The Powers That Be

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17 Responses

  1. Dani says:

    I believe it is the rest of the world which is “out of sync” with Israel

  2. Menachem Lipkin says:

    What’s your source for both assertions contained in this statement?

    “This latter statement is inaccurate: the mathematical models were in Jewish hands from the time that the Torah was given, to a degree of accuracy that required NASA to replicate.”

  3. dr. bill says:

    I wonder why if the “average molad,” (not the real molad which varies month to month) was given at sinai, it was even slightly off, even in the 6th decimal place.

    I find these claims, both unnecessary and counter to the Mishnah in Avot that lists astronomical knowledge as “parparuot le’chokhma.” This claim is not in Hilchot Kiddush haChodesh, the first (jewish) source to detail the calculation. Ramabm refers to the right to be mikadaish al pi re’eah as HLMM, not the details of the calculation, The calculation, which is in the next chapter, makes no such claim. (the rambam’s use of HLMM is also different from the way the term is used/implied in your article as well.) the oldest existing source for the calculation, an arab astronomer, who recorded the calculation in the times of the geonim, was impressed by the incredible insight the rabbis exhibited.

    I suspect the rabbis chose to adapt (with the 4 dechiot) an accurate Greek metonic cycle over a slightly more accurate Roman cycle, because it could be more easily remembered. the inaccuracy of less than an hour every 600 years, an error delaying Rosh Chodesh BTW, will require a sanhedrin to correct in about 6000 years. As we know, many amoraim were proud of their knowledge of science; we should be as well.

  4. Yaakov Menken says:

    Yes, it’s part of the Oral Law — Rabban Gamliel states that he received from the House of Hillel (his grandfather) that the time between new moons is “29 days, and 1/2 a day, and 2/3 of an hour, and 73 “chalakim” (a “chelek” being 1/1080 hours). This totals 29.53059 days. [See Rosh HaShanah 25a] This calculation was originally used to prove that witnesses who thought they saw the moon earlier were mistaken — in the example there, people mistook a cloud as the new moon’s crescent on a cloudy evening.

    The following is from Wikipedia: “A synodic month is 29.53059 days (29 days, 12 hours, 44 minutes, 2.8 seconds) and is measured from New Moon to New Moon.”

    Not in the Rambam? He may not repeat the Gemara in R”H which says it’s HLMM, but he gives the details. He says that our calculation is done by comparing the time that the first year began with the start of the “prior” year, referring to the year which ended on the sixth day of Creation. The first new moon coincided with the Creation of Adam, 2 hours after daybreak (14 hours from sunset, the start of a Jewish day) into the sixth day. The prior year’s first new moon began 5 and 204/1080 hours into the second day.

    Rabbeinu Bechayah says that you can find the time of the pre-creation New Year’s encoded in the Torah.

    In actuality, this is an approximation: “Because of perturbations in the orbits of the Earth and Moon, the actual time between lunations may range from about 29.18 to about 29.93 days. The long-term average duration is 29.530589 days (29 d 12 h 44 min 2.9 s).” The calculation provided by Rabban Gamliel is the closest approximation that could be provided in “chalakim,” and is accurate to one day in 14,000 years… and again, if it is decreasing over time, it is of course possible that the average Molad was precisely 29.53059 days b’zman Adam HaRishon. [Note that Wikipedia has less precision: although 29.530589 is smaller than 29.53059, the latter is converted to hours, minutes, and 0.1 seconds less, which is obviously wrong.]

    At roughly the same time that Rabban Gamliel was saying this (in the middle of the 1st Century CE), the church was adopting the Julian calendar, in which the vernal equinox was to occur on March 25. By the year 1582, the equinox had moved back to March 11. Pope Gregory XIII dropped October 5 – 14 from the calendar that year such that March 21 became the equinox (it was March 21 in 325, the year the Council of Nicaea met), redid the calculation of leap years, and put us on the current and more accurate schedule — which has an error of about one day per 3,300 years.

