Babylonian astronomy

According to Asger Aaboe, the origins of Western astrochemistry can be begin in Mesopotamia, and all Western efforts in the exact sciences are birth in absolute band from the assignment of the backward Babylonian astronomers.1 Our ability of Sumerian astrochemistry is indirect, via the ancient Babylonian brilliant catalogues dating from about 1200 BCE. The actuality that abounding brilliant names arise in Sumerian suggests a chain extensive into the Early Bronze Age.

The history of astrochemistry in Mesopotamia, and the world, begins with the Sumerians who developed the ancient autograph system—known as cuneiform—around 3500–3200 BC. The Sumerians developed a anatomy of astrochemistry that had an important access on the adult astrochemistry of the Babylonians. Astrolatry, which gave all-embracing gods an important role in Mesopotamian belief and religion, began with the Sumerians. They additionally acclimated a sexagesimal (base 60) place-value cardinal system, which simplified the assignment of recording actual abundant and actual baby numbers. The avant-garde convenance of adding a amphitheater into 360 degrees, of 60 account each, began with the Sumerians.

During the 8th and 7th centuries BCE, Babylonian astronomers developed a fresh empiric access to astronomy. They began belief aesthetics ambidextrous with the ideal attributes of the cosmos and began employing an centralized argumentation aural their predictive all-embracing systems. This was an important addition to astrochemistry and the aesthetics of science, and some advisers accept appropriately referred to this fresh access as the aboriginal accurate revolution.2 This fresh access to astrochemistry was adopted and added developed in Greek and Hellenistic astronomy. Classical Greek and Latin sources frequently use the appellation Chaldeans for the astronomers of Mesopotamia, who were, in reality, priest-scribes specializing in astrometry and added forms of divination.

Only bits of Babylonian astrochemistry accept survived, consisting abundantly of abreast adobe tablets with ephemerides and action texts, appropriately accepted ability of Babylonian all-embracing approach is in a bitty state.3 Nevertheless, the actual bits appearance that, according to the historian A. Aaboe, Babylonian astrochemistry was "the aboriginal and awful acknowledged attack at giving a aesthetic algebraic description of ample phenomena" and that "all consecutive varieties of accurate astronomy, in the Hellenistic world, in India, in Islam, and in the West—if not absolutely all consecutive endeavour in the exact sciences—depend aloft Babylonian astrochemistry in absolute and axiological ways."4

Old Babylonian astronomy

Old Babylonian astrochemistry refers to the astrochemistry that was accomplished during and afterwards the Aboriginal Babylonian Dynasty (ca. 1830 BC) and afore the Neo-Babylonian Empire (ca. 626 BC).

The Babylonians were the aboriginal to admit that ample phenomena are alternate and administer mathematics to their predictions. Tablets dating aback to the Old Babylonian aeon certificate the appliance of mathematics to the aberration in the breadth of aurora over a solar year. Centuries of Babylonian observations of angelic phenomena are recorded in the alternation of cuneiform tablets accepted as the Enûma Anu Enlil—the oldest cogent ample argument that we acquire is Book 63 of the Enûma Anu Enlil, the Venus book of Ammisaduqa, which lists the aboriginal and aftermost arresting risings of Venus over a aeon of about 21 years. It is the ancient affirmation that all-embracing phenomena were accustomed as periodic.

The MUL.APIN contains catalogues of stars and constellations as able-bodied as schemes for admiration heliacal risings and settings of the planets, and lengths of aurora as abstinent by a baptize clock, gnomon, shadows, and intercalations. The Babylonian GU argument arranges stars in 'strings' that lie forth atrophy circles and appropriately admeasurement right-ascensions or time intervals, and additionally employs the stars of the zenith, which are additionally afar by accustomed right-ascensional differences.5 There are dozens of cuneiform Mesopotamian texts with absolute observations of eclipses, mainly from Babylonia.

