Category Archives: History of Astronomy

The emergence of modern astronomy – a complex mosaic: Part XI

Despite the high level of anticipation De revolutionibus cannot be in anyway described as hitting the streets running; it was more a case of dribbling out very slowly into the public awareness. There are several reasons for this. Today there is a well-oiled machine, which goes into operations when an important new book is published. Book reviews and adverts in the relevant journals and newspapers, books delivered in advance to bookshops all over the country, radio and television interviews with the author and so on.

Absolutely none of this apparatus existed in anyway in the fifteenth century. There were no journals or newspapers, where reviews and adverts could be published. Information about a new publication was distributed over the academic grapevine by mail; the grapevine was quite efficient with scholars communicating with each other throughout Europe but the mail system wasn’t. Letters often took months and quite often never arrived at all. There were no bookstores, as we know them today and no book distribution network. Petreius had a stall on the local market place but he probably would not have sold many copies of De revolutionibus in Nürnberg itself.


A 19th century painting of the Nürnberg market place

In this context it is interesting that the town library doesn’t own a copy of the 1st edition. For other sales, other than by mail, Petreius would have transported copies of the book packed into barrels to the annual fairs in Leipzig and Frankfurt, where, as well as private customers, other printer publishers would buy copies of the book to take back to their home towns to supplement their own production for their local customers. The Leipzig fair took place at Easter and in autumn, the Frankfurt fair only in autumn. Easter 1543 was in April so the distribution of De revolutionibus only really began in the autumn of that year.


Frankfurt Book Fair 1500

The next factors that slowed the reception of De revolutionibus were the price and the content. As a large book with a complex mathematical content with lots of tables and diagrams, De revolutionibus was a very expensive book putting it outside of the financial range of students or anybody without a substantial income or private fortune. A first edition bought by the astrologer Valentin Engelhart (1516-1562) in 1545 cost 1 florin = 12 groschen. A students university matriculation fees at this time cost between 6 and 10 groschens. It is indicative that Kepler could only afford to acquire a second hand copy. Owen Gingerich speculates that the high cost of the book is the reason for the comparatively high survival of copies, Gingerich estimates about fifty per cent. It was very expensive so people took good care of it. The high price and the complex contents very much limited potential sales.


De Revolutionibus woodcut of the heliocentric cosmos Source: Latin Wikisource

In terms of content this was a major, heavy duty, large-scale mathematical text and not in anyway something for the casual reader, no mater how well read. Copernicus’ Mathemata mathematicis scribuntur was meant very seriously. This suggests that the potential circle of purchasers was fairly strictly limited to the comparatively small group of mathematical astronomers, who would be capable of reading and understanding Copernicus’ masterpiece. Given his record in the field of mathematical and astronomical/astrological publishing Petreius naturally already had a group of customers to whom he could offer his latest coup in this genre, otherwise he probably would not have published De revolutionibus. However, even if he could get this very specialist book to its specialist group of readers, they would require a comparatively long time to read, work through and digest its complex contents. The earliest known published reaction to De revolutionibus was Gemma FrisiusDe radio astronomico et geometrico a booklet of a multipurpose astronomical and geometrical instrument published in 1545 two years after Copernicus’ volume.

Here at this comparatively early point Frisius, who knew of Copernicus’ hypothesis through the Narratio Prima and and had been invited by Dantiscus, Prince-Bishop of Frombork, one of his patrons, to come to Frombork and work with Copernicus, displays a very cautious attitude towards the new heliocentric astronomy although he is very critical towards Ptolemaeus’ work.


Johannes Dantiscus Source: Wikimedia Commons

Given that the main purpose of astronomy was, at this time, still to provide astronomical data for astrology, navigation and cartography many of those potentially interested in the new astronomy were waiting for new planetary tables and ephemerides before passing judgement. The earliest planetary tables, the Tabulae prutenicae (Prutenic Tables) based on De revolutionibus, but not exclusively, were produced by the professor for the higher mathematics (music and astronomy) at Wittenberg Erasmus Reinhold (1511–1553) and first published in 1551.


Source: Wikimedia Commons

These tables were financed by Albrecht I, Duke of Prussia hence the name Prutenic i.e. Prussia.


Albrecht, Duke of Prussia portrait by Lucas Cranach the elder Source: Wikimedia Commons

Interestingly Reinhold was not a supporter of heliocentricity. Ephemerides based on the Prutenic Tables were produced in the Netherlands by Johannes Stadius (1527–1579) a pupil of Gemma Frisius in 1554 with an introductory letter by his old teacher.


Johannes Stadius Source: Wikimedia Commons

A second set of ephemerides, also based on the Prutenic Tables, were produced in England by John Feild (c. 1525–1587), a pupil of John Dee (1527–1608) in 1557. Dee was another pupil of Gemma Frisius, so this might be a case of the academic grapevine in operation. These tables and ephemerides played an important roll in spreading awareness of the new heliocentric hypothesis.

Whereas with a modern publication reception will probably be judged in terms of months or even weeks for a popular book and a few years for a serious academic title; looking at De revolutionibus to judge its reception we really need to cover the sixty plus years following its publication up to the invention of the telescope, the next major game changer in astronomy.

There is a popular misconception that that reception can be quantified in terms of those for and those against the heliocentric hypothesis. This is very much not the case. As I tried to make clear at the beginning of this series the sixteenth century was very much characterised by very lively debates on various aspects of astronomy–the nature, status and significance of comet, a lively revival of the Aristotelian homocentric spheres model of the cosmos and a growing dissatisfaction with the quality of the available astronomical data. There were small smouldering fires of debate everywhere within the European astronomical community, Copernicus’ De revolutionibus turned them into a raging bush fire; the reactions to its publication were multifaceted and the suggested changes it provoked were wide-ranging and highly diverse. It would be more than a hundred years before the smoke cleared and a general consensus could be found within the astronomical community.







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Filed under Early Scientific Publishing, History of Astrology, History of Astronomy, Renaissance Science

Unsound History of the Sound of Space

Those readers, who have been around for a number of years, will know that from time to time the Renaissance Mathematicus has hosted guest posts. One thing that we are very proud of is the very high standard of the authors, who have delivered up, at our invitation, those literary #histSTM highpoints. We only host the best! Todays guest post continues this tradition with a real star of the world of science, science writing and #histSTM, Tom McLeish FRS. Tom was Professor of Physics at Durham University, where he was one of the initiators and chief investigators of the on going Ordered Universe international research project: Interdisciplinary Readings of Medieval Science: Robert Grosseteste (c.1170–1253).


!4th Century portrait of Robert Grosseteste, Bishop of Lincoln Source: Wikimedia Commons

Tom is now Professor of Natural Philosophy in the Department of Physics at the University of York (I think he’s doing a slow tour of the beautiful cathedral cities of England). His most recent, in fact very recent, publication is a book that you all should read The Poetry and Music of Science: Comparing Creativity in Science and Art (OUP, 2019).

Recently he tweeted some truly horrendous #histSTM errors in a BBC publication, I’ll let him explain further, and I immediately thought that would be something for the HIST_SCI HULKTMbut then thought it would be nice if Tom wrote a guest post about it himself. I asked, he said yes and so I give you the HIST_SCI HULK’s mild mannered, but very erudite cousin Tom McLeish.

For some years now I have been treating myself to the weekly delight and lifelong education in the history of science that is Thony Christie’s ‘Renaissance Mathematicus’ blog. To be invited to write a guest instalment is therefore a great surprise and joy. But I’ll rapidly wrap up my imposter syndrome in a few tight twists of context before getting on with the main task of joining the host author in calling out bad and sloppy history of science – and calling for getting it right – for both writers and readers of this blog know that getting history right matters.

As much as I look forward to the weekly arrival of the R-mathematicus email alert, I also anticipate the annual publication of the BBC Proms guide. Science and music are equal passions for me, and as far as I am concerned, music doesn’t get more exciting than the best classical music festival in the world – the London Promenade series of summer concerts at the Royal Albert Hall. Although the science I do professionally turns around the physics of soft materials and biophysics, astronomy was my childhood gateway to the study of nature, and is still my own amateur scientific passion. So when I discovered that a chosen theme of this year’s Prom concerts was space, responding to the 50thanniversary of the first human moon landing, I became understandably excited. Sure enough, the usually well-researched and written Proms Guide contained a promising article by Neil Brand, The Sound of Space.

