Born Johannes Kepler A 1610 portrait of Johannes Kepler by an unknown artist December 27, 1571Weil der Stadt near Stuttgart, Germany November 15, 1630 (aged 58)Regensburg, Bavaria, Germany Baden-Württemberg; Styria; Bohemia; Upper Austria Astronomy, astrology, mathematics and natural philosophy University of Linz University of Tübingen Kepler's laws of planetary motionKepler conjecture Lutheran

Johannes Kepler (pronounced /ˈkɛplɚ/) (December 27, 1571 – November 15, 1630) was a German mathematician, astronomer and astrologer, and key figure in the 17th century astronomical revolution. Events 537 - The Hagia Sophia is completed 1512 - The Spanish Crown issues the Laws of Burgos, governing the Weil der Stadt is a small town of somewhat less than 20000 inhabitants located in the Stuttgart Region of the German state of Baden-Württemberg. Stuttgart Region ( Baden-Württemberg, Germany consists of the city of Stuttgart and the surrounding districts of Ludwigsburg, Esslingen Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe. Events 655 - Battle of Winwaed: Penda of Mercia is defeated by Oswiu of Northumbria. Regensburg ( also Ratisbon, Ratisbona Řezno originally Castra Regina) is a City (population 131000 in 2007 in Bavaria, Germany Bavaria ( German:, with an area of 70553 Km² (27241 square miles and almost 12 Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe. Baden-Württemberg is one of the 16 states ( Bundesländer) of the Federal Republic of Germany. Styria (Steiermark is a state or Bundesland, located in the southeast of Austria. Bohemia (Čechy; Bohemia Czechy is a historical region in central Europe, occupying the western two-thirds of the traditional Czech Lands, currently the Upper Austria (Oberösterreich Horní Rakousko is one of the nine states or Bundesländer of Austria. Astronomy (from the Greek words astron (ἄστρον "star" and nomos (νόμος "law" is the scientific study Astrology (from Greek grc ἄστρον astron, "constellation star" and grc -λογία -logia) is a group of Systems Mathematics is the body of Knowledge and Academic discipline that studies such concepts as Quantity, Structure, Space and For the current in the 19th century German idealism see Naturphilosophie Natural philosophy or the philosophy of nature (from Johannes Kepler University of Linz (JKU Linz or just JKU -- the full German name is Johannes Kepler Universität Linz, the short version is Universität Linz, Alma mater is Latin for "nourishing mother" It was used in Ancient Rome as a title for the mother Goddess, and in Medieval Eberhard Karls University of Tübingen ( German: Eberhard Karls Universität Tübingen, sometimes called the "Eberhardina Carolina" is a public university In Astronomy, Kepler's Laws of Planetary Motion are three mathematical laws that describe the motion of Planets in the Solar System. In Mathematics, the Kepler conjecture is a Conjecture about Sphere packing in three-dimensional Euclidean space. Lutheranism is a major branch of Western Christianity that identifies with the teachings of the sixteenth-century German reformer Martin Luther Events 537 - The Hagia Sophia is completed 1512 - The Spanish Crown issues the Laws of Burgos, governing the Events 655 - Battle of Winwaed: Penda of Mercia is defeated by Oswiu of Northumbria. The German people (Deutsche are an Ethnic group, in the sense of sharing a common German culture, descent and speaking the German language as A mathematician is a person whose primary area of study and research is the field of Mathematics. Historically Astronomy was more concerned with the classification and description of phenomena in the sky while Astrophysics attempted to explain these phenomena An astrologer practices one or more forms of Astrology. Typically an astrologer draws a Horoscope for the time of an event such as a person's birth and interprets He is best known for his eponymous laws of planetary motion, codified by later astronomers based on his works Astronomia nova, Harmonices Mundi, and Epitome of Copernican Astronomy. In Astronomy, Kepler's Laws of Planetary Motion are three mathematical laws that describe the motion of Planets in the Solar System. Johannes Kepler 's Astronomia nova, published in 1609 contains the results of the astronomer's ten-year long investigation of the motion of Mars Harmonices Mundi ( Latin: The Harmony of the Worlds, 1619) is a book by Johannes Kepler.

