topics: |  astronomy | history | biography |

This is the story of Nicolas Copernicus' life. It traces the early development of the heliocentric idea, and the eventual publication of his magnum opus. Working at a remote outpost in Poland, often under the shadow of war from Albrecht of Prussia and others, he formulated the heliocentric theory that changed our vision of the universe.

It is a fascinating tale, well worth the quick read.

When did Copernicus first arrive at his ideas?

The first outline of the idea was communicated in a much-copied letter, the Commentariolus or Brief Sketch, from ca. 1510:

"The center of the earth is not the center of the universe, but only the center towards which heavy things move and the center of the lunar sphere.... All spheres surround the Sun as though it were in the middle of all of them, and therefore the center of the universe is near the Sun, ... What appear to us as motions of the Sun arise not from its motion but from the motion of the Earth and our sphere, with which we revolve about the Sun like any other planet."

At the time of the Commentariolus, Copernicus was in his mid-thirties. In the coming decades, he would write out an elaboration of the ideas in a book format, following the format of Ptolemy's Almagest, and intended as an update of that classic text. However, he was worried that it may have severe repercussions, and he did not publish it.

Three decades later, in 1939, the mathematician Rheticus visited Copernicus and spent a year as a pupil of the aging Copernicus. Rheticus wrote a precis of the work, (later published as the Narratio Prima), which he sent to an astronomer mentor in Nuremberg. This precis was widely copied, and did not stir too much trouble. Copernicus eventually consented to let Rheticus publish the manuscript. It came out from the press of Johannes Petreius of Nuremberg, a leading scientific printer of the time.

Thus, De Revolutionibus Orbium Coelestium (On the Revolutions of
the Heavenly Spheres), came to be printed in 1542.  It is
said that a copy of the book reached Copernicus in 1543, on the very day he
was dying.


title page of de Revolutionibus Orbium Celestium,
published by Rheticus shortly before Copernicus's death
in 1543.

Influences on Copernicus

Personally, I would have liked to see more about the ideas of Copernicus.
In particular, the text does not mention any sources who may have
influenced Copernicus.  The focus is more on his life rather than his
ideas.  Though there is a good bit of discussion about the books from his
library, it does not discuss the issue of possible influences.

Not that this is easy.  As Andre Goddu suggests:

	The origin of Copernicus's cosmology is a matter of speculation for
	there is insufficient evidence to determine conclusively the path he
	followed. ...
	Some authors believe that Copernicus arrived at his theory by way of
	a technical, mathematical analysis. Others separate the question of
	the origin of Copernicus's cosmological theory from the question of
	the origin of Copernicus's mathematical system.

	Copernicus wrote two treatises on the heliocentric theory, the brief
	sketch known as Commentariolus and the larger, technical treatise, De
	revolutionibus published in 1543. Neither provides an account of how
	Copernicus arrived at the theory.

		Andre Goddu, Reflections on the origin of Copernicus's cosmology
		J. History of Astronomy, v.37:37--53, 2006.
		http://adsabs.harvard.edu/full/2006JHA....37...37G


I am sure Sobel could have discussed Martianus Capella, mentioned by
Copernicus in Book I of De revolutionibus.  Capella, who lived in Algeria
in the 5th c., wrote an encyclopedic work called
De nuptiis Philologiae et Mercurii (c. 420AD).  This work describes a
modified geocentric astronomical model, which has the moon, the sun, the
three outer planets, and the stars, revolving around the Earth.  Mercury and
Venus, however, circle the Sun.  This view, he suggests, is preferrable to
the anomalies of the Ptolemaic system, from which he reasons (via logical
processes prescribed at the time).  The failure of the Ptolemaic model meant
that either there was a new centre of motion or that there was no principle
of order at all.  The latter being absurd, Copernicus argues for the former.

Evolution of Copernicus' early ideas : Andre Goddu

Andre Goddu provides the following summary of the process by which Copernicus
may have arrived at his ideas:

    To sum up, here is the likely order for Copernicus's path to his cosmological
    theory:

    1. 1493-95: purchases copies of the Alfonsine Tables, Regiomontanus's Tabula
       directionum, and Tabella sinus recti.

    2. 1496: goes to Bologna and begins working with Domenico Maria de Novara.

    3. Acquires a copy of Regiomontanus's Epitome. Over the next ten years he
       works his way through the Epitome.

    4. Between 1497 and sometime before 1514, Copernicus comes to the following
       conclusions:

    	(a) accepts the axiom about uniform circular motions of the celestial
    	    bodies,
    	(b) rejects Ptolemy's equant model as a violation ofthe axiom,
    	(c) either sees some description of the so-called Tusi couple, or
    	    independently hits on the solution, 
    	(d) concludes to what he regards as an obvious feature of Ptolemaic
    	    models, namely, that there is no unique centre of all heavenly
    	    motions, and
    	(e) learns from Regiomontanus 's Epitome that Ptolemy's lunar model
    	    effectively predicts a doubling in the size of the Moon at
    	    quadrature.