The first page takes the reader on a musical pathway through the scores for science fiction films – an area of expertise for Brand, and a good read. But his thesis that the cosmos and music have been linked for centuries requires some history of science. This is where, as is sadly so often the case, the source-checking (frankly even encyclopaedia checking) runs out. A first indication that trouble is afoot appears in the categorisation of Cicero’s Dream of Scipioas a ‘philosophical treatise’. This marvellous dream-discourse is just the closing portion of the 6thbook of Cicero’s De res publica– the whole work really a political treatise, though highly expansive. It is very significant for the imaginative tradition of viewing the Earth from Space, as I have noted elsewhere , but does indeed mention the ‘music of the spheres’, the author’s point. So we read on for now.


The Universe, the Earth in the centre, surrounded by the seven planets within the zodiacal signs Images from a 12th-century manuscript of Macrobius’ Commentarii in Somnium Scipionis Source: Copenhagen, Det Kongelige Bibliotek, ms. NKS 218 4° via Wikimedia Commons

Enter Johannes Kepler (1571-1630), one of my personal Renaissance/Early-Modern astronomical heroes. I ceaselessly find it impressive that Kepler was able to deduce the three propositions concerning planetary motion that we now refer to as ‘Kepler’s Laws’, including the discovery of the elliptical orbit of Mars (and the other planets) from naked eye observations. He could not have done this, however, without the equally heroic contribution of Danish astronomer Tycho Brahe, who improved the accuracy of stellar positional measurements over his predecessors by two orders of magnitude – and this without a telescope. It was Tycho’s observations that enabled Kepler to deduce the elliptical planetary motion, work begun around 1601 but first published in his Astronomia Nova of 1609. Given that the first telescopic astronomical observations were not made until Thomas Harriot and then Galileo Galilei turned their primitive telescopes skyward in 1609, it is strange that Brand is able to assure us that Kepler used ‘observation through early telescope lenses’ to establish his laws of motion.

A decade’s error may perhaps be forgivable (though not the silence on Tycho Brahe), but errors of, several centuries and more stretches all generosity on my part. For Brand then attempts to link Kepler casually to the adoption of music within the ‘quadrivium’ of mathematical subjects taught in medieval universities.

It is elementary educational history that the structure of the ‘Liberal Arts’, for which the quadrivium formed the second year of study, was conceived by the time the late Roman commentator Macrobius wrote about them (interestingly in a lengthy commentary on the Dream of Scipio, see above!) around 430 AD. There is strong corroboration for this early adoption two centuries later from Isidore of Seville in his compendious Etymologies. Music remained a mathematical art from late antiquity, through the cathedral schools and early universities of the high middle ages to Kepler’s own time.

Brand’s final science-history sin is an even stranger one. For in the next section he introduces us to William Herschel, a Hanoverian, who emigrated to England in 1757. Herschel is a fascinating figure, most famous for his discovery of the first new planet since antiquity – Uranus, in 1781.


William Herschel 1785 portrait by Lemuel Francis Abbott Source: Wikimedia Commons

But in an astonishingly dense sweep of double confusion, Brand tells us that Herschel managed this feat ‘through careful calculation with superb new and enormously large optical telescopes.’ The discovery was actually made by observing the tiny greenish disk of Uranus move over several nights against the background of stars, and through a relatively small reflecting telescope[1]. Herschel’s massive 40’ reflector was not operational before 1789, and no more than a twinkle in its designer’s eye in 1781. Brand’s other confusion is, of course, with the discovery of Neptune. This was indeed effected by calculation (simultaneously by Le Verrier in France and Adams in England), following perturbations noticed in the orbit of Uranus. Le Verrier’s theoretical predictions of the whereabouts of the planet that accounted for Uranus’ wanderings lead to the 1846 observational discovery of Neptune in Berlin by Johan Galle.

The reason that the mangling of Herschel’s history is strange, especially in a BBC Proms Guide, is that he was first a musician, not an astronomer. Composer, singer and oboist, his first position in England was as director of the military band in Durham. His later moves to Birmingham and then Bath were also to musical posts, and only in the last did his astronomical interests begin to dominate. His famous sister Carolyn accompanied him, also as a singer, and in parallel career development became an astronomer in her own right, discovering several comets, and recording their observations meticulously. But in the musical phase of his career, William himself composed 24 symphonies and three remarkable oboe concertos among other pieces. It is perhaps the greatest pity of all that, in a year dedicated to music and astronomy, none has found a place at any of the 2019 Prom performances, where they might have embodied a beautiful and historical sound of space.

[1]If you are ever in the area, the Herschel Museum of Astronomy  in Bath, situated in Herschel’s old place of residence, is a delight and you can go out into the back garden where he made his discovery of Uranus.


Filed under History of Astronomy, Myths of Science

The emergence of modern astronomy – a complex mosaic: Part X

The publication in the spring of 1543 Copernicus’ De revolutionibus orbium coelestium (On the Revolutions of the Heavenly Spheres) had been widely advertised in advance by his own Commentariolus, distributed in manuscript from about 1510 and Rheticus’ De libris revolutionum Copernici narratio prima (1stedition Danzig 1540 and 2ndedition Basel 1541), so there was a certain level of anticipation to finally be able to view the mathematical models on which Copernicus had based his heliocentric hypothesis. The interest was particularly great as this was the first major, extensive work of mathematical astronomy since Ptolemaeus’ Syntaxis Mathematiké was published in the middle of the second century CE. The inaccuracy of the tables and ephemerides based on Ptolemaeus’ work had been grounds for concern amongst astronomers and astrologers for several centuries by the time Copernicus’ magnum opus appeared. So what did the eager reader get for his money when he finally got De revolutionibus in his hands?

De revolutionibus is closely modelled on Ptolemaeus’ Syntaxis Mathematiké or more accurately, as is clear from internal textual evidence, Peuerbach’s and Regiomontanus’ Epytoma in almagesti Ptolemei, which together with Peuerbach’s Theoricarum novarum planetarum had been the book from which Copernicus had learnt his astronomy. However unlike the Syntaxis Mathematiké and the Epytoma, which both have thirteen books, De revolutionibus only has six books.

These six books are preceded by a title page and three separate documents. As well as the title, the title page contains the following message, which almost certainly stems from the publisher, Johannes Petreius, rather than from Copernicus:


Source: Wikimedia Commons

Diligent reader, in this work, which has just been created and published, you have the motion of the fixed stars and planets, as these motions have been reconstituted on the basis of ancient as well as recent observations, and have been moreover been embellished by new and marvellous hypotheses. You also have most convenient tables, from which you will be able to compute those motions with the utmost ease for any time whatever. Therefor buy, read, enjoy.[1]


This is followed by the motto, in Greek, that supposedly graced the gates of Plato’s Academy:

Let no one untrained in geometry enter here

The first opening document is the Ad lectorum added by Andreas Osiander that I dealt with in Part IX. The second is a letter that Copernicus received from Nicolas Schönberg, Cardinal of Capua, in 1536 urging him to make his new cosmology public. Publishing this display of support by a leading Church official, Schönberg was secretary to the pope, was obviously intended to deflect any potential theological objections to his work. This is very obviously also the intention of the third document, the book’s preface, a dedication to His Holiness, Pope Paul III. In this preface Copernicus defends and justifies his heterodox cosmological hypothesis. The strongest statement coming shortly before the conclusion:

Perhaps there will be babblers who claim to be judges of astronomy although completely ignorant of the subject and, badly distorting some passages of Scripture to their purpose, will dare to find fault with my undertaking and censure it. I disregard them even to the extent of despising their criticism as unfounded. For it is not unknown that Lactantius, otherwise an illustrious writer but hardly an astronomer, speaks quite childishly about the earth’s shape, when he mocks those who declared that the earth has the form of a globe. Hence scholars need not be surprised if any such person will likewise ridicule me. Astronomy is written for astronomers.

(The Latin text of the final phrase is Mathemata mathematicis scribuntur, which is often translated as mathematics is written for mathematicians, but I think Rosen is right to translate it as astronomy and astronomers because in the Renaissance the terms mathematicus, astronomicus and astrologus are actually synonyms.)

With his “astronomy is written for astronomers” Copernicus a stridently telling potential readers I will only accept criticism from people who know what they are talking about. Copernicus citing Lactantius, as an ignorant critic has a certain historical irony. Lactantius a notorious flatearther had been almost entirely forgotten and committed to the trashcan of history but was brought back into circulation by Copernicus’ citation.