  5. Netanel Livni says:

    >Yes, it’s part of the Oral Law

    So is chanuka and megilla, but they are not from Sinai. R’ Gamliel writes that he has a tradition, not that the tradition is of Sianitic origin. He doesn’t even use the term halacha leMoshe miSinai (and even if he did, there are rishonim that say that such a phrase does not necessarily mean that it was actually given at Sinai, but rather that it is an ancient tradition). Further, the Rambam is fairly clear that the source of these calculations of the beit din is the same as the calculations of all astronomers:

    הלכות קידוש החודש פרק ב

    בית דין מחשבין בדרכים שהאצטגנינין מחשבין בהם, ויודעין הלבנה כשתיראה בחודש זה, אם תהיה בצפון השמש או בדרומה, ואם תהיה רחבה או קצרה, ולהיכן יהיו ראשי קרניה נוטין.

    הלכות קידוש החודש פרק ו

    בזמן שעושין על הראייה, היו מחשבין ויודעין שעה שיתקבץ בה הירח עם החמה בדקדוק הרבה, כדרך שהאצטגנינין עושין, כדי לידע אם ייראה הירח או לא ייראה

    It is very very clear that the Rambam was well aware that the source of this knowledge was the study of astronomy and not revelation at Sinai.

  6. Yaakov Menken says:

    > R’ Gamliel writes that he has a tradition, not that the tradition is of Sianitic origin.

    He writes “mekublani” — I received it, as a Kabbalah. I’m not aware of other cases off-hand in which a Tanna or Amora refers to a Kabbalah and means anything else. I could be wrong but would like to see evidence. For example, I am not aware of either Purim or Chanukah (or any of their numerous Halachos) referred to as a Kabbalah.

    It’s only possible to “determine” the the Rambam relied upon astronomy via selective quotation from the Rambam rather than a full reading of the Halachos. In Kiddush HaChodesh 6:8 he states that we begin all calculations from a pre-Adam “molad”:

    והמולד הראשון שממנו תתחיל, הוא מולד שהיה בשנה ראשונה של יצירה, והוא היה בליל שני חמש שעות בלילה ומאתיים וארבעה חלקים, סימן להם ב’ ה’ ר”ד; וממנו היא התחלת החשבון.

    The Church itself tells us that neither the Greeks nor certainly the Romans knew this calculation. See Dr. Bill’s quotation from the Arab astronomer who was amazed by the knowledge of the Rabbis.

    This is found in Yalkut Shimoni (Devarim 3:4): R’ Shmuel bar Nachman said in the name of R’ Yonason, from where do we know that it is a mitzvah for every person to calculate the seasons (tekufos) and mazalos? Because it says, “and you shall guard and you shall do, for it is your wisdom and your insight in the eyes of the nations.” What is this wisdom and insight which is [understood and appreciated] in the eyes of the nations? We must say that this refers to the calculation of the seasons and mazalos.

    Now how could the Yalkut Shimoni say this, if in fact this knowledge was derived from “the calculations of all astronomers?” It would be nonsense.

  7. dr. bill says:

    The methods to determine the possibility of a real observable molad, and the average period between lunations are very different, as you explain. Knowing only the average, the number given above, is not that useful b’zman that we are mikadesh al pi re’eah.

    what was remarkable to the arab astronomer was the ability of chazal to use the greek metonic cycle, the average period between lunations (probably known from eclipse data), and the dechiot to construct our calendar. Note that chazal were off on the length of a solar year, which causes a very minor (and inconsequential) drift towards summer in the beginning of Pesach (about 1 day every 300 years); their up to the 6th decimal place accuracy was wrt the more important average lunar month. (the julian calendar and the tekufot of shmuel used for tal u’mattar/birkhat hachamah are off by a day every 125 years or so, almost 3 times the inaccuracy of tekufor of r. adda.)

    as to the source of the kabalah, there is a famous adjacent area where some speculate that the term kabalah was also used even for a secular source, a much more complex topic. that aside, as i hinted above, HLMM, according to Rambam, is used even for old traditions that do NOT go back to Sinai, areas for ma’asrot adjacent to EY, i seem to recall.

    my point is that chazal used (and depended on) scientific knowledge and viewed as legitimate without the need for it having a revealed source.

