Astrology in Ancient Judaism, Astronomy in Ancient Judaism

J. Neusner, A. Avery-Peck and W. S. Green (eds.), The Encyclopaedia of Judaism, V, Supplement Two, Leiden - Boston: Brill, 2004, pp. 2031-2044  Meir Bar-Ilan



In Antiquity astronomy was not only a kind of applied mathematics but rather a way of knowing God(s), science and Religion combined. When God is depicted as counting the stars and giving them names (Psalms 147:4; Isa. 40:26), it is apparent that any believer in God who practices astronomy works together with God while imitating Him, imitatio Dei, as the ultimate religious practice.



While the Bible has comparatively a lot to say on medicine, astronomy is rarely mentioned or alluded to. The idea that there were “rules of Heaven” (Jer. 33:25; Job 38:33) doesn’t say much about the observation of stars or having any understanding in Astronomy, especially in a text that wholly rejects star-worship. Only God knows the exact number of stars, as well as their names (Isa 40:26; Psa. 147:4), while such a task is beyond man’s ability (Gen. 15:5). The prophets and the sages were aware of at least seven different stars and constellations (Jer. 44:17-19; Amos 5:8, 5:26; Job 9:9; 38:32). Though what we consider as Astronomy is missing, its offshoot as a deep consciousness of a calendar exists, even slightly. The way the luminaries are said to have been created (Genesis 1:14) shows awareness of the role of both luminaries in the calendar. The story of the Flood (Gen. 7-8) reveals calendrical thinking, as of an awareness of 11 days gap between a lunar and a solar year (according to the Massoretic text). The five “stops” in the Flood narrative shows awareness of (a solar) calendar. The Scroll of Esther shows another kind of calendar thinking, as well as astrology, but astronomy is absent.

Post- Biblical

Theophrastos (372-288/7 BCE), a disciple of Aristotle, wrote that the Jews watch the stars at night and pray to God. Since Theophrastos wrote in the context of sacrifices, it is evident that he was writing about priests in the Temple where the exact date had significance for the ritual, sacrifices and festivals (=calendar). Though there is no other evidence that priests were engaged in Astronomy (Psa. 8:4 is not sufficient), it goes well with the Mesopotamian tradition where there was a connection between astronomers and priests. Moreover, before the destruction of the Temple (in 70 CE) there was a priestly court in Jerusalem where testimonies of the sighting new moon were analyzed (m. Rosh Hashana 1:7), so there is no reason to doubt Theophrastos’ evidence

Post-biblical writings reveal much more interest in Astronomy than in former generations, at least as can be seen from textual creativity. In 1 Henoch, a Priestly Aramaic book that was edited out of (at least) 5 books, there is an astronomical work (ch. 72-82), from the 3rd century BCE. The Astronomy book is based on Mesopotamian astronomy as seen by its measuring the movements the Sun’s rising point at the along the horizon as well as from other aspects. The book shows a unique combination of Astronomy and religious mystical cognition, based on a 364 day solar year, beginning on Nissan 1. The advantage of this calendar is its simplicity together with its fixed days of the festivals on the week-days (e.g. the 1/1 is always on a Wednesday). However, losing a day and (almost) a quarter every year leads to a gross deviation from astronomical (“real”) time. The priest who wrote the book of Jubilees, though deeply interested in rewriting the Bible according to a profound understanding of chronology, based his calculations on a 364 day year similar to 1 Enoch (Jub. 6:32-38). The people in Qumran had (or: tried to have) the “Jubilees” calendar of a solar year, made of 364 days, as in the Temple Scroll, but it is most likely that they used other calendars (though not simultaneously). The day began probably at sunrise as in Lev. 7:15 and Rabbinic Priestly traditions as in t. Zebahim 6:18. Some 20 texts found in Qumran show a deep consciousness of calendrical issues that, although they do not support a new calendar, they do exemplify the importance of the role of the calendar in Qumran. 2 Enoch (that was not found in Qumran) comes from another priestly milieu, most probably: from Jerusalem, where Enoch was a hero. The author writes of a more complex calendar than that in 1 Enoch, of 365 ¼ days a year, with 7 years of intercalation in a cycle of 19 years, and a great cycle of (19*28=) 532 years (2 Enoch 6:21-26). The author gives the order of the planets in a non-Hellenistic system: Saturn, Venus, Mars, Sun, Jupiter, Mercury, Moon. It is quite obvious that this calendar shows a better knowledge of astronomy (and more ‘modern’) than the one in 1 Enoch, reflecting Hellenistic, combined with Mesopotamian, influence.

Rabbinic attitude

Rabbinic astronomy cannot be considered as a continuation of earlier priestly concepts. Rabbinic astronomy began rather as a popular and practical occupation, with anti-priestly affinities, and only through generations of tradition did it gain a scientific value. In the days of the Temple Rabbis made intercalations according to natural phenomena (t. Sanhedrin 2:2-3). In the beginning Rabbis were relying on any testimony (such as cattle-herders; p. Sanhedrin 1:2, 18,3), but after a few generations they intercalated according to astronomical calculations, in a much more professional way (t. Sanhedrin 2:7). The same process of development happened in observing the new moon: in the first and second centuries the Rabbis needed witnesses of the new moon (so badly as letting the witnesses transgress the Shabbat – m. Rosh Hashana 1:5-6). Several centuries later the Rabbis needed these witnesses no longer; they relied on their own calculations, establishing a Jewish calendar. The exact development of the Rabbinic attitude towards astronomy and the calendar is difficult to describe since the evidence is either blurred or contradictory, but the bottom line is clear. The Rabbis’ decisions exemplify a process of a long course of deepening awareness of scientific (that is: Hellenistic and Mesopotamian) Astronomy. However, the Amoraim themselves were not aware of this process, being of the opinion that the knowledge of seasons and intercalations was part of the knowledge of the children of Issachar, as already written in the Bible (1 Chro. 12:33; Genesis Rabba 72).

Few sundials have been found in the Land of Israel, as another proof of astronomers’ activity (in an era when keeping time was done by astronomers, not instruments). The Rabbis used sundials to a small extent (m. Eduyot 3:8; Mechilta deRashbi 12), leaving no impression on their main interest: Halakha.

The Earth and Cosmos

It should be borne in mind that the Rabbis, while having a religious obligation concerning astronomy, with regard to the Biblical rules of observing the calendar, at least to observe the rules of the Temple, had no motivation for learning Geography. For that reason, while Ptolemy excelled in Astronomy and Geography as well (based on similar doctrines), the Rabbis were interested in Astronomy only, while ignoring the scientific study of Geography. For that reason there are Jewish traditions of non-scientific concepts about the cosmos. For example: “Egypt is 400 over 400 parsah (Persian parsang), and Egypt is 1/60 of Kush, and Kush is 1/60 of the world, and the world is 1/60 of a garden”, etc. (b. Pesahim 94a). The schematic narrative shows that this was a kind of midrash and not a strictly geographic concept. This understanding should be applied to a tradition that appears on the same page: “From Earth to Heaven – walking distance of 500 years, and the thickness of Heaven - walking distance of 500 years, and from one Heaven to another - walking distance of 500 years”. The Rabbis thought that the heavens were made of water and fire. According to Biblical concepts (Job 26:11) the world rests on columns (b. Hagiga 12a). However, the Rabbis described the world as a ball (p. Aboda Zara 3:1, 42c). Rava (3rd-4th centuries in Babylon) said that the whole world is 6,000 parsah (b. Pesahim 94a), which is about 24,872 miles, close to modern estimates.