Before Kepler, planets' paths were computed by combinations of the circular motions of the celestial orbs. A planet, as defined by the International Astronomical Union (IAU is a celestial body Orbiting a Star or stellar remnant that is The celestial spheres or celestial orbs were the fundamental celestial entities of the cosmological celestial mechanics first invented by Eudoxus, and developed by Aristotle After Kepler, astronomers gradually shifted their attention from orbs to orbits. In Physics, an orbit is the gravitationally curved path of one object around a point or another body for example the gravitational orbit of a planet around a star [1] Kepler's laws also provided one of the foundations for Isaac Newton's theory of universal gravitation. Sir Isaac Newton, FRS (ˈnjuːtən 4 January 1643 31 March 1727) Biography Early years See also Isaac Newton's early life and achievements Newton 's law of universal Gravitation is a physical law describing the gravitational attraction between bodies with mass

During his career, Kepler was a mathematics teacher at a seminary school in Graz, Austria, an assistant to astronomer Tycho Brahe, the court mathematician to Emperor Rudolf II, a mathematics teacher in Linz, Austria, and an adviser to General Wallenstein. Graz (etymologically from Slovene: Gradec IPA /gradeʦ/ "little castle" with a population of around 290000 as of 2008 (of which 252852 have principal Austria (Österreich ( officially the Republic of Austria (Republik Österreich Tycho Brahe, born Tyge Ottesen Brahe ( December 14 1546 &ndash October 24 1601) was a Danish nobleman Rudolf II ( July 18, 1552, Vienna, Austria - January 20, 1612, Prague, Bohemia, now part of Linz is the third largest city of Austria and capital of the state of Upper Austria (Oberösterreich Austria (Österreich ( officially the Republic of Austria (Republik Österreich He also did fundamental work in the field of optics, invented an improved version of the refracting telescope (the Keplerian Telescope), and helped to legitimize the telescopic discoveries of his contemporary Galileo Galilei. A refracting or refractor telescope is a dioptric Telescope that uses a lens as its objective to form an image A refracting or refractor telescope is a dioptric Telescope that uses a lens as its objective to form an image A telescope is an instrument designed for the observation of remote objects and the collection of Electromagnetic radiation. Galileo Galilei (15 February 1564 &ndash 8 January 1642 was a Tuscan ( Italian) Physicist, Mathematician, Astronomer, and Philosopher

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 the more prestigious discipline of natural philosophy). Astronomy (from the Greek words astron (ἄστρον "star" and nomos (νόμος "law" is the scientific study Astrology (from Greek grc ἄστρον astron, "constellation star" and grc -λογία -logia) is a group of Systems The quadrivium comprised the four subjects or arts taught in Medieval universities after the trivium. The term liberal arts refers to a particular type of educational Curriculum broadly defined as a Classical education. Physics (Greek Physis - φύσις in everyday terms is the Science of Matter and its motion. For the current in the 19th century German idealism see Naturphilosophie Natural philosophy or the philosophy of nature (from Kepler also incorporated religious arguments and reasoning into his work, motivated by the religious conviction that God had created the world according to an intelligible plan that is accessible through the natural light of reason. Nature, in the broadest sense is equivalent to the natural world, physical universe, material world or material universe. Reason involves the ability to think understand and draw Conclusions in an Abstract way as in Human thinking [2] Kepler described his new astronomy as "celestial physics",[3] as "an excursion into Aristotle's Metaphysics",[4] and as "a supplement to Aristotle's On the Heavens",[5] transforming the ancient tradition of physical cosmology by treating astronomy as part of a universal mathematical physics. Aristotle (Greek Aristotélēs) (384 BC – 322 BC was a Greek philosopher a student of Plato and teacher of Alexander the Great. Metaphysics is one of the principal works of Aristotle and the first major work of the branch of philosophy with the same name On the Heavens (or De Caelo) is Aristotle 's chief cosmological treatise it contains his astronomical theory [6]

## Early years

The Great Comet of 1577, which Kepler witnessed as a child, attracted the attention of astronomers across Europe. The Great Comet of 1577, known properly as C/1577 V1, was an object that passed close to Earth during the year 1577 AD

