Johannes Kepler (/ˈkɛplər/; German: [joˈhanəs ˈkɛplɐ];
December 27, 1571 – November 15, 1630) was a German mathematician,
astronomer, and astrologer.
Kepler is a key figure in the 17th-century scientific revolution. He
is best known for his laws of planetary motion, based on his works
Astronomia nova, Harmonices Mundi, and Epitome of Copernican
Astronomy. These works also provided one of the foundations for Isaac
Newton's theory of universal gravitation.
Kepler was a mathematics teacher at a seminary school in Graz, where
he became an associate of Prince Hans Ulrich von Eggenberg. Later he
became an assistant to the astronomer
Tycho Brahe in Prague, and
eventually the imperial mathematician to Emperor Rudolf II and his two
successors Matthias and Ferdinand II. He also taught mathematics in
Linz, and was an adviser to General Wallenstein. Additionally, he did
fundamental work in the field of optics, invented an improved version
of the refracting telescope (the Keplerian telescope), and was
mentioned in the telescopic discoveries of his contemporary Galileo
Galilei. He was a corresponding member of the
Accademia dei Lincei
Accademia dei Lincei in
Kepler lived in an era when there was no clear distinction between
astronomy and astrology, but there was a strong division between
astronomy (a branch of mathematics within the liberal arts) and
physics (a branch of natural philosophy). Kepler also incorporated
religious arguments and reasoning into his work, motivated by the
religious conviction and belief that God had created the world
according to an intelligible plan that is accessible through the
natural light of reason. Kepler described his new astronomy as
"celestial physics", as "an excursion into Aristotle's
Metaphysics", and as "a supplement to Aristotle's On the
Heavens", transforming the ancient tradition of physical cosmology
by treating astronomy as part of a universal mathematical physics.
1 Early years
2.1 Mysterium Cosmographicum
2.2 Marriage to Barbara Müller
2.3 Other research
3.1 Work for Tycho Brahe
3.2 Advisor to Emperor Rudolph II
3.3 Astronomiae Pars Optica
3.4 The Supernova of 1604
3.5 Astronomia nova
3.6 Dioptrice, Somnium manuscript, and other work
3.7 Work in mathematics and physics
3.8 Personal and political troubles
Linz and elsewhere (1612–1630)
4.1 Second marriage
4.2 Epitome of Copernican Astronomy, calendars, and the witch trial of
4.3 Harmonices Mundi
Rudolphine Tables and his last years
6 Reception of his astronomy
7 Historical and cultural legacy
7.1 History of science
7.2 Editions and translations
7.3 Popular science and historical fiction
7.4 Veneration and eponymy
9 See also
10 Notes and references
12 External links
Kepler's birthplace, in Weil der Stadt
The Great Comet of 1577, which Kepler witnessed as a child, attracted
the attention of astronomers across Europe
Kepler was born on December 27, the feast day of St John the
Evangelist, 1571, in the
Free Imperial City
Free Imperial City of
Weil der Stadt
Weil der Stadt (now
part of the
Stuttgart Region in the German state of
Baden-Württemberg, 30 km west of Stuttgart's center). His
grandfather, Sebald Kepler, had been Lord Mayor of the city. By the
time Johannes was born, he had two brothers and one sister and the
Kepler family fortune was in decline. His father, Heinrich Kepler,
earned a precarious living as a mercenary, and he left the family when
Johannes was five years old. He was believed to have died in the
Eighty Years' War
Eighty Years' War in the Netherlands. His mother, Katharina
Guldenmann, an innkeeper's daughter, was a healer and herbalist. Born
prematurely, Johannes claimed to have been weak and sickly as a child.
Nevertheless, he often impressed travelers at his grandfather's inn
with his phenomenal mathematical faculty.
He was introduced to astronomy at an early age, and developed a love
for it that would span his entire life. At age six, he observed the
Great Comet of 1577, writing that he "was taken by [his] mother to a
high place to look at it." In 1580, at age nine, he observed
another astronomical event, a lunar eclipse, recording that he
remembered being "called outdoors" to see it and that the moon
"appeared quite red". However, childhood smallpox left him with
weak vision and crippled hands, limiting his ability in the
observational aspects of astronomy.
In 1589, after moving through grammar school, Latin school, and
seminary at Maulbronn, Kepler attended
Tübinger Stift at the
University of Tübingen. There, he studied philosophy under Vitus
Müller and theology under
Jacob Heerbrand (a student of Philipp
Melanchthon at Wittenberg), who also taught
Michael Maestlin while he
was a student, until he became Chancellor at
Tübingen in 1590. He
proved himself to be a superb mathematician and earned a reputation as
a skilful astrologer, casting horoscopes for fellow students. Under
the instruction of Michael Maestlin, Tübingen's professor of
mathematics from 1583 to 1631, he learned both the Ptolemaic
system and the Copernican system of planetary motion. He became a
Copernican at that time. In a student disputation, he defended
heliocentrism from both a theoretical and theological perspective,
maintaining that the
Sun was the principal source of motive power in
the universe. Despite his desire to become a minister, near the
end of his studies, Kepler was recommended for a position as teacher
of mathematics and astronomy at the Protestant school in Graz. He
accepted the position in April 1594, at the age of 23.
Platonic solid model of the solar system, from Mysterium
Kepler's first major astronomical work,
Mysterium Cosmographicum (The
Cosmographic Mystery) , was the first published defense of the
Copernican system. Kepler claimed to have had an epiphany on July 19,
1595, while teaching in Graz, demonstrating the periodic conjunction
Jupiter in the zodiac: he realized that regular polygons
bound one inscribed and one circumscribed circle at definite ratios,
which, he reasoned, might be the geometrical basis of the universe.
After failing to find a unique arrangement of polygons that fit known
astronomical observations (even with extra planets added to the
system), Kepler began experimenting with 3-dimensional polyhedra. He
found that each of the five Platonic solids could be inscribed and
circumscribed by spherical orbs; nesting these solids, each encased in
a sphere, within one another would produce six layers, corresponding
to the six known planets—Mercury, Venus, Earth, Mars, Jupiter, and
Saturn. By ordering the solids selectively—octahedron, icosahedron,
dodecahedron, tetrahedron, cube—Kepler found that the spheres could
be placed at intervals corresponding to the relative sizes of each
planet's path, assuming the planets circle the Sun. Kepler also found
a formula relating the size of each planet's orb to the length of its
orbital period: from inner to outer planets, the ratio of increase in
orbital period is twice the difference in orb radius. However, Kepler
later rejected this formula, because it was not precise enough.
Close-up of an inner section of Kepler's model
As he indicated in the title, Kepler thought he had revealed God's
geometrical plan for the universe. Much of Kepler's enthusiasm for the
Copernican system stemmed from his theological convictions about the
connection between the physical and the spiritual; the universe itself
was an image of God, with the
Sun corresponding to the Father, the
stellar sphere to the Son, and the intervening space between to the
Holy Spirit. His first manuscript of Mysterium contained an extensive
chapter reconciling heliocentrism with biblical passages that seemed
to support geocentrism.
With the support of his mentor Michael Maestlin, Kepler received
permission from the
Tübingen university senate to publish his
manuscript, pending removal of the Bible exegesis and the addition of
a simpler, more understandable description of the Copernican system as
well as Kepler's new ideas. Mysterium was published late in 1596, and
Kepler received his copies and began sending them to prominent
astronomers and patrons early in 1597; it was not widely read, but it
established Kepler's reputation as a highly skilled astronomer. The
effusive dedication, to powerful patrons as well as to the men who
controlled his position in Graz, also provided a crucial doorway into
the patronage system.
Though the details would be modified in light of his later work,
Kepler never relinquished the Platonist polyhedral-spherist cosmology
of Mysterium Cosmographicum. His subsequent main astronomical works
were in some sense only further developments of it, concerned with
finding more precise inner and outer dimensions for the spheres by
calculating the eccentricities of the planetary orbits within it. In
1621, Kepler published an expanded second edition of Mysterium, half
as long again as the first, detailing in footnotes the corrections and
improvements he had achieved in the 25 years since its first
In terms of the impact of Mysterium, it can be seen as an important
first step in modernizing the theory proposed by Nicolaus Copernicus
in his "De Revolutionibus orbium coelestium". Whilst Copernicus sought
to advance a heliocentric system in this book, he resorted to
Ptolemaic devices (viz., epicycles and eccentric circles) in order to
explain the change in planets' orbital speed, and also continued to
use as a point of reference the center of the earth's orbit rather
than that of the sun "as an aid to calculation and in order not to
confuse the reader by diverging too much from Ptolemy." Modern
astronomy owes much to "Mysterium Cosmographicum", despite flaws in
its main thesis, "since it represents the first step in cleansing the
Copernican system of the remnants of the Ptolemaic theory still
clinging to it." 
Marriage to Barbara Müller
Portraits of Kepler and his wife in oval medallions
In December 1595, Kepler was introduced to Barbara Müller, a
23-year-old widow (twice over) with a young daughter, Regina Lorenz,
and he began courting her. Müller, an heiress to the estates of her
late husbands, was also the daughter of a successful mill owner. Her
father Jobst initially opposed a marriage despite Kepler's nobility;
though he had inherited his grandfather's nobility, Kepler's poverty
made him an unacceptable match. Jobst relented after Kepler completed
work on Mysterium, but the engagement nearly fell apart while Kepler
was away tending to the details of publication. However, Protestant
officials—who had helped set up the match—pressured the Müllers
to honor their agreement. Barbara and Johannes were married on April
In the first years of their marriage, the Keplers had two children
(Heinrich and Susanna), both of whom died in infancy. In 1602, they
had a daughter (Susanna); in 1604, a son (Friedrich); and in 1607,
another son (Ludwig).