    5. Next, Copernicus assembles and reflects on irregularities,
       inconsistencies, and several striking facts that are explained
       neither by Ptolemy nor by geocentrism:

    	(a) No unique principle for the ordering of the planets- sidereal
    	    periods for superior planets, zodiacal period for Mercury and
    	    Venus.
    	(b) Authorities differ on the placement of Mercury and Venus- above
    	    the Sun (Plato), around the Sun (Egyptian or Capellan
    	    arrangement), or below the Sun (Ptolemy).
    	(c) All of the planetary models have large epicycles, but the one for
    	    Mars is conspicuously huge in relation to those for the other
    	    superior planets because its retrograde arcs are the widest.
    	(d) The size of the epicycle for Mars also reflects the fact that its
    	    variatons in distance are more than two times greater than those
    	    of other superior planets. 
    	(e) Venus's retrograde arc is larger than Mercury's.

    6. Concludes that variations in the distances of the planets from the Earth
       cannot be due to the motions of the planets alone but must be due in part
       to the Earth's orbital motion around the Sun. He probably also realizes at
       this point that the phenomenon of retrograde motion is an optical illusion
       caused by the Earth's motion relative to the motions of the other planets.

    7. The larger variations in the distances of Mars indicate that the Earth's
       orbit must be closer to Mars than to the other superior planets. The
       phenomenon of bounded elongation means that Venus and Mercury must be
       closer to the Sun. Venus's retrograde arc is larger than Mercury's, hence
       the Earth's orbit is between the orbits of Mars and Venus.

    8. Calculates the sidereal periods of Venus and Mercury, confirming the
       correspondence between distance and period, and orders the planets
       according to sidereal periods.

    9. Interprets Epitome, xii. 1-2 heliocentrically, realizing that the Earth's
       orbit can compensate to an extent for the large epicycles in Ptolemy's
       planetary models.

    10. Performs the calculations in U.

    11. Begins writing Commentariolus.

    12. Completes Commentariolus, probably in 1510 but no later than 1514.

Goddu notes that steps 4 and 5 may have had some re-arrangements.
Altogether, these help explain Copernicus's decision to put the Earth in
orbit around the Sun as an initial hypothesis, based on which he worked out
further calculations over the next decades.

Influence of Arab Science?

Copernicus was familiar with the work of  some of the Arab astronomers.
In the tenth chapter of de Revolutionibus, (The Order of the Heavenly
Spheres), Copernicus writes that planets "are tiny bodies in comparison
with the sun. Venus, although bigger than Mercury, can occult barely a
hundredth of the sun. So says Al-Battani of Raqqa, who thinks that the
sun's diameter is ten times larger [than Venus's], and therefore so minute
a speck is not easily descried in the most brilliant light."

Noel Swerdlow noted of Copernicus' Commentariolus that his model of Mercury
is mistaken, and that "[s]ince it is Ibn ash-Shatir's model, this is further
evidence, and perhaps the best evidence, that Copernicus was in fact copying
without full understanding from some other source".

Regarding the motion of mercury, Copernicus adopted the al-Tusi couple,
and provided a diagram that bears uncanny resemblance to the diagram in the
original Arab text (not translated at the time).  Here are the two diagrams,
from George Saliba, Islamic Science and the Making of the European Renaissance
(2007)


	The notational similrities pointed out by George Saliba

Arabic/Islamic Science and Copernicus: George Saliba

	from http://www.columbia.edu/~gas1/project/visions/case1/sci.2.html

Between the years 1957 and 1984, Otto Neugebauer, Edward Kennedy, Willy
Hartner, Noel Swerdlow, and the present author, as well as others, have
managed to determine that the mathematical edifice of Copernican astronomy
could not have been built, as it was finally built, by just using the
mathematical information available in such classical Greek mathematical and
astronomical works as Euclid's Elements and Ptolemy's Almagest. 
What was needed, and was in fact deployed by Copernicus (1473-1543) himself,
was the addition of two new mathematical theorems.

Both of those theorems were first produced some three centuries before
Copernicus and were used by astronomers working in the Islamic world for
the express purpose to reform Greek astronomy. 

These two theorems were first proposed and proven in the Arabic
astronomical works some three centuries earlier, and they were used for
the same part of the argument in Islamic astronomy as they do in
Copernican astronomy. Furthermore, they were both used in the context of
creating alternatives to Greek astronomy, although Copernicus did
introduce the heliocentric idea, whereas the Arabic ideas were used to
show how a series of spherical motion could show

In other words, the research that has accumulated over the last forty odd
years has  now established that the mathematical basis of Copernican
astronomy was mainly inherited from the Greek sources -- mostly from Euclid
and Ptolemy -- except for two important theorems that were added later on by
astronomers working within the Islamic world and writing mainly in
Arabic. Furthermore, the same recent findings have now demonstrated the
context within which these theorems first appeared in the Arabic astronomical
sources, namely, the context of criticizing and reformulating the Greek
astronomical tradition.  We also know that the works containing such theorems
were mostly produced during the thirteenth century and thereafter.  Accounts
of such works have been detailed in various publications. 