The first eleven chapters of Book I give a general overview of Copernicus’ heliocentric hypothesis and present his cosmology. Here Copernicus makes very clear his strict adherence to the ancient Greek axiom that the motion of celestial bodies is uniform circular motion, which would prove to be the biggest drawback of his entire system and eventually lead to its downfall. Chapter twelve deals with the maths of cords of circles, chapter thirteen the trigonometry of plain triangles and chapter fourteen spherical trigonometry. These chapters constitute the section of the book that Rheticus had published in advance in Copernicus’ name De lateribus et angulis triangulorum (On the Sides and Angles of Triangles), which appeared in 1542.


Book II of De revolutionibus deals with the principles of spherical astronomy and closes with a catalogue of the fixed stars, which is largely Ptolemaeus’ star catalogue. Book III is devoted to the Sun, Book IV to the moon and Books V & VI deal with the motion of the planets in a heliocentric system.

De revolutionibus is a weighty, mathematical tome running to 330 large format pages in Edward Rosen’s English translation and definitely not for the casual reader or the faint of heart. Some historians have claimed that it was a bad seller and compare its publication figures with Christoph Clavius’ commentary on the Sphere of Sacrobosco, In Sphaeram Ioannis de Sacro Bosco commentaries, which went through numerous editions in the late sixteenth and early seventeenth centuries. This is an unfair comparison. Clavius’ volume is a university textbook on the basics of geocentric astronomy written for undergraduates. De revolutionibus is an advanced mathematical text written, as Copernicus said, for working astronomers. There were only a fairly small number of scholars in Europe in the second half of the sixteenth century, who possessed the necessary knowledge and level of mathematical skill to read and understand it. In the sixteenth century there were only two editions, the first in Nürnberg in 1543 and the second unchanged edition in Basel in 1566 published by Petreius’ cousin Heinric Petri. Each edition has been estimated to have been around five hundred copies.


Title page, 2nd edition, Basel, Officina Henricpetrina, 1566 Source: Wikimedia Commons

Owen Gingerich carried out a detailed survey over many years of all the known surviving copies of both the first and second editions and it is clear that every notable mathematician/astronomer in Europe in the second half of the sixteenth century possessed a copy of De revolutionibus. Gingerich also surveyed the marginalia in all the surviving copies and one general result was that nearly all the readers ignored the first, heliocentric cosmological Book, confining themselves to the mathematical models in the other five books. We will be looking somewhat more closely at the reception history of Copernicus’ magnum opus in the next part of this series.


[1]All English quotes from De revolutionibus are taken from On the Revolutions, translated and commentary by Edward Rosen, Johns Hopkins University Press, Baltimore and London, ppb. 1992


Filed under History of Astronomy, Renaissance Science

A disservice to the history of Islamic Astronomy

In an article on their website about their history Astronomy magazine claims to be the greatest magazine about astronomy in the world. If this were the case, one would expect them to maintain a high level of journalism and fact checking in the articles that they present to their readers. Unfortunately in at least one case this is far from being the truth. Recently I was guided by a link on Facebook to one of their articles, How Islamic scholarship birthed modern astronomy by Shannon Stirone. As always, interested in anything on the history of astronomy, particularly with such a provocative title I thought I would take a look and when I did then wished I hadn’t.

Ms Stirone makes a grand claim right away in the first paragraph:

Civilizations around the world have incorporated astronomical observations into everything from their architecture to their storytelling and while the pinnacle of the science is most commonly thought to have been during the Renaissance, it actually began a thousand years earlier and 5,000 miles to the East.

Unfortunately, she then goes completely off the rails in the very next paragraph:

Around the 6th century AD, Europe entered what’s known as the Dark Ages. This period of time from around 500 AD until to the 13th century witnessed the suppression of intellectual thought and scholarship around the continent because it was seen as a conflict to the religious views of the church. During this time the written word became scarce, and research and observations went dormant.

To repeat something that I seem to be saying rather oft recently, historians do not use the term Dark Ages anymore preferring the more neutral term Early Middle Ages but of course when you are about to spout pure historical bullshit using the derogatory term Dark Ages is a good way to prepare your unsuspecting readers. There was no “suppression of intellectual thought and scholarship around the continent because it was seen as a conflict to the religious views of the church.” In fact as Steve McCluskey points out in his excellent Astronomies and Cultures in Early Medieval Europe what learning and culture was kept alive during very troubling economic and political times in Europe was kept alive in the Christian monasteries, who of course also maintained a thriving written culture.  We move on:

While Europe was in an intellectual coma, the Islamic empire which stretched from Moorish Spain, to Egypt and even China, was entering their “Golden Age”. Astronomy was of particular interest to Islamic scholars in Iran and Iraq and until this time around 800 AD, the only astronomical textbook was Ptolemy’s Almagest, written around 100 AD in Greece. This venerable text is still used as the main reference for ancient astronomy in academia to this day. Muslim scholars waited 700 years for this fundamental Greek text to be translated into Arabic, and once it was, they got to work understanding its contents. 

Ignoring the dreadful writing style we get told, “Muslim scholars waited 700 years for this fundamental Greek text to be translated into Arabic.” Now if we follow the traditional dating and say that Islam begins in 622 CE then apparently the first translation of the Syntaxis Mathematiké (Almagest is of course the Arabic name for Ptolemaeus’ masterpiece) into Arabic was in the fourteenth century according to Ms Stirone’s reckoning. If, however, we take to conventional beginning of Islamic science to be the early eighth century then the poor Islamic astronomers had to wait until the fifteenth century! Even worse they, apparently, even had to wait for somebody else to translate if for them or at least that is what Ms Stirone’s wording would seem to imply. Apart from this Ptolemaeus lived and worked in Alexandria in Egypt not in Greece and the Syntaxis Mathematiké was written in about 150 CE not 100.

Next we jump to Ibn Yunus (c.950–1009):

Astronomers like Ibn Yunus from Egypt found faults in Ptolemy’s calculations about the movements of the planets and their eccentricities. Ptolemy was trying to find an explanation for how these bodies orbited in the sky, including how the Earth moved within these parameters. Ptolemy calculated that the wobble of the Earth, or precession as we now know it, varied 1 degree every 100 years. 

Later, astronomer Ibn Yunus found that Ptolemy was quite wrong and that in fact it was 1 degree every 70 years.

In fact Ptolemaeus knew it as precession because, as our author later admits  in her article he wasn’t aware that it was caused by wobble of the earth’s axis. Despite a fifth dan black belt in googling, I couldn’t find a source for Ibn Yunus’ value of the precession either on the Internet or in any of my books, so I’ll be generous and assume that our author is this time correct. However, what we have here is a wonderful example of presentism. Because Ibn Yunus’ value is close to the correct value we pick it out and ignore all the other incorrect values proffered by other leading Islamic astronomers. At the time nobody knew whose value was correct. Even worse various Islamic astronomers believed that the rate of precession varied over time and introduced the false concept of trepidation, which was passed on into European astronomy in the Renaissance. Not everything proffered by Islamic astronomy was correct or helpful.

We then get told:

This discovery by Ibn Yunus and others like Ibn al-Shatir changed the landscape of astronomy forever. The heliocentric model eventually proposed by Copernicus in the 16th century was built on this body of work.


Copernicus did indeed use the mathematical models developed by al-Shatir and others but there was nothing in the Islamic astronomy that he utilised that suggested or led to heliocentrism, as the quote above would seem to suggest. Also, Copernicus was one of the Renaissance astronomers who had to deal with the Islamic inheritance of the false theory of trepidation. Now on to mathematics:

The math required for astronomy was also advanced in large part by Islamic scholars. They developed spherical trigonometry and algebra, two forms of math fundamental to precise calculations of the stars. 

The algebra that Islamic mathematicians developed didn’t play a role in astronomy; trigonometry, however, did. Spherical trigonometry was originally developed by Hipparchus of Nicaea (c.190–c.120 BCE) and used by Ptolemaeus in his Syntaxis Mathematiké. Indian astronomers produced a better version of Ptolemaeus’ trigonometry and this was taken over and to some extent improved by Islamic mathematicians, who then passed it on to Europe in the Renaissance. We move onto observatories and observational instruments:

In the 8th century under Caliph al-Mamun al-Rashid, the first observatory was built in Baghdad and subsequent observatories were built around Iraq and Iran. Since this was before the telescope had been developed, the astronomers of the time invented observational sextants. These tools, some as large as 40 meters, were critical to the study of the angle of the sun, movement of the stars, and the understanding of the orbiting planets.