House of Kepler and Barbara Müller in Gössendorf, near Graz
Following the publication of Mysterium and with the blessing of the
Graz school inspectors, Kepler began an ambitious program to extend
and elaborate his work. He planned four additional books: one on the
stationary aspects of the universe (the
Sun and the fixed stars); one
on the planets and their motions; one on the physical nature of
planets and the formation of geographical features (focused especially
on Earth); and one on the effects of the heavens on the Earth, to
include atmospheric optics, meteorology, and astrology.
He also sought the opinions of many of the astronomers to whom he had
sent Mysterium, among them
Reimarus Ursus (Nicolaus Reimers
Bär)—the imperial mathematician to Rudolph II and a bitter rival of
Tycho Brahe. Ursus did not reply directly, but republished Kepler's
flattering letter to pursue his priority dispute over (what is now
Tychonic system with Tycho. Despite this black mark, Tycho
also began corresponding with Kepler, starting with a harsh but
legitimate critique of Kepler's system; among a host of objections,
Tycho took issue with the use of inaccurate numerical data taken from
Copernicus. Through their letters, Tycho and Kepler discussed a broad
range of astronomical problems, dwelling on lunar phenomena and
Copernican theory (particularly its theological viability). But
without the significantly more accurate data of Tycho's observatory,
Kepler had no way to address many of these issues.
Instead, he turned his attention to chronology and "harmony," the
numerological relationships among music, mathematics and the physical
world, and their astrological consequences. By assuming the
possess a soul (a property he would later invoke to explain how the
sun causes the motion of planets), he established a speculative system
connecting astrological aspects and astronomical distances to weather
and other earthly phenomena. By 1599, however, he again felt his work
limited by the inaccuracy of available data—just as growing
religious tension was also threatening his continued employment in
Graz. In December of that year, Tycho invited Kepler to visit him in
Prague; on January 1, 1600 (before he even received the invitation),
Kepler set off in the hopes that Tycho's patronage could solve his
philosophical problems as well as his social and financial ones.
Work for Tycho Brahe
On February 4, 1600, Kepler met
Tycho Brahe and his assistants Franz
Benátky nad Jizerou
Benátky nad Jizerou (35 km from
Prague), the site where Tycho's new observatory was being constructed.
Over the next two months, he stayed as a guest, analyzing some of
Tycho's observations of Mars; Tycho guarded his data closely, but was
impressed by Kepler's theoretical ideas and soon allowed him more
access. Kepler planned to test his theory from Mysterium
Cosmographicum based on the
Mars data, but he estimated that the work
would take up to two years (since he was not allowed to simply copy
the data for his own use). With the help of Johannes Jessenius, Kepler
attempted to negotiate a more formal employment arrangement with
Tycho, but negotiations broke down in an angry argument and Kepler
Prague on April 6. Kepler and Tycho soon reconciled and
eventually reached an agreement on salary and living arrangements, and
in June, Kepler returned home to
Graz to collect his family.
Political and religious difficulties in
Graz dashed his hopes of
returning immediately to Brahe; in hopes of continuing his
astronomical studies, Kepler sought an appointment as a mathematician
to Archduke Ferdinand. To that end, Kepler composed an
essay—dedicated to Ferdinand—in which he proposed a force-based
theory of lunar motion: "In Terra inest virtus, quae Lunam ciet"
("There is a force in the earth which causes the moon to move").
Though the essay did not earn him a place in Ferdinand's court, it did
detail a new method for measuring lunar eclipses, which he applied
during the July 10 eclipse in Graz. These observations formed the
basis of his explorations of the laws of optics that would culminate
in Astronomiae Pars Optica.
On August 2, 1600, after refusing to convert to Catholicism, Kepler
and his family were banished from Graz. Several months later, Kepler
returned, now with the rest of his household, to Prague. Through most
of 1601, he was supported directly by Tycho, who assigned him to
analyzing planetary observations and writing a tract against Tycho's
(by then deceased) rival, Ursus. In September, Tycho secured him a
commission as a collaborator on the new project he had proposed to the
Rudolphine Tables that should replace the Prutenic Tables
of Erasmus Reinhold. Two days after Tycho's unexpected death on
October 24, 1601, Kepler was appointed his successor as the imperial
mathematician with the responsibility to complete his unfinished work.
The next 11 years as imperial mathematician would be the most
productive of his life.
Advisor to Emperor Rudolph II
Kepler's primary obligation as imperial mathematician was to provide
astrological advice to the emperor. Though Kepler took a dim view of
the attempts of contemporary astrologers to precisely predict the
future or divine specific events, he had been casting well-received
detailed horoscopes for friends, family, and patrons since his time as
a student in Tübingen. In addition to horoscopes for allies and
foreign leaders, the emperor sought Kepler's advice in times of
political trouble. Rudolph was actively interested in the work of many
of his court scholars (including numerous alchemists) and kept up with
Kepler's work in physical astronomy as well.
Officially, the only acceptable religious doctrines in
Catholic and Utraquist, but Kepler's position in the imperial court
allowed him to practice his Lutheran faith unhindered. The emperor
nominally provided an ample income for his family, but the
difficulties of the over-extended imperial treasury meant that
actually getting hold of enough money to meet financial obligations
was a continual struggle. Partly because of financial troubles, his
life at home with Barbara was unpleasant, marred with bickering and
bouts of sickness. Court life, however, brought Kepler into contact
with other prominent scholars (Johannes Matthäus Wackher von
Wackhenfels, Jost Bürgi, David Fabricius, Martin Bachazek, and
Johannes Brengger, among others) and astronomical work proceeded
Astronomiae Pars Optica
A plate from Astronomiae Pars Optica, illustrating the structure of
eyes of various species.
As Kepler slowly continued analyzing Tycho's
available to him in their entirety—and began the slow process of
tabulating the Rudolphine Tables, Kepler also picked up the
investigation of the laws of optics from his lunar essay of 1600. Both
lunar and solar eclipses presented unexplained phenomena, such as
unexpected shadow sizes, the red color of a total lunar eclipse, and
the reportedly unusual light surrounding a total solar eclipse.
Related issues of atmospheric refraction applied to all astronomical
observations. Through most of 1603, Kepler paused his other work to
focus on optical theory; the resulting manuscript, presented to the
emperor on January 1, 1604, was published as Astronomiae Pars Optica
(The Optical Part of Astronomy). In it, Kepler described the
inverse-square law governing the intensity of light, reflection by
flat and curved mirrors, and principles of pinhole cameras, as well as
the astronomical implications of optics such as parallax and the
apparent sizes of heavenly bodies. He also extended his study of
optics to the human eye, and is generally considered by
neuroscientists to be the first to recognize that images are projected
inverted and reversed by the eye's lens onto the retina. The solution
to this dilemma was not of particular importance to Kepler as he did
not see it as pertaining to optics, although he did suggest that the
image was later corrected "in the hollows of the brain" due to the
"activity of the Soul." Today, Astronomiae Pars Optica is
generally recognized as the foundation of modern optics (though the
law of refraction is conspicuously absent). With respect to the
beginnings of projective geometry, Kepler introduced the idea of
continuous change of a mathematical entity in this work. He argued
that if a focus of a conic section were allowed to move along the line
joining the foci, the geometric form would morph or degenerate, one
into another. In this way, an ellipse becomes a parabola when a focus
moves toward infinity, and when two foci of an ellipse merge into one
another, a circle is formed. As the foci of a hyperbola merge into one
another, the hyperbola becomes a pair of straight lines. He also
assumed that if a straight line is extended to infinity it will meet
itself at a single point at infinity, thus having the properties of a
The Supernova of 1604
See also: Kepler's Supernova
Kepler's Supernova SN 1604
In October 1604, a bright new evening star (SN 1604) appeared, but
Kepler did not believe the rumors until he saw it himself. Kepler
began systematically observing the nova. Astrologically, the end of
1603 marked the beginning of a fiery trigon, the start of the about
800-year cycle of great conjunctions; astrologers associated the two
previous such periods with the rise of
Charlemagne (c. 800 years
earlier) and the birth of Christ (c. 1600 years earlier), and thus
expected events of great portent, especially regarding the emperor. It
was in this context, as the imperial mathematician and astrologer to
the emperor, that Kepler described the new star two years later in his
De Stella Nova. In it, Kepler addressed the star's astronomical
properties while taking a skeptical approach to the many astrological
interpretations then circulating. He noted its fading luminosity,
speculated about its origin, and used the lack of observed parallax to
argue that it was in the sphere of fixed stars, further undermining
the doctrine of the immutability of the heavens (the idea accepted
Aristotle that the celestial spheres were perfect and
unchanging). The birth of a new star implied the variability of the
heavens. In an appendix, Kepler also discussed the recent chronology
work of the Polish historian Laurentius Suslyga; he calculated that,
if Suslyga was correct that accepted timelines were four years behind,
then the Star of Bethlehem—analogous to the present new star—would
have coincided with the first great conjunction of the earlier
The location of the stella nova, in the foot of Ophiuchus, is marked
with an N (8 grid squares down, 4 over from the left).