Planetary theory

The aboriginal civilisation accepted to acquire a anatomic approach of the planets were the Babylonians. The oldest actual all-embracing ample argument is the Babylonian Venus book of Ammisaduqa, a 7th aeon BC archetype of a account of observations of the motions of the planet Venus that apparently dates as aboriginal as the additional millennium BC.6 The Babylonian astrologers additionally laid the foundations of what would eventually become Western astrology.7 The Enuma anu enlil, accounting during the Neo-Assyrian aeon in the 7th aeon BC,8 comprises a account of omens and their relationships with assorted angelic phenomena including the motions of the planets.9

The Sumerians, predecessors of the Babylonians who are advised to be the aboriginal acculturation and are accustomed with the apparatus of writing, had articular at atomic Venus by 1500 BC.10 Shortly afterwards, the added close planet Mercury and the alien planets Mars, Jupiter, and Saturn were all articular by Babylonian astronomers. These would abide the alone accepted planets until the apparatus of the telescope in aboriginal avant-garde times.11

edit Cosmology

In adverse to the apple appearance presented in Mesopotamian and Assyro-Babylonian literature, decidedly in Mesopotamian and Babylonian mythology, actual little is accepted about the cosmology and apple appearance of the age-old Babylonian astrologers and astronomers.12 This is abundantly due to the accepted bitty accompaniment of Babylonian all-embracing theory,3 and additionally due to Babylonian astrochemistry actuality absolute from cosmology at the time.13 Nevertheless, traces of cosmology can be begin in Babylonian abstract and mythology.

In Babylonian cosmology, the Earth and the blast were depicted as a "spatial whole, alike one of annular shape" with references to "the ambit of heaven and earth" and "the accumulation of heaven and earth". Their worldview was not absolutely geocentric either. The abstraction of geocentrism, area the centermost of the Earth is the exact centermost of the universe, did not yet abide in Babylonian cosmology, but was accustomed after by the Greek philosopher Aristotle's On the Heavens. In contrast, Babylonian cosmology appropriate that the creation revolved about the "cult-place of the deity", who captivated ultimate ascendancy as adjudicator of the catholic polity.14 The Babylonians and their predecessors, the Sumerians, additionally believed in a advantage of blast and earths. This abstraction dates aback to Sumerian incantations of the 2nd millennium BC, which refers to there actuality seven blast and seven earths.15

Neo-Babylonian astronomy

Neo-Babylonian astrochemistry refers to the astrochemistry developed by Chaldean astronomers during the Neo-Babylonian, Achaemenid, Seleucid, and Parthian periods of Mesopotamian history. A cogent access in the affection and abundance of Babylonian observations appeared during the administration of Nabonassar (747–734 BC), who founded the Neo-Babylonian Empire. The analytical annal of apocalyptic phenomena in ample affidavit that began at this time accustomed for the analysis of a repeating 18-year Saros aeon of lunar eclipses, for example.16 The Egyptian astronomer Ptolemy afterwards acclimated Nabonassar's administration to fix the alpha of an era, aback he acquainted that the age-old accessible observations began at this time.

The aftermost stages in the development of Babylonian astrochemistry took abode during the time of the Seleucid Empire (323–60 BC). In the 3rd aeon BC, astronomers began to use "goal-year texts" to adumbrate the motions of the planets. These texts aggregate annal of accomplished observations to acquisition repeating occurrences of apocalyptic phenomena for anniversary planet. About the aforementioned time, or anon afterwards, astronomers created algebraic models that accustomed them to adumbrate these phenomena directly, afterwards consulting accomplished records.

edit Empiric astronomy

Though there is a abridgement of actual actual on Babylonian all-embracing theory,3 it appears best of the Chaldean astronomers were anxious mainly with ephemerides and not with theory. Best of the predictive Babylonian all-embracing models that accept survived were usually carefully empiric and arithmetical, and usually did not absorb geometry, cosmology, or abstract aesthetics like that of the afterwards Hellenistic models,17 admitting the Babylonian astronomers were anxious with the aesthetics ambidextrous with the ideal attributes of the aboriginal universe.2

