we don't need to! But in ancient times, before the computer, these were the items they would have carefully watched and tracked!

The "old moon" is a critical observation. The old moon tells you how long till conjunction and hence, which day will be the 1st of the new month. Sadly, many people today, accepting of the idea of "sighting the new crescent" simply have no idea the "old crescent" is also visible before the old month ends. One must be up before sunrise to see the old crescent. That's a problem for most of us in our time, but not for the ancient Levites who were assigned the responsibility! They would carefully watch the old moon, and record its appearance, the thickness of the sliver, the angle of its "horns", and height above the horizon, month after month, year after year, and they would compare those observations with when the "new" crescent was seen, and build a knowledge of just when the conjunction was! They did not need to "see" conjunction to bound when it happened! That is, they knew on which day the conjunction happened and the moon was renewed!

1st Quarter4 reveals much! 1st Quarter is when the moon is 1/4 the way through its "month" (by position around the earth, not by time), and it looks exactly half illuminated, on its way to becoming a full moon. Almost no one today realizes it, but a true 1st Quarter moon rises at local noon, and it is on the local noon meridian at sunset, and it sets at midnight. An assessment of the time the 1st quarter moon rises before or after local noon; the apparent distance of the 1st quarter moon from your local noon meridian at sunset; and knowledge of the day of the calendar month of the day of 1st Quarter are all evidence of the (coming) day of full moon and evidence of the length of the current month. For those not aware: The visible terminator of the moon is observed as "concave" before 1st quarter, and "convex" after 1st Quarter. You see the terminator as a "straight line" indicating the moon is exactly at 1st Quarter.)

Approach to full moon. Similarly, the appearance of the moon after 1st Quarter becomes more and more gibbous. Generally, just before the sun sets one evening, if you see the moon rise - not yet full - it indicates the moon is not yet full and it is not yet the 15th! If you have begun your calendar correctly, the rising gibbous moon before sunset the 13th "reveals" solid evidence your calendar is correct!

Full moon rising. Ideally, the moon is perfectly full when it rises exactly as the sun sets. This discussion must be simplified, but, from your location, the moon might not yet be full and rise a bit before sunset, or may rise after sunset having already been "full". (It is possible for the moon to rise after sunset, yet also not yet be full. Skilled observers understand and comprehend these observational issues, but that is too much detail for this article). Nevertheless, the moon should rise near the time of sunset, and become full sometime through the evening as your calendar says it is the middle of the month, sunset the 14th, becoming the 15th. So watching the full/nearly full moon rise time is a very important clue, which tells you if your calendar is correct.

The setting "full" moon. Almost unknown to the world at large is the appearance of the full moon before sunrise and what it reveals about its age! If the moon has already gone through "full" then it will set after sunrise! If it sets before sunrise, then it likely has not yet been "full". It's an important clue, and the skilled observer knows this! (Again, I've had to over simplify, because there are times when the moon will be just setting at sunrise, yet it is not yet full. The point is the skilled observer will be aware of these conditions.)

Watch for 3rd Quarter. Similar to 1st Quarter, 3rd Quarter is a visible and noteworthy stage. A 3rd Quarter moon rises at midnight, and sets at noon. So just where the moon is in your sky when you see the "straight" terminator of the 3rd Quarter moon is a clue to how old it is and how many days are left in the month.

Keep a record of months. The average lunation is approximately 29.53 days. This means that calendar "months" must alternate between 29 and 30 whole days to "balance" the moon's "month" (a lunation). But since several months in a row can exceed 29.5 days, it means that sometimes successive months must be 30 days! In fact, this can happen up to 4 months in a row! (Similarly, it is possible for two consecutive months to be 29 days!) So a record of the observations of the moon, and a record of the days of the preceding months, is very helpful in assessing if the upcoming month will be a 29 or 30 day month.

What does this all mean? It means simply this: By observing the moon throughout the entire month and not by the "sighted" new moon alone, the skilled observer assigned the task knows exactly the period when the moon is passing through conjunction, even though conjunction itself is not and cannot be seen and thus, which sunset will become the 1st day of the new month. No crescent "sighting" is necessary. Indeed, with this knowledge, upon sighting the crescent, you realize that the first crescent is only a sign that the month has already begun! This is, in fact, the original meaning of the "sighted crescent"! It only confirmed that the new month had begun.