  8. Netanel Livni says:

    >He writes “mekublani” — I received it, as a Kabbalah

    Exactly. How does logic dictate that a Kabbalah is necessarily from Sinai. It could simply mean that he received the method of the astronomical calculations from previous generations. To claim that every instance of the word mekublani implies a Sinaitic origin quickly turns absurd. First it has to account for why two terms are necessary (mekublani and halacha leMoshe miSinai – which as i wrote, not everyone accepts in its literal sense). It also needs to account for why mekublani itself is used in two different ways. It seems to always be a precise trace of a tradition. For example, in Nazir 56b we read כך מקובלני מרבי מיאשא שקיבל מאבא שקבל מן הזוגות שקבלו מן הנביאים הלכה למשה מסיני or Tosefta Yadayim 2:7 where we read כך מקובלני מרבן יוחנן בן זכאי שקיבל מן הזוגות והזוגות מן הנביאים ממשה. Why would we assume that in instances where the use of mekublani term leaves out the entire chain of tradition that it goes all the way back? All we can assume that it means is that the sage in question is stating where he received a particular halacha. Not that the halacha is of Sinaitic origin.

    Your quotation of the Rambam is irrelevant. He writes explicitly in several places that the sages relied on astronomical calculations. To use pilpulei hevel to darshen the Rambam’s formulation of the astronomical calculations so that their starting point is a hypothetical first molad in order to claim that therefore he believes them to be of Sinatic origin is perplexing.

    >The Church itself tells us that neither the Greeks nor certainly the Romans knew this calculation. See Dr. Bill’s quotation from the Arab astronomer who was amazed by the knowledge of the Rabbis.

    The church was very wrong on this. Hillel’s Synodic month is identical to the Babylonian System B and was also quoted by Hipparchus (who was the source for Ptolemy). Further, our tradition seems to be that chazal learned astronomy from the nations of the world. For example, the Rambam in the Moreh 2:8 writes:

    וכבר ידעת שהכריעו השקפת חכמי אומות העולם על השקפתם בעניינים הללו של התכונה, והוא אומרם בפירוש “ונצחו חכמי אומות העולם”

    That is to say, that the rabbis accepted the gentiles’ astronomical system (he almost certainly meant the Greek system). This is just one of several places where the Rambam attributes astronomical knowledge to Greek sources. (He did after all, learn his own astronomy from a gentile source)

    Regarding the yalkut shimoni. It is a midrash (and a very late one at that), not an halachic source. (have you seen this ‘mitzva’ in any of standard codes?) and even if it IS a mitzva, then it most certainly is an asmachta to use the pasuk.

    All in all, we must have some minimal historical analysis when dealing with these issues. To you it may be edifying to believe that chazal received this calculation as a tradition that was based on revelation. But if someone else hears such a claim only to later learn that it is … well … false, then it could cause a lot of damage.

  9. Daniel Weltman says:

    >the mathematical models were in Jewish hands from the time that the Torah was given, to a degree of accuracy that required NASA to replicate.

    Rabbi Menken, there is a danger in this statement. It implies a demonstration of the Torah’s incomparable knowledge of something that, in the scientific and cultural milieu, is impossible to explain naturally. In fact though, a similar degree of accuracy was attained by the Babylonian calendar. The degree of accuracy, then, did not require NASA to replicate.

    I personally know people who made huge life changes based on “proofs” of this nature, and when they find that the statements were less than true, feel cheated and fooled.

  10. Bob Miller says:

    If the ancients had the will and the means to design an accurate enough calendar based on observation, which seems to have been the case, what would have been the purpose of imparting such knowledge through revelation?

  11. Yaakov Menken says:

    It is delightful to have both Netanel and Dr. Bill strengthening my case.

    First, Netanel response to my request for evidence of cases in which the word “mekublani,” from Kabbalah, received tradition, is not a reference to Halacha L’Moshe MiSinai, the Oral Law, by providing two examples in which the word mekublani is used explicitly to trace the line of transmission back to the Prophets and to Moses himself. Why would we assume that in this instance, uniquely, mekublani does not refer to Oral Law, when it is used exclusively to refer to the Oral Law in all other cases? I requested examples in which a Tanna or Amora refers to a Kabbalah and means anything else; if this is the best that Netanel can offer, then as I said, it greatly strengthens my case.

    As I’m short on time, I’ll simply add that misreading the Rambam in the Yad cannot be rectified by misreading him in the Moreh and confusing the length of the lunar month with stargazing.