In the whole of Rabbinic literature covering the first five centuries of this era, there is no evidence that any of the Rabbis read any non-Jewish book on Astronomy, though the Rabbis did have many relationships with non-Jews. These relationships were face to face, some with philosophers and some with astronomers. However, it seems that the Rabbis found their own way in astronomy independently with several observations. The four points of the compass (the cardinal points that divide the horizon) were well known to the Rabbis (b. Erubin 56a). The Rabbis thought that a solar year has 365 days (b. Rosh Hashana 6b) while a lunar year has 354 days (t. Nazir 1:3). It took the Rabbis some generations to realize that their data was not precise enough, certainly for calendrical purposes. The state of the Rabbis’ knowledge of astronomy was improving in the course of centuries in moon-observation and intercalations.

Those who saw the new moon appeared before a court, first of priests and then of Rabbis, who checked the witnesses and evaluated their testimonies (m. Rosh Hashana 1:7). The different courts had different rules and it is highly probable that they had different calendars at the same period. R. Yohanan b. Zakkai (1st century), one of the founders of the Rabbinic tradition, was said to know all the Torah, Tequfuth (seasons, the moments of equinoxes and solstices) and Geometry included (b. Sukkah 28a), that is calendrical calculations and astronomy. No evidence is given to support this claim.

The 11 days (=365 – 354) difference between a solar and a lunar year is attested to as an astronomical observation. R. Shimon b. Gamliel said that it is very simple to observe, with a scratch on the wall, that the solar year is longer than the lunar year by 11 days (Genesis Rabba 33:8). Even earlier, the author of Seder Olam (attributed to R. Yossi), thought that this gap of 11 days between a solar and a lunar year is already attested to in the flood story (Seder Olam 4).

The idea that the length of a lunar month is approximately 29.5 days is implicit in the halakhot concerning the intercalation of a month (t. Arakhin 1:8), in which 12 months yield (365-11=) 354 days. However, in the Talmud it is stated that Rabban Gamliel (II, the Prince, 2nd century CE) said, according to his family tradition: “A new moon (doesn’t appear) in less than 29 days and a half, two thirds of an hour and 73 parts” (b. Rosh Hashana 25a). This length equals Ptolemy’s value in sexagesimal fractions: 29:31,50,8,20d. However, In modern scholarship there is almost an agreement (though without a manuscript to rely upon) that this testimony was honed by adding a few words so as to support greater exactness, for 3 reasons: 1) in the whole of talmudic literature this “part” (dividing an hour into 1080), is unique. 2) this kind of exactitude has no parallel in Talmudic literature. 3) after saying “no less than” (=minimum), there is no reason to expect exactitude, which is a self-contradiction. This analysis shows that Rabban Gamilel’s words were either “29 days and a half” only (as preferred) that yields a lunar year of (minimum) 354 days, or “29 days and a half, two thirds of an hour” (more doubtful), that yields a lunar year of 354 1/3 days.

Rabban Gamliel had all sorts of images of lunar crescents against which he could check the witnesses (m. Rosh Hashana 2:8). While he stated the opinions of the sages of Israel as against the sages of the nations, we are told that the sages of Israel contend that the sphere is fixed while the zodiac signs are cycling, but the sages of the nations say the opposite. R. Judah the Prince, as the last referee, added an argument to prove the Jewish opinion (b. Pesahim 94b). However, in another dispute, stated at the same place, concerning the path of the sun at night, R. Judah the Prince said that the opinion of the sages of the nations seems to be superior. According to Maimonides (Guide 2:8), the Rabbis held the Pythagorean opinion, while the opposing sages were Aristotelians, and they were victorious.

Shemuel was one of the most famous Amoraim in 3rd century CE Babylonia. He was an astronomer and astrologer as well (and maybe even a physician), as attested to in his various sayings. Shemuel was of the opinion that a lunar year is not less than 352 days and not more than 356 days (b. Arakhin 9b), that is mean length of 29:12 days. Except for observations of the sun and of the moon in regard to the calendar, the Amoraim (Land of Israel, 3-5 centuries), watched a minimum of 2 stars after sunset as denoting a new day (p. Berakhot 1:1, 2:2), but this observation had no astronomical value. There are very few other astronomical observations among the Rabbis. Among them was the observation that when Kima (mentioned already in Amos 5:8, Job 9:9, 38:31), sets in 17/2 (=Iyar), the fountains give less water, and that is why the flood began on that day (b. Ber. 59a; b. Rosh Hashana 11b). Shemuel said that Kima is a cold star compounded of some100 stars (b. Berakhot 58b). Later Kima was identified with the Pleiades. Shemuel said that Kesil is a hot star without which the world would not survive (ibid). Shemuel said: “the paths of the sky are known to me like the paths of Nehardea, except for a comet whose nature I do not know” (b. Berakhot 58b). After Shemuel’s statement the Talmud continued: “we have learnt that it (a comet) never passes through Kesil, and if it does – the world will be destroyed” (Kesil is mentioned in Amos 5:8; Job 38:31 and identified by ibn Ezra as “the heart of the Crab”). Shemuel was asked: “(Is it true), we see that it passes?! And he answered: “This is impossible, either the comet goes above it or beneath it. (p. Berakhot 9:2, 13c). The Rabbis said that there is a star that rises once in 70 years and deceives sailors (b. Horayot 10a). It is assumed they meant the comet later named after Halley, a comet that appeared around 140 CE (and 70 is taken as a round number for a cycle of around 78 years).

In a sermon that R. Afes (3rd century) gave in Antioch (Genesis Raba 10:1) there appear data concerning the times of the planets’ circling the earth in a very scientific way (compare to Vitruvius, On Architecture, 9:1). This sermon was given on the occasion of reading the beginning of Genesis, and the whole sermon has a flavor of combining Torah and science (as in modern times).

Bar Kappara (Land of Israel, 2-3 centuries CE) said: “one who knows how to calculate the seasons and zodiacal signs (in calendrical issues), but he doesn’t do so – of him Scripture says: ‘But they regard not the work of the Lord, Neither have they considered the work of His hands’ (Isa. 5:12)”. R. Johanan said that there is a religious commandment to calculate the seasons and the zodiac signs (=months), (b. Shabbat 75a). These opinions are a continuation of a long tradition that sees the study of astronomy as a religious practice.


The Jewish calendar is lunisolar, that is as in Mesopotamia. The calendar has no pretension to be exact every day, from an astronomical perspective, but in the long run it shows adaptations to both solar and lunar cycles. Almost every year is slightly different in length than the former year. Every year has either 12 or 13 lunar months. Months begin in the evening when the lunar crescent is first visible after conjunction. The calendar played a religious role, in determining the day on which festivals occur.

While for modern man a calendar is nothing more than a booklet with which one can plan one’s schedule, for the Rabbis the calendar was the authority for either a Rabbinic or a sectarian Jew (m. Rosh Hashana 2:9; b. Berakhot 63a-b). According to the Rabbis, their contemporaries, non-Rabbinic Jews, did their best to distort the authoritative Rabbinic calendar (m. Rosh Hashana 1:1-2; t. Rosh Hashana 1:15). Josephus while describing the sects is silent concerning this issue, but his silence should not be overemphasized. Hizqia, a 3rd century Amora in the Land of Israel, explained that the villains who do not understand the deeds of God in Psa. 28:5 are those who do not know the Tequfuth (Shoher Tob 28), that is, heretics. This notion of the 1st-3rd centuries was left to oblivion until it became crucial again in the 9th-10th centuries. Karaites, needless to say Samaritans, have their own calendar until this very day.