The extended line of research that culminated in
Astronomia nova (A
New Astronomy)—including the first two laws of planetary
motion—began with the analysis, under Tycho's direction, of Mars'
orbit. Kepler calculated and recalculated various approximations of
Mars' orbit using an equant (the mathematical tool that Copernicus had
eliminated with his system), eventually creating a model that
generally agreed with Tycho's observations to within two arcminutes
(the average measurement error). But he was not satisfied with the
complex and still slightly inaccurate result; at certain points the
model differed from the data by up to eight arcminutes. The wide array
of traditional mathematical astronomy methods having failed him,
Kepler set about trying to fit an ovoid orbit to the data.
In Kepler's religious view of the cosmos, the
Sun (a symbol of God the
Father) was the source of motive force in the solar system. As a
physical basis, Kepler drew by analogy on William Gilbert's theory of
the magnetic soul of the
De Magnete (1600) and on his own
work on optics. Kepler supposed that the motive power (or motive
species) radiated by the
Sun weakens with distance, causing faster
or slower motion as planets move closer or farther from it.
Perhaps this assumption entailed a mathematical relationship that
would restore astronomical order. Based on measurements of the
aphelion and perihelion of the
Earth and Mars, he created a formula in
which a planet's rate of motion is inversely proportional to its
distance from the Sun. Verifying this relationship throughout the
orbital cycle, however, required very extensive calculation; to
simplify this task, by late 1602 Kepler reformulated the proportion in
terms of geometry: planets sweep out equal areas in equal
times—Kepler's second law of planetary motion.
Diagram of the geocentric trajectory of
Mars through several periods
of apparent retrograde motion (Astronomia nova, Chapter 1, 1609)
He then set about calculating the entire orbit of Mars, using the
geometrical rate law and assuming an egg-shaped ovoid orbit. After
approximately 40 failed attempts, in early 1605 he at last hit upon
the idea of an ellipse, which he had previously assumed to be too
simple a solution for earlier astronomers to have overlooked.
Finding that an elliptical orbit fit the
Mars data, he immediately
concluded that all planets move in ellipses, with the sun at one
focus—Kepler's first law of planetary motion. Because he employed no
calculating assistants, however, he did not extend the mathematical
analysis beyond Mars. By the end of the year, he completed the
manuscript for Astronomia nova, though it would not be published until
1609 due to legal disputes over the use of Tycho's observations, the
property of his heirs.
Dioptrice, Somnium manuscript, and other work
In the years following the completion of Astronomia Nova, most of
Kepler's research was focused on preparations for the Rudolphine
Tables and a comprehensive set of ephemerides (specific predictions of
planet and star positions) based on the table (though neither would be
completed for many years). He also attempted (unsuccessfully) to begin
a collaboration with Italian astronomer Giovanni Antonio Magini. Some
of his other work dealt with chronology, especially the dating of
events in the life of Jesus, and with astrology, especially criticism
of dramatic predictions of catastrophe such as those of Helisaeus
Kepler and Roeslin engaged in a series of published attacks and
counter-attacks, while physician Philip Feselius published a work
dismissing astrology altogether (and Roeslin's work in particular). In
response to what Kepler saw as the excesses of astrology on the one
hand and overzealous rejection of it on the other, Kepler prepared
Tertius Interveniens [Third-party Interventions]. Nominally this
work—presented to the common patron of Roeslin and Feselius—was a
neutral mediation between the feuding scholars, but it also set out
Kepler's general views on the value of astrology, including some
hypothesized mechanisms of interaction between planets and individual
souls. While Kepler considered most traditional rules and methods of
astrology to be the "evil-smelling dung" in which "an industrious hen"
scrapes, there was an "occasional grain-seed, indeed, even a pearl or
a gold nugget" to be found by the conscientious scientific
astrologer. Conversely, Sir Oliver Lodge observed that Kepler was
somewhat disdainful of astrology, as Kepler was "continually attacking
and throwing sarcasm at astrology, but it was the only thing for which
people would pay him, and on it after a fashion he lived."
Karlova street in Old Town, Prague – house where Kepler
In the first months of 1610,
Galileo Galilei—using his powerful new
telescope—discovered four satellites orbiting Jupiter. Upon
publishing his account as
Sidereus Nuncius [Starry Messenger], Galileo
sought the opinion of Kepler, in part to bolster the credibility of
his observations. Kepler responded enthusiastically with a short
published reply, Dissertatio cum Nuncio Sidereo [Conversation with the
Starry Messenger]. He endorsed Galileo's observations and offered a
range of speculations about the meaning and implications of Galileo's
discoveries and telescopic methods, for astronomy and optics as well
as cosmology and astrology. Later that year, Kepler published his own
telescopic observations of the moons in Narratio de Jovis
Satellitibus, providing further support of Galileo. To Kepler's
Galileo never published his reactions (if
any) to Astronomia Nova.
After hearing of Galileo's telescopic discoveries, Kepler also started
a theoretical and experimental investigation of telescopic optics
using a telescope borrowed from Duke Ernest of Cologne. The
resulting manuscript was completed in September 1610 and published as
Dioptrice in 1611. In it, Kepler set out the theoretical basis of
double-convex converging lenses and double-concave diverging
lenses—and how they are combined to produce a Galilean
telescope—as well as the concepts of real vs. virtual images,
upright vs. inverted images, and the effects of focal length on
magnification and reduction. He also described an improved
telescope—now known as the astronomical or Keplerian telescope—in
which two convex lenses can produce higher magnification than
Galileo's combination of convex and concave lenses.
One of the diagrams from Strena Seu de Nive Sexangula, illustrating
the Kepler conjecture
Around 1611, Kepler circulated a manuscript of what would eventually
be published (posthumously) as Somnium [The Dream]. Part of the
purpose of Somnium was to describe what practicing astronomy would be
like from the perspective of another planet, to show the feasibility
of a non-geocentric system. The manuscript, which disappeared after
changing hands several times, described a fantastic trip to the moon;
it was part allegory, part autobiography, and part treatise on
interplanetary travel (and is sometimes described as the first work of
science fiction). Years later, a distorted version of the story may
have instigated the witchcraft trial against his mother, as the mother
of the narrator consults a demon to learn the means of space travel.
Following her eventual acquittal, Kepler composed 223 footnotes to the
story—several times longer than the actual text—which explained
the allegorical aspects as well as the considerable scientific content
(particularly regarding lunar geography) hidden within the text.
Work in mathematics and physics
As a New Year's gift that year (1611), he also composed for his friend
and some-time patron, Baron Wackher von Wackhenfels, a short pamphlet
entitled Strena Seu de Nive Sexangula (A New Year's Gift of Hexagonal
Snow). In this treatise, he published the first description of the
hexagonal symmetry of snowflakes and, extending the discussion into a
hypothetical atomistic physical basis for the symmetry, posed what
later became known as the Kepler conjecture, a statement about the
most efficient arrangement for packing spheres.
Personal and political troubles
In 1611, the growing political-religious tension in
Prague came to a
head. Emperor Rudolph—whose health was failing—was forced to
abdicate as King of
Bohemia by his brother Matthias. Both sides sought
Kepler's astrological advice, an opportunity he used to deliver
conciliatory political advice (with little reference to the stars,
except in general statements to discourage drastic action). However,
it was clear that Kepler's future prospects in the court of Matthias
Also in that year, Barbara Kepler contracted Hungarian spotted fever,
then began having seizures. As Barbara was recovering, Kepler's three
children all fell sick with smallpox; Friedrich, 6, died. Following
his son's death, Kepler sent letters to potential patrons in
Württemberg and Padua. At the
University of Tübingen
University of Tübingen in
Württemberg, concerns over Kepler's perceived Calvinist heresies in
violation of the
Augsburg Confession and the Formula of Concord
prevented his return. The University of Padua—on the recommendation
of the departing Galileo—sought Kepler to fill the mathematics
professorship, but Kepler, preferring to keep his family in German
territory, instead travelled to Austria to arrange a position as
teacher and district mathematician in Linz. However, Barbara relapsed
into illness and died shortly after Kepler's return.
Kepler postponed the move to
Linz and remained in
Rudolph's death in early 1612, though between political upheaval,
religious tension, and family tragedy (along with the legal dispute
over his wife's estate), Kepler could do no research. Instead, he
pieced together a chronology manuscript, Eclogae Chronicae, from
correspondence and earlier work. Upon succession as Holy Roman
Emperor, Matthias re-affirmed Kepler's position (and salary) as
imperial mathematician but allowed him to move to Linz.
Linz and elsewhere (1612–1630)
A statue of Kepler in Linz
In Linz, Kepler's primary responsibilities (beyond completing the
Rudolphine Tables) were teaching at the district school and providing
astrological and astronomical services. In his first years there, he
enjoyed financial security and religious freedom relative to his life
in Prague—though he was excluded from
Eucharist by his Lutheran
church over his theological scruples. It was also during his time in
Linz that Kepler had to deal with the accusation and ultimate verdict
of witchcraft against his mother Katharina in the Protestant town of
Leonberg. That blow, happening only a few years after Kepler’s
excommunication, is not seen as a coincidence but as a symptom of the
full-fledged assault waged by the Lutherans against Kepler.
His first publication in
Linz was De vero Anno (1613), an expanded
treatise on the year of Christ's birth; he also participated in
deliberations on whether to introduce Pope Gregory's reformed calendar
to Protestant German lands; that year he also wrote the influential
mathematical treatise Nova stereometria doliorum vinariorum, on
measuring the volume of containers such as wine barrels, published in
On October 30, 1613, Kepler married the 24-year-old Susanna
Reuttinger. Following the death of his first wife Barbara, Kepler had
considered 11 different matches over two years (a decision process
formalized later as the marriage problem). He eventually returned
to Reuttinger (the fifth match) who, he wrote, "won me over with love,
humble loyalty, economy of household, diligence, and the love she gave
the stepchildren." The first three children of this marriage
(Margareta Regina, Katharina, and Sebald) died in childhood. Three
more survived into adulthood: Cordula (born 1621); Fridmar (born
1623); and Hildebert (born 1625). According to Kepler's biographers,
this was a much happier marriage than his first.
