Most non-specialists get their knowledge of the history of astronomy from general surveys of the subject or from even more general surveys of the history of science. The information contained in these on Ptolemaeus, Copernicus and the other boys in the history of astronomy band is often from secondary if not tertiary or even quaternary sources and as a result also often inaccurate if not completely false. The solution to this problem is of course to read the originals but not all of us are blessed with the linguistic abilities necessary to tackle second century Greek or Early Modern Latin, to say nothing of Galileo’s seventeenth century Tuscan. However, the current scholar interested in the classical texts from the history of astronomy is blessed with modern, annotated English translations of these and in this post I want to briefly present these and some secondary literature to assist in understanding them.

We start with the mother ~~load~~ lode, Ptolemaeus’ *Mathēmatikē Syntaxis* more commonly known by its Arabic name, the *Almagest*.

A imaginary portrait of Ptolemaeus from 1564 Source: Wikimedia Commons

This is by no means the earliest astronomical text in the European tradition but much of what we know about ancient Greek astronomy we only know through references by Ptolemaeus. He is of course preceded by the Babylonians and the ancient Egyptians but neither of these traditions has a comparable text to *Mathēmatikē Syntaxis*. Also Ptolemaeus stands patron for a tradition in astronomical observation, calculation and recording that remained largely unchanged for fifteen hundred years down to the work of the first Astronomer Royal, John Flamsteed. The methods were over the centuries refined but remained fundamentally the same. Even the invention of the telescope did not initially change much in the methodology of astronomy to be found in Ptolemaeus’ *Great Treatise*, a title for the work that is the origin of the Arabic name.

There is an excellent, annotated, English translation of *Ptolemy’s Almagest* by G.J. Toomer.[1] Even with Toomer’s excellent guidance the *Almagest* is not an easy text for non-specialists to comprehend so readers might find the following secondary literature useful. We start with Olaf Pedersen’s *A Survey of the Almagest.***[2]** Pedersen (1920–1997) was one of the best historians of astronomy for antiquity and the Middle Ages and his opinions are always well founded. I would also recommend Liba Taub’s *Ptolemy’s Universe: The Natural Philosophical and Ethical Foundations of Ptolemy’s Astronomy***[3]** for some solid background to Ptolemaeus’ work.

We now take a major jump of fourteen hundred years to Copernicus’ *De revolutionibus orbium coelestium* (*On the Revolutions of the Heavenly Spheres*), published in Nürnberg in 1543 by Johannes Petreius.

Copernicus followed the layout of Ptolemaeus’ *Almagest* and viewed his own volume as a modern version of the Ptolemaeus’ work, so to speak. There are several English translations but the one that I would recommend is quasi the official one. In 1973, the 500^{th} anniversary of Copernicus’ birth, The Polish Academy of Sciences started a project to produce a uniform edition of Copernicus’ extant works. As well as publishing the Latin originals they published a set of authorised translations in the main modern European languages, the English translation is Edward Rosen’s *On the Revolutions*.[4] For various reasons I’m not a big fan of Rosen but as a historian he really knows his Copernicus and his commentaries are very good. A useful but specialist addition to understanding *De revolutionibus* is Swerdlow’s and Neugebauer’s *Mathematical astronomy in Copernicus’ De revolutionibus*,[5] which is justifiably regarded as a classic in the history of astronomy.

Next up is my personal favourite astronomer Johannes Kepler and here we have not just one but four books that we have to consider.

Portrait of Johannes Kepler 1610 by unknown artist. Source: Wikimedia Commons

We start with Kepler’s first ever publication the *Mysterium Cosmographicum* (1596). This book with its theory that the planets in their spheres are separated by the five Platonic solids appears totally bizarre to us today. However, if you want to understand Kepler’s astronomical thoughts then you should start here because its divine geometry remained Kepler’s leitmotif for all of his astronomical work. He published a second edition in 1621 following the publication of his magnum opus the *Harmonice Mundi*. There is an English translation of the second edition, *Mysterium Cosmographicum* – *The Secret of *the* Universe*,[6] which is unfortunate no longer in print.

Kepler’s Platonic solid model of the Solar system from Mysterium Cosmographicum (1596) Source: Wikimedia Commons

From the point of view of modern astronomy, much more important is Kepler’s *Astronomia nova*, which contains his first two laws of planetary motion and the story of how he arrived at them. There is an excellent annotated English translation of this book from William Donahue.[7] I would also recommend James Voelkel’s *The Composition of Kepler’s Astronomia nova *potential readers,**[8]** which explains the strange narrative structure of Kepler’s book and why he employed it. Donahue has also published a short introduction to the *Astronomia nova* for students.[9]

Kepler regarded his *Harmonice Mundi* as his astronomical magnum opus. A big sprawling book it covers a wide range of topics that I sketched in a blog post here. It is of course most famous for containing his third law of planetary motion. There is an excellent, annotated English translation by E.J. Aiton, A.M. Duncan and J.V. Field.[10]

Our fourth astronomical book from Kepler book is his *Epitome Astronomiae Copernicanae* published in three sections 1618, 1620 and 1621. Unfortunately only a part of this book (Books VI & V of seven) is available in English translation.[11]

The counterpart to Kepler is of course Galileo Galilei and he has been much better served by his translators.