The bud of a calendar can be seen in the 3rd-4th centuries CE. Some Rabbis initiated rules concerning the “postponing” of Rosh Hashana so that it would not occur on either a Wednesday or a Friday, for the convenience that Yom Kippur should not fall either before or after Shabbath (b. Rosh Hashana 20a). R. Simon ruled that those who calculated the calendar should make sure that The Day of Willow (Tishre 21) does not occur on the Shabbath, so that they will not be able to observe the commandment of beating the willow (p. Sukkah 4:1, 54b). The meaning of this rule is that Rosh Hashana should not fall on a Sunday so already from the days of the Amoraim, there existed a rule that “Rosh Hashana never falls on Sunday, Wednsday or Friday” (in initials: “lo ADU Rosh”). In later generations the calendar had to include more rules from different aspects. For example, Ellul should always have 29 days only, a rule that was stated as a (false) historical fact (b. Rosh Hashana 19b). The accumulation of rules during many centuries (from about 3rd-10th centuries CE) changed the calendar from a calendar de facto only to a calendar by which Millennia can be calculated in advance. This process of being “under construction” doesn’t allow us today to calculate the exact day in the month before the 10th century CE.

Shemuel is the first Rabbi to give the duration of the solar year more precisely than the Tannaim. Shemuel said: “in between every tequfa (season) there are 91 days and 7 ½ hours” (B. Erubin 56a), that is an average that yields a solar year of 365 ¼ days, in accordance with the Julian year. He showed his astronomical knowledge by sending to the Land of Israel a calendar with intercalations for 60 years in advance, a calculation that was not enough however to impress R. Yohanan (b. Hulin 95b). Shemuel was also sure he could make calculations of the calendar (without the need for witnesses) for the whole Diaspora (Babylonia), but he was shown that he wasn’t aware of some of the rules of the calendar (b. Rosh Hashana 20b), or else this rule had no Babylonian origin. A certain Amora in the Land of Israel, R. Yohanan b. Media, said he calculated a date (24/7) mentioned on the Bible (Neh. 9:1), saying that it didn’t fall on Shabbat (p. Aboda Zara 1:1, 39b). Though it is not clear on what basis this calculation was based, still it doesn’t necessarily mean that R. Yohanan b. Media was an expert in intercalations. The idea that R. Ada b. Ahaba (3rd century Babylonia) was an expert in the calendar (with more precise data than that of Shemuel, such as the length of the tequfa: 91:7:28), was known only to medieval Rabbis, and it is not rooted in the Talmud. The dispute over the authenticity of calculations attributed to R. Ada has not been settled yet, but it should be noted that in the Talmud there is no mention concerning R. Ada’s capabilities.


According the Rabbis, intercalation, that is adding a lunar month to the year, is based on the idea of observing the month of the Abib in the spring (b. Rosh Hashana 7a; b. Sanhedrin 13b), while the Mesopotamians had the same idea (without having the Bible) based on astronomical observations. The Rabbis considered the discussion among them whether to intercalate the year as most prestigious (b. Sanhedrin 11a), and in later generations this discussion was considered esoteric (b. Rosh Hashana 20b; b. Kethuboth 112a). Applying secrecy to a Rabbinic doctrine is most unusual, whatever the exact meaning of that was. The Rabbinic calendar continues the Mesopotamian tradition in that only Addar is intercalated, that is the last month of the year, maybe also because agricultural observation is meaningful only in Addar. The Mesopotamians intercalated Ellul as well, and though the Rabbis were aware of the possibility of adding another Ellul, it was understood that it was done under pressure only (t. Sanhedrin 2:7). The month of Ab may have once been intercalated (b. Sanhedrin 12a). To enable keeping the laws of Shebi‘it, and because of natural phenomena, the Rabbis had no systematic order of intercalation (t. Shebi‘it 2:9, 2:12). According one of the basic calculations of the Tannaim (t. Sanhedrin 2:7), a cycle of 19 years of intercalations might occur but a set of 7 years intercalated in a cyclic of 19 years is not attested to in the Rabbinic sources before the 7th century CE. This system was practiced in Babylonia from around the fourth century BCE, and it reasonable from several perspectives. Medieval Rabbis claimed that once there had been a Tannaitic rule on intercalations cycle of 19 years, but it was lost. However, authentic Rabbinic sources contradict such a claim (though not all contemporary Rabbinic authorities agreed on this). At the beginning of this era, intercalations were made for non-astronomical reasons, such as the state of livestock and fruits (t. Sanhedrin 2:6; b. Sanhedrin 11b). That is to say that from its very beginning the Jewish calendar was more an agricultural calendar (as well as a religious one) than a precise astronomical calendar.

Date of foundation

According to medieval authorities (Abraham b. Hiya and Nahmanides quoting R. Hai Gaon), the Jewish calendar, based on calculations, began with R. Hillel (the 2nd) son of Jehuda in 359. However, not only is this fact not attested to in Talmudic sources, but even later authorities (ibn Ezra, Maimonides) failed to mention R. Hillel, so there is doubt concerning Hillel’s role in the development of the calendar. It has bean claimed that a certain piece of paper with an old text was found in the ruins of Tiberias, attributing to Hillel some share in calendar issues, but it is not clear whether this paper is authentic. It should be noted that in the Middle-Ages there were other opinions concerning the beginnings of the calendar. R. Hai (b. Nahshon) said that the calendar had been established by R. Ishak Nafha, but no Talmudic tradition attests to that. An Arab writer wrote that a certain Eliezer b. Paroah (elsewhere unknown) initiated the Jewish calendar, once again without any confirmation. R. Saadya Gaon claimed that the calendar was “a rule to Moses on (Mount) Sinai” thus giving the calendar authority by its antiquity (and theological aspect). It seems that all these explanations (as well as other medieval concepts attributed to the sages of the Talmud), were given against the background of various disputations over the “correct” calendar.

Later scholars and Rabbinic authorities were sure that their own understanding was the same as their ancestors’ and speculation became facts of History. Theology went hand in hand with astronomy and since astronomy required an epoch, that is a beginning of the calendar based on astronomical observations by deduction, naturally the Creation of the luminaries was taken as such an epoch, that is the beginning of the calendar. Jews began to calculate their dates according to Annus Mundi not earlier than the 7th century, though there were different systems of calculations for few hundreds years later.


In Talmudic literature there are only sporadic statements concerning the stars. However, the observance of the new moon in regard to the Jewish calendar as well as discussing intercalations is one of the main issues of tractate Rosh Hashana. That is, there was full awareness of the daily calendar while its scientific background was ignored, ignorance that gradually disappeared in later centuries.

In the lost Midrash of 49 Middot, from the Land of Israel, probably from the 4th-5th centuries, there is a sermon that has fortunately been preserved (Yalkut Shimoni, Shemot 418). The Rabbi found a correspondence between the zodiacal signs in the heavens and the way the tribes of Israel dwelled in the desert. He stated: “Tribe of Judah in the East, Isachar and Zebulun with him. Against them in heavens are Aries, Taurus and Gemini. With the Sun, together they serve five parts out of eight”. Probably he meant that out of the 1800 in the Eastern horizon, the Sun on the longest day, rises at azimuth of 67.50. However his words are understood, it is evident that the Rabbi (and his audience) knew something about Astronomy, which played a role in the synagogue.