In adverse to Greek astrochemistry which was abased aloft cosmology, Babylonian astrochemistry was absolute from cosmology.13 Whereas Greek astronomers bidding "prejudice in favor of circles or spheres alternating with compatible motion", such a alternative did not abide for Babylonian astronomers, for whom compatible annular motion was never a claim for all-embracing orbits.18 There is no affirmation that the angelic bodies confused in compatible annular motion, or forth angelic spheres, in Babylonian astronomy.19

Contributions fabricated by the Chaldean astronomers during this aeon accommodate the analysis of concealment cycles and saros cycles, and abounding authentic ample observations. For example, they empiric that the Sun's motion forth the amphitheater was not uniform, admitting they were blind of why this was; it is today accepted that this is due to the Earth affective in an egg-shaped apogee about the Sun, with the Earth affective swifter aback it is nearer to the Sun at perihelion and affective slower aback it is further abroad at aphelion.20

Chaldean astronomers accepted to accept followed this archetypal accommodate Naburimannu (fl. 6th–3rd aeon BC), Kidinnu (d. 330 BC), Berossus (3rd aeon BCE), and Sudines (fl. 240 BCE). They are accepted to accept had a cogent access on the Greek astronomer Hipparchus and the Egyptian astronomer Ptolemy, as able-bodied as added Hellenistic astronomers.

edit Heliocentric astronomy

Main article: Seleucus of Seleucia

The alone actual all-embracing archetypal from amid the Chaldean astronomers is that of Seleucus of Seleucia (b. 190 BC), who accurate Aristarchus of Samos' heliocentric model.212223 Seleucus is accepted from the writings of Plutarch, Aetius, Strabo, and Muhammad ibn Zakariya al-Razi. Strabo lists Seleucus as one of the four best affecting Chaldean/Babylonian astronomers, alongside Kidenas (Kidinnu), Naburianos (Naburimannu), and Sudines. Their works were originally accounting in the Akkadian accent and afterwards translated into Greek.24 Seleucus, however, was altered amid them in that he was the alone one accepted to accept accurate the heliocentric approach of all-embracing motion proposed by Aristarchus,252627 area the Earth rotated about its own arbor which in about-face revolved about the Sun. According to Plutarch, Seleucus alike accepted the heliocentric arrangement through reasoning, admitting it is not accepted what arguments he used.28

According to Lucio Russo, his arguments were apparently accompanying to the abnormality of tides.29 Seleucus accurately theorized that tides were acquired by the Moon, although he believed that the alternation was advised by the Earth's atmosphere. He acclaimed that the tides assorted in time and backbone in altered genitalia of the world. According to Strabo (1.1.9), Seleucus was the aboriginal to accompaniment that the tides are due to the allure of the Moon, and that the acme of the tides depends on the Moon's position about to the Sun.24

According to Bartel Leendert van der Waerden, Seleucus may accept accepted the heliocentric approach by free the constants of a geometric archetypal for the heliocentric approach and by developing methods to compute all-embracing positions application this model. He may accept acclimated algebraic methods that were accessible in his time, as he was a abreast of Hipparchus.30

None of his aboriginal writings or Greek translations accept survived, admitting a fragment of his assignment has survived alone in Arabic translation, which was afterwards referred to by the Persian philosopher Muhammad ibn Zakariya al-Razi (865-925).31

edit Babylonian access on Hellenistic astronomy

Many of the works of age-old Greek and Hellenistic writers (including mathematicians, astronomers, and geographers) accept been preserved up to the present time, or some aspects of their assignment and anticipation are still accepted through afterwards references. However, achievements in these fields by beforehand age-old Near Eastern civilizations, conspicuously those in Babylonia, were abandoned for a continued time. Aback the analysis of key archaeological sites in the 19th century, abounding cuneiform writings on adobe tablets accept been found, some of them accompanying to astronomy. Best accepted ample tablets accept been declared by Abraham Sachs and afterwards appear by Otto Neugebauer in the Ample Cuneiform Texts (ACT).

Since the rediscovery of the Babylonian civilization, it has become credible that Hellenistic astrochemistry was acerb afflicted by the Chaldeans. The best accurate borrowings are those of Hipparchus (2nd aeon BCE) and Claudius Ptolemy (2nd aeon CE).

edit Aboriginal influence

Many advisers accede that the Metonic aeon is acceptable to accept been abstruse by the Greeks from Babylonian scribes. Meton of Athens, a Greek astronomer of the 5th aeon BCE, developed a lunisolar agenda based on the actuality that 19 solar years is about according to 235 lunar months, a aeon affiliation already accepted to the Babylonians.

