Astronomies and cultures in early medieval Europe Stephen C. McCluskey 1998 Cambridge University Press

A summary

Frank Verbunt

16th February 2007

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 1 / 32 Outline

1 Introduction Legacies: Greek astronomy Legacies: Celtic

2 Early Medieval astronomy Why should a Christian study astronomy? Astronomical problems in the Bible Division of the year Easter computus Monastic Timekeeping Astronomy in the liberal arts

3 Later Medieval astronomy Fusion of traditions Encounter with Arabic astronomy The rebirth of Ptolemaic astronomy

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 2 / 32 Legacies: Greek astronomy

Greek astronomy: Ptolemy Plinius Maior Historia Naturales Books by Ptolemy: Qualitative, i.e. no computations Megale Syntaxis (Almagest): book 2: the Earth is a sphere self-contained overview of within nested spheres of planets astronomy & stars; motion of spheres Planetary Hypotheses: book 6: length of (longest) day physical model of system of as function of latitude spheres (>al-Farghani) book 18: stellar calendar in Handy Tables: expanded some detail, regional variation) tables from Almagest, with Plinius knows about inclination of instructions for use ecliptic, retrograde motion of planets, All of this is lost in early medieval and the 233 months eclipse cycle times

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 3 / 32 Practical Astronomy: time of year

Time of year from the Sun Time of year from stars length of day (impractical) first appearance of star length of shadow last appearance of star (impractical) locus of rising/setting

Yearly motion of Sun on horizon (Ayiomamitis 051221)

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 4 / 32 Celtic Astronomy: Calendar of Coligny

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 5 / 32 Celtic Astronomy

Calendar of Coligny four festivals (+92 d:) 2 Rivros (+91 d:) 4 Cutios (+93 d:) 2 Equos (+91 d:) 4 Cantlos possibly these festival days are mid-quarter days: Samhain, beg. Nov Imbolc, beg. Feb Beltaine, beg. May Lughnasa, beg. Aug

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 6 / 32 Celtic influence of festive days

Samhain and Imbolc Beltaine and Lughnasa Samhain is end of Summer, Beltaine fertility festival (May when for 1 day the living and day) > Blessed Virgin, May dead are in contact > All 2,3 (800-902) Saints, Nov. 1 (798) Lughnasa festival of Lugh Imbolc festival of 3 sisters ‘the shining one’ (Sun), Brigit who did poetry, bringer of plenty, wargod > medicine, metalwork > St. king St. Oswald, Aug. 5 Brigit, Feb. 1 midwife (Northumbria 390-467) or bishop St. Justus (Lyons = Lugdunum 642-685)

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 7 / 32 Why should a Christian study Astronomy? Topics

Why should a Christian study Topics astronomy? problems in the Bible for practical matters division of year in 4 equal (Augustine, Bede) parts also to comtemplate the Easter computus perfection of the creator monastic timekeeping (Hrabanus Maurus 780-856) geometrical astronomy in Hence astronomy is part of quadrivium clerical education (Christian of Stavelot d.>880)

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 8 / 32 Astronomical problems in the Bible

Astronomical problems with Discussed by: the Bible = Vulgate Jerome ( 327-420) world as a perfect creation vs. Augustine (fl.396-430) disturbances wrought by God Theodore of Mopsuestia (d.428) 1 Christmas star Cassiodorus ( 490-583) 2 darkening of Sun at Gregorius Magnus ( 540-604) crucifixion (i.e. passover when Moon is full) One solution: men’s knowledge is imperfect: the apparent irregularities 3 Joshua lets Sun stand still were planned by God at beginning 4 Isaiah moves back the Contra astrology: planets and stars shadow of a sundial are created objects, hence cannot determine things

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 9 / 32 Astronomical problems with the Bible: Christmas star

Vulgate St. James Bible Matthew 2:1 Cum ergo natus esset Jesus 2:1 Now when Jesus was born in in Bethlehem Juda in diebus Bethlehem of Judaea in the days Herodis regis, ecce magi ab of Herod the king, behold, there oriente venerunt Jerosolymam, came wise men from the east to 2:2 dicentes: Ubi est qui natus est Jerusalem, rex Judaeorum? vidimus enim 2:2 Saying, Where is he that is stellam ejus in oriente, et venimus born King of the Jews? for we adorare eum. have seen his star in the east, and are come to worship him.