Baraita deMazalot is a unique astronomical and astrological tractate. It gives astronomical data in unprecedently scientific ways. The author describes two different systems, an Egyptian and a Babylonian one, regarding the position of the stars in the zodiacal signs at the moment of creation. The author gives the exact distances from the Earth to the Moon, from the Moon to Mercury and so forth in a manner resembling the Mesopotamian beru ina same, x heavenly units equal to y earthly units. The author quotes not only Rabbinic sources but states the opinions of “the sages of the Gentiles”, “the sages of Egypt, Chaldeans and the Babylonians”. There is no doubt that the writer drew some of his data from Ptolemy (not necessarily directly), but his other sources remain to be analyzed. The author used Greek terminology, such as trigon (triangle), Stirigamos (standing) and diametron (diameter). The writer was probably a Rabbi who lived in the Land of Israel in 5th-6th centuries, and one of his sermons shows his competence very well.

R. Elazar Ha-Qalir, in the 6-7 centuries, was a master of the Hebrew language, a sage who knew all Rabbinic traditions and a prolific poet who wrote hundreds, if not more, Piyyutim, many of them still in use until this very day. In a famous Piyyut of his (“az raita ve-Safarta”, to parashat Sheqalim), his abilities as a mathematician and geographer are clear. However, in a Piyyut, only recently discovered (“or Hama u-Lebana”), it becomes apparent that he was an astronomer as well. In his Piyyut Ha-Qalir gives data of astronomical value: a solar year is 365 ¼ days (like Shemuel), and a lunar year is 354 1/3 days (without explicit precedent). His intercalation cycle was of 19 years (“Ehad beEhad Gashu”), but he had another solar cycle of 28 years (similar to b. Berakhot 59b), and more data in his Piyyutim has not yet been evaluated (e.g. his Piyyut: “abi kol Hoze”). It is assumed he was the head of the Yeshiva, the Jewish academy, in Tiberias and played a role in the process of intercalations.

Pirqe de Rabbi Eliezer is a midrash from the Land of Israel, from the 7th or the beginning of the 8th century (though it claims to be older with pseudepigraphic beginning and other statements). Chapters 5-7 discuss the calendar in prosaic Hebrew in a way similar to Ha-Qalir’s poetics. The author’s solar year is 365 ¼ days and his lunar month is 29:12:793 (assumed to be a Talmudic tradition). The author continues by stating that the length of a lunar year (as precisely multiplied by 12) is 354:8:876, exactly like in Midrash Agada, Buber ed., Genesis 1:14, Midrash Sod Ha-‘Ibur, and in our “modern” data (though very slightly bigger than the ‘real’ time). This precision makes the author of this midrash a good candidate for the founder of the Jewish calendar. The author’s astronomy is combined with angels and he uses the terminology of “large hour”, that is two hours, and giving the heavenly windows names, unknown earlier. The author teaches that a human eye can see the new moon 16 hours after the lunar conjunction. The author gives his calculations in regard to ecliptical limits: A solar eclipse will occur if the moon’s latitude at conjunction is at most 60 “ma’alot” (units), and a lunar eclipse at most 40 “ma‘alot” (units). The moon’s great cycle is of 21 years while the sun cycles every 28 years and this leads to a great cycle of 84 years (21*4=28*3), that is (approximately) one hour of God (based on Psa. 90:4), though this cycle is not easy to explain. However, his system of intercalation is based on a 19 year-cycle, like the “modern” Jewish calendar, while adding one lunar month in the years 3, 6, 8, 11, 14, 17, 19. From the way the author portrays Biblical heroes as having secret knowledge of intercalation, and from his own description of the process of making decisions on this issue, it is evident that the author played an active role in calendar decisions. That is to say the author, Rabbi and astronomer, was one of the heads of the Yeshiva in Tiberias where they met at least once in 2-3 years to consider whether to intercalate the year or not. The author’s data, together with Talmudic halakhah, reveal that the author’s calendar could have been as exact as ours.

The “editor” of the Aramaic Targum attributed to Jonathan b. Uziel in his translation of Genesis 1:16 made an addition that places him among the most knowledgeable scholars of the calendar. The translator says: “both (luminaries) were equal in their foundation: 21 hours minus 672 parts of an hour”. That is: every month has 29:12:793 days so the “difference” of the new moon from one year to another (an “ordinary” year), is 4:8:876 (so far like Ravina according Rashi in b. Arakhin 9b). Now, Adam was created on the New Year (according to Rabbinic tradition), and it was on a Friday, that is 6:14 (considered by Jews of Babylonia to be the beginning of the calendar). From this it is clear that the new moon in the previous year was at 2:5:204 (considered by Jews of Palestine to be the beginning of the calendar). However, since it is written that the luminaries were created on Wednesday, on the very same day, it must have been in the year before (6:14 - 4:8:876 - 4:8:876), that is 4:20:408. In other words, both luminaries were created on 4:(21 hours – 672 parts). In short, the calculation of the translator is based on two virtual years before Adam was created, showing the type and level of the astronomy of the translator, and it seems that the translator used the same system as R. Elazar HaQalir.

Baraita deShmuel is an Astronomical and Astrological tractate, based on Biblical knowledge combined with Greek science, as is clear from its inclusion of a few Greek words, such as ametron (without measure). The author uses some of his own terminology. Some of his Hebrew words are mere translations. A degree is called “hail”, that is an army-corps (following b. Berakhot 32b). The author uses “large hour” as does Pirqe de Rabbi Eliezer. The author shows his ability to use a “reed”, Qane (a precursor of the theodolite, already known in Egyptian Astronomy), which makes him the first Jewish author to do so. The author gives the values of the noon-shadow during the year (Cancer 0; Leo and Gemini 2; Virgo and Taurus 4… Capricorn 12). The author gives the oblique ascension of the zodiac signs such as “Aries 200, Libra (the cane of Libra) 400, from Aries to the cane (of Libra) one should add 40 for each sign” (=Taurus 240; Gemini 280; Cancer 320; Leo 360; Virgo 400; Libra 400; Scorpio 360; etc.). This is precisely a scheme of the Babylonian System A. Some Biblical verses are quoted in a midrashic manner. However, the text is full of astronomical data such as the time it takes each of the planets to circle the Earth, and the apogee and nadir of the zodiac signs. There is a special treatment of the Teli, that is Draco (mentioned no less than 17 times), and other stars are mentioned as well. The author mentions the year 4536 Anno Mundi (= 776 CE), and this is used to conclude that the text was composed that year, though there are doubts concerning the authenticity of that text. The author gives the limit of 120 21’ for both solar and lunar eclipses. The tractate was attributed to Shemuel the Babylonian (sharing a solar year of 365 ¼ days), though its dependence on Baraita deMazalot is very clear. This derivation leads to the probability that the text was composed in the Land of Israel with dependence on Babylonian-type arithmetical methods in Hellenistic culture.