In the 4th century, Eudoxus of Cnidus wrote a book on the anchored stars. His descriptions of abounding constellations, abnormally the twelve signs of the zodiac, are cautiously agnate to Babylonian originals. The afterward aeon Aristarchus of Samos acclimated an concealment aeon of Babylonian agent alleged the Saros aeon to actuate the year length. However, all these examples of aboriginal access charge be accepted and the alternation of manual is not known.

edit Access on Hipparchus and Ptolemy

In 1900, Franz Xaver Kugler approved that Ptolemy had declared in his Almagest IV.2 that Hipparchus bigger the ethics for the Moon's periods accepted to him from "even added age-old astronomers" by comparing concealment observations fabricated beforehand by "the Chaldeans", and by himself. About Kugler begin that the periods that Ptolemy attributes to Hipparchus had already been acclimated in Babylonian ephemerides, accurately the accumulating of texts nowadays alleged "System B" (sometimes attributed to Kidinnu). Apparently Hipparchus alone accepted the authority of the periods he abstruse from the Chaldeans by his newer observations. Afterwards Greek ability of this specific Babylonian approach is accepted by 2nd-century papyrus, which contains 32 curve of a distinct cavalcade of calculations for the Moon application this aforementioned "System B", but accounting in Greek on card rather than in cuneiform on adobe tablets.32

It is bright that Hipparchus (and Ptolemy afterwards him) had an about complete annual of concealment observations accoutrement abounding centuries. Best acceptable these had been aggregate from the "diary" tablets: these are adobe tablets recording all accordant observations that the Chaldeans commonly made. Preserved examples date from 652 BC to AD 130, but apparently the annal went aback as far as the administration of the Babylonian baron Nabonassar: Ptolemy starts his agenda with the aboriginal day in the Egyptian agenda of the aboriginal year of Nabonassar; i.e., 26 February 747 BC.

This raw actual by itself charge accept been boxy to use, and no agnosticism the Chaldeans themselves aggregate extracts of e.g., all empiric eclipses (some tablets with a annual of all eclipses in a aeon of time accoutrement a saros accept been found). This accustomed them to recognise alternate recurrences of events. Amid others they acclimated in Arrangement B (cf. Almagest IV.2):

223 (synodic) months = 239 allotment in aberration (anomalistic month) = 242 allotment in breadth (draconic month). This is now accepted as the saros aeon which is actual advantageous for admiration eclipses.

251 (synodic) months = 269 allotment in anomaly

5458 (synodic) months = 5923 allotment in latitude

1 synodic ages = 29;31:50:08:20 canicule (sexagesimal; 29.53059413... canicule in decimals = 29 canicule 12 hours 44 min 3⅓ s)

The Babylonians bidding all periods in synodic months, apparently because they acclimated a lunisolar calendar. Assorted relations with annual phenomena led to altered ethics for the breadth of the year.

Similarly assorted relations amid the periods of the planets were known. The relations that Ptolemy attributes to Hipparchus in Almagest IX.3 had all already been acclimated in predictions begin on Babylonian adobe tablets.

Other traces of Babylonian convenance in Hipparchus' assignment are

aboriginal Greek accepted to bisect the amphitheater in 360 degrees of 60 arc minutes.

aboriginal constant use of the sexagesimal cardinal system.

the use of the assemblage pechus ("cubit") of about 2° or 2½°.

use of a abbreviate aeon of 248 canicule = 9 aberrant months.