Epitome of Copernican Astronomy, calendars, and the witch trial of his
Further information: Epitome astronomiae Copernicanae
Kepler's Figure 'M' from the Epitome, showing the world as belonging
to just one of any number of similar stars.
Since completing the Astronomia nova, Kepler had intended to compose
an astronomy textbook. In 1615, he completed the first of three
Epitome astronomiae Copernicanae
Epitome astronomiae Copernicanae (Epitome of Copernican
Astronomy); the first volume (books I–III) was printed in 1617, the
second (book IV) in 1620, and the third (books V–VII) in 1621.
Despite the title, which referred simply to heliocentrism, Kepler's
textbook culminated in his own ellipse-based system. The Epitome
became Kepler's most influential work. It contained all three laws of
planetary motion and attempted to explain heavenly motions through
physical causes. Though it explicitly extended the first two laws
of planetary motion (applied to
Mars in Astronomia nova) to all the
planets as well as the
Moon and the Medicean satellites of
Jupiter, it did not explain how elliptical orbits could be derived
from observational data.
As a spin-off from the
Rudolphine Tables and the related Ephemerides,
Kepler published astrological calendars, which were very popular and
helped offset the costs of producing his other work—especially when
support from the Imperial treasury was withheld. In his
calendars—six between 1617 and 1624—Kepler forecast planetary
positions and weather as well as political events; the latter were
often cannily accurate, thanks to his keen grasp of contemporary
political and theological tensions. By 1624, however, the escalation
of those tensions and the ambiguity of the prophecies meant political
trouble for Kepler himself; his final calendar was publicly burned in
Geometrical harmonies in the perfect solids from Harmonices Mundi
In 1615, Ursula Reingold, a woman in a financial dispute with Kepler's
brother Christoph, claimed Kepler's mother Katharina had made her sick
with an evil brew. The dispute escalated, and in 1617 Katharina was
accused of witchcraft; witchcraft trials were relatively common in
central Europe at this time. Beginning in August 1620, she was
imprisoned for fourteen months. She was released in October 1621,
thanks in part to the extensive legal defense drawn up by Kepler. The
accusers had no stronger evidence than rumors. Katharina was subjected
to territio verbalis, a graphic description of the torture awaiting
her as a witch, in a final attempt to make her confess. Throughout the
trial, Kepler postponed his other work to focus on his "harmonic
theory". The result, published in 1619, was
Harmonices Mundi ("Harmony
of the World").
Main article: Harmonices Mundi
Kepler was convinced "that the geometrical things have provided the
Creator with the model for decorating the whole world". In
Harmony, he attempted to explain the proportions of the natural
world—particularly the astronomical and astrological aspects—in
terms of music. The central set of "harmonies" was the musica
universalis or "music of the spheres", which had been studied by
Ptolemy and many others before Kepler; in fact, soon after
publishing Harmonices Mundi, Kepler was embroiled in a priority
dispute with Robert Fludd, who had recently published his own harmonic
Kepler began by exploring regular polygons and regular solids,
including the figures that would come to be known as Kepler's solids.
From there, he extended his harmonic analysis to music, meteorology,
and astrology; harmony resulted from the tones made by the souls of
heavenly bodies—and in the case of astrology, the interaction
between those tones and human souls. In the final portion of the work
(Book V), Kepler dealt with planetary motions, especially
relationships between orbital velocity and orbital distance from the
Sun. Similar relationships had been used by other astronomers, but
Kepler—with Tycho's data and his own astronomical theories—treated
them much more precisely and attached new physical significance to
Among many other harmonies, Kepler articulated what came to be known
as the third law of planetary motion. He then tried many combinations
until he discovered that (approximately) "The square of the periodic
times are to each other as the cubes of the mean distances." Although
he gives the date of this epiphany (March 8, 1618), he does not give
any details about how he arrived at this conclusion. However, the
wider significance for planetary dynamics of this purely kinematical
law was not realized until the 1660s. When conjoined with Christiaan
Huygens' newly discovered law of centrifugal force, it enabled Isaac
Newton, Edmund Halley, and perhaps
Christopher Wren and Robert Hooke
to demonstrate independently that the presumed gravitational
attraction between the
Sun and its planets decreased with the square
of the distance between them. This refuted the traditional
assumption of scholastic physics that the power of gravitational
attraction remained constant with distance whenever it applied between
two bodies, such as was assumed by Kepler and also by
Galileo in his
mistaken universal law that gravitational fall is uniformly
accelerated, and also by Galileo's student Borrelli in his 1666
Rudolphine Tables and his last years
Name "Copernicus" in a manuscript report by Kepler concerning the
Rudolphine Tables (1616).
Title page of the Tabulae Rudolphinae, Ulm, 1627
Kepler's horoscope for General Wallenstein
In 1623, Kepler at last completed the Rudolphine Tables, which at the
time was considered his major work. However, due to the publishing
requirements of the emperor and negotiations with Tycho Brahe's heir,
it would not be printed until 1627. In the meantime, religious tension
— the root of the ongoing
Thirty Years' War
Thirty Years' War — once again put
Kepler and his family in jeopardy. In 1625, agents of the Catholic
Counter-Reformation placed most of Kepler's library under seal, and in
1626 the city of
Linz was besieged. Kepler moved to Ulm, where he
arranged for the printing of the Tables at his own expense.
In 1628, following the military successes of the Emperor Ferdinand's
armies under General Wallenstein, Kepler became an official advisor to
Wallenstein. Though not the general's court astrologer per se, Kepler
provided astronomical calculations for Wallenstein's astrologers and
occasionally wrote horoscopes himself. In his final years, Kepler
spent much of his time traveling, from the imperial court in
Ulm to a temporary home in Sagan, and finally to Regensburg.
Soon after arriving in Regensburg, Kepler fell ill. He died on
November 15, 1630, and was buried there; his burial site was lost
after the Swedish army destroyed the churchyard. Only Kepler's
self-authored poetic epitaph survived the times:
Mensus eram coelos, nunc terrae metior umbras
Mens coelestis erat, corporis umbra iacet.
I measured the skies, now the shadows I measure
Skybound was the mind, earthbound the body rests.
Kepler's belief that God created the cosmos in an orderly fashion
caused him to attempt to determine and comprehend the laws that govern
the natural world, most profoundly in astronomy. The phrase "I
am merely thinking God's thoughts after Him" has been attributed to
him, although this is probably a capsulized version of a writing from
Those laws [of nature] are within the grasp of the human mind; God
wanted us to recognize them by creating us after his own image so that
we could share in his own thoughts.
Reception of his astronomy
Kepler's laws of planetary motion
Kepler's laws of planetary motion were not immediately accepted.
Several major figures such as
René Descartes completely
ignored Kepler's Astronomia nova. Many astronomers, including Kepler's
teacher, Michael Maestlin, objected to Kepler's introduction of
physics into his astronomy. Some adopted compromise positions. Ismaël
Bullialdus accepted elliptical orbits but replaced Kepler's area law
with uniform motion in respect to the empty focus of the ellipse,
while Seth Ward used an elliptical orbit with motions defined by an
Several astronomers tested Kepler's theory, and its various
modifications, against astronomical observations. Two transits of
Venus and Mercury across the face of the sun provided sensitive tests
of the theory, under circumstances when these planets could not
normally be observed. In the case of the transit of Mercury in 1631,
Kepler had been extremely uncertain of the parameters for Mercury, and
advised observers to look for the transit the day before and after the
Pierre Gassendi observed the transit on the date
predicted, a confirmation of Kepler's prediction. This was the
first observation of a transit of Mercury. However, his attempt to
observe the transit of
Venus just one month later was unsuccessful due
to inaccuracies in the Rudolphine Tables. Gassendi did not realize
that it was not visible from most of Europe, including Paris.
Jeremiah Horrocks, who observed the 1639
Venus transit, had used his
own observations to adjust the parameters of the Keplerian model,
predicted the transit, and then built apparatus to observe the
transit. He remained a firm advocate of the Keplerian
Epitome of Copernican
Astronomy was read by astronomers throughout
Europe, and following Kepler's death, it was the main vehicle for
spreading Kepler's ideas. In the period 1630 - 1650, this book was the
most widely used astronomy textbook, winning many converts to
ellipse-based astronomy. However, few adopted his ideas on the
physical basis for celestial motions. In the late 17th century, a
number of physical astronomy theories drawing from Kepler's
work—notably those of
Giovanni Alfonso Borelli
Giovanni Alfonso Borelli and Robert
Hooke—began to incorporate attractive forces (though not the
quasi-spiritual motive species postulated by Kepler) and the Cartesian
concept of inertia. This culminated in Isaac Newton's Principia
Mathematica (1687), in which Newton derived Kepler's laws of planetary
motion from a force-based theory of universal gravitation.
Historical and cultural legacy
Tycho Brahe and Kepler in Prague, Czech Republic
The GDR stamp featuring Kepler
History of science
Beyond his role in the historical development of astronomy and natural
philosophy, Kepler has loomed large in the philosophy and
historiography of science. Kepler and his laws of motion were central
to early histories of astronomy such as Jean-Étienne Montucla's 1758
Histoire des mathématiques and Jean-Baptiste Delambre's 1821 Histoire
de l'astronomie moderne. These and other histories written from an
Enlightenment perspective treated Kepler's metaphysical and religious
arguments with skepticism and disapproval, but later Romantic-era
natural philosophers viewed these elements as central to his success.
