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Home , Celestial spheres, Heliocentrism

Lecture 9:! ! Copernicus’s De revolutionibus orbium caelestium (1543)! (On the revolutions of the )! ! ! —a rejection of received ! ( + )! ! simultaneous with Reformation —a coincidence?! ! ! changing claims about what does:! make models or describe ? spreads A C across R H Europe I R 2nd-11th Access to lost I from 5thT ct on; S recoveredO ca T split of 1277 condemnations; 1200 East & but Christianization T I +use in universities E West 13th ct on A 1054 L N I I A ! attacked by T N Protestant new philosophies Y I schism 16-17th ct S 16th ct M 2 Some questions to keep in mind: ! what made astronomers choose one theory over another? ! what did non-astronomers think of these choices? ! ! a few factors governing theory choice in cosmology in 16th-17th ct: ! tradition/authority in philosophy ! tradition/authority in religion ! “beauty” of the theory ! empirical support Astronomy the oldest ! -empirical observations since the Babylonians ! -essential for keeping time/ calendar (for harvest + religious holidays) ! -considered valuable for : the heavens influence human bodies, plants, and animals (times for planting, for conceiving, for travelling...) ! ! Babylonian astro-- observation,! prediction, no modeling Account of astro events around battle of 331BCE: Day 13 [20 September]: Sunset to moonrise: 8º. There was a lunar . Its totality was covered at the moment when set and rose. During totality the west wind blew, during clearing the east wind. During the eclipse, deaths and plague occurred. Day 14: All day clouds were in the sky. Day 15: Sunset to moonrise: 16º. There were clouds in the 2 sky. The was 3 /3 cubits below [the ] Alpha Arietis, the moon having passed to the east. A meteor which flashed, its light was seen on the ground; very overcast, lightning flashed. At that time, Jupiter was in Scorpio; was in Leo, at the end of the month in Virgo; Saturn was in Pisces; and , which had set, were not visible. That month, the river level was [lacuna]. On the 11th of that month, panic occurred in the camp before the king. The Macedonians encamped in front of the king. Cuneiform tablets on astro: oldest On the 24th [1 October], in the morning, the king of the from 652/651BCE; youngest 61/60 BCE. [Alexander] erected his standard and attacked. Opposite each other they fought and a heavy defeat of the troops of the source: king [Darius] he [Alexander] inflicted. The king [Darius], his http://www.livius.org/di-dn/diaries/ troops deserted him and to their cities they went. They fled to astronomical_diaries.html the east. A Roman parapegma (3rd-4th CE): to match astro data with civil calendar

• At the top there are 7 holes for seven days of the . • There are 24 holes in the circle. • The central circle is divided into 4 parts. • There is one hole at the centre of a circle. Using three pegs on this stone calendar it was possible to set: 1. The Day of week, 2. The Month, 3. The Day of month.

source: http://pakhomov.com/parapegma.html Ptolemy (ca 90-168 CE) active in Egypt; wrote in Greek on geography, astronomy, astrology 15th ct depiction of the body as connected to the Horoscope that Galileo drew up for the birth of his patron Cosimo de Medici II

source: http://www.dioi.org/kn/galileo/index.htm each carried on a crystalline sphere the spheres can make music as they turn Arabic manuscript of Ptolemy’s (from al- =Arabic “the” + megistos = Greek “greatest” Source: Thomas Kuhn, The ;(1957) see also his Structure of Scientific Revolutions(1962) Ptolemy’s! point to explain! non uniform! circular motion! (i.e. elliptical! motion)! ! is constant! relative to a point! different from the center! of the circle! (=focal pt of the ) the Ptolemaic system =geocentrism Ptolemaic model:! ! complicated!-dozens of epicycles! !!!!!-equant for all , and moon! ! and accurate: excellent predictive power for 1500 years ! ! needs updating the parameters by 16th ct, but that’s no problem! ! ! Problem is… it doesn’t make much sense as a description of physical reality medieval astro: John of Sacrobosco (Holywood) (1195-1256), here in printed form (16th) Peurbach manuscript ca. 1460s 1st humanist return to Ptolemy’s original text =much more thorough study equant point epicycle to explain non uniform circular motion: velocity is constant around a point (Terra) other than the ctr of the circular motion (G) Arabic ms by Nasir al-Din al-Tusi (1201-74) building on Ptolemy and interested in physical plausibility e.g. “” (=extra epicycles) to replace equant point 1473-1543, a cathedral canon (administrator) in Frombork, Epytoma! ! Joannis de Monte Regio! ! in Almagestum Ptolemei! ! =humanist translation

“ on the hypotheses of the movements of the heavens” (1514): manuscript not published, but circulated

stations and retrogradations of planets as viewable in a show today-- the tracks made by successive viewings

To the reader on the! hypotheses of this work! ! this is just a model… Letter of Cardinal! Nicolaus Schonberg! encouraging Copernicus! to help with calendar reform Copernicus inspired by Church’s call for calendar reform.! Gregorian calendar reform finally instituted in 1582 (Oct 4 to 15)! but much later in Protestant lands (1752 in England!) To Pope Paul III Tiedeman Giese, bishop of Chelmno, thanked by Copernicus in his preface ! !

To the reader on the! hypotheses of this work one contemporary! reader aware of! Osiander’s! authorship of the! first preface (1498-1552) author of the fictionalist preface ! Question for section: Was Copernicus a realist? or a fictionalist?

View of Frombork (Frauenburg), Poland: ! Copernicus was not a great observational astronomer but he updated Ptolemy’s data ! explaining

effect disappears if the background is too far away from observer

! ! Copernicanism was empirically indistinguishable from two alternative cosmographies: Ptolemaic/geocentric (ancient) and Tychonic/geoheliocentric (new in late 16th ct) ! choice between these 3 involves weighing other factors: conceptual economy/ “beauty” match of the cosmography with physics and with literal and traditional biblical interpretation status of these diff disciplines (astro, phys, theo) ! See Thomas Kuhn, The Structure of Scientific Revolutions (1962) and The Copernican Revolution (1957) Joshua 10:12-14! ! …and [Joshua] said in the sight of Israel:! “Sun stand though still at Gibeon,! and thou Moon in the valley of Arjalon”! And the sun stood still, and the moon stayed! until the nation took vengeance on their enemies.! ! RSV Protestant attitudes toward pagan learning: ! they vary Luther at first quite hostile ! but Melanchthon, the “pedagogue of Germany” is much less so ! Protestant universities multiply, teach Aristotle [even with medieval commentaries] Luther on what kind of interpretation is best ! "No violence is to be done to the words of , whether by man or ; but they are to be retained in their simplest meaning wherever possible and to be understood in their grammatical and literal sense unless the context plainly forbids, lest we give our adversaries occasion to make a mockery of all the scriptures.” “The Babylonian Captivity of the Church” (1520)