Kepler was born on December 27, 1571, at the Imperial Free City of Weil der Stadt (now part of the Stuttgart Region in the German state of Baden-Württemberg, 30 km west of Stuttgart's center). Events 537 - The Hagia Sophia is completed 1512 - The Spanish Crown issues the Laws of Burgos, governing the In the Holy Roman Empire, a free imperial city (in German: freie Reichsstadt) was a City formally ruled by the Emperor only &mdash Weil der Stadt is a small town of somewhat less than 20000 inhabitants located in the Stuttgart Region of the German state of Baden-Württemberg. Stuttgart Region ( Baden-Württemberg, Germany consists of the city of Stuttgart and the surrounding districts of Ludwigsburg, Esslingen Baden-Württemberg is one of the 16 states ( Bundesländer) of the Federal Republic of Germany. His grandfather, Sebald Kepler, had been Lord Mayor of that town, but by the time Johannes was born, the Kepler family fortune was on the decline. His father, Heinrich Kepler, earned a precarious living as a mercenary, and he left the family when Johannes was five years old. A mercenary is a person who takes part in an armed conflict who is not a national or a party to the conflict and is "motivated to take part in the hostilities essentially by He was believed to have died in the Eighty Years' War in the Netherlands. The Dutch Revolt, Eighty Years' War or the Revolt of the Netherlands (1568—1648 was the revolt of the Seventeen Provinces in the Low Countries His mother Katharina Guldenmann, an inn-keeper's daughter, was a healer and herbalist who was later tried for witchcraft. Witchcraft, in various historical anthropological religious and mythological contexts is the use of certain kinds of Supernatural or magical powers Born prematurely, Johannes claimed to have been a weak and sickly child. He was, however, a brilliant child; he often impressed travelers at his grandfather's inn with his phenomenal mathematical faculty. [7]

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. The Great Comet of 1577, known properly as C/1577 V1, was an object that passed close to Earth during the year 1577 AD "[8] At age nine, he observed another astronomical event, the Lunar eclipse of 1580, recording that he remembered being "called outdoors" to see it and that the moon "appeared quite red". A lunar eclipse occurs whenever the Moon passes through some portion of the Earth's shadow [8] However, childhood smallpox left him with weak vision and crippled hands, limiting his ability in the observational aspects of astronomy. Smallpox is an Infectious disease unique to humans caused by either of two virus variants named Variola major and Variola minor. [9]

In 1589, after moving through grammar school, Latin school, and lower and higher seminary in the Württemberg state-run Protestant education system, Kepler began attending the University of Tübingen as a theology student, and studied philosophy under Vitus Müller[10]. Württemberg, formerly known as Wirtemberg, is an area and a former state in Swabia, a region in southwestern Germany. Eberhard Karls University of Tübingen ( German: Eberhard Karls Universität Tübingen, sometimes called the "Eberhardina Carolina" is a public university Theology is the study of a god or the gods from a religious perspective He proved himself to be a superb mathematician and earned a reputation as a skillful astrologer, casting horoscopes for fellow students. Astrology (from Greek grc ἄστρον astron, "constellation star" and grc -λογία -logia) is a group of Systems In Astrology, a horoscope is a chart or diagram representing the positions of the Sun Moon planets the Astrological aspects, and sensitive angles Under the instruction of Michael Maestlin, he learned both the Ptolemaic system and the Copernican system of planetary motion. Michael Maestlin (also Mästlin Möstlin or Moestlin ( 30 September 1550 in Göppingen, Germany - 20 October 1631) was a In Astronomy, the geocentric model of the Universe is the superseded theory that the Earth is the center of the universe and other In Astronomy, heliocentrism is the theory that the Sun is at the center of the Solar System. 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. In Astronomy, heliocentrism is the theory that the Sun is at the center of the Solar System. The Sun (Sol is the Star at the center of the Solar System. [11] 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, Austria (later the University of Graz). Graz (etymologically from Slovene: Gradec IPA /gradeʦ/ "little castle" with a population of around 290000 as of 2008 (of which 252852 have principal Austria (Österreich ( officially the Republic of Austria (Republik Österreich The University of Graz ( German, Karl-Franzens-Universität Graz) a University located in Graz, Austria, is the second-largest He accepted the position in April 1594, at the age of 23. [12]