William Whewell, in his influential History of the Inductive Sciences
of 1837, found Kepler to be the archetype of the inductive scientific
genius; in his Philosophy of the Inductive Sciences of 1840, Whewell
held Kepler up as the embodiment of the most advanced forms of
scientific method. Similarly, Ernst Friedrich Apelt—the first to
extensively study Kepler's manuscripts, after their purchase by
Catherine the Great—identified Kepler as a key to the "Revolution of
the sciences". Apelt, who saw Kepler's mathematics, aesthetic
sensibility, physical ideas, and theology as part of a unified system
of thought, produced the first extended analysis of Kepler's life and
Alexandre Koyré's work on Kepler was, after Apelt, the first major
milestone in historical interpretations of Kepler's cosmology and its
influence. In the 1930s and 1940s, Koyré, and a number of others in
the first generation of professional historians of science, described
the "Scientific Revolution" as the central event in the history of
science, and Kepler as a (perhaps the) central figure in the
revolution. Koyré placed Kepler's theorization, rather than his
empirical work, at the center of the intellectual transformation from
ancient to modern world-views. Since the 1960s, the volume of
historical Kepler scholarship has expanded greatly, including studies
of his astrology and meteorology, his geometrical methods, the role of
his religious views in his work, his literary and rhetorical methods,
his interaction with the broader cultural and philosophical currents
of his time, and even his role as an historian of science.
Philosophers of science—such as Charles Sanders Peirce, Norwood
Russell Hanson, Stephen Toulmin, and Karl Popper—have repeatedly
turned to Kepler: examples of incommensurability, analogical
reasoning, falsification, and many other philosophical concepts have
been found in Kepler's work. Physicist
Wolfgang Pauli even used
Kepler's priority dispute with
Robert Fludd to explore the
implications of analytical psychology on scientific investigation.
Editions and translations
Modern translations of a number of Kepler's books appeared in the
late-nineteenth and early-twentieth centuries, the systematic
publication of his collected works began in 1937 (and is nearing
completion in the early 21st century).
An edition in eight volumes, Kepleri Opera omnia, was prepared by
Christian Frisch (1807–1881), during 1858 to 1871, on the occasion
of Kepler's 300th birthday. Frisch's edition only included Kepler's
Latin, with a Latin commentary.
A new edition was planned beginning in 1914 by Walther von Dyck
(1856–1934). Dyck compiled copies of Kepler's unedited manuscripts,
using international diplomatic contacts to convince the Soviet
authorities to lend him the manuscripts kept in Leningrad for
photographic reproduction. These manuscripts contained several works
by Kepler that had not been available to Frisch. Dyck's photographs
remain the basis for the modern editions of Kepler's unpublished
Max Caspar (1880–1956) published his German translation of Kepler's
Mysterium Cosmographicum in 1923. Both Dyck and Caspar were influenced
in their interest in Kepler by mathematician Alexander von Brill
(1842–1935). Caspar became Dyck's collaborator, succeeding him as
project leader in 1934, establishing the Kepler-Kommission in the
following year. Assisted by Martha List (1908–1992) and Franz Hammer
(1898–1979), Caspar continued editorial work during World War II.
Max Caspar also published a biography of Kepler in 1948. The
commission was later chaired by Volker Bialas (during 1976–2003) and
Ulrich Grigull (during 1984–1999) and Roland Bulirsch
Popular science and historical fiction
Kepler has acquired a popular image as an icon of scientific modernity
and a man before his time; science popularizer
Carl Sagan described
him as "the first astrophysicist and the last scientific
The debate over Kepler's place in the
Scientific Revolution has
produced a wide variety of philosophical and popular treatments. One
of the most influential is Arthur Koestler's 1959 The Sleepwalkers, in
which Kepler is unambiguously the hero (morally and theologically as
well as intellectually) of the revolution.
A well-received, if fanciful, historical novel by John Banville,
Kepler (1981), explored many of the themes developed in Koestler's
non-fiction narrative and in the philosophy of science. Somewhat
more fanciful is a recent work of nonfiction, Heavenly Intrigue
(2004), suggesting that Kepler murdered
Tycho Brahe to gain access to
Veneration and eponymy
In Austria, Kepler left behind such a historical legacy that he was
one of the motifs of a silver collector's coin: the 10-euro Johannes
Kepler silver coin, minted on September 10, 2002. The reverse side of
the coin has a portrait of Kepler, who spent some time teaching in
Graz and the surrounding areas. Kepler was acquainted with Prince Hans
Ulrich von Eggenberg personally, and he probably influenced the
Eggenberg Castle (the motif of the obverse of the
coin). In front of him on the coin is the model of nested spheres and
polyhedra from Mysterium Cosmographicum.
The German composer
Paul Hindemith wrote an opera about Kepler
entitled Die Harmonie der Welt, and a symphony of the same name was
derived from music for the opera.
Philip Glass wrote an opera called
Kepler based on Kepler's life (2009).
Kepler is honored together with
Nicolaus Copernicus with a feast day
on the liturgical calendar of the Episcopal Church (USA) on May
Main article: List of things named after Johannes Kepler
Directly named for Kepler's contribution to science are Kepler's laws
of planetary motion,
Kepler's Supernova (Supernova 1604, which he
observed and described) and the Kepler Solids, a set of geometrical
constructions, two of which were described by him, and the Kepler
conjecture on sphere packing.
The Kepler crater as photographed by
Apollo 12 in 1969
In astronomy: The lunar crater Kepler (Keplerus, named by Giovanni
Riccioli, 1651), the asteroid
1134 Kepler (1929), Kepler (crater on
Kepler Launch Site
Kepler Launch Site for model rockets (2001), the Kepler
Mission, a space photometer launched by
NASA in 2009, Johannes
Kepler ATV (
Automated Transfer Vehicle
Automated Transfer Vehicle launched to resupply the ISS in
Johannes Kepler University of
Kepler College (Seattle, Washington), besides several institutions of
primary and secondary education, such as
Johannes Kepler Grammar
School, at the site where Kepler lived in Prague, and Kepler
Streets or squares named after him: Keplerplatz Vienna (station of
Vienna U-Bahn), Keplerstraße in Hanau near Frankfurt am Main,
Keplerstraße in Munich, Germany, Keplerstraße and Keplerbrücke in
Graz, Austria, Keplerova ulice in Prague.
Kepler Mountains and
Kepler Track in Fiordland National Park,
South Island, New Zealand;
Kepler Challenge (1988).
Kepler, a high end graphics processing microarchitecture introduced by
Nvidia in 2012.
Mysterium Cosmographicum (The Sacred Mystery of the Cosmos) (1596)
De Fundamentis Astrologiae Certioribus (On Firmer Fundaments of
Astronomiae Pars Optica (The Optical Part of Astronomy) (1604)
De Stella nova in pede Serpentarii (On the New Star in Ophiuchus's
Astronomia nova (New Astronomy) (1609)
Tertius Interveniens (Third-party Interventions) (1610)
Dissertatio cum Nuncio Sidereo (Conversation with the Starry
De nive sexangula (On the Six-Cornered Snowflake) (1611)
De vero Anno, quo aeternus Dei Filius humanam naturam in Utero
benedictae Virginis Mariae assumpsit (1614)
Eclogae Chronicae (1615, published with Dissertatio cum Nuncio
Nova stereometria doliorum vinariorum (New Stereometry of Wine
Ephemerides nouae motuum coelestium (1617-30)
Epitome astronomiae Copernicanae
Epitome astronomiae Copernicanae (Epitome of Copernican Astronomy)
(published in three parts from 1618 to 1621)
Epitome astronomiae copernicanae, 1618
Harmonices Mundi (Harmony of the Worlds) (1619)
Mysterium cosmographicum (The Sacred Mystery of the Cosmos), 2nd
Tabulae Rudolphinae (Rudolphine Tables) (1627)
Somnium (The Dream) (1634)
A critical edition of Kepler's collected works (Johannes Kepler
Gesammelte Werke, KGW) in 22 volumes is being edited by the
Kepler-Kommission (founded 1935) on behalf of the Bayerische Akademie
Vol. 1: Mysterium Cosmographicum. De Stella Nova. Ed. M. Caspar. 1938,
2nd ed. 1993. Paperback ISBN 3-406-01639-1.
Vol. 2: Astronomiae pars optica. Ed. F. Hammer. 1939, Paperback
Vol. 3: Astronomia Nova. Ed. M. Caspar. 1937. IV, 487 p. 2. ed. 1990.
Paperback ISBN 3-406-01643-X. Semi-parchment
Vol. 4: Kleinere Schriften 1602–1611. Dioptrice. Ed. M. Caspar, F.
Hammer. 1941. ISBN 3-406-01644-8.
Vol. 5: Chronologische Schriften. Ed. F. Hammer. 1953. Out-of-print.
Vol. 6: Harmonice Mundi. Ed. M. Caspar. 1940, 2nd ed. 1981,
Vol. 7: Epitome Astronomiae Copernicanae. Ed. M. Caspar. 1953, 2nd ed.
1991. ISBN 3-406-01650-2, Paperback ISBN 3-406-01651-0.
Vol. 8: Mysterium Cosmographicum. Editio altera cum notis. De Cometis.