Galileo Galilei. Portrait by Leoni Source: Wikimedia Commons

We start with the book that established his reputation the *Sidereus Nuncius*. Here we have an excellent annotated translation by Albert van Helden.[12] Galileo is of course famously erudite and highly readable and so one doesn’t initially need any secondary literature to understand him. However, the reader is warned that Galileo is anything but honest in published works and one should check with the vast secondary Galileo literature before taking anything he say as true, in particular about supposed rivals. His infamous *Dialogo* has long been available in a standard English translation by Stillman Drake.[13]

For our final classic we spring to the end of the seventeenth century and Isaac Newton’s *Principia*.

This a copy of a painting by Sir Godfrey Kneller (1689). Source: Wikimedia Commons

The best English translation can be acquired in one volume with the best introduction to the text by one of its translators I. Bernard Cohen.[14] The two, guide and *Principia*, are available as separated volumes if you prefer. For those who find Newton heavy going despite Cohen’s assistance there is Chandrasekhar’s *Newton’s Principia for the common reader*.[15] Also recommended is *The Cambridge Companion to Newton*.[16]

I own most of the books that I have listed here but I won’t claim to have read them from cover to cover. (I have read the *Harmonice Mundi* from cover to cover!) However when reading about the history of astronomy I find it useful and informative to check what a particular scholar actually said rather than what somebody else thinks they said.

A couple of more general histories of astronomy that I would recommend for the wanna be historian of the subject as starting points and to provide a more general background into which to place the classics that I’ve listed above are John North’s *Cosmos*,[17] the *Cambridge Illustrated History of Astronomy*,[18] Linton’s *From Eudoxus to Einstein*,[19] and Crowe’s *Theories of the World*.[20]

By the time you’ve worked your way through that lot you can start your own history of astronomy blog – happy reading!

[1] *Ptolemy’s Almagest*, Translated and Annotated by G.J. Toomer, with a foreword by Owen Gingerich, Princeton University Press, Princeton, New Jersey, 1998

[2] Olaf Pedersen, *A Survey of the Almagest*, Odense University Press, 1974.

[3] Liba Taub, *Ptolemy’s Universe: The Natural Philosophical and Ethical Foundations of Ptolemy’s Astronomy*, Open Court Publishing Company, Chicago, 1993

[4] Nicolas Copernicus Complete Works, *On the Revolutions*, translation and commentary by Edward Rosen, The Johns Hopkins University Press, Baltimore & London, 1978

[5] Swerdlow, N.M., O. Neugebauer: *Mathematical astronomy in Copernicus’ De revolutionibus*, Springer, New York, 1984

[6] Johannes Kepler, *Mysterium Cosmographicum* – *The Secret of the Universe*, (Facsimile of 2^{nd} ed., 1621, and English translation on facing pages) translated by A.M. Duncan, introduction and commentary by E.J. Aiton, preface by I: Bernard Cohen, Abaris Books, New York, 1981

[7] Johannes Kepler, *Astronomia Nova* (New Revised Edition), translated by William H. Donahue, Green Lion Press, Santa Fe, 2015

[8] James Voelkel, *The Composition of Kepler’s Astronomia nova*, Princeton University Press, Princeton, 2001

[9] Selections from Kepler’s *Astronomia Nova*, A science Classics Module for Humanities Studies, Selected, translated, and annotated by William H. Donahue, Green Cat Books, Santa Fe, 2008

[10] *The Harmony of the World* *by Johannes* *Kepler*, Translated into English with an Introduction and Notes by E.J. Aiton, A.M. Duncan & J.V. Field, Memoirs of the American Philosophical Society Held at Philadelphia for Promoting Useful Knowledge, Volume 209, 1997

[11] Johannes Kepler, *Epitome of Copernican Astronomy & Harmonies of the World*, Translated by Charles Glenn Wallis, Prometheus Books, New York, 1995

[12] Galileo Galilei, *Sidereus Nuncius or The Sidereal Messenger*, Translated with introduction, conclusion, and notes by Albert Van Helden, University of Chicago Press, Chicago and London, 1989

[13] Galileo, *Dialogue Concerning the Two Chief World Systems*, Translated with revised notes by Stillman Drake, University of California Press, Berkley, Los Angeles, London, 1967

[14] Isaac Newton, *The Principia: Mathematical Principles of Natural Philosophy*, A new translation by I. Bernard Cohen and Anne Whitman, assisted by Julia Budenz, Preceded by *A Guide to Newton’s Principia* by I. Bernard Cohen.

[15] Subramanyan Chandrasekhar, *Newton’s Principia for the Common Reader*, Clarendon Press, Oxford, 1995

[16] The Cambridge Companion to Newton, 2nd edition, ed. Robert Iliffe and George E. Smith, Cambridge University Press, Cambridge, 2016

[17] John North, *Cosmos*: *An Illustrated History of Astronomy and Cosmology*, University of Chicago Press, Chicago & London, 2008

[18] *The Cambridge Illustrated History of Astronomy*, ed. Michael Hoskin, Cambridge University Press, Cambridge, 1997

[19] C.M. Linton, *From Eudoxus to Einstein: A History of Mathematical Astronomy*, CUP, Cambridge etc., 2004

[20] Michael J. Crowe, *Theories of the World*: *From Antiquity to the Copernican Revolution*, Dover Publication Ltd., New York, 2001