## Graz (1594–1600)

### Mysterium Cosmographicum

Kepler's Platonic solid model of the Solar system from Mysterium Cosmographicum (1596)

Johannes Kepler's first major astronomical work, Mysterium Cosmographicum (The Cosmographic Mystery), was the first published defense of the Copernican system. In Geometry, a Platonic solid is a convex Regular polyhedron. The Solar System consists of the Sun and those celestial objects bound to it by Gravity. Mysterium Cosmographicum, (lit The Cosmographic Mystery, alternately translated Cosmic Mystery, The Secret of the World or some variation Kepler claimed to have had an epiphany on July 19, 1595, while teaching in Graz, demonstrating the periodic conjunction of Saturn and 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. Events 711 - Muslim forces under Tariq ibn Ziyad defeat the Visigoths led by their king Roderic. Conjunction is a term used in Positional astronomy and Astrology. General properties These properties apply to both convex and star regular polygons 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. What is a polyhedron? We can at least say that a polyhedron is built up from different kinds of element or entity each associated with a different number of dimensions He found that each of the five Platonic solids could be uniquely 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. In Geometry, a Platonic solid is a convex Regular polyhedron. The celestial spheres or celestial orbs were the fundamental celestial entities of the cosmological celestial mechanics first invented by Eudoxus, and developed by Aristotle The VENUS ( V ictoria E xperimental N etwork U nder the S ea project is a cabled sea floor observatory operated by the University EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 By ordering the solids correctly—octahedron, icosahedron, dodecahedron, tetrahedron, cube—Kepler found that the spheres could be placed at intervals corresponding (within the accuracy limits of available astronomical observations) to the relative sizes of each planet’s path, assuming the planets circle the Sun. An octahedron (plural octahedra is a Polyhedron with eight faces In Geometry, an icosahedron ( Greek: eikosaedron, from eikosi twenty + hedron seat /ˌaɪ A dodecahedron is any Polyhedron with twelve faces but usually a regular dodecahedron is meant a Platonic solid composed of twelve regular Pentagonal A tetrahedron (plural tetrahedra) is a Polyhedron composed of four triangular faces three of which meet at each vertex. A cube is a three-dimensional solid object bounded by six square faces facets or sides with three meeting at each vertex. 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. The orbital period is the time taken for a given object to make one complete Orbit about another object However, Kepler later rejected this formula, because it was not precise enough. [13]

Closeup of inner section of the 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. Theology is the study of a god or the gods from a religious perspective Spirituality, in a narrow sense concerns itself with matters of the Spirit, a concept closely tied to religious belief and Faith, a transcendent reality God is the principal or sole Deity in Religions and other belief systems that worship one deity. Jesus of Nazareth (7–2 BC / BCE —26–36 AD / CE) In mainstream Christianity, the Holy Spirit or Holy Ghost is one of the three entities of the Holy Trinity which make up the single substance His first manuscript of Mysterium contained an extensive chapter reconciling heliocentrism with biblical passages that seemed to support geocentrism. [14]

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. Michael Maestlin (also Mästlin Möstlin or Moestlin ( 30 September 1550 in Göppingen, Germany - 20 October 1631) was a 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. Patronage is the support encouragement privilege and often financial aid given by a person or an organization [15]

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 publication. [16]

### 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, and he began courting her. Müller, heir 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, church officials — who had helped set up the match — pressured the Müllers to honor their agreement. Barbara and Johannes were married on April 27, 1597. Events 1124 - David I becomes King of Scotland. 1296 - Battle of Dunbar: The Scots are defeated [17]

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). [18]

### Other research in 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. [19]

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. Nicolaus Reimers (* 2 February 1551 in Hennstedt (Dithmarschen - 16 October 1600 in Prague) also Reimarus Ursus Rudolf II ( July 18, 1552, Vienna, Austria - January 20, 1612, Prague, Bohemia, now part of Tycho Brahe, born Tyge Ottesen Brahe ( December 14 1546 &ndash October 24 1601) was a Danish nobleman Ursus did not reply directly, but republished Kepler's flattering letter to pursue his priority dispute over (what is now called) the Tychonic system with Tycho. The Tychonic system (or Tychonian system) was a model of the Solar system published by Tycho Brahe in the late 16th century which combined what he saw as 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. [20]