Although the mural sextant was a new development made by Islamic observers, ancient Greek astronomers also used instruments to make similar observations and measurements. Also the telescope was invented not developed. We continue:

Around this same time in 964, after more and more observations took place, one of Iran’s most famous astronomers Abd al-Rahman al-Sufi published The Book of Fixed Stars, one of the most comprehensive texts on constellations in the sky.  Abd al-Rahman al-Sufi was also the first astronomer to observe the Andromeda galaxy and the Large Magellanic Cloud. These observations would have been made purely with the naked eye since the telescope hadn’t yet been created. Of course he didn’t know it was a galaxy at the time, he marked it down as a “cloud” in his notes. This work would later prove to be useful to famed Danish astronomer Tycho Brahe.

Remember we are talking about how Islamic scholarship birthed modern astronomy, so I have to ask in what sense is this true for al-Sufi’s Book of Fixed Stars? A very beautiful manuscript that was known in many version in the Middle Ages and Renaissance, it is a synthesis of the Ptolemaic star catalogue and the pre-Islamic Arabic astronomical tradition. As a catalogue of the constellations it adds nothing to Ptolemaeus except a lot of Arabic names for stars that poor monoglot English speakers have difficulty spelling and even more difficulty pronouncing, Betelgeuse anyone? His records of the Large Magellanic and Andromeda nebulae are of historical interest but it would be centuries before astronomers would eventually understand what they are and al-Sufi only got credit for their “discovery” with hindsight. Next up al-Tusi:

Later in the 13th century, scientist and philosopher Nasir al-Din al-Tusi created the famous Tusi Couple. […] The Tusi Couple would later become critical to Copernicus’ understanding of these motions during his work in the Renaissance.

In the ellipsis we get a rather confused explanation of the fact that the Tusi Couple enables the construction of linear motion using circles. Yes, Copernicus did use the Tusi Couple but Copernicus’ insistence on reproducing all celestial motion with circular motion was his greatest error not his greatest achievement. Next up, he never fails to be included, is Ibn al-Haytham:

One of Islam’s most famous astronomers and scientific thinkers, Ibn al-Haytham, is known as “the father of optics” because he was the first person to crack the code about how we perceive light. He figured out that light traveled in a straight line into our eyes but not out. For hundreds of years it was thought by people like Ptolemy that our eyes actually emitted light, like an interior flashlight. His work developed the camera obscura and eventually aided in the development of the telescope.

That light travels in straight lines was a well-known fact in ancient Greek optics. There were also not just extra-mission theories of optics in ancient Greece but also intromission ones. Ibn al-Haytham’s achievement was to show that it was possible to combine an intromission theory of vision with the geometrical optics of Euclid, which was based on an extra-mission theory. To do so he used the punctiform theory of light reflection of al-Kindi, who propagated an extra-mission theory. It’s all much more complicated than it is, as here, usually presented. Although al-Haytham used the camera obscura it had been known since antiquity. His work in optics played no role in the invention of the telescope.

Perhaps the most significant contribution Ibn al-Haytham gave to the world was a methodical way of conducting experiments repeatedly in order to test a theory, this became known as the scientific method, the foundation for science as we know it.

If I ever get a tattoo it will be a quite long list of names, including Ibn al-Haytham’s, followed by the clause “…did not invent the scientific method!” We move onto higher education:

Throughout this time, from the beginning of the Golden Age until the early Renaissance, many universities and madrasas, or schools were being constructed around the Islamic empire. In 859 AD the first university was built in Fez, Morocco. It was conceived of and started by Fatima al-Fihri, the daughter of a wealthy merchant. Scholars from all over the world including Christian and Jewish scientists traveled there to study astronomy, math and philosophy.

One of my personal peeves is the use of the word university as a general term for institutes of higher education. Universities are institutes of higher education created in the High Middle Ages in Europe with a specific format and educational content. Earlier Islamic institutes of higher education are not universities. This is not saying that universities are in anyway superior just different. I’m not an expert on the history of Al Quaraouiyine the mosque and madrassa founded by Fatima al-Fihri, she only actually provided the funds for its establishment, which she inherited from her father, but I very much doubt the claim that Christian and Jewish scientists travelled there to study astronomy, maths, and philosophy, as it was basically a Muslim religious institutions for teaching Islamic theology.

Many schools and mosques around this time were overseen and managed by Muslim women who themselves had been educated in subjects ranging from literature to algebra, a form of math also perfected by Islam. One of the most well known astronomical tools called an Astrolabe was created by the Greek thinker Hipparcus but was perfected by islamic scientists, particularly women. Mariam al-Astrulabi was a Syrian female astrolab maker from the 10th century. She’s best known for perfecting the art of making these instruments which calculated the altitude of celestial bodies in the sky. In her honor, astronomer Henry E. Holt named a main belt asteroid after her in 1990.

Anybody like to comment on the “many schools and mosques around this time were overseen and managed by Muslim women”? Paint me sceptical. I’m not just sceptical about, “One of the most well known astronomical tools called an Astrolabe was created by the Greek thinker Hipparcus but was perfected by islamic scientists, particularly women. Mariam al-Astrulabi was a Syrian female astrolab maker from the 10th century.” I will admit that my knowledge of Islamic astrolabe makers is far from perfect but as far as I know Mariam al-Astrulabi is the only known female Islamic astrolabe maker and she is not known for perfecting the art of making these instruments.

The light from stars contain a history themselves; it’s taken tens of thousands of years in some cases for their story to travel through space and reach our eyes and mirrors of our telescopes. A millenia later, around 200 stars bear the Arabic names of astronomers who made significant contributions to the field.

Although many, many stars have Arabic names they were named by astronomers not after them. If you really want to know the meaning of the Arabic star names I recommend Paul Kunitzsch and Tim Smart, A Dictionary of Modern Star Names: A Short Guide to 254 Star Names and Their Derivations, Sky & Telescope, Cambridge Massachusetts, 2006.

Studying the cosmos is something more ingrained in the international culture than meets the eye. If you’ve ever stared at the belt of Orion or Alcor and Mizar, the binary stars in the Big Dipper, then you’ve gotten a small glimpse into the legacy created by Muslim scientists around the world.

The only thing that is really correct in this article in the fact that Islamic astronomers and astrologers made major contributions to the history of astronomy, which deserves to be elucidated and honoured but this shambling mess of an article does not do the job.  Given the size of the magazine Astronomy’s readership it is sad that they published this shoddy piece of journalism instead of commissioning somebody, who knows what they are actually talking about to write an article actually worthy of the inheritance of Islamic astronomy.
































Filed under History of Astronomy

The emergence of modern astronomy – a complex mosaic: Part IX

In 1542 the manuscript of De revolutionibusarrived at Petreius’ printing office in Nürnberg followed by Rheticus who intended to see it through the press. I argued in Part VII that Johannes Petreius had in fact commissioned Rheticus to see if Copernicus had written anything substantial on his astronomical theories and if so to persuade him to allow Petreius to publish it. Petreius’ printing office was certainly the right address for the publication of a major new work on astronomy, as he was certainly the leading scientific publisher–astrology, astronomy, mathematics–in the Holy Roman Empire of German States and probably the whole of Europe but who was Johannes Petreius?


The Petreius printing office in Nürnberg Photo by the author

He was born Hans Peter, whereby Peter is the family name, into a family of wealthy farmers in the Lower Franconia village of Langendorf near Hammelburg in 1496 or 1497. He matriculated at the university of Basel in 1512, graduating BA in 1515 and MA in 1517. He next appears as a witness in a court case in Basel in 1519, where he is described, as working as a proofreader for the Basler printer publisher Adam Petri. This explains why he had chosen to study in Basel, as Adam Petri was his uncle. Petri is the Swizz German version of the name Peter. Presumably, having learnt the black art, as printing was known, from his uncle he moved to Nürnberg in 1523 and set up his own printing office. The was almost certainly an attempt by the Peter family to cash in on the gradual collapse of the Koberger printing office following the death of Aton Koberger in 1513. The Petri-Froben-Amerbach printing cooperative had been Koberger’s licensees in Basel, printing his titles on commission.