Hyperaspistes. Commentary F. Hammer. 1955. Paperback
Vol 9: Mathematische Schriften. Ed. F. Hammer. 1955, 2nd ed. 1999.
Vol. 10: Tabulae Rudolphinae. Ed. F. Hammer. 1969.
Ephemerides novae motuum coelestium. Commentary V. Bialas.
1983. ISBN 3-406-01658-8, Paperback ISBN 3-406-01659-6.
Vol. 11,2: Calendaria et Prognostica. Astronomica minora. Somnium.
Commentary V. Bialas, H. Grössing. 1993. ISBN 3-406-37510-3,
Paperback ISBN 3-406-37511-1.
Vol. 12: Theologica. Hexenprozeß. Tacitus-Übersetzung. Gedichte.
Commentary J. Hübner, H. Grössing, F. Boockmann, F. Seck. Directed
by V. Bialas. 1990. ISBN 3-406-01660-X, Paperback
Vols. 13–18: Letters:
Vol. 13: Briefe 1590–1599. Ed. M. Caspar. 1945. 432 p.
Vol. 14: Briefe 1599–1603. Ed. M. Caspar. 1949. Out-of-print. 2nd
ed. in preparation.
Vol 15: Briefe 1604–1607. Ed. M. Caspar. 1951. 2nd ed. 1995.
Vol. 16: Briefe 1607–1611. Ed. M. Caspar. 1954.
Vol. 17: Briefe 1612–1620. Ed. M. Caspar. 1955.
Vol. 18: Briefe 1620–1630. Ed. M. Caspar. 1959.
Vol. 19: Dokumente zu Leben und Werk. Commentary M. List. 1975.
Vols. 20–21: manuscripts
Vol. 20,1: Manuscripta astronomica (I). Apologia, De motu Terrae,
Hipparchus etc. Commentary V. Bialas. 1988. ISBN 3-406-31501-1.
Paperback ISBN 3-406-31502-X.
Vol. 20,2: Manuscripta astronomica (II). Commentaria in Theoriam
Martis. Commentary V. Bialas. 1998. Paperback ISBN 3-406-40593-2.
Vol. 21,1: Manuscripta astronomica (III) et mathematica. De Calendario
Gregoriano. In preparation.
Vol. 21,2: Manuscripta varia. In preparation.
Vol. 22: General index, in preparation.
The Kepler-Kommission also publishes Bibliographia Kepleriana (2nd ed.
List, 1968), a complete bibliography of editions of Kepler's works,
with a supplementary volume to the second edition (ed. Hamel 1998).
History of astronomy
History of physics
Kepler's laws of planetary motion
List of things named after Johannes Kepler
Notes and references
^ "Kepler". Random House Webster's Unabridged Dictionary.
dead link] accessed 9/7/2017
^ Barker and Goldstein. "
Theological Foundations of Kepler's
Astronomy", pp. 112–13.
^ Kepler. New Astronomy, title page, tr. Donohue, pp. 26–7
^ Kepler. New Astronomy, p. 48
^ Epitome of Copernican
Astronomy in Great Books of the Western World,
Vol 15, p. 845
^ Stephenson. Kepler's Physical Astronomy, pp. 1–2; Dear,
Revolutionizing the Sciences, pp. 74–78
^ Caspar. Kepler, pp. 29–36; Connor. Kepler's Witch, pp.
^ a b Koestler. The Sleepwalkers, p. 234 (translated from Kepler's
^ Caspar. Kepler, pp. 36–38; Connor. Kepler's Witch, pp.
^ Connor, James A. Kepler's Witch (2004), p. 58.
^ a b Barker, Peter; Goldstein, Bernard R. "
Theological Foundations of
Kepler's Astronomy", Osiris, 2nd Series, Vol. 16, Science in Theistic
Contexts: Cognitive Dimensions (2001), p. 96.
^ Westman, Robert S. "Kepler's Early Physico-Astrological
Problematic," Journal for the History of Astronomy, 32 (2001):
^ Caspar. Kepler, pp. 38–52; Connor. Kepler's Witch, pp.
^ Caspar. Kepler, pp. 60–65; see also: Barker and Goldstein,
Theological Foundations of Kepler's Astronomy."
^ Barker and Goldstein. "
Theological Foundations of Kepler's
Astronomy," pp. 99–103, 112–113.
^ Caspar. Kepler, pp. 65–71.
^ Field. Kepler's Geometrical Cosmology, Chapter IV, p 73ff.
^ Dreyer, J.L.E. A History of
Thales to Kepler, Dover
Publications, 1953, pp. 331, 377–379.
^ Caspar, Kepler. pp. 71–75.
^ Connor. Kepler's Witch, pp. 89–100, 114–116; Caspar.
Kepler, pp. 75–77
^ Caspar. Kepler, pp. 85–86.
^ Caspar, Kepler, pp. 86–89
^ Caspar, Kepler, pp. 89–100
^ Using Tycho's data, see 'Two views of a system' Archived July 21,
2011, at the Wayback Machine.
^ Caspar, Kepler, pp. 100–08.
^ Caspar, Kepler, p. 110.
^ Caspar, Kepler, pp. 108–11.
^ Caspar, Kepler, pp. 111–22.
^ Caspar, Kepler, pp. 149–53
^ Caspar, Kepler, pp. 146–148, 159–177
^ Finger, "Origins of Neuroscience," p. 74. Oxford University Press,
^ Caspar, Kepler, pp. 142–146
^ Morris Kline, Mathematical Thought from Ancient to Modern Times, p.
299. Oxford University Press, 1972.
^ Caspar, Kepler, pp. 153–157
^ Caspar, Kepler, pp. 123–128
^ On motive species, see Lindberg, "The Genesis of Kepler's Theory of
Light," pp. 38–40.
^ "Kepler's decision to base his causal explanation of planetary
motion on a distance-velocity law, rather than on uniform circular
motions of compounded spheres, marks a major shift from ancient to
modern conceptions of science ... [Kepler] had begun with
physical principles and had then derived a trajectory from it, rather
than simply constructing new models. In other words, even before
discovering the area law, Kepler had abandoned uniform circular motion
as a physical principle." Peter Barker and Bernard R. Goldstein,
"Distance and Velocity in Kepler's Astronomy", Annals of Science, 51
(1994): 59–73, at p. 60.
^ Koyré, The Astronomical Revolution, pp. 199–202.
^ Caspar, Kepler, pp. 129–132
^ Caspar, Kepler, p. 133
^ Caspar, Kepler, pp. 131–140; Koyré, The Astronomical
Revolution, pp. 277–279
^ Caspar, Kepler, pp. 178–81
^ Caspar, Kepler, pp. 181–85. The full title is Tertius
Interveniens, das ist Warnung an etliche Theologos, Medicos vnd
Philosophos, sonderlich D. Philippum Feselium, dass sie bey billicher
Verwerffung der Sternguckerischen Aberglauben nict das Kindt mit dem
Badt aussschütten vnd hiermit jhrer Profession vnwissendt zuwider
handlen, translated by C. Doris Hellman as "Tertius Interveniens, that
is warning to some theologians, medics and philosophers, especially D.
Philip Feselius, that they in cheap condemnation of the star-gazer's
superstition do not throw out the child with the bath and hereby
unknowingly act contrary to their profession."
^ Lodge, O.J., Johann Kepler in "The World of Mathematics", Vol. 1
(1956) Ed. Newman, J.R., Simon and Schuster, pp. 231.
^ Caspar, Kepler, pp. 192–197
^ Koestler, The Sleepwalkers p. 384
^ Caspar, Kepler, pp. 198–202
^ Lear, Kepler's Dream, pp. 1–78
^ Schneer, "Kepler's New Year's Gift of a Snowflake,"
^ Kepler, Johannes (1966) . Hardie, Colin, ed. De nive sexangula
[The Six-sided Snowflake]. Oxford: Clarendon Press.
^ Caspar, Kepler, pp. 202–204
^ Connor, Kepler's Witch, pp. 222–226; Caspar, Kepler,
^ Caspar, Kepler, pp. 208–11
^ Mazer, Arthur (2010). Shifting the Earth: The Mathematica Quest to
Understand the Motion of the Universe. Hoboken, NJ: John Wiley &
Sons, Inc. ISBN 978-1-118-02427--0.
^ Caspar, Kepler, pp. 209–20, 227–240
^ Ferguson, Thomas S. (1989), "Who solved the secretary
problem ?", Statistical Science, 4 (3): 282–289,
doi:10.1214/ss/1177012493, JSTOR 2245639, When the celebrated
Johannes Kepler (1571–1630), lost his first wife
to cholera in 1611, he set about finding a new wife using the same
methodical thoroughness and careful consideration of the data that he
used in finding the orbit of
Mars to be an ellipse ... The
process consumed much of his attention and energy for nearly 2
^ Quotation from Connor, Kepler's Witch, p 252, translated from an
October 23, 1613 letter from Kepler to an anonymous nobleman
^ Caspar, Kepler, pp. 220–223; Connor, Kepler's Witch,
^ Caspar, Kepler, pp. 239–240, 293–300
^ a b Gingerich, "Kepler, Johannes" from Dictionary of Scientific
Biography, pp. 302–04
^ By 1621 or earlier, Kepler recognized that Jupiter's moons obey his
third law. Kepler contended that rotating massive bodies communicate
their rotation to their satellites, so that the satellites are swept
around the central body; thus the rotation of the
Sun drives the
revolutions of the planets and the rotation of the
Earth drives the
revolution of the Moon. In Kepler's era, no one had any evidence of
Jupiter's rotation. However, Kepler argued that the force by which a
central body causes its satellites to revolve around it, weakens with
distance; consequently, satellites that are farther from the central
body revolve slower. Kepler noted that Jupiter's moons obeyed this
pattern and he inferred that a similar force was responsible. He also
noted that the orbital periods and semi-major axes of Jupiter's
satellites were roughly related by a 3/2 power law, as are the orbits
of the six (then known) planets. However, this relation was
approximate: the periods of Jupiter's moons were known within a few
percent of their modern values, but the moons' semi-major axes were
determined less accurately.