Instead, he turned his attention to chronology and "harmony," the numerological relationships among music, mathematics and the physical world, and their astrological consequences. Definition A chronology may be either relative &mdashthat is locating related events relative to each other&mdashor ''absolute'' &mdashlocating Numerology is any of many Systems Traditions or Beliefs in a mystical or Esoteric relationship between Numbers and physical Astrology (from Greek grc ἄστρον astron, "constellation star" and grc -λογία -logia) is a group of Systems By assuming the Earth to 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. In Astrology, an aspect is an Angle the planets make to each other in the horoscope and also to the ascendant midheaven descendant and nadir Meteorology (from Greek grc μετέωρος metéōros, "high in the sky" and grc -λογία -logia) is the Interdisciplinary 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. Prague (ˈprɑːg Praha (ˈpraɦa see also other names) is the Capital and Largest city of the Czech Republic. New Year See also New Year The Ancient Romans began their consular year on January 1st since 153 BC Philosophy is the study of general problems concerning matters such as existence knowledge truth beauty justice validity mind and language A problem is an obstacle which makes it difficult to achieve a desired goal objective or purpose [21]

## Prague (1600–1612)

### Work for Tycho Brahe

Tycho Brahe

On February 4, 1600, Kepler met Tycho Brahe and his assistants Franz Tengnagel and Longomontanus at Benátky nad Jizerou (~50 km from Prague), the site where Tycho's new observatory was being constructed. Events 211 - Roman Emperor Septimius Severus dies leaving the Roman Empire in the hands of his two quarrelsome sons Tycho Brahe, born Tyge Ottesen Brahe ( December 14 1546 &ndash October 24 1601) was a Danish nobleman Franz Gansneb Tengnagel von Camp (1576 – 1622 was a Westphalian nobleman and the son-in-law and assistant of astronomer Tycho Brahe. Christen Sørensen Longomontanus (or Longberg) ( October 4, 1562 &ndash October 8, 1647) was a Danish Astronomer Benátky nad Jizerou (ˈbɛnatkɪ ˈnadjɪzɛroʊ̯ Benatek is a Town on the Jizera river in the Central Bohemian Region of the Czech Republic 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 left for Prague on April 6. Jan Jesenius (also written as Jessenius or known as Ján Jesenský; 1566 Wrocław &ndash 1621 Prague) was a Physician, Politician Events 46 BC - Julius Caesar defeats Caecilius Metellus Scipio and Marcus Porcius Cato in the Battle of Thapsus 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. [22]

Political and religious difficulties in Graz dashed his hopes of returning immediately to Tycho; in hopes of continuing his astronomical studies, Kepler sought an appointment as 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"). [23] 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. A lunar eclipse occurs whenever the Moon passes through some portion of the Earth's shadow These observations formed the basis of his explorations of the laws of optics that would culminate in Astronomiae Pars Optica. [24]

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. Events 338 BC - A Macedonian army led by Philip II defeated the combined forces of Athens and Thebes in the Through most of 1601, he was supported directly by Tycho, who assigned him to analyzing planetary observations and writing a tract against Tycho's (now deceased) rival Ursus. In September, Tycho secured him a commission as a collaborator on the new project he had proposed to the emperor: the Rudolphine Tables that should replace the Prussian Tables of Erasmus Reinhold. The Rudolphine Tables ( Latin: Tabulae Rudolphinae) consist of a Star catalog and planetary tables published by Johannes Kepler in 1627 The Prutenic Tables (Tabulae prutenicae Prutenische oder Preußische Tafeln were Ephemeris (astronomical tables by astronomer Erasmus Reinhold published Erasmus Reinhold ( October 22, 1511 &ndash February 19, 1553) was a German Astronomer and Mathematician Two days after Tycho's unexpected death on October 24, 1601, Kepler was appointed his successor as imperial mathematician with the responsibility to complete his unfinished work. Events 69 - Second Battle of Bedriacum, forces under Antonius Primus the commander of the Danube armies loyal to Vespasian, defeat He illegally appropriated Tycho's observations, the property of his heirs, which subsequently led to four year delays each to the publications of two of his works whilst he negotiated copyright permissions for the use of Tycho's data. The next 11 years as imperial mathematician would be the most productive of his life. [25]