As far as we know, none of the Arabic works containing these theorems had
ever been translated into Latin, at least not translated in the same fashion
we know of other Arabic scientific sources that were translated during the
earlier Middle Ages. Hence there is no easy explanation of direct
transmission in the same fashion one could account for the transmission of
Avicenna's medical works into Latin or Averroes's philosophical works or the
hundreds of other Arabic texts that could be easily documented as having been
"translated" into Latin during the great well known (but least studied)
translation period of Arabic texts during the early Middle Ages.  Moreover,
we also know that those same theorems, once produced, they continued to be
extensively used, in various shapes and forms, in Arabic astronomical texts
well before the time of Copernicus, contemporaneously with him and even after
his time. 

Finally, it is now better understood that the Arabic astronomical texts that
deployed these theorems formed part of a rather well established tradition in
Arabic astronomy whose purpose was to criticize, object to, and create
alternatives to the inherited Greek astronomy rather than preserve it, tinker
with it, and deliver it to Europe during the Arabic Latin translations of the
Middle Ages as is so often repeated. That much is already well known and has
been relatively well established by the research of the last forty years or
so.

Extracts

from preface

No one knows what never Rheticus said to change Copernicus's mind about going
public. Their dialogue in the two-act play that begins on page 81 is my
invention, although the characters occasionally speak the very words they
wrote themselves in various letters and treatises. I had intended the play to
stand on its own, but I thank my perceptive editor, George Gibson, for urging
me to plant it in the broad context of history by surrounding the imagined
scenes with a fully documented factual narrative that tells Copernicus's
life story and traces the impact of his seminal book, On the Revolutions of
the Heavenly Spheres, to the present day.

Nicolas at Krakow

A page of Gothic script in the archives of the Collegium Maius at the
Jagiellonian University attests that Nicolaus Copernicus , age eighteen, paid
his tuition fees in full for the fall of 1 49 1 .  He studied logic, poetry,
rhetoric, natural philosophy, and mathematical astronomy.

According to the courses in his curriculum, his father's copper and other
common substances could not be considered elements in the modern sense of the
periodic table. Rather, they comprised some combination of the four classic
elements: earth, water, air, and fire.

The heavens, in contrast, consisted entirely of a fifth essence, called
ether, which differed from the other four by virtue of being inviolate and
everlasting. Ordinary objects on Earth moved more or less along straight
paths , whether seeking their natural places in the world order or being
compelled by outside agents. Heavenly bodies, however, lay cocooned in
celestial spheres that spun in eternal perfect circles.



Aristotle's Heavens:
On earth, bodies were made of earth, water, air, and fire.  and their natural
motion was in straight lines.  The Moon and other celestial bodies consisted
of a fifth essence, immune to change or destruction. In the perfect heavens,
bodies moved with uniform circular motion.

Astronomy as beautiful

The motions of the planets captured Copernicus's interest from the start
of his university studies . At college he purchased two sets of tables for
calculating their positions and had these bound together, adding sixteen
blank pages where he copied parts of a third table and wrote miscellaneous
notes.

Copernicus more than once explained his attraction to astronomy in terms of
beauty, asking rhetorically, "What could be more beautiful than the heavens,
which contain all beautiful things?" He also cited the "unbelievable
pleasure of mind" he derived from contemplating "things established in the
finest order and directed by divine ruling."


The Zodiac : from Ptolemy's Almagest, by Regiomontanus.

As much a prince as a prelate, his uncle Lukasz Watzenrode, as the Bishop
of Varmia governed a province of more than four thousand square miles (most
of which belonged to him personally) with tens of thousands of
inhabitants. He reported directly to the King of Poland. Indeed, Watzenrode
served as trusted counselor to three successive kings over the course of his
episcopate, sharing with them his dreams of Polish glory and his hatred for
the white-cloaked Knights of the Teutonic Order...

Journey to Italy 1501

In August 1501, Nicolas and his elder brother Andreas, both canons with the
cathedral at Varmia, travelled to Padua for further studies.

In his novel Doctor Copernicus, John Banville imagines the brothers equipping
themselves for their journey "with two stout staffs, good heavy jackets lined
with sheepskin against the Alpine cold, a tinderbox, a compass, four pounds
of sailor's biscuit and a keg of salt pork." This and other rich descriptions
- one of which pictures "Nicolas" sewing gold coins into the lining of his
cloak for safekeeping - leap the gaps in the true life story.  Historians
have pieced that together from his few published works and the scattered
archives where he left his name. His lifetime of correspondence comes down
today to just seventeen surviving signed letters . (Of these, three concern
the woman who lived with him as cook and housekeeper, and probably concubine
as well.)

"The inns were terrible, crawling with lice and rogues and poxed whores,"
Banville continues the brothers' travel narrative. "And then one rainy
evening as they were crossing a high plateau under a sulphurous lowering sky
a band of horsemen wheeled down on them, yelling. They were unlovely
ruffians, tattered and lean, deserters from some distant war. . . .  The
brothers watched in silence their mule being driven off. Nicolas's
suspiciously weighty cloak was ripped asunder, and the hoard of coins spilled
out." It could all have happened, just that way.