Source: Wikimedia Commons

Hans Peter now sporting the Latinised name, Johannes Petreius, succeeded in establishing himself against the local competition and by 1535 was the leading printer publisher in Nürnberg. Like most other printer publishers Petreius’ main stock in trade was printing religious volumes but in the 1530s he began to specialise in printing scientific texts. Exactly why he chose to follow this business path is not known but it was probably the ready availability of the large number of mathematical, astrological and astronomical manuscripts brought to Nürnberg by Regiomontanus when he set up his own printing office in 1471. This hypothesis is supported by the fact that several of Petreius’ earliest scientific publications were all of manuscripts from this collection, all of which were edited for publication by Johannes Schöner, who would later be the addressee of Rheticus’ Narratio  Prima.

This series of publications started with Schöner’s edition of Regiomontanus’ own De Triangulis in 1533, a very important work in the history of trigonometry. This was also one of the volumes that Rheticus took with him to Frombork, as a present for Copernicus.

Schöner followed this with Regiomontanus’ Tabulae astronomicaein 1536. Petreius’ activities in the area were not however restricted to Schöner’s output. Earlier he published the first Greek edition of Ptolemaeus’ Tetrabiblos, under the title Astrologica, edited by Joachim Camerarius (1500–1574), which included Camerarius’ translation into Latin of Books I & II and partial translations of Books III & IV together with his notes on Books I & II and the Greek text of the Centiloquium, a collection of one hundred astrological aphorism falsely attributed to Ptolemaeus, with a Latin translation by Giovanni Pontano (1426–1503).


Opening chapter of the first printed edition of Ptolemy’s Tetrabiblos, transcribed into Greek and Latin by Joachim Camerarius (Nuremberg, 1535). Source: Wikimedia Commons

A year earlier Petreius had published Johann Carion’s Practica new – auffs 1532 mit einer auslegung des gesehen cometen. Through these publications it is clear that the principle interest is in astrology and it is here that money was to be made. Over the next twenty plus years Petreius published more texts from Regiomontanus edited by Schöner, some of Schöner’s own works on astronomy and cartography, reckoning and algebra books from Christoph Rudolff  (c. 1500–before 1543) and Michael Stifel (1487–1567). Various scientific texts edited by Peter Apian including his and Georg Tannstetter’s edition of Witelo’s Perspectiva (1535), another of the volumes that Rheticus took with him to Frombork for Copernicus. Various Arabic astrological texts, the Tractatus astrologicae (1540) of Lucas Gauricus (1575–1558), who along with Schöner and Cardano was one of the most important astrologers of the first half of the sixteenth century. Petreius became the publisher of Gerolamo Cardano (1501–1576) north of the Alps, publishing his works on mathematics, astronomy, medicine, astrology and philosophy, all of which were highly successful.


Source: Wikimedia Commons

He also published alchemical works from Abū Muḥammad Jābir ibn Aflaḥ better known in the West as Geber. As well as all this, Petreius commissioned and published the first German translation of Vitruvius’ De architectura, a bible for Renaissance artist-engineers.

Petreius’ scientific catalogue was very wide but also had depth, including as it did various classics by Regiomontanus, Schöner, Stifel, Cardano and Witelo. If anybody could adequately present Copernicus’ masterpiece to the world then it was Johannes Petreius.

Rheticus had originally intended seeing Copernicus’ manuscript through the press but Philipp Melanchthon had other plans for his errant protégée. In the meantime Rheticus had, at the request of Joachim Camerarius, who was now rector of the University of Leipzig and had obviously been impressed by Rheticus during their meeting in Tübingen, been offered a chair in mathematics at Leipzig.


Joachim Camerarius, 18th-century engraving by Johann Jacob Haid. Source: Wikimedia Commons

In the autumn of 1542 Rheticus, under pressure from Melanchthon, left Nürnberg and preceded to Leipzig, where he was appointed professor of higher mathematics i.e. astronomy and music and his direct involvement in De revolutionibus came to an end. Petreius still needed an editor to see Copernicus’ weighty tome through the press and this duty was taken over, with serious consequences by Nürnberg’s Lutheran Protestant preacher, Andreas Osiander (1496 or 1498–1552).


Andreas Osiander portrait by Georg Pencz Source: Wikimedia Commons

Osiander was born in the small town of Gunzenhausen to the south of Nürnberg, the son of Endres Osiander a smith and Anna Herzog. His father was also a local councillor who later became mayor. He matriculated at the University of Ingolstadt in 1515 where he, amongst other things, studied Hebrew under the great humanist scholar and great uncle of Melanchthon, Johannes Reuchlin. In 1520 he was ordained a priest and called to Nürnberg to teach Hebrew at the Augustinian Cloister, a hot bed of reformatory debate, where he also became a reformer. In 1522 he as appointed preacher at the St Lorenz church and became a leading voice for religious reform. Osiander achieved much influence and power in Nürnberg when the city-state became the very first Lutheran Protestant state.

Osiander first became involved with Petreius when the latter started publishing his religious polemics. Petreius also published numerous religious works by both Luther and Melanchthon. Where or how Osiander developed his interest and facility in the mathematical sciences is simply not know but they are attested to by Cardano in the preface to one of his books published by Petreius. In fact it was Osiander, who was responsible for the correspondence between Cardano and the Petreius printing office and he edited Cardano’s books there. When or how Osiander became an editor for Petreius is also not known. In his capacity as editor of De revolutionibus Osiander committed what many have as one of the greatest intellectual crimes in the history of science, he added the infamous ad lectorum, an address to the reader with which the book opens.


Latin Wikisource

The ad lectorum is an essay that it pays to read in full but here we will just consider the salient points, Osiander writes:

There have already been widespread reports about the new novel hypothesis of this work, which declares that the earth moves whereas the sun is at rest in the centre of the universe.

Here Osiander lets us know that knowledge of Copernicus’ heliocentric hypothesis was already widespread–spread by the Commentariolus, the Narratio Prima and by rumour–indicating that there was going to be a high level of expectancy to learn the mathematical details of the system. He goes on:

Hence certain scholars, I have no doubt, are deeply offended and believe that the liberal arts, which were established long ago on a sound basis, should not be thrown in confusion.

Anticipating criticism from conservative circles Osiander goes into defensive mode:

But if these men are willing to examine the matter closely, they will find that the author has done nothing that is blameworthy. For it is the duty of an astronomer to compose the history of the celestial motions through careful and expert study. Then he must conceive and devise the causes of these motions or hypotheses about them. Since he cannot in any way attain to the true causes, he will adopt whatever suppositions enable the motions to be computed correctly from the principles of geometry for the future as well as the past.

Here we have the crux of Osiander’s defence. Astronomers are here to produce geometrical models in order to provide accurate predictions of celestial motions and not to determine the unobtainable true causes of those motions. This argument has been dubbed instrumentalist and some hail Osiander as the first instrumentalist philosopher of science. Instrumentalism is a metaphysical attitude to scientific theories that enjoyed a lot of popularity in modern physics in the twentieth century; it doesn’t matter if the models we use describe reality, all that matters in that they predict the correct numerical results. Osiander expands on this viewpoint:

For these hypotheses need not be true or even probable. On the contrary, if they provide a calculus consistent with the observations, that alone is enough.

Here we have the core of why the ad lectorum caused so much outrage over the centuries. Osiander is stating very clearly that the mathematical models of astronomers are useful for predictive purposes but not for describing reality. A view that was fairly commonplace over the centuries amongst those concerned with the subject. Copernicus, however, very clearly deviates from the norm in De revolutionibus in that he presents his heliocentric system as a real model of the cosmos. Osiander’s ad lectorum stands in clear contradiction to Copernicus’ intentions. Osiander then goes into more detail illustrating his standpoint before closing his argument as follows:

…the astronomer will take as his first choice that hypothesis which is easiest to grasp. The philosopher will perhaps rather seek the semblance of the truth. But neither of them will understand or state anything certain, unless it has been divinely revealed to him.

Here we have Osiander restating the standard scholastic division of responsibilities, astronomers provide mathematical models to deliver accurate predictions of celestial motions for use by others, philosophers attempt to provide explanatory models of those motions but truth can only be delivered by divine revelation. The modern astronomy, whose gradual emergence we are tracing had to break down this division of responsibilities in order to become accepted as we shall see in later episodes. Osiander closes with a friendly appeal to the reader to permit the new hypotheses but not to take them too seriously, and thereby make a fool of himself.

Therefore alongside the ancient hypotheses, which are no more probable, let us permit these new hypotheses also the become known, especially since they are admirable as well as simple and bring with them a huge treasure of very skilful observations. So far as hypotheses are concerned, let no one expect anything certain from astronomy, which cannot furnish it, lest he accept as the truth ideas conceived for another purpose, and depart from this study a greater fool than he entered it. Farewell.