### 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 detailed horoscopes for friends, family and patrons since his time as a student in Tübingen. In Astrology, a horoscope is a chart or diagram representing the positions of the Sun Moon planets the Astrological aspects, and sensitive angles In addition to horoscopes for allies and foreign leaders, the emperor sought Kepler's advice in times of political trouble (though Kepler's recommendations were based more on common sense than the stars). 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. [26]

Officially, the only acceptable religious doctrines in Prague were Catholic and Utraquist, but Kepler's position in the imperial court allowed him to practice his Lutheran faith unhindered. See " Utraquist school " for a kind of Bilingual schools Utraquism (from the Latin sub utraque specie, meaning 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 rapidly. Johannes Matthaeus Wacker von Wackenfels (1550 - 1619 "was an active diplomat scholar and author with an avid interest in history and philosophy Joost Bürgi, or Jobst Bürgi ( February 28 1552, Lichtensteig, Switzerland - January 31 1632)active primarily David Fabricius ( March 9, 1564, Esens - May 7, 1617, Osteel) was a German theologian who made two major [27]

### Astronomiae Pars Optica

A plate from Astronomiae Pars Optica, illustrating the structure of eyes.

As he continued analyzing Tycho's Mars observations — now 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. A solar eclipse occurs when the Moon passes between the Sun and the Earth so that the Sun is wholly or partially obscured Related issues of atmospheric refraction applied to all astronomical observations. Atmospheric Refraction is the deviation of Light or other Electromagnetic wave from a straight line as it passes through the atmosphere due to the 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). New Year See also New Year The Ancient Romans began their consular year on January 1st since 153 BC 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. A' pinhole camera' is a very simple Camera with no lens and a single very small Aperture. Parallax is an apparent displacement or difference of orientation of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between Astronomiae Pars Optica is generally recognized as the foundation of modern optics (though the law of refraction is conspicuously absent). In Optics and Physics, Snell's law (also known as Descartes' law or the law of refraction) is a formula used to describe the relationship [28]

### The Supernova of 1604

Remnant of 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. Supernova 1604, also known as Kepler's Supernova, Kepler's Nova or Kepler's Star, was a Supernova which occurred in the Milky Way, Supernova 1604, also known as Kepler's Supernova, Kepler's Nova or Kepler's Star, was a Supernova which occurred in the Milky Way, Kepler began systematically observing the star. Astrologically, the end of 1603 marked the beginning of a fiery trigon, the start of the ca. In astrology, a fire sign refers to any of the three signs Aries, Leo, or Sagittarius. 800-year cycle of great conjunctions; astrologers associated the two previous such periods with the rise of Charlemagne (ca. A Great Conjunction (also known as a Grand Conjunction) is a conjunction of the planets Jupiter and Saturn. Charlemagne (ˈʃɑrlɨmeɪn Carolus Magnus or Karolus Magnus meaning Charles the Great) (747 – 28 January 814 was King of the Franks from 768 to his 800 years earlier) and the birth of Christ (ca. Christ is the English term for the Greek ( Khristós) meaning "the anointed " 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 since Aristotle that the celestial spheres were perfect and unchanging). The celestial spheres or celestial orbs were the fundamental celestial entities of the cosmological celestial mechanics first invented by Eudoxus, and developed by Aristotle The birth of a new star implied the variability of the heavens. In an appendix, Kepler also discussed the recent chronology work of 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 800-year cycle. Definition A chronology may be either relative &mdashthat is locating related events relative to each other&mdashor ''absolute'' &mdashlocating See also Star of Bethlehem (plant. The Star of Bethlehem, also called the Christmas Star, is a star in Christian tradition [29]

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). Ophiuchus (Ὀφιοῦχος ˌɒfiːˈuːkəs is one of the 88 Constellations and was also one of the 48 listed by Ptolemy.