The cathedral of Varmia [Warmia] stood, as it still stands today, on a
hilltop overlooking the Vistula Bay.  The great brick church rises in
Gothic turrets and spires from a stone foundation laid in the fourteenth
century. A few small buildings , a bell tower, and a covered well huddle
around the church, surrounded in turn by high fortified walls , crowned
with crenellations and arrow loops. The moat and barbican are gone, but the
gateways retain the thick, grudging wooden doors and medieval grates that
even now can fall with fatal weight.

Brief Sketch (Commentariolus) ca. 1510

	"The center of the earth is not the center of the universe, but only
	the center towards which heavy things move and the center of the
	lunar sphere....  All spheres surround the Sun as though it
	were in the middle of all of them, and therefore the center of the
	universe is near the Sun, ...  What appear to us as motions of the
	Sun arise not from its motion but from the motion of the Earth and
	our sphere, with which we revolve about the Sun like any other
	planet."

by May of 1514, when the Krakow physician and medical professor called
Matthew of Miechow inventoried his private library, it contained "A
manuscript of six leaves containing a Theorica [astronomy essay] in which the
author asserts that the Earth moves while the Sun stands still."

The manuscript was lost, until some copies made by Tycho Brahe re-surfaced
in the late 19th c.   Here are some comments by Copernicus scholar Noel
Swerdloow. 

from A translation of the Commentariolus, by Noel Swerdlow

		 Proc. American Philosophical Society,  (1973) p.423--512

Copernicus certainly did nothing in his later work to advertise either
the existence or authorship of such a treatise, and it would probably
have vanished entirely had not Tycho Brahe received a copy in 1575 and
afterwards had other copies prepared and sent to various astronomers in
Germany.' But even Tycho's efforts nearly failed to save Copernicus's
first draft of his planetary theory, for the treatise seems to have
disappeared from sight in the seventeenth century and was not
rediscovered until an incomplete manuscript was found in Vienna in
1877. Within three years a second, this time complete, manuscript was
found in Stockholm, and only a little over ten years ago a third
manuscript was located in Aberdeen. All three are probably descended
from Tycho's copy, are far removed from the original, and preserve a
faulty, possibly an exceedingly faulty, text.

The treatise, scarcely eight folios in length, is called in the
manuscripts Nicolai Copernici de hypothesibus motuum coelestium a se
constitutis commentariolus (A Brief Description by Nicolaus Copernicus
Concerning the Models of the Motions of the Heavens That He
Invented)... Since it refers to models that Copernicus invented himself,
the title can hardly be by Copernicus.  So it was either [already] on
the manuscript given to Tycho or is by Tycho himself. That Copernicus
left the treatise untitled and unsigned is by no means certain even
though the only known possible reference to it during his life specifies
neither author nor title. He may in fact have called it something like
De hypothesibus motuum coelestium, but there is no evidence for any
speculation. The work is today generally known as the Commentariolus.

He begins with a single principle governing planetary theory - [that
any representation of the apparent motions of the planets must be
composed exclusively of uniform circular motions.  This principle is
deduced from the assumption that all planetary motions are controlled
by the rotation of spheres. The only motion permitted to a sphere is
a uniform rotation about its diameter; it can neither rotate
uniformly with respect to any other line nor rotate with a
non-uniform velocity.

[The spherical rotation model can be found in the principal textbook of
planetary theory in Copernicus's time, the Theoricae novae planetarum by
the Austrian astronomer Georg Peurbach (1423-1461).  Peurbach gives
elaborate descriptions they of these spherical representations... [from]
the proper alignment of the eccentric sphere that carries the epicyclic
sphere through its proper path, to the inclinations of the axes about
which the spheres rotate, and to all the different motions of the
spheres and axes required to produce the apparent planetary motions in
longitude and latitude, and the precession of the apsidal and nodal
lines along with the sphere of the fixed stars. ... Copernicus assumes
that the reader is familiar with such models, and usually describes
planetary motions in terms of rotations of spheres and inclinations of
axes.]

Summary

He then raises objections to the theories of his predecessors. Next he
explains that he has invented a planetary theory in conformity with his
first principle, and this is followed by a set of seven postulates.
These have almost nothing to do with either the principle or the
objections, but instead assert the surprising theory that the earth and
planets revolve around the sun and give some further consequences of
this theory. He states next that he is planning a larger book to show
that his theory both conforms with his first principle and is consistent
with computations and observations, but, he remarks, any competent
astronomer will be able to figure this out for himself. Then he returns
to his assertion of the motion of the earth, and defends it against
criticism. This concludes his introduction. Following this he gives the
order of the planets without bothering to mention that he has offered a
solution to a problem that had plagued astronomy since its inception. He
then describes his models for the motions of the earth, moon, and
planets in longitude and latitude, and concludes by counting up the
circles used in the models.

Do the models serve the objectives?