Kepler discussed Jupiter's moons in his Epitome Astronomiae
Copernicanae [Summary of Copernican Astronomy] (
Linz ("Lentiis ad
Danubium"), (Austria): Johann Planck, 1622), book 4, part 2, page 554.
(For a more modern and legible edition, see: Christian Frisch, ed.,
Joannis Kepleri Astronomi Opera Omnia, vol. 6 (Frankfurt-am-Main,
(Germany): Heyder & Zimmer, 1866), page 361.)
Original : 4) Confirmatur vero fides hujus rei comparatione
quatuor Jovialium et Jovis cum sex planetis et Sole. Etsi enim de
corpore Jovis, an et ipsum circa suum axem convertatur, non ea
documenta habemus, quae nobis suppetunt in corporibus Terrae et
praecipue Solis, quippe a sensu ipso: at illud sensus testatur, plane
ut est cum sex planetis circa Solem, sic etiam se rem habere cum
quatuor Jovialibus, ut circa corpus Jovis quilibet, quo longius ab
illo potest excurrere, hoc tardius redeat, et id quidem proportione
non eadem, sed majore, hoc est sescupla proportionis intervallorum
cujusque a Jove: quae plane ipsissima est, qua utebantur supra sex
planetae. Intervalla enim quatuor Jovialium a Jove prodit Marius in
suo Mundo Joviali ista: 3, 5, 8, 13 (vel 14 Galilaeo) ...
Periodica vero tempora prodit idem Marius ista: dies 1. h. 18 1/2,
dies 3 h. 13 1/3, dies 7 h. 3, dies 16 h. 18: ubique proportio est
major quam dupla, major igitur quam intervallorum 3, 5, 8, 13 vel 14,
minor tamen quam quadratorum, qui duplicant proportiones
intervallorum, sc. 9, 25, 64, 169 vel 196, sicut etiam sescupla sunt
majora simplis, minora vero duplis.
Translation : (4) However, the credibility of this [argument] is
proved by the comparison of the four [moons] of
Jupiter and Jupiter
with the six planets and the Sun. Because, regarding the body of
Jupiter, whether it turns around its axis, we don't have proofs for
what suffices for us [regarding the rotation of ] the body of the
Earth and especially of the Sun, certainly [as reason proves to us]:
but reason attests that, just as it is clearly [true] among the six
planets around the Sun, so also it is among the four [moons] of
Jupiter, because around the body of
Jupiter any [satellite] that can
go farther from it orbits slower, and even that [orbit's period] is
not in the same proportion, but greater [than the distance from
Jupiter]; that is, 3/2 (sescupla ) of the proportion of each of the
distances from Jupiter, which is clearly the very [proportion] as [is
used for] the six planets above. In his [book] The World of Jupiter
[Mundus Jovialis, 1614], [Simon] Mayr [1573–1624] presents these
distances, from Jupiter, of the four [moons] of Jupiter: 3, 5, 8, 13
(or 14 [according to] Galileo) ... Mayr presents their time
periods: 1 day 18 1/2 hours, 3 days 13 1/3 hours, 7 days 3 hours, 16
days 18 hours: for all [of these data] the proportion is greater than
double, thus greater than [the proportion] of the distances 3, 5, 8,
13 or 14, although less than [the proportion] of the squares, which
double the proportions of the distances, namely 9, 25, 64, 169 or 196,
just as [a power of] 3/2 is also greater than 1 but less than 2.
^ Wolf, A History of Science, Technology and Philosophy,
pp. 140–41; Pannekoek, A History of Astronomy, p 252
^ Caspar, Kepler, pp. 239, 300–01, 307–08
^ Caspar, Kepler, pp. 240–264; Connor, Kepler's Witch, chapters
I, XI-XIII; Lear, Kepler's Dream, pp. 21–39
^ Quotation from Caspar, Kepler, pp. 265–266, translated from
^ The opening of the movie
Mars et Avril by
Martin Villeneuve is based
on German astronomer Johannes Kepler's cosmological model from the
17th century, Harmonices Mundi, in which the harmony of the universe
is determined by the motion of celestial bodies.
Benoît Charest also
composed the score according to this theory.
^ Caspar, Kepler, pp. 264–66, 290–93
^ Caspar, Kepler, pp. 266–90
^ Miller, Arthur I. (March 24, 2009). Deciphering the cosmic number:
the strange friendship of
Wolfgang Pauli and Carl Jung. W. W. Norton
& Company. p. 80. ISBN 978-0-393-06532-9. Retrieved
March 7, 2011.
^ Westfall, Never at Rest, pp. 143, 152, 402–03; Toulmin and
Goodfield, The Fabric of the Heavens, p 248; De Gandt, 'Force and
Geometry in Newton's Principia', chapter 2; Wolf, History of Science,
Technology and Philosophy, p. 150; Westfall, The Construction of
Modern Science, chapters 7 and 8
^ Koyré, The Astronomical Revolution, p. 502
^ Caspar, Kepler, pp. 308–328
^ Caspar, Kepler, pp. 332–351, 355–61
^ Koestler, The Sleepwalkers, p. 427.
^ Letter (9/10 Apr 1599) to the Bavarian chancellor Herwart von
Hohenburg. Collected in Carola Baumgardt and Jamie Callan, Johannes
Kepler Life and Letters (1953), 50
^ For a detailed study of the reception of Kepler's astronomy see
Wilbur Applebaum, "Keplerian
Astronomy after Kepler: Researches and
Problems," History of Science, 34(1996): 451–504.
^ Koyré, The Astronomical Revolution, pp. 362–364
^ North, History of
Astronomy and Cosmology, pp. 355–60
^ Helden, Albert van (1976). "The Importance of the Transit of Mercury
of 1631". Journal for the History of Astronomy. 7: 1–10.
^ HM Nautical Almanac Office (June 10, 2004). "1631 Transit of Venus".
Archived from the original on October 1, 2006. Retrieved August 28,
^ Allan Chapman, "Jeremiah Horrocks, the transit of Venus, and the
'New Astronomy' in early 17th-century England," Quarterly Journal of
the Royal Astronomical Society, 31 (1990): 333–357.
^ North, History of
Astronomy and Cosmology, pp. 348–349
^ Wilbur Applebaum and Robert Hatch, "Boulliau, Mercator, and
Venus in sole visa: Three Unpublished Letters," Journal for
the History of Astronomy, 14(1983): 166–179
^ Lawrence Nolan (ed.), The Cambridge Descartes Lexicon, Cambridge
University Press, 2016, "Inertia."
^ Kuhn, The Copernican Revolution, pp. 238, 246–252
^ Jardine, "Koyré's Kepler/Kepler's Koyré," pp. 363–367
^ Jardine, "Koyré's Kepler/Kepler's Koyré," pp. 367–372;
Shapin, The Scientific Revolution, pp. 1–2
^ Pauli, "The Influence of Archetypical Ideas"
^ Gingerich, introduction to Caspar's Kepler, pp. 3–4
^ Ulrich Grigull, "Sechzig Jahre Kepler-Kommission", in:
Sitzungsberichte der Bayerischen Akademie der Wissenschaften [Sitzung
vom 5. Juli 1996], 1996.
^ kepler-kommission.de. Ulf Hashagen,
Walther von Dyck
Walther von Dyck (1856–1934).
Mathematik, Technik und Wissenschaftsorganisation an der TH München,
^ Quote from Carl Sagan, Cosmos: A Personal Voyage, episode III: "The
Harmony of the Worlds". Kepler was hardly the first to combine physics
and astronomy; however, according to the traditional (though disputed)
interpretation of the Scientific Revolution, he would be the first
astrophysicist in the era of modern science.
^ Stephen Toulmin, Review of The Sleepwalkers in The Journal of
Philosophy, Vol. 59, no. 18 (1962), pp. 500–503
^ William Donahue, "A Novelist's Kepler," Journal for the History of
Astronomy, Vol. 13 (1982), pp. 135–136; "Dancing the grave
dance: Science, art and religion in John Banville's Kepler," English
Studies, Vol. 86, no. 5 (October 2005), pp. 424–438
^ Marcelo Gleiser, "Kepler in the Dock", review of Gilder and Gilder's
Heavenly Intrigue, Journal for the History of Astronomy, Vol. 35, pt.
4 (2004), pp. 487–489
^ "Eggenberg Palace coin". Austrian Mint. Archived from the original
on May 31, 2011. Retrieved September 9, 2009.
^ "Calendar of the Church Year according to the Episcopal Church".
Charles Wohlers. Retrieved October 17, 2014.
^ Ng, Jansen (July 3, 2009). "
Kepler Mission Sets Out to Find Planets
Using CCD Cameras". DailyTech. Archived from the original on March 10,
2009. Retrieved July 3, 2009.
^ "GJK.cz". GJK.cz. Retrieved October 17, 2014.