There is a widespread belief that Osiander somehow smuggled his ad lectorum into De revolutionibus without the knowledge of either Copernicus or Petreius but the historical evidence speaks against this. There are surviving fragments of a correspondence between Osiander and Copernicus that make it clear that Osiander discussed the stratagem of presenting De revolutionibus as a hypothesis rather that fact with him; although we don’t know how or even if Copernicus reacted to this suggestion. More telling is the situation between Petreius and Osiander.

There is absolutely no way that Osiander could have added the ad lectorum without Petreius’ knowledge. This is supported by subsequent events. When the book appeared Tiedemann Giese was outraged by the presence of the ad lectorum and wrote a letter to the city council of Nürnberg demanding that it be removed and the book reissued without this blemish. The council consulted Petreius on the subject and he let them know in no uncertain terms that it was his book and what he put in it was his business and nobody else’s.

Petreius’ reaction illustrates an important point that modern commentators often overlook. Our concept of copyright didn’t exist in the sixteenth century, the rights to a publish work in general lay with the publisher and not the author. This is clearly demonstrated by the fact that when a publication provoked the ire of the authorities, civil or clerical, it was the printer publisher, who first landed before the court and then in goal rather than the author.

The ad lectorum was anonym but any reader, who was paying attention should have realised through the phrasing that Copernicus was not the author. The Nürnberger astronomer and instrument maker Johannes Pratorius (1537–1615), another Wittenberg graduate, wrote in his copy of De revolutionibus that Rheticus, when Pratorius visited him in 1569, had revealed to him that Osiander was the author of the ad lectorum.


Source: Wikimedia Commons

Michael Maestlin’s copy contains the same information also from Rheticus via Peter Apian. Kepler’s second hand copy had this information added by its original owner Hieronymus Schreiber (birth date unknown–1547), yet another Wittenberg graduate, who had received a gift copy signed by Petreius, because he had substituted for Rheticus in Wittenberg during the latter’s time in Frombork. All of this indicates that Osiander’s authorship of the ad lectorem was circulating on the astronomers’ grapevine by 1570 at the latest. It was first put into print, and thus made general public, by Kepler in his Astronomia Nova in 1609.

As with most books in the Early Modern Period there was no publication date for De revolutionibus but it seems to have been finished by 20thApril 1543, as Rheticus signed a finished copy on this date. According to a legend, put in the world by Tiedemann Giese, Copernicus received his copy, which was placed into his hands, on his dying day the 24thMay 1543. Owen Gingerich, who is the expert on the subject, estimates that the 1stedition probably had a print run of about 400 copies, which carried the mathematical details of Copernicus’ hypothesis out into the wide world.







Filed under Early Scientific Publishing, History of Astrology, History of Astronomy, Renaissance Science

The emergence of modern astronomy – a complex mosaic: Part VIII

We left Georg Joachim Rheticus[1](1514–1574) just setting out on his journey from Feldkirch to Frombork for what would turn out to be one of the most fateful meetings in the history of science. Our wealthy professor of mathematics travelled in style accompanied by a famulus Heinrich Zell (?–1564), a Wittenberg student, who would later have a career as cartographer, astronomer and librarian. What is rarely mentioned in detail is that Rheticus travelled from Feldkirch to Wittenberg, which is where he collected Zell, and then having acquired permission to extend his sabbatical, continued on his way to Frombork. In total this is a journey of more than 1500 kilometres, hard enough even today but a major expedition in the middle of the sixteenth century.

We have no direct account of the initial meeting between the twenty-five year old mathematics professor and the sixty-six year old cathedral canon.


Portrait of Copernicus holding a lily of the valley, published in Nicolaus Reusner’s Icones (1587), based on a sketch by Tobias Stimmer (c. 1570), allegedly based on a self-portrait by Copernicus. Source: Wikimedia Commons

They obviously got on well, as Rheticus ended staying in the area for two and a half years. Shortly after his arrival Rheticus fell ill and Copernicus took him to Löbau, the home of his friend Tiedemann Giese (1480–1550) Bishop of Kulm, to convalesce.


Portrait of Tiedemann Giese by Hans Schenck, Source: Wikimedia Commons

This episode illustrates an important aspect of Rheticus’ visit. Here was a Lutheran Protestant professor of mathematics from the home of Lutheran Protestantism, Wittenberg University visiting a Catholic cathedral canon in the middle of a deeply Catholic area. Despite the fact that this visit took place in the middle of the Reformation and the beginnings of the Counter Reformation Rheticus was always treated as an honoured guest by all those, who received him whether Protestant, Albrecht, Duke of Prussia,


Albrecht, Duke of Prussia portrait by Lucas Cranach the elder Source: Wikimedia Commons

or Catholic, Copernicus, Giese and above all the Prince-Bishop of Frombork, Johannes Danticus (1485–1548), who although strongly anti-Reformation was also an admirer of Philipp Melanchthon (1497–1560), whom he had met personally.


Johannes Dantiscus Source: Wikimedia Commons

This courtesy across the religious divide amongst scholars during this period of European religious turmoil was actually very common and contradicts a popular image of hate, rejection and bigotry on all fronts and at all levels.

We know of Rheticus’ convalescence in Löbau, because he mentions it on the first page of his Narratio Prima (The First Account) the booklet he wrote shortly after his arrival in Frombork and the first published account of Copernicus’ heliocentric system. He explains that because of his illness he has had barely ten weeks to familiarise himself with the manuscript of Copernicus’ magnum opus in order to describe and explain it in the Narratio Prima, which is an open letter to Johannes Schöner, his Nürnberger astrology teacher and one of Johannes Petreius’ expert editors.


Johannes Schöner Source: Wikimedia Commons

The introduction also makes clear that he had promised Schöner, and probably through him Petreius, this report before leaving Nürnberg. Johannes Petreius’ dedicatory letter to Rheticus in his edition of the fourteenth-century physician Antonius de Motulmo’s De iudiciis nativitatumwas a direct response to the Narratio Prima. He goes on to give a very brief outline of the work, making no mention of the fact that Copernicus’ system is heliocentric. He says that he has mastered the first three books, of six, grasped a general idea of the forth and begun to conceive the hypotheses of the rest. He says he is going to skip the first two books for which he has a special plan; he originally intended to write a Narratio Secunda, which never materialised. He then plunges into his description.

The first four sections are technical astronomical accounts of: The Motion of the Fixed Stars, General Considerations of the Tropical Year, The Change in the Obliquity of the Ecliptic, and The Eccentricity of the Sun and the Motion of the Solar Apogee. In the fifth section, The Kingdom of the World Change with the Motion of the Eccentric, Rheticus changes tack completely and presents us with an astrological theory of cyclical historical change. I shall quote the beginning of this extraordinary section:

I shall add a prediction. We see that all kingdoms have had their beginnings when the centre of the eccentric was at a special point on the small circle. Thus, when the eccentricity of the sun was at its maximum, the Roman government became a monarchy; as the eccentricity decreased, Rome too declined, as aging, and then fell. When the eccentricity reached the boundary and quadrant of mean value, the Mohammedan faith was established; another great empire came into being and increased very rapidly, like the change in the eccentricity. A hundred years hence, when the eccentricity will be at its minimum, this empire too will complete its period.

This calculation does not differ much from the saying of Elijah, who prophesied under divine inspiration that the world would endure only 6,000 years, during which time nearly two revolutions are completed[2].

There is nothing about this to be found in Copernicus’ De revolutionibus but Copernicus certainly read the Narratio Prima before it was published and didn’t object to it or ask Rheticus to remove it. Such astrological cyclical theories of history were en vogue during the Early Modern Period. The most well known one was written by Johannes Carion (1499–1537), who together with Philipp Melanchthon was a student of Johannes Stöffler (1442–1531). Carion had also received language tuition from the slightly older Melanchthon.  Carion was court astrologer to the Elector Joachim I of Brandenburg (1484–1535).


Johann Carion, portrait by Lucas Cranach the Elder Source: Wikimedia Commons

Carion wrote a chronicle based on Biblical prophecies, which divided world history into three 2000-year periods. The chronicle was published shortly after Carion’s death. Following Carion’s death this chronicle passed into Melanchthon’s hands, who reworked it and published it again. Rheticus a student of Melanchthon obviously joined the Carion tradition in his astrological excurse in the Narratio Prima, which goes into long technical detail on the following pages.