It seems that the last adjustment to the Jewish calendar of Talmudic times was given by R. Saadya Gaon (882 Egypt – 942 Babylonia). He was not only versed in the whole of Jewish literature, a poet, a translator (into Arabic), and a famous opponent against the Karaites, but also a philosopher, a mathematician and an astronomer as well. In 922 there was a dispute between R. Saadya (before he came to Babylonia) and the head of the Yeshivah in the Land of Israel, R. Aaharon b. Meir. The dispute was over a minor issue (whether the conjunction of the moon after mid-day and 642 parts enables visibility of the new moon in the coming night = conjunction + less than around 18 hours). This Astronomical debate led to two different calendars of the Jews in the Land of Israel (Rosh Hashana of 4683 on Tuesday) and the Jews of Babylonia (Rosh Hashana on Thursday). At least for a year Rabbinic Jews in Babylonia and in the Land of Israel had two different calendars, but at the end R. Saadya won the case. Thus, the Jews in Israel accepted the superiority of their brethren in Babylonia, contrary to the priority of Judea and the Land of Israel in calendrical issues until that day (t. Sanhedrin 2:13; p. Sanhedrin 1:2, 19:1). This case marks the end of the developing process of the Jewish calendar, and all the rules of the calendar known then have prevailed until this very day.

The complexity of the Jewish calendar, relative to the Gregorian, is due to: 1) The Jewish calendar is based on synchronization of two different systems (lunisolar), while the Gregorian is based on one system only. 2). The rules of the Jewish calendar were not formulated at one time but rather accumulated during the ages. However, despite all this background, the Jewish calendar became scientific and cosmopolitan, where the Land of Israel plays no role. To sum up: the Jewish calendar is based on several assumptions and rules, influenced by different cultures in several generations. However, the Jewish calendar is based upon slight errors. It adds approximately one day every 216 years (as opposed to the Gregorian calendar – a day every 3700 years), and there is a slight error in calculating the tequfa (an addition of some 7.8 days per millenium). Therefore, it doesn’t seem appropriate to opine that God revealed an imprecise (or even: false) calendar to Moses. This deviation clarifies that some minute changes in the calendar in the future are to be expected (not without religious controversies).


In Rabbinic culture, astronomy changed its face from popular to scientific. At the beginning of this era, the Rabbis were concerned much more with medicine than with astronomy. However, in the course of time the interest in medicine faded away, while astronomy, with some hesitation, increased its status among the Rabbis until it became the science of most concern among the Jews in the first Millennium CE. Actually, this astronomy was not innovative according to modern terms, and even in their own Byzantine epoch and early Muslim culture nothing more than developing a calendar interested them, ignoring all the other aspects of astronomy. Astronomy was not considered an independent field by itself, but rather an instrument in observing religious law. The trend towards scientific astronomy culminated with R. Saadya Gaon, with whom science and Judaism reached an affinity as never before, resulting in a crystallized calendar.

However, just after all these controversies were settled and the calendar was shaped for the final time, astronomy lost its appeal as a religious practice. Of course, Jews continued to study the halakhot concerning the new moon as exemplified in Maimonides, for example, but Astronomy was no more divine than any other science. At any event, after the middle of the 10th century a new era in Jewish Astronomy began.


Beller, E., ‘Ancient Jewish Mathematical Astronomy’, Archive for History of Exact Sciences, 38 (1988), pp. 51-66.

Borenstein, H.Y., The Dispute between Rav Saadya Gaon and ben Meir over the Years 822-824, Warsow 1904 (Hebrew).

Bull, Robert J., ‘A Tripartite Sundial From Tell Er Ras On Mt. Gerizim’, BASOR, 219 (1975), pp. 29-37.

Dexinger, F., ‘Welt- und Menschenbild(er) des Judentums’, A. Resch (ed.), Die Welt der Weltbilder, Insbruck: Resch Verlag 1994, pp. 309-347.

Feldman, W. M., Rabbinical Mathematics and Astronomy, London: M. L. Cailingold, 1931 (3rd corrected edition, Hermon Press, 1978).

Gandz, S., Studies in Hebrew Astronomy and Mathematics, New York: Ktav, 1970.

Glessmer U., ‘Horizontal Measuring in the Babylonian Astronomical Compendium MUL.APIN and in the Astronomical Book of 1 En’, Henoch, 18 (1996), pp. 259-282.

Glessmer U., and M. Albani, ‘An Astronomical Measuring Instrument from Qumran’, D. W. Parry and E. Ulrich (eds.), The Provo International Conference on the Dead Sea Scroll, Leiden – Boston – Köln: Brill, 1999, pp. 407-442.

Glessmer U., ‘Calendars in the Qumran Scrolls’, Peter W. Flint and James C. VanderKam (eds.), The Dead Sea Scrolls After Fifty Years, Leiden – Boston – Köln: Brill, 1999, pp. 213-278.

Herr, M. D., ‘The Calendar’, S. Safrai and M. Stern (eds.), The Jewish People in the First Century, Compendia Rerum Iudaicarum ad Novum Testamentum, Assen – Amsterdam: Van Gorcum, 1976, II., pp. 834-864.

Lasker, Arnold A. and Daniel J. Lasker, ‘Birkat Hahammah: The Blessing of the Sun’, Conservative Judaism, 34/3 (1981), pp. 17-28.

Lim, Timothy H., ‘The Chronology of the Flood Story in a Qumran Text (4Q252)’, JJS, 43/2 (1992), pp. 288-298.

Milikowsky, Ch., ‘Kima and the Flood in Seder ‘Olam and B. T. Rosh Ha-Shana Stellar Time-Reconing and Uranography in Rabbinic Literature’, Proceedings of the American Academy for Jewish Research, 50 (1983), pp. 105-132.

Neugebauer, O., The ‘Astronomical’ Chapters of the Ethiopic Book of Enoch (72 to 82), Kobenhavn: Munksgaard, 1981.

Stern, S., ‘Qumran Calendars: Theory and Practice’, Timothy H. Lim (ed.), The Dead Sea Scrolls in Their Historical Context, Edinburgh: T&T Clark, 2000, pp. 179-186.

Stern, S., Calendar and Community, Oxford: Oxford University Press, 2001.

VanderKam, James C., Calendars in the Dead Sea Scrolls: Measuring time, London and New York: Routledge, 1998. Astrology


Unlike astronomy, the history of astrology was ignored by the Wissenschaft des Judentum as a wretched subject. In the 19th century, when astrology had already been condemned for centuries, the history of Jewish astrology seemed to be irrelevant, if not worse. In times of enlightenment there was a place for the history of the Jews as scientists, philosophers or doctors (vid. Maimonides), but not for those dealing with the occult (when astrology was considered a branch of that area). In the 20th century, G. Scholem, the founder of the scientific study of Jewish Mysticism, published several thousands of pages on Kabbalah and on all kinds of esoteric doctrines but less than one page on astrology. Unfortunately, there were scholars, who, enthusiastic to reveal Jewish astrology, did their work incompetently, and the whole issue waits to be (re)evaluated.

Astrology, like astronomy, was a science, based on astronomical observations, attributing to the heavenly bodies powers over earth and men. Ptolemy was not only the great astronomer of Antiquity, but the great astrologer as well, and this model of a scientist played its role until the 16th century with very few exceptions. Astrology was Astronomy’s counterpart. However, many modern scholars prefer to ignore that while discussing Astronomy and consider Astrology as a counterpart of Magic. Just as modern historiography is aware of the fact that history is not necessarily a report of man’s achievements only, but misdeeds and failures as well, historians of science should realize that Astrology was a science that was later found to be false, and it should be studied as science. The philosophy of this science, if any, was basically pre-Socratic (Pythagorean, to begin with), and “Natural Philosophy”. Astrology claimed it could predict the future of individuals, just as astronomy enables the prediction of the future of heavenly bodies. Moreover, astrology was thought to explain the causes of everything, among them diseases, and naturally to be able to cure the ill. Its medical basis, though uncritically thought to be Hippocratic, is based on the four humors, a pre-Socratic doctrine. Later the Stoics were fond of Astrology and other philosophies were adapted to Astrology.