    Dr. Bill similarly strengthens what I’ve said with regards to the calculation itself. We do not have a Mesorah for the length of the solar year. It is empirically obvious that an accurate calculation of the solar year, which is constant, is far easier to accomplish than an accurate calculation of the lunar synodic month, given that the latter exhibits a tremendous degree of variation (up to three quarters of a day, according to Wikipedia) depending upon the location of the sun, earth and moon, requiring roughly 19 years before they all line up again. How, then, does it make sense that the same astronomers whom they believe to have advised the Jews with a minor (and inconsequential) drift with regards to the solar year were much more accurate than the church, but much less accurate than they were regarding the lunar cycle, which they determined to a degree unequaled until the past 100 years?

    I am sorry that Daniel is uncomfortable with this fact, but it remains true nonetheless.

  12. Nachum says:

    Josephus, interestingly, says that the reason the first twenty generations lived so long was so they could make the astronomical observations needed for future generations. Nothing divine to it. (Of course, we know that even that isn’t necessary.)

  13. Daniel Weltman says:

    I am sorry that Daniel is uncomfortable with this fact, but it remains true nonetheless.

    Rabbi Menken, you wrote that it took NASA to replicate the accuracy of the Jewish calendar. In fact, I pointed out, the Babylonians were able to. Superiority claims such as the one you made are often used as “proof” upon prospective ba’alei teshuva. I personally know that a crisis of faith in Torah, God and especially the rabbis heretofore so revered is precipitated when some of these people learn simple fact that this claim (and similar ones) is not true. It is not discomfort, but the realization of the far-reaching effects this false claim can have on real people.

    Furthermore, you are assuming that accuracy as to the length of the lunar month is evidence of divine wisdom. However, consider that the Jewish calendar is not simply a lunar calendar, and its other parts reveal larger problems. The calendar is a lunar and solar amalgamation, meaning that although it is primarily lunar, it takes into account the solar year as well. This fact does not bode well for those who claim a divine measure of perfection from our calendar. The Hebrew calendar is predicated on the idea that 235 lunar months is equal to 228 solar months. Though this equation is accurate enough for a while, it causes the solar and lunar year to be off by enough that eventually, we would end up celebrating Pesach in the summer (this point is made in a post by the wolfishmusings blog, in a 2009 post entitled “The Accuracy (or lack thereof) of the Jewish Calendar”1). Although the calendar is corrected by pre-emptively adding a leap year, it still results, already, in serious problems for the Jewish year.

    A number of these problems are presented in a long but fascinating article on the Jewish calendar by Dr Irv Bromberg (University of Toronto, his article can be found by searching Google with “bromberg the seasonal drift of the hebrew calendar”). He provides an exhaustive and masterful presentation of the celestial realities, and a demonstration that 21% of our months are seasonally a month late. Since Cross-Currents does not accept links, I will provide some quotes. In his words:

    “Also shown is a dashed red horizontal line indicating the “early limit”, calculated as the year 4116 equinox moment minus 1/2 of a traditional molad interval. Any equinox moments plotted above that early limit indicate years in which the month of Nisan (and the months after it until the next Nisan) is at least one month “late” with respect to the equinox. For the present era, this shows that years 8, 19, 11 and 3 of each 19-year cycle are always one month late, year 3 of 19 having only recently emerged above the limit! So although the average drift of the calendar amounts to “only” 7 days and 10 hours, presently 4 out of every 19 years are one month late, and the remaining 15 years are “on time”! In other words, presently on average about 4/19 = 21% of all Hebrew calendar months are one month late! This figure is in good agreement with the simple arithmetic estimate of 24%, obtained above.”

    After this, he states good reasons for adjusting the calendar to correct this serious defect, along with an elegant solution to the problem:

    “For the following reasons, it would be preferable to correct the Hebrew calendar seasonal drift as soon as possible:”

    “The seasonal drift has accumulated to a highly significant degree: currently in every 8th, 19th, and 11th year of the traditional 19-year cycle, and soon also every 3rd year of the cycle, Passover is more than a month after the spring equinox, Purim is celebrated on the day before the day that “should have been” Passover, and the traditional Hebrew calendar continues to run “one month late” until the following spring season.”

    “To allow new grain crops to be eaten one month earlier in those years in which otherwise the 16th of Nisan would fall more than a month after the spring equinox (applies to the years just mentioned). Note that this continues to apply in the present era even though the omer sacrifice is not offered in the absence of the Temple, as orthodox Jews refrain from consuming products made from new grain crops until the 16th of Nisan.”