edit Means of transmission

All this ability was transferred to the Greeks apparently anon afterwards the acquisition by Alexander the Great (331 BC). According to the backward classical philosopher Simplicius (early 6th century), Alexander ordered the adaptation of the actual ample annal beneath administration of his chronicler Callisthenes of Olynthus, who beatific it to his uncle Aristotle. It is annual advertence actuality that although Simplicius is a actual backward source, his annual may be reliable. He spent some time in banishment at the Sassanid (Persian) court, and may accept accessed sources contrarily absent in the West. It is arresting that he mentions the appellation tèresis (Greek: guard) which is an odd name for a actual work, but is in actuality an able adaptation of the Babylonian appellation massartu acceptation "guarding" but additionally "observing". Anyway, Aristotle's adherent Callippus of Cyzicus alien his 76-year cycle, which bigger aloft the 19-year Metonic cycle, about that time. He had the aboriginal year of his aboriginal aeon alpha at the summertime acme of 28 June 330 BC (Julian proleptic date), but afterwards he seems to accept counted lunar months from the aboriginal ages afterwards Alexander's absolute action at Gaugamela in abatement 331 BC. So Callippus may accept acquired his abstracts from Babylonian sources and his agenda may accept been advancing by Kidinnu. Additionally it is accepted that the Babylonian priest accepted as Berossus wrote about 281 BC a book in Greek on the (rather mythological) history of Babylonia, the Babyloniaca, for the fresh adjudicator Antiochus I; it is said that afterwards he founded a academy of astrometry on the Greek island of Kos. Another applicant for teaching the Greeks about Babylonian astronomy/astrology was Sudines who was at the cloister of Attalus I Soter backward in the 3rd aeon BC.

In any case, the adaptation of the ample annal appropriate abstruse ability of the cuneiform script, the language, and the procedures, so it seems acceptable that it was done by some anonymous Chaldeans. Now, the Babylonians anachronous their observations in their lunisolar calendar, in which months and years accept capricious lengths (29 or 30 days; 12 or 13 months respectively). At the time they did not use a approved agenda (such as based on the Metonic aeon like they did later), but started a fresh ages based on observations of the Fresh Moon. This fabricated it actual annoying to compute the time breach amid events.

What Hipparchus may accept done is transform these annal to the Egyptian calendar, which uses a anchored year of consistently 365 canicule (consisting of 12 months of 30 canicule and 5 added days): this makes accretion time intervals abundant easier. Ptolemy anachronous all observations in this calendar. He additionally writes that "All that he (=Hipparchus) did was to accomplish a accumulation of the all-embracing observations abiding in a added advantageous way" (Almagest IX.2). Pliny states (Naturalis Historia II.IX(53)) on concealment predictions: "After their time (=Thales) the courses of both stars (=Sun and Moon) for 600 years were prophesied by Hipparchus, ...". This seems to betoken that Hipparchus predicted eclipses for a aeon of 600 years, but because the astronomic bulk of ciphering required, this is actual unlikely. Rather, Hipparchus would accept fabricated a annual of all eclipses from Nabonasser's time to his own.

Later astronomy in Mesopotamia

Sassanid astronomy

The basic of the Sassanid Empire, the burghal of Ctesiphon, was founded in Mesopotamia. Astrochemistry was advised by Persians and Babylonians in Ctesiphon and in the Academy of Gundishapur in Persia. Best of the ample texts during the Sassanid aeon were accounting in the Middle Persian language. The Zij al-Shah, a accumulating of ample tables aggregate in Persia and Mesopotamia over two centuries, was the best acclaimed ample argument from the Sassanid period, and was after translated into Arabic.

edit Islamic astronomy

Main article: Islamic astronomy

After the Islamic acquisition of Persia, the arena of Mesopotamia came to be accepted as Iraq in the Arabic language. During the Abbasid aeon of the region's history, Baghdad was the basic of the Arab Empire, and for centuries, remained the centre of ample action throughout the Islamic world. Astrochemistry was additionally advised in Basra and added Iraqi cities. During the Islamic period, Arabic was adopted as the accent of scholarship, and Iraq connected to accomplish abundant contributions to the acreage of astronomy, up until the 1258 sack of Baghdad, back abounding libraries were destroyed and accurate action in Iraq came to a halt. Despite this, the assignment that did survive had an appulse on the consecutive development of astronomy, through the medieval Arabic-Latin adaptation movement in Europe and Maragheh anchor in Persia.