The relation of Jews to astrology is complex, to say the least, from Biblical times until this very day. Many texts are waiting to be revealed and analyzed to expose the depth of the relationships between Judaism and Astrology throughout the ages.


Before the 5th century BCE (in Babylonia) there was no astrology in the sense of what later became known as such. Therefore, though Bilaam’s practices (Num. 22-23) seem to be connected to Astrology, they are more like propitiatory rituals (namburbis) to seven different Aramaic Gods (such as Ba‘al), that may be called “pre”-Astrology. Yoel 2:10 might be taken as belief in omens of several types: earthquakes, thunders, solar and lunar eclipses, yet they all represent God’s will. True, Jeremiah (10:2) told Israel not to be dismayed at the signs in the heavens, but apparently they did then and centuries later as well. The prophets were well aware of the role of the Astrologers in Babylonia (Isa. 47:13) and their connection to the Royal court (Dan. 2:27; 5:10). However, Astrology in “Biblical times” was not yet the developed astrology of the Hellenistic era.


In Jubilees 12:16 Abraham the Patriarch is depicted as an astrologer who observed the stars on 1/7 (later known as Rosh Hashana), to know how rainy the coming year would be. This connection between stars and rain is part of the Mesopotamian omen heritage, as the author of Jubilees (11:8) knew as well. The context is not polemical against Astrology but rather a claim, in an apologetic manner, that there is no contradiction between faith in God and Astrology. The Rabbis in later centuries were aware of the connection between Abraham and Astrology, claiming either that Abraham was an astrologer (b. Baba Batra 16b), or that he stopped practicing Astrology (b. Shabbat 156a)

A few of the texts found in Qumran disclose that some of the people who lived there were practicing Astrologists. Among them is an Aramaic text (4Q318), called a Brontologion, that interprets thunder in order to forecast the future. Though the text is short and has some lacuna, its concept is clear. First the writer demonstrates the system of the planets ruling over the days of the solar year (changes in sequence every 2, 2, 3 days = 2 1/3). The beginning of the text is corrupt but from 7 (of Ellul), under the Archer (Sagittarius), the writer gives, in a very technical way, the names of the ruling planets, ending in “(Adar) 27 and 28 under Fishes (Pisces), 2[9, 30 (31?) under Ram (Aries)]”. After listing the ruling planets as an introduction, the writer continues: “If it thunders on [a day under the rule of] the Bull (Taurus), it signifies changes in the world and toil for the cities, and destruction in the royal court…. If it thunders on the Twins (Gemini) – fear and distress caused by foreigners and by…” There is no doubt that the text derived from (Royal) Babylonian lunar Astrology such as Enuma Anu Enlil (the first half of the first Millenium BCE). The text is assumed to have been written in the first century BCE.

Other Qumran texts of Astrological character are: 4Q186, 4Q534 and 4Q561. 4Q186 has a physiognomic-astrological descriptions cryptographically. It is also written there: “And this is the nativity in which he was born: in the foot of the Bull” (=Taurus). This kind of precision (such as Taurus g) has no parallel in any known prediction in regard to the nativity of a man (usually, born under a “whole” zodiac sign). Therefore, it is more likely that the text discusses the nativity of the moon. The “molad” (=nativity), is a terminology well known from later Rabbinic sources, and the text alluded to the new moon if seen in Taurus’ lower part, either as an Astronomical position, or better as an omen (e.g: “when the new moon is in Taurus’ foot – happiness will come to Israel”).

The conjecture that these texts shouldn’t be taken as revealing the Qumranites adherence to astrology since they were “collected for critical argumentation against the ‘wisdom of the Chaldeans’” (like the conjecture that the texts found there had nothing to do with those who lived there), should be rejected for several reasons: 1) The Rabbis, who were much less stringent than the Qumranites, couldn’t tolerate sectarian books (t. Shabbat 13:5; b. Sanhedrin 100b), so the assumption that the Qumranites, like modern scholars, collected their opponents’ books seems to be inappropriate. 2). Depriving the Qumranites of Astrology doesn’t do them any historical justice. In later generations there were many pious Jews who practiced much “harder” Astrology than the one found in Qumran (fearing thunder included). 3) The Qumranites had already shown their deep interest in the calendar, that is Astronomy, a fact that leads automatically to some awareness of Astrology, even without any text in hand.

In sum, the Qumranites believed in Astrology like many other people in Hellenistic times. Their Astrology was Mesopotamian in origin, like their Astronomy, even though they did not admit it. This Astrology was basically omen-type, according to the development of Astrology at the time, and it was related to some others of their beliefs and practices, such as healing and belief in predestination.

Among Pseudepigraphic books there is only one book where Astrology plays a (minor) role: the Testament of Solomon. In that book, especially in ch. 18, there is a combination of Egyptian Astrology - of a low level: zodiac signs and 36 decans - and demonology, angelology, magic and medicine. This book is relatively late and originated among Christians. The Testament of Shem, is a book of Astrology, which was wrongfully attached to modern Pseudepigrapha. This is a Syriac book, composed around the 5th – 6th centuries (of Mesopotamian origin), with a title of “Book of Shem”, that is: a book about names. The book deals with astrology related to the letters of one’s name (close to Mandean astrology on the one side and to modern numerology on the other). Later, while copying the text, a scribe added to the headline, thus attributing the text to Shem, son of Noah, without any connection to the text. Modern study has failed to recognize that.

Rabbinic Judaism

Among the Tannaim (1st–3rd centuries) it seems there are no traces of Astrology, as well as their Astronomy that had not been developed yet. However, a few omens were known among them. R. Meir said that any eclipse is a bad sign for Israel, while another Tanna had a different view. He said: “When the sun is afflicted (solar-eclipse) – it is a bad omen for the Pagans, when the moon is afflicted - it is a bad omen for Israel, since Israel calculates according to the moon and the Pagans according to the sun. If the affliction is in the east – it is a bad omen for those who dwell in the east; in the west - it is a bad omen for those who dwell in the west; in the middle of the sky - it is a bad omen for the whole world. If the face (of the moon) looks like blood – war is coming to the world; if it looks like a sack – arrows of famine are coming to the world; if it looks like both – war and arrows of famine are coming to the world. If it was afflicted while rising – tribulation sojourns; while setting – (tribulation) comes fast. Some say the other way around” (t. Sukkah 2:6). Doubtless, these omens are Jewish adaptations of old Babylonian omens and lore. This tradition is repeated with a slight difference in another source, with the addition: “R. Joshaia says: when the zodiacal signs are afflicted in the east - it is a bad omen for those who dwell in the east; in the west – it is a bad omen for those who dwell in the west. R. Jonathan says: all these omens were given to the gentiles” (Mekhilta deRabbi Ishmael, Bo, Pisha, 1). Thus one can see here a dispute among the Tannaim over the validity of omens.