    “When Passover is more than a month after the spring equinox then also the following Sukkot (Feast of Booths) is a month later and, in the northern hemisphere, is colder and wetter than it would otherwise be (years 9, 1, 12, and soon also year 4 of the 19-year cycle, the above mentioned year numbers having been incremented at Rosh HaShanah), which makes dwelling in the traditional sukkah uncomfortable or impractical, notwithstanding the belief by many that time spent in the sukkah is “not supposed to be comfortable”.”

    “In such years, the rainy autumn season in Israel begins well in advance of the geshem prayer for rain on Shemini Atzeret.
    On the principle that a mitzvah should be performed as soon as possible (this applies to all calendar-related commandments and High Holy Days).”

    “In the past the amount of equinox drift and the solution to the problem was unknown or uncertain, so it could not be confidently corrected, but today, due to an excellent understanding of the celestial mechanics of Earth, Moon, and Sun, we do accurately know how much drift has accumulated, and the solution for correcting it and preventing further drift is simple and straightforward.”

    1 Cross Currents does not currently allow commenters to post links. I have tried to provide a way Rabbi Menken and readers to access the articles I refer to, but recognize that nothing is as easy as clicking a link. So please feel free to email me at and I would be happy to provide links.

  14. dr. bill says:

    daniel weltman, i wholeheartedly agree with your sentiments about claims of HLMM and unique scientific knowledge known (only) to chazal. I also agree that there is drift that could be eliminated if we had used the calendar prof. bromberg constructed. It has ONE fewer intercalculated month (than our calendar based on tekufot of r. adda) every 6000 or so years and requires a significant computerized calculation to develop. i noted above that a sanhedrin will have to remove one month from our calendar sometime in the next 3-5 thousand years. Your concerns about prayers for rain and a colder than necessary sukkot are not halakhic reasons requiring action.

    there is also no evidence that when we intercalculated based on observed reasons, chazal did not also have a drift. remember the sugyah of successive intercalculations. after all is said and done, late by a month is not a halakhic issue, early by a month is a problem and the calendar is never early.

    hopefully, we will have a sanhedrin well before 3 thousand years from now. the sanhedrin will either wait until they can drop a month and maintain our current calculation or choose a new calculation for the calendar, like prof. bromberg’s.

    if you want a topic in this area to discuss, check out the next time we say birchat hahamah.

  15. Daniel Weltman says:

    Dr Bill, I have a post on my own blog precisely about Birkat Hachama, and I point out there that the halachik calendar only has to be “good enough”. I have no problem with this. However, when it is claimed that the calendar is divine, and people become ba’alei teshuva based on this and the like claims, it is important to point out the flaws of the calendar. Our faith and dependency upon the great Torah and reverence of the sustaining and unique Oral Law need not rest on shaky and tenuous claims. Our masorah has so much to offer without these.

  16. Yaakov Menken says:

    What Daniel provided is interesting, edifying, and ultimately irrelevant, as he misquoted me and proceeded to address a strawman.

    I did not write that “it took NASA to replicate the accuracy of the Jewish calendar,” and in my previous comment already pointed out the difference between our understanding of the solar year, which is easier to calculate and yet we knew with less precision, vs. the lunar month, which varies radically, and which we knew to a level of accuracy unequaled by Copernicus, much less Ptolemy. This was something the Medrash says would demonstrate our wisdom in the eyes of the Nations, so if indeed the Babylonians had this information it is not difficult to discern how.

    For complete accuracy, I must point out that I spoke with an Adam Gadol (in context, a distinguished scholar) who told me that there are, in fact, exceptions to the rule that “mekublani” refers to a Kabbalah of Halacha L’Moshe MiSinai (I should also note that this does not refer to everything we today call the Oral Law, but specifically to that which was given to Moshe along with the Written Torah) — but that this wasn’t one of them. When G-d said “this shall be for you the first of months” [Exodus 12:2] He told Moshe exactly what he meant.

    I’m not going to have time to repeat myself again and get new material written, so I suggest we move on.

  17. Daniel Weltman says:

    Oh, and the concerns in italics are Professor Bromberg’s, not mine.

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