In the next section Rheticus returns to Copernicus’ astronomy, Special Consideration of the Length of the Tropical Year. Up till now we have no indication at all from Rheticus that the system he is describing is a heliocentric one. We are now about one third of the way through and Rheticus’ next section is General Considerations Regarding the Motions of the Moon,Together with the New Lunar Hypothesis. At the end of this section we can read:

These phenomena, besides being ascribed to the planets, can be explained, as my teacher shows, by a regular motion of the spherical earth; that is, by having the sun occupy the centre of the universe, while the earth revolves instead of the sun on the eccentric, which it has pleased him to name the great circle. Indeed, there is something divine in the circumstance that a sure understanding of celestial phenomena must depend on the regular and uniform motions of the terrestrial globe alone.

He casual drops the information that we are indeed in a heliocentric world system in passing, as if were the most natural thing in the world. Having in the previous sections demonstrated Copernicus’ abilities as a theoretical astronomer he finally lets the cat out of the bag. There now follow eight sections in which he explains how the new hypothesis functions with the whole of astronomy.

The book closes with a non-astronomical section, In Praise of Prussia. This is a general polemic about how wonderful Prussia and the Prussian are and how well Rheticus has been received and treated by his Prussian hosts. It does, however, contain a section describing Giese’s attempts to persuade Copernicus to publish De revolutionibus and that Copernicus’ response to these enticements is to suggest that he will publish his tables of astronomical data without revealing the methods used to obtain them.

The Narratio Prima is dated 23 September 1539 by Rheticus, who took the manuscript to Danzig where it was printed and published by Franz Rhode in 1540 with the help of a donation towards the printing costs from Johann von Werden (c. 1495–1554) the mayor of Danzig. The title page is interesting as it begins with an honourable address to Johannes Schöner followed by The Books of Revolutions then an equally honourable naming of Copernicus but Rheticus, the author, is simply described as a young student of mathematics[3].


Title page of the 1st edition of the Narratio Prima Source: Wikimedia Commons

The Narratio Prima was fairly obviously conceived as a test balloon for Copernicus’ heliocentric hypothesis. It seems to have been well received and one recipient took his enthusiasm for the text much further. Rheticus had sent a copy to his mentor Achilles Pirmin Gasser (1505-1577),


Achilles Permin Gasser Source: Wikimedia Commons

who published a second edition of the book with a new dedicatory letter and Rheticus named on the title page in Basel in 1541.


First page of a later edition of the Narratio Prima with Rheticus named as author

The positive reception of the Narratio Prima and the lack of negative reactions seem to have finally convinced Copernicus to allow De revolutionibus to be published.

The Narratio Prima is rather long winded, strong on rhetoric and polemic but rather weak on its scientific content. There are no diagrams and Rheticus tends to rely on philosophical arguments rather than mathematical ones. He does, however, display a high degree or erudition, his text is full of classical quotes and allusions, which doesn’t actually make it easier for those who don’t have a classical eduction to plow through his, at times, rather turgid prose.

A third edition of the Narratio Prima was included in the second edition of De revolutionibus published by Heinric Petri in Basel in 1566. The forth and a fifth editions were included in the first and second editions of Johannes Kepler’s Mysterium Cosmographicum in 1597 and 1621. As such, more people probably learnt of Copernicus’ heliocentric system from the Narratio Prima than any other source.

Rheticus stayed in Frombork helping Copernicus to prepare his manuscript for publication by Petreius in Nürnberg. In October 1541 Rheticus left for Wittenberg, where he published an edited and improved version of the trigonometrical section of Derevolutionibusunder Copernicus’s name, De lateribus et angulis triangulorum (On the Sides and Angles of Triangles), which appeared in 1542.


This very useful publication also helped to increase Copernicus’ reputation in astronomical and mathematical circles. Rheticus would dedicate much of his future life to the publication of improved trigonometrical table.

In 1542 the manuscript of De revolutionibus arrived at Petreius’ printing office in Nürnberg followed by Rheticus who intended to see it through the press.

[1]There are no known portraits of Rheticus

[2]The Elijah prophecy is from the Talmud not the Bible.

[3]AD CLARISSMUM VIRUM D. IOANNEM SCHONERUM, DE LIBRIS REVOLUTIONUM eruditissimi viri & Mathematici excellentissimi, Reverendi D. Doctoris Nicolai Copernici Torunnaei, Canonici Varmiensis, per quendam Iuvenem, Mathematicae studiosum NARRATIO PRIMA (To that Famous Man Johann Schöner Concerning the Books of Revolutions of That Most Learned Man and Excellent Mathematician, the Venerable Doctor Nicolaus Copernicus of Toruń, Canon of Warmia, by a certain young student of mathematics)




Filed under Early Scientific Publishing, History of Astrology, History of Astronomy, Renaissance Science

History of science on the Internet – the gift that keeps giving

Dear readers it is time once again for the Hist–Sci Hulk to flex his muscles and give a couple of Internet authors a good kicking for the crime of spreading history of science nonsense. First up we have a website called StarTeach Astronomy Education, who describe themselves as follows:


StarTeach Astronomy Education is a multimedia web-based astronomy education program designed especially for K-12 students and their teachers. The primary goal of the program is to aid in the classroom instruction of astronomy by providing a multimedia supplement that is available to schools with internet capability. In addition, it can also be used as research material for individual students.

The StarTeach Astronomy Education Program was created by Leslie Welser when she was a graduate student in the University of Nevada, Reno Physics Department. StarTeach has been recently updated to include topics for more advanced readers.

The section to which my attention was inadvertently directed was under the drop down menu Ancient Cultures with the title Arab and Islamic Astronomy.

Alone this title causes problem. Only yesterday I had an Internet exchange with Peter Adamson, the excellent creator of the History of Philosophy Without Any Gaps podcast and author of many books and articles based on that podcast, how exactly to describe the philosophy and science produced in the Middle Ages by the inhabitants of those areas of the world dominated by Islamic culture. The answer is certainly not Arab and Islamic, which would seem to suggest two separate areas of production or if only one that the astronomy was only produced by Islamic Arabs. The latter is definitively not the case as we have Arabs, Jews, Persians, Syriac Christians and various others. The subject is complex enough to warrant its own blog post, which I might or might not write sometime in the future.

The article opens with the following:

During the period when Western civilization was experiencing the dark ages [my emphasis], between 700-1200 A.D., an Islamic empire stretched from Central Asia to southern Europe.

The sound you can hear echoing around the world, is the sound of thousands of medievalist weeping and rending their clothes at the use of the term ‘the dark ages’. The preferred term is Early Middle ages. I should point out that the Arabic-Islamic dominance of a substantial part of the Eurasian landmass extended several centuries past 1200 CE and one of the things that Peter Adamson and I discussed is the fact that this empire actually split up fairly early into competing caliphates. Leaving out some minor quibbles we now come to this:

Another important religious use for astronomy was for the determination of latitude and longitude. Using the stars, particularly the pole star, as guides, several tables were compiled which calculated the latitude and longitude of important cities in the Islamic world.

Whereas you can determine latitude using altitude of the sun or the pole star and a bit of relatively simple trigonometry, you cannot determine longitude in this way. In fact the only way available in the Middle Ages to determine longitude astronomically is by simultaneous observation of eclipses, lunar or solar, and then comparing the timings. Next up with have:

Aside from religious uses, astronomy was used as a tool for navigation. The astrolabe, an instrument which calculated the positions of certain stars in order to determine direction, was invented by the Greeks and adopted and perfected by the Arabs (see picture below).

To quote David King, one of the world’s leading authorities on both the astrolabe and Islamic astronomy, the astrolabe was never used for navigation! It was actually the next sentences that finally provoked me into writing this blog post:

The sextant was developed by the Arabs to be a more sophisticated version of the astrolabe. This piece of technology ultimately became the cornerstone of navigation for European exploration.

When I first read this wonderful bullshit-double-whammy, I seriously started banging my head on my desk and praying for quick release from my pain. We are here confronted by a common problem in the history of science, the use of the same name for two or more completely different instruments. Our, by the way anonymous, I wouldn’t want to attach my name to this crap either, author apparently has no idea that the astronomical sextant and the navigational sextant are two completely different beast that apart from a scale representing one sixth of a circle, hence the name, have very little in common.