In another case the Tannaim said: “for four reasons there is a solar-eclipse”, and then there is a list of four crimes that cause a solar-eclipse (b. Sukkah 29a). A modern critic might claim that in the name of ethics, omens become truth, but it seems the other way around: omens are divine, telling people how (not) to act. R. Ishak b. Abdimi (Land of Israel, 2nd-3rd centuries CE), said that in the days of the Temple, on the last day of Sukkoth, people observed the direction of the smoke from the altar, for the omen-significance of the wind from any of the directions (b. Yoma 21b). The absence of a northern wind might be taken as a divine rebuke (b. Yebamoth 72a). R. Papa (Babylonia 4th century) ruled that on a misty day or on a day when there was a southern wind – one is not to circumcise or let blood since the weather condition was considered dangerous (b. Yebamoth 72a). One of the Amoraim didn’t declare a fast day since it was a misty day, understanding that phenomenon as denoting a curtain between Israel and their God (b. Berakhot 32b). An earthquake was taken as a sign from God expressing His displeasure with human behaviour (b. Berakhot 59a). Because of that, Bar Qappara (Land of Israel 2-3 centuries) ruled that after an earthquake, people should fast and pray to God (p. Berakhot 9:2, 13c). R. Nehorai claimed that earthquakes happen when Israel does not observe certain commandments: Teruma and Ma‘asroth. R. Aha thought earthquakes happen because of homosexuality while other sages said they happen because of a controversy among the Jews. (Rabbi) Shemuel stated that an earthquake is a sign that a royal reign will end (p. Berakhot 9:2, 13c). R. Jeremia b. Elazar said that for 25 years God used to send earthquakes to Sodom warning them to repent (Genesis Rabba, 49:6). So it seems that omens like a solar-eclipse, a lunar-eclipse, “disappearance” of a zodiac sign, a wind, a mist, an earthquake and comets played a role among Rabbinic Jews in Antiquity, at a certain extent. Some of these omens came directly from Babylonian sources, stated by Babylonian Rabbis, but apparently some omens derived from ancient Jewish sources.

Among the Amoraim (3rd-5th centuries), there is clearly much more astrological knowledge than among the Tannaim. At least two dichotomic attitudes on astrology prevailed among the Rabbis in the Land of Israel. “R. Hanina said: One’s Mazal (= a zodiac sign) is what makes one smart; one’s Mazal is what gives wealth; and there is Mazal to Israel”. R. Yohanan said: “there is no Mazal to Israel” (b. Shabat 156a). This well-known dispute (famous in its second half only) was said as a closure in regard to former testimony stated in the Talmud as follows. On the pinax of R. Joshua ben Levi, a famous Rabbi in 3rd century Land of Israel, there was a whole set of celestial omens. For example: “one who is born on a Monday will be a tartar, on a Tuesday – will be a wealthy man…under Venus – will be a wealthy man and adulterer, under Mercury – clever and smart”, etc. On that R. Hanina said “it is not the sign of the day but rather the sign of the hour that determines”. This concept is called Genethlialogy, that is predicting a person’s fate according to the star or zodiac sign that was rising at the time of his birth. According to R. Simon (even) each herb has its own zodiacal sign that strokes it and tells it to grow (Genesis Raba 10:6). “Everything depends on a zodiac sign, even a Torah-scroll in the shrine” (a quote of Pesiqta Rabbati in Geonim New Responsa).

Shemuel, in 3rd century Babylonia, after stating astronomical calculations (supra), ruled as follows: “there is no Nissan-season (vernal equinox) which falls in Jupiter that doesn’t break the trees. There is no Tebet-season (winter solstice) which falls in Jupiter that doesn’t dry out the seedlings (Aramaic addendum: provided that the (previous) new Moon was born either in Moon or in Jupiter” (b. Erubin 56a). This is a purely astrological omen of a kind that is difficult to attest to elsewhere in Rabbinic literature. Shemuel also ruled concerning blood-letting which should be done “only on a Sunday, a Wednesday and a Friday, not on a Monday and a Thursday… and (certainly) not on a Tuesday, since Mars governs that day” (b. Shabbat 129b). Other Babylonian Amoraim ruled that one is not allowed to consult Chaldeans (b. Pesahim 113b), and this might be explained as either a difference of opinion of the sages, as is common in the Talmud, or as a rule against predictions not based on Astrology (such as in t. Shabbat 7:14). According to Rava (3rd-4th centuries, Babylonia): “Life, children and livelihood (literally: food), depend not on one’s merit but on Mazal”. This might be taken as either mere luck, or dependence on a zodiacal sign (ibn Ezra in his long commentary on Exodus 32:32; Ecclesiastes 2:21). According to the Rabbis, or already in the Bible (Deut. 33:14), it is assumed that the moon ripens the fruits (Rashi ad loc.: squash and pumpkin; Genesis Raba 10; addendum 2 to ADRN version A). From post-talmudic texts it is clear that there were Jews who ordered a Mezuza to be written on Monday or Thursday only, resembling the rule of Shemuel.

Usually astrologers had bad reputations in the Rabbinic sources, and they were not allowed to predict concerning Jews. The Rabbis understood that the rules of Astrology don’t affect Jews who say “Shema” and pray (Tanhuma Shoftim 10), or give charity (b. Shabbat 156b). According to Rabbinic legends many astrologers were mistaken such as those who lived at the time of the flood (Kalla Rabbati 2:7), the astrologers of Pharaoh (b. Sanhedrin 101b; Berakhot 4a), and there were other cases in Rabbinic legends to exemplify the mischief of Astrology. However, in a (late) midrash King Solomon is depicted as a astrologer who after checking the zodiacal signs tried to free his daughter from her destined groom, in vain (Tanhuma, Buber ed., preface, p. 136).


In Rabbinic literature some sermons, in which the zodiacal signs play a literary role have been preserved. Some of the sermons written in the Land of Israel included Astrological ideas, such as in a sermon by R. Hama b. Hanina. In his sermon Haman is portrayed as an astrologer checking the zodiacal signs for the optimum date to achieve his goal (Esther Raba 7:11; Sifri deAgadeta on Esther, Buber ed.). In another sermon God is depicted as an astrologer who chooses by means of astrology the right month to give the Torah (Pesiqta Rabbati 20). King Solomon was an expert in Astrology, he excelled in the wisdom of the children of the East as well as in the wisdom of the Egyptians and Pharaoh (Pesiqta Rabbati 14). Though the extent of the belief in Astrology in these sermons is not clear, it seems that the audience, if not the Rabbis, knew astrology far better than is explicitly stated.

In the Book of Secrets (Sefer ha-Razim), from the 4th-5th centuries Land of Palestine, there are all sorts of magic prescriptions of which some 10% are of an unsophisticated astrological nature. The author recommends a certain procedure to be carried out on the 7th day of the month in the 7th hour (Heaven 1 line 52). The author knows that there are Angels that rule the zodiacal signs of men and women and then recommends a rite to be carried out “on the 29th of the month when the moon is ending” (2:33-36). This book, written by a non-Rabbinic Jew, attests to a kind of amalgamation of astrology (hemerology) and magic (similar to that found in Egyptian papyri) in a way that became famous centuries later.

Among the Hebrew liturgical poems, Piyyutim, composed around 4th-7th centuries, there are more than ten Piyyutim that mention the signs of the zodiac. The authors of most of these Piyyutim are anonymous, but a few were composed by R. Elazar Ha-Qalir. An anonymous Piyyut that discusses the zodiacal signs is a lamentation which is recited in Orthodox Judaism until this very day in the eve of 9th of Ab (“Az beHataenu Harab Miqdash”, composed around 4th-5th centuries). In the Palestinian Aramaic translation to the Bible, several Piyyutim (from the 4th-7th centuries) were incorporated. Among them are (at least) two astrological Piyyutim. One mentions the zodiacal signs using them as a literary figure only (like in the Hebrew Piyyutim), denoting “soft” astrology. However, another Piyyut (to be recited at the beginning of Nissan) reflects “hard” astrology, which involves a much deeper knowledge of astrology. As a matter of fact, that Piyyut demonstrates a poetic derivation of Mesopotamian omens known as Summa Sin ina tamaritsu (if the moon in its appearance).