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 10 / 32 Astronomy in the Bible: additional remarks

Additional remarks Mithras Mithras is often depicted with two assistants; these turned into the three sages in Christianity, to illustrate that Mithras bowed to Christ Bede of Jarrow compares Isaiah’s extra day to the absence of sunset in Thule (tradition:) creation at equinox, with full Moon: day (Sun) as long as night (Moon)

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 11 / 32 Division of the year

Julian calendar Important Christian dates 365.25 days to year Easter (⇒ computus) solstices/equinoxes at 25 births and conceptions of March, 24 June, 24 Sep, 25 Christ and John at December equinoxes and solstitia seasons start halfway these: Christmas either on Dec. 7 Feb, 9 May, 7 Aug, 7 Nov 25 (solstitium; Rome (Bede) 336), or 12 days Obviates need for astronomical (1/apostle) later: Jan. 6 observations to determine time of saints as markers of year! everyday life

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 12 / 32 Easter Computus

Jewish Passover Conversion to Easter select a lamb on Nisan 10, early jewish Christians: eat it at following full Moon, Easter = Nisan 14 then fast (unleavened bread) Rome: Easter on 1st Sunday Nisan is first month of year after Nisan 14 month begins with new computation always in Julian Moon: full Moon is Nisan year, using cycles 14/15 councils of Arles (314), Nicea (325): Easter on same Bible day everywhere (no method Matthew, Marc, Luke: last given) supper Nisan 14 19 yr = 235 m -0.06 d East John: crucifixion at Nisan 4 84 yr = 1039 m +1.28 d West 95 yr = 1175 m -0.31 d

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 13 / 32 Easter Computus: choices and conflicts

Easter choices Victorius of Aquitane, 457 equinox date: Mar 25 = 95 y, Mar 25 equinox Annunciation (Rome) or both dates given when Mar 21 (Nicea) Easter on Nisan 15 or 22 cycle of 19 y or 95 yr tables from 28 to 559 (Alexandria) or 84 y (West) allowed Easter date on Nisan Dionysios Exiguus, 525 15-21 or on Nisan 16-22 95 y, Mar 21 equinox Pope Leo notes in 451 that this Easter on Nisan 15-21 leads to different computer Easter tables until 626 dates in 455: study required extended by Anonymous for extra 95 y

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 14 / 32 Easter Computus: England

English computus Bede De temporum ratione 664 King Oswiu of relation postion Sun in Northumbria organizes zodiac and length of day synod at Whitby monastery equinoxes and solstitia set at to solve Easter date conflict degree 8 of signs (< Pliny): with queen. 25 Dec, 21 Mar, 24 Jun, 24 Bede of Jarrow collects Sep books from Rome: Pliny, observe (!) sunset near Virgil, Isidore, Macrobius equinox to determine need of results in book De temporum leap year: full Moon rises ratione due east on equinox

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 15 / 32 Monastic Timekeeping

Foundation of Monasteries Methods of timekeeping Martin of Tours (∼316-397) Gregory of Tours (∼573) see founds first Monasteries in West. below Rules given by Petrus Damian 1067: singing Cassian Institutes ∼420 psalms Benedict Rule ∼480-550 monastery Fleury, 10th cy: ‘the Master’ Rule clepsydra require prayers at night, hence Pacificus of Verona 776-844: need of timekeeping. After position of Polaris star with Cassiodorus (∼490-580) respect to 5th mag star near Introduction to divine and human pole readings Monasteries are intellectual centers

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 16 / 32 Monastic Timekeeping: Gregory of Tours

Gregory of Tours, ∼573 De cursu stellarum mentions Martianus Capella, length of day increases Virgil 1 h/month from 9 h in Dec to invents Christian 15 h in Jun, and back (OK for constellation names (e.g. Mediterranean, not for Cygnus > Cross above A Tours!) and Ω) visibility Moon increase by rejects astrology 1 h/day (or 0.5 hr/day) accepts comets as bad correlation list of rising stars omens with time to sunrise (visibility of horizon! effect on architecture/location of monasteries?)