The astronomical sextant, to which the author intended to refer here, is anything but more sophisticated than the astrolabe and is in fact much, much simpler. It is a simple scale engraved on a segment, one sixth of a circle, with sights mounted on it used to determine the position of stars. I refer the reader to the Wikipedia article for more details. The navigational sextant, also not derived from the astrolabe, is a much more complex beast invented in the seventeenth century, the story of which you can read here. A change of topic:

Science was considered the ultimate scholarly pursuit in the Islamic world, and it was strongly supported by the nobility. Most scientists worked in the courts of regional leaders, and were financially rewarded for their achievements. In 830, the Khalifah, al-Ma’muun, founded Bayt-al-Hikman, the ‘House of Wisdom’, as a central gathering place for scholars to translate texts from Greek and Persian into Arabic. These texts formed the basis of Islamic scientific knowledge.

I think Qur’anic scholars might well dispute the claim that “Science was considered the ultimate scholarly pursuit in the Islamic world.” Another topic to which I might one day devote a whole blog post is the fact that the House of Wisdom, as it is usually presented, such as here, is a myth. For details see Dimitri Gutas, Greek Thought, Arabic Culture: The Graeco-Arabic Translation Movement in Baghdad and Early ‘Abbāsid Society (2nd–4th/8th–10thcenturies).

I could go on and on but I will just consider one last gem:

One of the greatest Islamic astronomers was al-Khwarizmi (Abu Ja’far Muhammad ibn Musa Al-Khwarizmi), who lived in the 9th century and was the inventor of algebra[my emphasis].

The ancient Babylonians and the Indians would be amazed to discover that al-Khwarizmi invented algebra. His book, Al-kitāb al-mukhtaṣar fī ḥisāb al-ğabr wa’l-muqābala, introduced algebra into medieval Europe and part of its title gave the discipline its modern name but algebra was being practice literally millennia before al-Khwarizmi was born.

Interestingly this dog’s dinner of an article, that is intended to educate school kids, isn’t based on academic literature on the subject but offers as its sources links to five other Internet articles, three of which no longer exist and one of which is about the navigational sextant and as such irrelevant.

My second candidate for a Hist_Sci Hulk kicking is from Quillette a self styled platform for free thought and is a review by Jared Marcel Pollen (whoever he is) of Ben Shapiro’s The Right Side of History. An extremely tedious review of an extremely tedious book by an extremely tedious person that wouldn’t normally occupy my thought stream for longer than thirty seconds were it not for the following totally fucked up piece of history of astronomy.

This also allows Shapiro to skirt the obvious hostility the church showed toward intellectual inquiry for centuries. Shapiro writes as if the church had never banned a book or burned a heretic:

Contrary to popular opinion, new discoveries weren’t invariably seen as heretical or dangerous to the dominion of the Church; in fact, the Church often supported scientific investigation.

The Church was indeed the only place where any kind of inquiry could be conducted at the time. It was the only place where people were literate and enjoyed steady funding and access to instruments. But the Church only encouraged inquiry to the extent that it could reinforce and expand its own doctrine, which is a bit like the state telling you that you are free to make whatever art you like, just as long as you don’t criticize the regime.

What we have here is the standard popular presentation of the medieval Catholic Church as some sort of all-powerful totalitarian state. The reality was actually somewhat different. The Church was not able to exercise the sort of total intellectual control that Pollen is here claiming and surprisingly diverse positions were possible and existed in reality .

Also Pollens claim that, “The Church was indeed the only place where any kind of inquiry could be conducted at the time. It was the only place where people were literate and enjoyed steady funding and access to instruments” is of course total rubbish. Just to take the example of the three leading writers on astronomy in the reception phase of Copernican heliocentricity–Tycho Brahe, Johannes Kepler and Galileo Galilei–all three of them were court mathematicians outside of the various churches. There are plenty of other examples of important and influential scholars from this period, who found employment outside of the churches.

The first major scientific challenge to the Church was heliocentrism. But Shapiro claims this was hardly an issue: “Nicolas Copernicus studied in parochial school and served the Church of Warmia as medical advisor; his publication of De revolutionibus… in March 1542, included a letter to Pope Paul III.”

Copernicus was in fact a canon of Frombork cathedral and as such part of the government of the prince-bishopric of Warmia. His role was much wider than that of cathedral physician. De revolutionibus was published in 1543 not 1542 but did in fact contain a dedicatory letter to Pope Paul II.

In fact, Copernicus had finished his treatise years earlier (there are records indicating that the manuscript had been completed as early as the 1530s), but he withheld it, aware that its publication could be life-threatening, and circulated only a few anonymous copies to his close friends.

The bulk of De revolutionibus was, as far as we can tell, finished by about 1530, however the reasons for Copernicus not publishing at that time are complex and contrary to popular opinion had very little to do with any fear of persecution by the Church and its publication would certainly not have been life-threatening; that claim is complete rubbish based on hindsight and fail interpretations of the cases of Giordano Bruno and Galileo Galilei. Despite censoring Copernicus for his relationship with his housekeeper, Danticus, the Prince-Bishop of Warmia, supported Copernicus work and even invited Gemma Frisius, who Danticus supported, to come to Frombork to work with Copernicus. Tiedmann Giese, Bishop of Kulm, an influential cleric and Copernicus’ best friend, had been urging him to publish for years. Lastly Nicholas Schönberg, Cardinal of Capua, wrote a letter to Copernicus urging him to make his work public. This letter was included in the front material of De revolutionibus. As can be seen Copernicus had solid support for his work within the Church hierarchy. After its publication there was no initial opposition to De revolutionibus from the side of the Church. Copernicus is considered to have held back with publication because he couldn’t provide the proof of the heliocentric hypothesis that he wished to. There were no anonymous copies of De revolutionibus circulated to close friends! I assume our author is confusing De revolutionibus with the Commentariolus, Copernicus unpublished manuscript, which first propagated his heliocentric hypothesis from around 1510.

The book was only published in its entirety on the eve of Copernicus’s death, and the letter to the pope, which was also anonymous, was not written by Copernicus, but by Andreas Osiander, a Lutheran preacher who had been given the job of overseeing the book’s publication. It was an attempt to soften the blow, and states, inter alia, that the author’s findings are only meant to aid the computation of the heavens, and do not even need to be considered true in order for the calculations to be useful.

The implication that Copernicus only gave De revolutionibus free for publication when he was dying is once again total rubbish. Rheticus took the finished manuscript away from Frombork in September 1541 more than eighteen months before Copernicus’ demise. The next sentence is mindboggling for anybody who knows anything about De revolutionibus and its publication history. Copernicus dedicated De revolutionibus to His Holiness Pope Paul III. The anonymous text added by Andreas Osiander during publication was the infamous ad lectorem a totally different text altogether.

The Church would continue to uphold the geocentric model for at least another 150 years, and wouldn’t get around to officially pardoning Galileo until 1992. However, Shapiro claims the persecution of Galileo was merely a PR move by the Church; an attempt to crack down on dissent in response to Protestant accusations of leniency and hypocrisy. The trial of Galileo also saw dozens of astronomical works, including De Revolutionibus, placed on the Church’s “List of Prohibited Books”

Not the geocentric but the geo-heliocentric model of Tycho Brahe, was upheld not only by the Church but also by a very large number astronomers for many decades because the heliocentric model proved extremely difficult to prove. I can’t really comment on Shapiro’s claim, not having read his book and not intending to do so, but whatever the Church’s reasons for the persecution Galileo, and they are very complex, they have absolutely nothing to do with Protestant accusations of leniency and hypocrisy. Galileo is said to have obtained permission from Urban to write his Dialogo, because he claimed that the Protestants were mocking the Catholic Church because of its ignorant stance in the astronomy/cosmology debate. It would appear that Shapiro got his fact confused to put it diplomatically.

“Dozens of astronomical works” is a crass exaggeration and those books that were placed on the Index were placed there in 1616, following Galileo’s first run in with the Church and not in 1633 following his trial. Interestingly, and I get weary of repeating this, De revolutionibus was only placed on the Index until corrected, which surprisingly was completed by 1620; the corrected version with only those parts corrected which claimed heliocentricity to be a fact rather than a hypothesis, was then given free by the Church.

What we have here in total is a collection of half remember facts and myths stirred up together with an added sauce of nonsense and then spewed onto the page without any consideration for truth, facts or accuracy. Kind of sums up Quillette in my opinion.






Filed under History of Astronomy, History of Mathematics, Renaissance Science