The Book of Creation (Sefer Yetsira) is the first book on Astrology in Hebrew, written by a multi-talented scholar, who was obviously a linguist, a mathematician, and an astronomer as well as having other capabilities. He wrote a small book (some 2000 words), where he shows his knowledge, inter alia, of medical astrology. His theories, later characterized as homo-Zodiacus, reflect (Neo-)Pythagorean, Hellenistic, and Byzantine concepts. The book was written in the 5th-6th centuries, probably in Tiberias. Several centuries later this book became the “trigger” of the Kabbala, and more than 60 commentaries have been written on it during the ages (without necessarily acknowledging the astrology in it).

Baraita deMazalot (supra) includes unique astrological data, taken from various sources. The author focused on Genethlialogy, foretelling the life-span of a person who was born under a specific zodiacal sign. For example, one who is born under Saturn will live 57 years, an idea that resembles Paulus of Alexandria (4th century). The responsibility of each of planets is described, such as: “Saturn governs poverty, wretchedness, sore, desolation, sickness, hidden blow in the body and corn”, in accordance with Ptolemy (a concept derived from Mesopotamia). Since some of this tractate’s ideas penetrated the Kabbala, some modern scholars have been surprised to find a similarity between Middle-Ages Kabbalistic concepts and old Mesopotamian texts without knowing the role of this book in the chain of astrological tradition.

In Pirqe de Rabbi Eliezer there is no explicit Astrology though the author states: “The zodiacal signs ‘serve’ the birth of the moon as well as the births (or: generations or: history) of humans, and on these the world stands. And anyone who is smart and clever – he knows the births of the moon and of humans as well”. However, when the author states that each of the zodiacal signs rules 2 1/3 days (3 in a week), just as the Astrological text from Qumran, it seems that either the author knew astrology better than he intended to disclose or that the text was censored in later generations.

In Baraita deShmuel there is a unique set of omens for the weather. For example: “When the season begins under Mercury – heat”. Rain and dew happen only under specific conjunctions of the signs and the planets such as Cancer and Sun or Virgin and Venus or Gemini and Mercury, etc. Though the author tries to show that his knowledge is based on the Bible, it is quite clear that he drew his knowledge from other sources as well.

The sages made use of astral omens as a tool to explain some Biblical verses. For example, Exodus 10:10 was understood as referring to a star of bad omen (Rashi ad loc., Mid. Canticles, Greenhut ed.), or that Moses overcame the Amelekites with his sophisticated knowledge of astrology (Exodus 17:12; Rashi ad loc., Tanhuma Beshalah 28). The ‘editor’ of the Second Targum on Ecclesiastes included astrology in his translation quite systematically. However, the infiltration of astrological concepts into the Targum is attested to in other verses in the Aramaic translation of the Bible (e.g. 1 Chron. 12:32). Since in the Second Targum on Song of Songs 7:5 there is an allusion to scribes and those in the Sanhedrin who make intercalations, it may be assumed that the translator had evidence of his own eyes, no doubt, in Tiberias (ibid. Numbers 34:8).

A unique text that combines astrology with Metoscopy and Chiromancy has been found in the Geniza. This Hebrew text was probably composed by a Rabbi in the Land of Israel in the Byzantine era and it is the earliest piece of its kind. A recent discovery in the Geniza shows the similarities between Hermetic literature and Jewish Astrology. A text in Aramaic tells the reader the “character” of each day in a month: what is the name of the ruling angel, what is appropriate or not appropriate to do on that day, with a set of omens without precedent. For example, on the 21st of the month: “Whatever is lost - will not be found”, or “Whoever is born - shall fall into the hands of wild animals”. On each day the author adds also the name of a herb that is appropriate to be picked on that day, no doubt to be used as a medicament. The text has magical characters and its Aramaic, with Greek names, might indicate its original provenance. Though it is difficult to evaluate the text’s origin, since it is part of a chain in a long history of astral omens, with some caution it is assumed that it was composed in the Land of Israel between the 5th-8th centuries.

In a text called “Pishra de-Rabbi Hanina ben Dosa”, the influence of Hermetic literature on Jewish matters can be seen. In a long text in Aramaic, assumed to be from around the 5th till the 8th century, the author gives instructions to a magician, what to do, that is how to “solve” (=pishra) all sorts of problems when he is asked. Each of the cases should be directed to a different angel, first without being aware of the days of the week. However, later the author directs that his procedures of “solving” the situation depend strictly on the days of the week, the days of the month, the months under a specific zodiacal sign, and the hours under a specific planet. That is to say, magic, angelology and hemerology combined, all aim to cure all sorts of ailments.

When the first synagogues with zodiacal signs were excavated in the land of Israel in the first half of the 20th century, some scholars conjectured this was proof of an unorthodox Judaism. Now that we have six synagogues of this kind, together with the many texts ignored until now, it is clear that these synagogues actually reflect Rabbinic Judaism of its time. Under the roofs of the synagogues, astral signs were depicted and written, astrological sermons were given, and astrological data were chanted in prayer and Targum.

Most of the astrologers remain anonymous; however, we do know the names of a few of them. Mash’allah ibn Athri, a Jew of a Persian origin (ca. 762-815) was active in the ‘Abbasid court in Baghdad (and may have converted to Islam). He wrote in Arabic a few books on astrology (based on former astrologers), some of which were later translated into Hebrew by R. Abraham ibn Ezra.

The well-known Jewish blessing “Mazal tob” (=good zodiacal sign) on family occasions is assumed to be invented in the 11th century at the latest.


In Late Antiquity, like their contemporaries, Jews lived under starry skies, where the role of astrology was much larger than old Jewish texts tend to admit. It is true, a few people condemned and rejected astrology, but no doubt the adherents of this esteemed science and divination were far more numerous, Jews included. Astrology played its role not only in day to day behavior, but reached the mainstream of the Jewish religion, synagogues, liturgy, sermons, Piyyut and Targum. For a modern scholar who is not afraid to examine the sources, there is no reason to ignore or deny the importance of astrology in Jewish religion and culture in Antiquity.


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Charlesworth, James H., ‘Jewish Interest in Astrology during the Hellenistic and Roman Period’, W. Hasse (ed.), Aufstieg und Niedergang der Romischen Welt (ANRW), II.20.2 Berlin – New York: Walter de Gruyter, 1987, pp. 926-950.

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Greenfield, J. C. and M. Sokoloff, ‘An Astrological Text from Qumran (4Q318) and Reflections on some Zodiacal Names’, Revue de Qumran, 16/64 (1995), pp. 507-525.

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Shaked, Sh., ‘A Palestinian Jewish Aramaic Hemerologion’, Jerusalem Studies in Arabic and Islam, 15 (1992), pp. 28-42.

Sarfatti, Gad B., ‘An Introduction to the “Baraita De-Mazalot”’, Bar-Ilan, 3 (1965), pp. 56-82 (Hebrew).

Tocci, Franco Michelini, ‘Note e Discussioni: Note e documenti di letterature religiosa e parareligiosa giudaica’, Annali Istituto Orientale di Napoli, 46 (1986), pp. 101-108.

Zatelli, Ida, ‘Astrology and the Worship of the Stars in the Bible’, ZAW, 103 (1991), pp. 86-99.