The models in the Theoricae novae planetarum, however, do not strictly
preserve uniform circular motion since they are based on Ptolemy's models
which themselves violate this principle. The most important violation is the
bisection of the eccentricity of the sphere carrying the planet's
epicycle in the representation of the first anomaly so that the center of the
epicycle remains at a constant distance from the diameter of its sphere while
the sphere itself rotates uniformly with respect to a point lying on a line
removed from the diameter. It was this flaw in received planetary theory that
Copernicus desired above all to eliminate; indeed, he explains in the
Commentariolus that this was the problem that initiated his
investigations.

Nearly two hundred years earlier, a number of Islamic astronomers of the
Maragha school raised the same objection to Ptolemy's models, specifically to
the spherical models described by Ptolemy in his Planetary Hypotheses. The
Maragha astronomers developed various alternatives to Ptolemy's bisected
eccentricity that preserve uniform spherical rotation. [In particular, the]
planetary theory Ibn ash-Shatir (1304-1375/6) of Damascus
contains exactly the same replacement of the bisected eccentricity by two
epicycles found in the Commentariolus. Further, Ibn ash-Shatir's lunar-theory
is also identical to that of Copernicus, and several of the Maragha
astronomers made use of two devices for the generation of rectilinear motion
from two circular motions also used by Copernicus.

The work of the Maragha astronomers, while extremely interesting in itself,
is probably the most important and exciting discovery for the study of
Copernicus. 

It has, however, raised more questions than it has answered, for no
intermediary showing the transmission of the Maragha theory to the west has
yet been discovered. Recently an example of the use of one of the Maragha
devices has been found in an Italian Aristotelian treatise on planetary
theory that is contemporary with and independent of Copernicus.3

The search for the transmission of this material from the Near East to, I
think, Italy, perhaps by way of Byzantine sources, is a critical problem in
Copernican scholarship.

FOOTNOTE in Swerdlow: 
	Neugebauer has found figures of a model using Tulsi's device for
	generating rectilinear motion from a circle rolling on the internal
	circumference of a circle of twice its radius. 
	Amico uses the other method of generating rectilinear motion 
	and Copernicus uses both. All of this suggests that Italy, where
	Copernicus lived for most of the period from 1496 to 1503, is the
	place to look for further evidence of the transmission of the
	Maragha planetary theory. I would not be surprised if there exists
	in Italy a Latin treatise from the late fifteenth century
	describing these models and catalogued, if at all, under the
	uninformative title Theorica planetarum.

Error in the Commentariolus is identical to Ibn ash-Shatir

Copernicus's Commentariolus:
   For by this composite motion, the center of the larger epicycle is
   carried on a straight line, just as we have explained concerning latitudes
   that are librated. Thus, when the earth is in the positions noted with
   respect to the apsis of Mercury, the center of the larger epicycle is
   closest to the center of the sphere, and when the earth is at quadratures
   [to the apsis], the center of the larger epicycle is farthest from the
   center of sphere. p.503

Swerdlow's analysis:
	There is something very curious about Copernicus's
	description. The principal effect of Ptolemy's model is to produce
	the greatest elongations at +/- 120 deg from apogee. This is also
	true of Copernicus's model, as he demonstrates in De rev. V, 28,
	but he says nothing about it here. Instead he describes a totally
	fictitious apparent motion of Mercury that is really only a
	description of the expanding and contracting radius of its orbit
	in the model.

	The statement that Mercury "appears" to move in a smaller orbit when
	the earth is in the apsidal line and in a larger orbit when the earth
	is 90 deg from the apsidal line is utter nonsense as a description of
	the apparent motion of Mercury. No one - not Ptolemy, not
	Regiomontanus, not even Copernicus in De revolutionibus- gives such
	a description of Mercury's apparent motion because this is not
	Mercury's apparent motion. But it is a description of the motion of
	Mercury in the model.

	Copernicus apparently does not realize that the model was designed,
	not to give Mercury a larger orbit (read epicycle) when the earth
	(read center of the epicycle) is 90 deg from the apsidal line, but to
	produce the greatest elongations when the earth (center of the
	epicycle) is  120 deg from the aphelion (apogee). This misunderstanding
	must mean that Copernicus did not know the relation of the model to
	Mercury's apparent motion. Thus it could hardly be his own invention
	for, if it were, he would certainly have described its fundamental
	purpose rather than write the absurd statement that Mercury "appears"
	to move in a larger orbit when the earth is 90 deg from the apsidal
	line.

	The only alternative, therefore, is that he copied it without fully
	understanding what it was really about. Since it is Ibn ash-Shatir's
	model, this is further evidence, and perhaps the best evidence, that
	Copernicus was in fact copying without full understanding from some
	other source, and this source would be an as yet unknown transmission
	to the west of Ibn ash-Shatir's planetary theory.