^ "... in 1614,
Johannes Kepler published his book "De vero anno
quo aeternus dei filius humanum naturam in utero benedictae Virginis
Mariae assumpsit", on the chronology related to the Star of
Bethlehem.", The Star of Bethlehem, Kapteyn Astronomical Institute
Andersen, Hanne; Peter Barker; and Xiang Chen. The Cognitive Structure
of Scientific Revolutions, chapter 6: "The Copernican Revolution." New
York: Cambridge University Press, 2006. ISBN 0-521-85575-6
Armitage, Angus. John Kepler, Faber, 1966.
Banville, John. Kepler, Martin, Secker and Warburg, London, 1981
Barker, Peter and Bernard R. Goldstein: "
Theological Foundations of
Kepler's Astronomy". Osiris, Volume 16. Science in Theistic Contexts.
University of Chicago Press, 2001, pp. 88–113
Caspar, Max. Kepler; transl. and ed. by C. Doris Hellman; with a new
introduction and references by Owen Gingerich; bibliographic citations
Owen Gingerich and Alain Segonds. New York: Dover, 1993.
Connor, James A. Kepler's Witch: An Astronomer's Discovery of Cosmic
Order Amid Religious War, Political Intrigue, and the Heresy Trial of
His Mother. HarperSanFrancisco, 2004. ISBN 0-06-052255-0
De Gandt, Francois. Force and Geometry in Newton's Principia,
Translated by Curtis Wilson,
Princeton University Press
Princeton University Press 1995.
Dreyer, J. L. E. A History of
Thales to Kepler. Dover
Publications Inc, 1967. ISBN 0-486-60079-3
Ferguson, Kitty. The nobleman and his housedog:
Tycho Brahe and
Johannes Kepler: the strange partnership that revolutionized science.
London: Review, 2002. ISBN 0-7472-7022-8 – published in the US
as: Tycho & Kepler: the unlikely partnership that forever changed
our understanding of the heavens. New York: Walker, 2002.
Field, J. V.. Kepler's geometrical cosmology. Chicago University
Press, 1988. ISBN 0-226-24823-2
Gilder, Joshua and Anne-Lee Gilder: Heavenly Intrigue: Johannes
Kepler, Tycho Brahe, and the Murder Behind One of History's Greatest
Scientific Discoveries, Doubleday (May 18, 2004).
ISBN 0-385-50844-1 Reviews bookpage.com, crisismagazine.com
Gingerich, Owen. The Eye of Heaven: Ptolemy, Copernicus, Kepler.
American Institute of Physics, 1993. ISBN 0-88318-863-5 (Masters
of modern physics; v. 7)
Gingerich, Owen: "Kepler, Johannes" in Dictionary of Scientific
Biography, Volume VII. Charles Coulston Gillispie, editor. New York:
Charles Scribner's Sons, 1973
Greenbaum and Boockmann: "Kepler's Astrology", Culture and
Special Double Issue, 2012.
Jardine, Nick: "Koyré's Kepler/Kepler's Koyré," History of Science,
Vol. 38 (2000), pp. 363–376
Johannes Kepler New
Astronomy trans. W. Donahue,
forward by O. Gingerich,
Cambridge University Press
Cambridge University Press 1993.
Kepler, Johannes and Christian Frisch. Joannis Kepleri Astronomi Opera
Omnia (John Kepler, Astronomer; Complete Works), 8 vols.(1858–1871).
vol. 1, 1858, vol. 2, 1859, vol. 3, 1860, vol. 6, 1866, vol. 7, 1868,
Frankfurt am Main and Erlangen, Heyder & Zimmer, – Google Books
Kepler, Johannes, et al. Great Books of the Western World. Volume 16:
Ptolemy, Copernicus, Kepler, Chicago: Encyclopædia Britannica, Inc.,
1952. (contains English translations by of Kepler's Epitome, Books IV
& V and Harmonices Book 5)
Koestler, Arthur. The Sleepwalkers: A History of Man's Changing Vision
of the Universe. (1959). ISBN 0-14-019246-8
Koyré, Alexandre: Galilean Studies Harvester Press 1977.
Koyré, Alexandre: The Astronomical Revolution:
Copernicus-Kepler-Borelli Ithaca, NY: Cornell University Press, 1973.
ISBN 0-8014-0504-1; Methuen, 1973. ISBN 0-416-76980-2;
Hermann, 1973. ISBN 2-7056-5648-0
Kuhn, Thomas S. The Copernican Revolution: Planetary
Astronomy in the
Development of Western Thought. Cambridge, MA: Harvard University
Press, 1957. ISBN 0-674-17103-9
Lindberg, David C.: "The Genesis of Kepler's Theory of Light: Light
Metaphysics from Plotinus to Kepler." Osiris, N.S. 2. University of
Chicago Press, 1986, pp. 5–42.
Lear, John. Kepler's Dream. Berkeley: University of California Press,
M.T.K Al-Tamimi. "Great collapse Kepler's first law", Natural Science,
2 (2010), ISSN 2150-4091
North, John. The Fontana History of
Astronomy and Cosmology, Fontana
Press, 1994. ISBN 0-00-686177-6
Pannekoek, Anton: A History of Astronomy, Dover Publications Inc 1989.
Pauli, Wolfgang. Wolfgang Pauli — Writings on physics and
philosophy, translated by Robert Schlapp and edited by P. Enz and Karl
von Meyenn (Springer Verlag, Berlin, 1994). See section 21, The
influence of archetypical ideas on the scientific theories of Kepler,
Johannes Kepler and
Robert Fludd (1574–1637).
Schneer, Cecil: "Kepler's New Year's Gift of a Snowflake." Isis,
Volume 51, No. 4. University of Chicago Press, 1960,
Shapin, Steven. The Scientific Revolution. Chicago: University of
Chicago Press, 1996. ISBN 0-226-75020-5
Stephenson, Bruce. Kepler's physical astronomy. New York: Springer,
1987. ISBN 0-387-96541-6 (Studies in the history of mathematics
and physical sciences; 13); reprinted Princeton:Princeton Univ. Pr.,
1994. ISBN 0-691-03652-7
Stephenson, Bruce. The Music of the Heavens: Kepler's Harmonic
Astronomy, Princeton University Press, 1994. ISBN 0-691-03439-7
Toulmin, Stephen and June Goodfield. The Fabric of the Heavens: The
Astronomy and Dynamics. Pelican, 1963.
Voelkel, James R. The Composition of Kepler's Astronomia nova,
Princeton University Press, 2001. ISBN 0-691-00738-1
Westfall, Richard S.. The Construction of Modern Science: Mechanism
and Mechanics. John Wiley and Sons, 1971. ISBN 0-471-93531-X;
reprinted Cambridge University Press, 1978. ISBN 0-521-29295-6
Westfall, Richard S. Never at Rest: A Biography of Isaac Newton.
Cambridge University Press, 1981. ISBN 0-521-23143-4
Wolf, A. A History of Science, Technology and Philosophy in the 16th
and 17th centuries. George Allen & Unwin, 1950.
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Full text of Kepler. by Walter Bryant (public domain biography)
Kommission zur Herausgabe der Werke von
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JohannesKepler.Info Kepler information and community website, launched
on December 27, 2009
Harmonices mundi ("The Harmony of the Worlds") in fulltext facsimile;
Liscia, Daniel A. Di. "Johannes Kepler". In Zalta, Edward N. Stanford
Encyclopedia of Philosophy.
De Stella Nova
De Stella Nova in Pede Serpentarii ("On the new star in Ophiuchus's
foot") in full text facsimile at Linda Hall Library
The Correspondence of
Johannes Kepler in EMLO
Walter W. Bryant. Kepler at
Project Gutenberg (1920 book, part of Men
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Electronic facsimile-editions of the rare book collection at the
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Johannes Kepler at Curlie (based on DMOZ)
Audio – Cain/Gay (2010)
Johannes Kepler and His Laws
of Planetary Motion
Christianson, Gale E., Kepler's Somnium: Science Fiction and the
Kollerstrom, Nicholas, Kepler's Belief in Astrology
References for Johannes Kepler
Plant, David, Kepler and the "Music of the Spheres"
Kepler, Napier, and the Third Law at MathPages
Calderón Urreiztieta, Carlos. Harmonice Mundi • Animated and
multimedia version of Book V
Reading the mind of God 1997 drama based on his life by Patrick
Johannes Kepler 2010 drama based on his life by Robert Lalonde
O'Connor, John J.; Robertson, Edmund F., "Johannes Kepler", MacTutor
Mathematics archive, University of St Andrews .
Online Galleries, History of Science Collections, University of
Oklahoma Libraries High resolution images of works by and/or portraits
Johannes Kepler in .jpg and .tiff format.
From the Lessing J. Rosenwald Collection at the Library of Congress:
Tabvlæ Rudolphinæ qvibvs astronomicæ scientiæ ... Typis J.
Johannes Kepler that are available in digital facsimile from
the website of the Linda Hall Library:
(1604) Ad vitellionem paralipomena
(1606) De stella nova in pede Serpentarii
(1618) Epitome astronomiae Copernicanæ
BBC Radio 4 – In Our Time –
Johannes Kepler – 29 December 2016
Melvyn Bragg and guests discuss the German astronomer Johannes Kepler
Kepler's laws of planetary motion
Mysterium Cosmographicum (1596)
Astronomia nova (1609)
Epitome Astronomiae Copernicanae
Epitome Astronomiae Copernicanae (1617–21)
Harmonices Mundi (1619)
Rudolphine Tables (1627)
Katharina Kepler (mother)
Jakob Bartsch (son-in-law)
ISNI: 0000 0001 2100 8552
BNF: cb11909597m (data)