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 17 / 32 Astronomy in the liberal arts: Astronomy for poets

Known books on astronomy New books on astronomy Latin version of Ptolemy’s Martianus Capella (fl. Handy Tables translated 410-439) Marriage of ∼530: Praeceptum canonis Philology and Mercury Ptolomei, used after ∼ 1000 Boethius (∼580-524) Cicero Phaenomena, Dream Consolation of Philosophy of Scipio Cassiodorus (∼551) Macrobius (∼360->422) on Introduction to divine and Plato Timaeus. human readings mentions Chalcidius (early 4th cy) Ptolemy Comments on Timeaus Isidore of Seville (∼570-636) De natura rerum

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 18 / 32 Astronomy in the liberal arts: items

Earth is sphere, climate zones Gossuin de Metz, 13th Cy. planets in platonic order (i.e. Sun immediately above Moon) > large size of universe e.g. dSaturn = 46646dMoon non-uniform notion of Sun and planets (i.e. epicycles, qualitatively) e.g. 32 d for Gem, 28 d for Sag 19 yr cycle of Moon vague idea of eclipses No explanations, often wrong in details: e.g. each zodiacal sign rises in 2 hr

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 19 / 32 Fusion of traditions: Court of Charlemagne in Aachen

Charlemagne corresponds excerpts of Pliny, Macrobius, with Alcuin (student of Bede) Capella on calendar, motion Sun and descriptions of constellations: Moon in Zodiac ‘star catalogues’, i.e. picture Computus, not beyond Pliny and number of stars (no Dungal of St. Denis uses coordinates) average time between distances and latitudes of eclipses in Pliny to compute planets (not connected to 2 eclipses in 810 periods) collection of computus texts length of day from linear (e.g. Bede De temporum interpolation ratione) and tables: qualitative earth-sky geometry: calendars, positions Sun in diagram positions sunrise at zodiac solstitia, equinoxes

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 20 / 32 Fusion of traditions: Charlemagne and successors

Charlemagne Leiden Aratus: Cassiopeia Charlemagne has ‘Silver table of celestial sphere, stars, course of planets’

Louis le Pieux ‘Leiden Aratus’ positions of planets observed (!) at equinoctial full moon planet periods, apogea, perigea, exaltations (from Pliny) comets seen as omen

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 21 / 32 Mantle descriptio tocius orbis of Henry II

(personified) Sun, Moon; Christ, St.John, Mary; constellations; celestial circles; and some astrology: ‘When Scorpio rises, deaths increase’

earlier mantles with stars: Mithras, Aaron (in Bible)

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 22 / 32 Fusion of traditions: Rise of astrology

Astrology: Hrabanus Maurus Computus textbooks (∼840) Hrabanus Maurus (820) various forms of Helperic of Auxerre (end 9th prognostication: planet cy) suggests to determine positions at day (geneathlic solstices by projecting astrology) or hour (horoscopic sunbeam through slit on wall astrology) of birth, apparently at sunrise for king or state Abbo of Fleury (∼978) condemns fear for eclipse heliacal/cosmic rising/setting (average) positions Sun, Moon of stars; planet periods computed, planets observed 6,12,18,24,30 y (!) pure conversion sky to horizon numerology, 2 h rise time of beyond capability signs

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 23 / 32 Encounter with Arabic astronomy

Topics Calendar of Cordoba Zij of al-Khwarizmi Astrolabe Islamic astronomers understood Ptolemy fully from 8th century.

Psalter of Blanche of Castille, mother of Louis IX ⇒

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 24 / 32 Calendar of Cordoba: Kitab al-anwa’; Zij al-Khwarizmi

written by Bishop Recemund of Zij al-Khwarizmi (‘algorithm’) Elvira and ‘Arib ibn Sa’d. many copies survive anwa’ (sing.: naw) times of translation Petrus Alfonsi heliacal/cosmical rising/setting (1116): no tables of constellations translation Adelard of Bath, duration of day, computed emended ∼1150 Robert of geometrically for Cordoba Chester: tables based on four different dates for vernal Sindhind for average position equinox (Sindhind, Greek and corrections to actual medicine, measurement positions Sun & planets al-Battani 882) > undermines tables of Toledo re-computed belief in western calendars for Marseille by Raymond reaches west via John of Gorze (in <1450 Cordoba 953-955)