	[C did correct this description of the motion of Mercury in 
	de revolutionibus (V.25), but this error in the Commentariolus
	is surprising. ] Since the maximum elongations (in Aquarius and
	Gemini), +/- 120 deg from the least elongations (in Libra), are the
	real purpose of the variation of the radius of Mercury's orbit, it is
	most unlikely that Copernicus would fail to mention this unless he
	was unaware of it. p.504

Nicolas in Frauenburg (Frombok) 1510-1543

In 1510, around the time when he wrote the Commentorialus, Copernicus
was thirty-seven years old, and had returned to Poland as a canon of the
chapter at Varmia.  In 1511, the chapter named Copernicus its chancellor,
charged with overseeing the financial accounts and composing all official
correspondence. He moved into an official residence or curia at Frauenburg
("city of our lady", Frombork), not far from the fortified walls of
the Bishops castle in Varmia.


Today's Frombork, on the Vistula lagoon.
from magic-photographer.com

Nicolas owned three astronomical instruments: a triquetrum, a
quadrant, and an armillary sphere.  These were set up in the yard of his
new house. Here is a triquetrum:


   With an wooden TRIQUETRUM like this, Nicolas could gauge a body's
   altitude by sliding the hinged bar until its peepholes framed the
   planet or star, and then reading its elevation from the
   calibrated lower scale.

In January 1520, Frauenburg was sacked by the knights of Albrecht of Prussia.
Nicolas fled to Allenstein, where he sought the help of various kings to
defend Varmia.  King Sigsimund sent in his troops in November.

On February 19, 1520, his forty-seventh birthday, he judged Jupiter, at 6:00
A.M., to be 4°3' to the west of "the first, brighter star in the forehead of
the Scorpion."

On April 30, Copernicus marked the moment of opposition at 11:00
A.M.... Jupiter was then moving in reverse, or "retrograde," and also making
its closest approach to Earth.

Allenstein survived the predations of Albrecht, who signed a peace treaty
in April, and Copernicus returned to Frauenburg in June 1921.

Ptolemy: Moon should appear 4x larger

On the path Ptolemy had charted centuries earlier, the Moon altered its
distance from Earth so dramatically over the course of the month as to make
it appear four times larger at its closest approach than at its most distant
point.  Observers never saw the Moon do anything of the kind, however. Its
reliable diameter barely ever changed, yet Ptolemy and most of his followers
ignored that glaring fact. Copernicus addressed the discrepancy by offering
an alternate course that preserved the Moon's appearance .

Ptolemy had reported in the Almagest how he derived the Moon's motion by
tracking it through three eclipses of similar duration and geometry.
Copernicus was following suit by observing his own three eclipses: one
through the midnight hours of October 6-7, 1511; a second more recently, on
September 5-6 , 1522; and the third on August 26,
1523. With these data, he meant to reroute the Moon.


	Johann Stoeffler's Calendarium Romanum magnum, published in 1518,
	predicted eclipses for the years 1518 to 1573. Copernicus
	annotated his copy with his own observation notes between 1530 and
	1541. The special alignment of Earth, Moon, and Sun at eclipse,
	called syzygy, provided a natural check on celestial positions.

Visit by Georg Joachim Rheticus-

In 1539, a young German professor from the U. Wittenberg, Georg Joachim
Rheticus, visited Copernicus at Frauenburg and became his only pupil.
Rheticus managed to convince Copernicus to let him publish the manuscript
for the revolutionibus orbium coelestium, which Copernicus himself did
not feel emboldened enough to bring out.

[from De revolutionibus orbium coelestium:
   Rheticus read Copernicus' manuscript and immediately wrote a
   non-technical summary of its main theories in the form of an open letter
   addressed to Schöner, his astrology teacher in Nürnberg; he published
   this letter as the Narratio Prima in Danzig in 1540. Rheticus' friend
   and mentor Achilles Gasser published a second edition of the Narratio in
   Basel in 1541. Due to its friendly reception, Copernicus finally agreed
   to publication of more of his main work—in 1542, a treatise on
   trigonometry, which was taken from the second book of the still
   unpublished De revolutionibus. Rheticus published it in Copernicus'
   name.]

Under strong pressure from Rheticus, and having seen that the first general
reception of his work had not been unfavorable, Copernicus finally agreed to
give the book to his close friend, Bishop Tiedemann Giese, to be delivered to
Rheticus in Wittenberg for printing by Johannes Petreius at Nürnberg
(Nuremberg). It was published just before Copernicus' death, in 1543.

In the preface, Copernicus explicitly describes his reluctance to publish:

	In the dedicatory preface of De revolutionibus, Copernicus tells Pope
	Paul III and any interested reader of his great reluctance to
	publish the theory of the motion of the earth for fear of ridicule by
	an ignorant public. His apprehension, he explains, was so great
	that he was almost driven to giving up his work altogether, but at
	last the entreaties of his friends convinced him to publish the
	results of the investigations that he had concealed [for several decades]
		- from Noel Swerdlow,1973, The derivation... A translation of
		  the Commentariolus with commentary, Proc. American
		  Philosophical Society, p.423--512:

Contents of de Revolutionibus (from wikipedia)

De revolutionibus is divided into six "books" (sections or parts), following
closely the layout of Ptolemy's Almagest which it updated and replaced:

* Book I chapters 1-11 are a general vision of the heliocentric theory, and a
  summarized exposition of his cosmology. The world (heavens) is spherical,
  as is the earth, and the land and water make a single globe. The celestial
  bodies, including the earth, have regular circular and everlasting
  movements. The earth rotates on its axis and around the sun. Answers to why
  the ancients thought the earth was central. The order of the planets around
  the sun and their periodicity. Chapters 12-14 give theorems for chord
  geometry as well as a table of chords.