Achieving the same by modern techniques

In our time we don't have to watch the moon all month year after year! Today we are blessed with the ability to compute the time of lunar conjunction. We can use that to our advantage! It turns out there is a 100% correlation with observation if you do the following:

Why this works: Conjunction, that time when the moon passes through the plane between the earth and the sun, necessarily must happen on the last day of the Hebrew calendar month for the next sunset to become the 1st day of the new calendar month. Also, the 1st whole day of the new calendar month must be just after conjunction, or the calendar will not indicate the half-way point of the month on the proper day when the moon is becoming full! Since a calendar month must have either 29 or 30 whole days, assessing the time of conjunction from sunset - the demark for a Hebrew Day - makes perfect sense. If conjunction happens "in" the current day, i.e., before sunset, then the old (lunar) month has ended. If conjunction happens "in" the period after sunset, then it happened in what must be the 30th day.

This method exactly duplicates the method of observation! By observing the moon throughout the month, even though the moment of conjunction remains "unseen", the observables (described simplistically above) provide the same assessment of whether or not the current month needs a 30th day. The advantage of the "modern" method is that one does not need a "team" of skilled observers to record endless years of data. Modern knowledge of astronomical computation provides a quick and accurate answer.

There is the potential (though exceedingly rare) that there might be a month when the moon is in conjunction at the same moment as sunset in Jerusalem. What does one do then? Is the conjunction counted in the current day or the next? By observation, realize they would not have had any idea that conjunction was simultaneous with sunset, so what would they have done by observation alone? And what "rule" should we apply to our modern computation?

If the conjunction is at the same moment as the sunset, it is actually the "ideal" condition! Very clearly, this is the ONLY possible condition when the day can end and new day begin at the same moment as the moon is renewed. In this case, the 1st day of the new calendar month began as the moon "month" began it's "1st day". So by modern methods of computation, this is a no-brainer - that sunset becomes the 1st day of the new month and that would be the rule.

By observational techniques alone, depending on the technique used, only the "day of" conjunction is estimated, or the day of conjunction and the approximate time of conjunction is estimated. By either method, having no advanced knowledge that the actual time of conjunction would be the same time as sunset, they could have only gotten it "right" or "wrong"! If they got it "right", then their estimate was correct, if they got it "wrong", then the current month becomes a 30-day month and the new month likely becomes a 29-day month when it would have been a 30-day month and the unknown "error" is naturally resolved the next month.

Now you know the "rules" for the calendar we advocate at The Refiner's Fire. If conjunction is before (or exactly at sunset) in Jerusalem, that sunset becomes the 1st day of the new calendar month. If conjunction is after sunset in Jerusalem, then the current calendar month requires a 30th day.


1"Adar", the last month of the Hebrew moed-year, originates from an ancient Canaanite meaning: "to be dark". See http://www.angelfire.com/pa2/passover/months-of-the-jewish-calendar.html. Thus, it is not a stretch to say that the moed-year ends in darkness. This is not a convincing argument, but it is interesting.

2Darkness is a sign. Please understand this statement. As stated, since the moon is always visible during any day of the month except when it is in conjunction, then the unseen moon is decidedly a sign. The very absence of the moon when it would otherwise be expected to be visible is, itself, a sign. This is not true of all things which are "unseen". Take for example a total lunar eclipse. If there is a total lunar eclipse and it is not seen from Israel, then as far as Israel is concerned, the lunar eclipse did not happen!

3Some argue that the "modern" definition of "new moon" is different than the ancient. Not true. The term "new moon" has always been defined by the moon passing between the earth and the sun as the period in which it is not visible! This is discernible from observation alone! Modern astronomy may define it as the moment when the celestial longitude of the moon and the sun are the same, but the meaning in ancient times was actually the same! Ancient observers knew full-well that when the moon passed between the earth and the sun, it passed from "old" to "new" at an "unseen" point in time. Thus, they knew full-well that once the moon was again "visible" it was already PAST "new". A visible crescent was always nothing more than an indication to the observer that the month had already begun!

4Proponents of the silly "Lunar Sabbath" calendar will argue that "1st Quarter" will always be on a Sabbath. But the folly in their theory is that "1st Quarter" would only happen on the "7th" or "8th" day of the month (depending on the particular "Lunar Sabbath" calendar variant), every month, only if the moon's orbit was circular. But the moon's orbit is not circular (as can be ascertained by simple observation)! So by actual observations the day of "1st Quarter" can be early or it can be late, but not "always" on the 7th day of the month. Nevertheless, watching for 1st Quarter, to a skilled observer, is a huge clue about when when the next conjunction can be expected, and whether full moon will be "early" or "late".

5Also not substantiated in this article is the fact that astronomical events, if indicative of anything, must be sanctified from the Holy Land, the seat of YHWH's residence on earth, Jerusalem. We do not, for example, determine if a month has begun by whether or not the moon went into conjunction before or after sunset from, for example, Hawaii!

Other articles to consider if you are interested in more on this topic:

Revised November 8, 2020