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 25 / 32 Astrolabes and Manuals for Astrolabes

Astrolabe Introductions quantitative measuring Lupitus of Barcelone (fl. instrument 975-995, rejects astrology) model of the Universe Gerbert of Aurillac (∼945-1003) for determination of time in (also teaches unequal hours (un)equal hours from Sun or from Martianus, without stars understanding) western addition: eccentric (unknown author) manuscript in circle for location of Sun in Reichenau ∼1000 Zodiac Fulbert of Chartres (∼960-1028) menomic rhyme with 8 arabic star names no geometric understanding

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 26 / 32 Astrolabes: Better understanding

Hermann of Reichenau Walcher of Great Malvern (1013-1054) De mensura 1092: first recorded western astrolabii measurement with astrolabe instructions for construction measures and collects of astrolabe eclipse times, compares with coordinates for 27 stars his own tables equinox at Mar 18 (from re-discovers unequal motion Latin martyrologies) Moon Problem of date of equinox now claims trepidation of clear and acute equinoxes praises astrology for medicin

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 27 / 32 The rebirth of Ptolemaic astronomy: Translations

Arabic authors Greek authors Abu Ma‘Shar Greater Euclid Elements Adelard Introduction to astrology John of (>1113) Seville (1133), Hermann of Ptolemy Almagest arabic Carinthia (1140) text, tr. Gerard of Cremona Ibn al Muthana, principles (1144) underlying tables of al Ptolemy Almagest greek text Khwarizmi, tr. Hugh of Santalla presented to Roger of Sicily (1119-1151) by Manuel Commenus, tr. simpler: al-Farghani On the student of medicine (∼1160) science of the stars (dimensions of spheres, rise times of signs) John of Seville (1135), Gerard of Cremona (∼1135)

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 28 / 32 The rebirth of Ptolemaic astronomy: Education

Corpus astronomicum Simpler books: Education from monasteries to John Sacrobosco (∼1130) universities (cathedral schools). De Sphaera Many new books, often based on John Pecham (∼1215) al-Farghani, collected in Corpus Tractatus de Sphaera are Astronomicum epicycles real? Yes! they computus: tables of Sun in do’nt break the spheres? (cf. ecliptic, based on new al-Bitruji) techiques Roger Bacon Compotus algorismus: basics of astronomical calculations theorica planetum: qualitative explanation of epicycles

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 29 / 32 The rebirth of Ptolemaic astronomy: Education

Grosseteste (∼1215) Much used text: Anonymous De Sphaera Theorica planetarum (∼1250) general geometry geometry of Ptolemy’s theory, equation of time including complex Mercury orbit of Moon with Ptolemy’s use tables to compute position eccentric of planet altitude of star as function of adapt tables for other latitude latitude Campanus of Novara (1261-1264 ) Computus correctorius all major points of Ptolemy change of equinox depending Planetary Hypotheses: stars on length of year al-Battani is at 73,387,747+10/66 miles best (Christ born at equinox) builds and uses equatorium Demands on students are low, but good books are available

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 30 / 32 The rebirth of Ptolemaic astronomy: William of St.Cloud

calender based on accurate confirms al-Battani precession arabic numbers (with Peter of 1◦/66 y i.e. no trepidation Nightingale, 1190s): no use obliquity from noon-shadow at of 19yr cycle, hence not equinoxes: 23◦340 (correct: perpetual. 23◦3105300) date of entry of Sun in each suggests to show change in sign distance to Sun from measuring observes Sun, Moon, Mars, diameter with pinhole through Jupiter, Saturn between year 1285 and 1292 to test and measures conjunctions of Mars, improve tables Jupiter, Saturn, Moon with stars. importance lunar phase for physicians

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 31 / 32 Summary

Early Middle Ages Recovering astronomy incorporation pagan festivals >800 improved schools: books into Christian calendar on astronomy struggle with Bible first based on late-Latin authors: astronomy simplistic struggle with Easter revival of astrology (also for computus medicin) night time from stars >1100 gradual introduction of arabic knowledge These topics enter monastic education gradual introduction of new observations

A summary (Frank Verbunt) Astronomy in early medieval Europe 16th February 2007 32 / 32