* Book II describes the principles of spherical astronomy as a basis for the
  arguments developed in the following books and gives a comprehensive
  catalogue of the fixed stars.

* Book III describes his work on the precession of the equinoxes and treats
  the apparent movements of the Sun and related phenomena.

* Book IV is a similar description of the Moon and its orbital movements.

* Book V explains how to calculate the positions of the wandering stars based
  on the heliocentric model and gives tables for the five planets.

* Book VI deals with the digression in latitude from the ecliptic of the five
  planets.

Copernicus argued that the universe comprised eight spheres. The outermost
consisted of motionless, fixed stars, with the Sun motionless at the
center. The known planets revolved about the Sun, each in its own sphere, in
the order: Mercury, Venus, Earth, Mars, Jupiter, Saturn. The Moon, however,
revolved in its sphere around the Earth. What appeared to be the daily
revolution of the Sun and fixed stars around the Earth was actually the
Earth's daily rotation on its own axis.

For philosophical reasons, Copernicus clung to the belief that all the
orbits of celestial bodies must be perfect circles and to a belief in the
unobserved crystalline spheres.  This forced Copernicus to retain the
Ptolemaic system's complex system of epicycles, to account for the observed
deviations from circularity and to square his calculations with
observations.

And The Sun Stood Still : A Play in Two Acts

Includes this play as the middle part of the book.


[dialogue between COPERNICUS at age 65, with Rheticus.  Roles also for
Anna, his housekeeper and concubine, Bishop Danticus of Varmia, and others.

RHETICUS. Sir, I seek to restore the queen of mathematics, that is,
	Astronomy, to her palace, as she deserves , and to redraw the
	boundaries of her kingdom.
COPERNICUS. I can't help you.
RHETICUS. Only you can help me.

[...]
RHETICUS. And of course he [Martin Luther] knows nothing of mathematics. He
	only rejected your theory because it contradicts the Bible. He quoted
	Joshua 10:12 . You know the part, where Joshua says , "Sun,
	stand thou still upon Gibeon."
COPERNICUS. Yes, yes. I know it all too well.
RHETICUS. "And thou, Moon, in the valley of Ajalon."
COPERNICUS & RHETICUS . (together)
	"And the Sun stood still."
RHETICUS. Exactly, sir. The Sun stood still . And that's his
	point. Because, if the Sun were already standing still, as you claim,
	then why would Joshua have commanded it to do so?

...
[RHETICUS grabs at random pages and reads them with growing excitement.]

RHETICUS. I can't believe you did all this work yourself.
COPERNICUS. I want you to see the section on Mercury. I've always known
	there was something wrong with my value for the anomaly. Maybe now,
	with Schoner's observations to add to . . .
RHETICUS. No one has a resource like this.  What you've done here is
	. . . It's nothing short of extraordinary. It's more than the
	intellect or the labors of a single individual could accomplish. And
	yet you have accomplished it.

RHETICUS keeps examining the manuscript, exclaiming.

COPERNICUS. I told you, I've decided not to publish.
RHETICUS. You can't keep this to yourself.  It isn't right. Secrecy has no
	place in science anymore.
COPERNICUS. Easy for you to say. You would not face the scorn that I have to
	fear.

---

By summer's end in 1539, Rheticus had learned enough from Copernicus to
write an informed summary of his thesis . He framed this precis as a letter
to another mentor, Johann Schoner, a widely respected astrologer,
cartographer, and globe maker in Nuremberg and presumably the person who
referred Rheticus to Copernicus in the first place.

Rheticus may have read a copy of the Brief Sketch in Schoner's library before
visiting Copernicus, or he could have come with only a vague notion of the
new cosmology. Now he found himself one of two or at most three people in the
world to have paged through the complete draft version of On the Revolutions.

"My teacher has written a work of six books," he told Schoner, "in which,
in imitation of Ptolemy, he has embraced the whole of astronomy...

[Thus begins the journey of this idea that would change the universe]

from Department of Rare Books, Univ Rochester Library

			http://www.lib.rochester.edu/index.cfm?PAGE=3338


page from De revolutionibus orbium coelestium, libri
VI. Basle: Heinrich Petri, 1566.

In 1539 Rheticus traveled to Frauenburg to become Copernicus' only
pupil. Copernicus was then 67 years old, and by 1540 gave Rheticus permission
to publish the Narratio prima, or the "First Report" on the new heliocentric
system. The favorable reception accorded Rheticus' tract convinced Copernicus
to allow his young pupil to take to Germany the De revolutionibus for
printing. Rheticus decided that this revolutionary work deserved to be
published in Nuremberg by Johannes Petreius, the leading scientific printer
in northern Europe. 142 woodcuts displaying geometrical diagrams and letter
characters were commissioned to illustrate, and clarify, the complexity of
Copernicus' thesis. Only six of these woodcuts were used twice.

The printing of the work began shortly after the arrival in Nuremberg of
Rheticus from Wittenberg in May 1542. Indeed, he was enthusiastically
involved in most of the printing process, acting as a proofreader until
mid-October, when he left Nuremberg to take up his new position as a
professor in Leipzig. Then, proofreading was turned over to Andreas Osiander,
pastor of the Sankt Lorenz Kirche in Nuremberg. Printing was finished by 20
April 1543.  Petreius issued an errata leaf for the first 146 folios of the
book -- out of a total of 196 folios. The sophisticated character of some of
these corrections suggests that Copernicus proofread a great part of the
book. Possibly, gatherings of printed leaves were gradually sent to him for
inspection. Apparently, Copernicus received the book a month after its
publication, the very day on which he died.

... the first edition of 1543 included the infamous anonymous foreword, in
fact written by Andreas Osiander, containing the following words: "these
hypotheses need not to be true nor even probable."

Inquisition and Copernicus' text

Our [UofR] copy is actually the second edition published by Heinrich
Petri in Basle in 1566. The second edition differs from the first in two
ways: It includes, between folios 196 and 213, the third edition of
Rheticus' Narration prima, and it also contains, at the end of the Index
capitulorum, a five-line recommendation from the leading mathematician
at Wittenberg, Erasmus Reinhold, extracted from his Tabulae
Prutenicae. Otherwise, the second edition is practically a page-by-page
reprint of the first edition. Although the second edition corrected some
of the more obvious typographical mistakes, it also introduced new
ones. Curiously, the second edition failed to address the corrections
noted on Petreius' errata sheet.

The copy at the University of Rochester is particularly interesting because
it shows different types of censorship as issued by the Church. In the Index
librorum prohibitorum of 1557, Pope Paul IV cited the printer Johannes
Petreius. Following the council of Trent (1545-1564), the Index included the
names of numerous Protestant authors such as Georg Joachim Rheticus and
Johann Schöner, the dedicatee of Rheticus' treatise. One can easily see that
the title page has the names of Rheticus and Schöner pasted over. Moreover,
the entire Narratio prima has been removed from our copy.

In 1616, the Inquisition placed De revolutionibus on its Index until
corrected -- Decree XIV. In 1620, in Decree XXI, the required corrections
were officially announced. This is an extraordinary measure since for very
few books did the Index specify the type of changes to be made. The ten
emendations were designed to make Copernicus' book appear hypothetical and
not the description of a real physical work. One may wonder why the Church
took 77 years to react against an astronomical treatise whose content
seriously challenged the traditionally accepted idea that placed a static
earth in the center of the universe. One of the reasons is that numerous
scientists only viewed the treatise as a useful manual to calculate planetary
positions for any conceivable time, emphasizing, however, the hypothetical
character of Copernicus' main thesis.

One of the deleted paragraphs (tr.  Edward Rosen):

	"Perhaps there will be babblers who claim to be judges of astronomy
	although completely ignorant of the subject and, badly distorting
	some passage 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 persons will
	likewise ridicule me. Astronomy is written for astronomers. To them
	my work too will seem, unless I am mistaken, to make some
	contribution also to the Church, at the head of which Your Holiness
	now stands."

author

Dava Sobel has written the bestselling Longitude, Galileo's Daughter,
and The Planets. She lives in East Hampton, New York.

Also on Book Excerptise

     

* Nicolaus Copernicus: Making the Earth a Planet
   by Owen Gingerich and James MacLachlan (2005)

	In the 1500s, medicine students had to learn "medical
 	astrology".  Here one determined appropriate "bleeding" points
 	guided by astrological signs. 

	[This may seem laughable today, but I wonder how many of today's
 	measures in medicine would appear as laughable in the
 	2500s.] 

* Understanding the Heavens: Thirty Centuries of Astronomical Ideas
   by Jean-Claude Pecker (2001)

	Up to the time of Copernicus, al-Bitruji's book was the new gospel
 	and it was an anti-Ptolemaic one. ...Undoubtlessly, it made room
 	for the new and original thinking of Copernicus two centuries
 	later. p.154

* Indian astronomy: an introduction
   by S. Balachandra Rao (1994)

	Sometimes, the sun may remain in the same rAshi for more
	than a lunar month; in such situations, one has an extra month
	(adhikamAsa, chapters 5 & 6)

* Science and Civilisation in China: v.4
    Physics and Physical Technology, part I: Physics
    by Joseph Needham and Wang Ling and Kenneth G Robinson (1977)

	The Indian [trigonometry] was taken over by the Arabs and
	transmitted to Europe, while in the other direction Indian monks
	or lay mathematicians who took service with the Chinese bureau of
	astronomy spread the new development farther east.  ...

Send your jottings to Book Excerptise

to contribute some excerpts from your favourite book to book excerptise. send us a plain text file with page-numbered extracts from your favourite book. You can preface your extracts with a short review.
email to (bookexcerptise [at] gmail [dot] com).