### Astronomia nova

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. Johannes Kepler 's Astronomia nova, published in 1609 contains the results of the astronomer's ten-year long investigation of the motion of Mars In Astronomy, Kepler's Laws of Planetary Motion are three mathematical laws that describe the motion of Planets in the Solar System. 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). Equant (or Punctum aequans) is a Mathematical concept developed by Claudius Ptolemy in the 2nd century AD to account for the observed A minute of arc, arcminute, or MOA is a unit of angular measurement, equal to one sixtieth (1/60 of one degree. 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. [30]

Within 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. In many religions the supreme Deity ( God) is given the title and attributions of Father. As a physical basis, Kepler drew by analogy on William Gilbert's theory of the magnetic soul of the Earth from De Magnete (1600) and on his own work on optics. William Gilbert, also known as Gilbard ( Colchester, England, May 24, 1544 &ndash London, England, November 30 De Magnete Magneticisque Corporibus et de Magno Magnete Tellure ( On the Magnet and Magnetic Bodies and on That Great Magnet the Earth) is a scientific Kepler supposed that the motive power (or motive species)[31] radiated by the Sun weakens with distance, causing faster or slower motion as planets move closer or farther from it. [32][33] 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. In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from 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 — the second law of planetary motion. [34]

Diagram of the geocentric trajectory of Mars through several periods of retrograde motion. In Astronomy, the geocentric model of the Universe is the superseded theory that the Earth is the center of the universe and other Direct motion is the motion of a Planetary body in a direction similar to that of other bodies within its system and is sometimes called prograde 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. In geometry an oval or ovoid (from Latin ovum, 'egg' is any Curve resembling an egg or an Ellipse. 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. In Mathematics, an ellipse (from the Greek ἔλλειψις literally absence) is a Conic section, the locus of points in a Finding that an elliptical orbit fit the Mars data, he immediately concluded that all planets move in ellipses, with the sun at one focus — the 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. [35]

### Dioptrice, the 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). An ephemeris (plural ephemerides; from the Greek word ἐφήμερος ephemeros "daily" is a table of values that gives the positions of He also attempted (unsuccessfully) to begin a collaboration with Italian astronomer Giovanni Antonio Magini. Giovanni Antonio Magini (in Latin, Maginus) ( June 13, 1555 – February 11, 1617) was an Italian astronomer 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 Roeslin. Definition A chronology may be either relative &mdashthat is locating related events relative to each other&mdashor ''absolute'' &mdashlocating Introduction The chronology of Jesus is linked to a number of Jewish festivals [36]

Kepler and Roeslin engaged in 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 "also perhaps a good little grain" to be found by the conscientious scientific astrologer. [37]

In the first months of 1610, Galileo Galilei — using his powerful new telescope — discovered four satellites orbiting Jupiter. Galileo Galilei (15 February 1564 &ndash 8 January 1642 was a Tuscan ( Italian) Physicist, Mathematician, Astronomer, and Philosopher A telescope is an instrument designed for the observation of remote objects and the collection of Electromagnetic radiation. Upon publishing his account as Sidereus Nuncius (Starry Messenger), Galileo sought the opinion of Kepler, in part to bolster the credibility of his observations. Sidereus Nuncius (usually translated into English as Sidereal Messenger, although Starry Messenger and Sidereal Message are 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 disappointment, however, Galileo never published his reactions (if any) to Astronomia Nova. [38]

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. [39] The resulting manuscript was completed in September of 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. A refracting or refractor telescope is a dioptric Telescope that uses a lens as its objective to form an image In Optics, a real image is a representation of an actual object (source formed by rays of Light passing through the Image. virtual images, upright vs. In Optics, a virtual image is an image in which the outgoing rays from a point on the object never actually intersect at a point 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. A refracting or refractor telescope is a dioptric Telescope that uses a lens as its objective to form an image [40]

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). In Mathematics, the Kepler conjecture is a Conjecture about Sphere packing in three-dimensional Euclidean space. Somnium ( Latin for The Dream) is a fantasy written between 1620 and 1630 by Johannes Kepler in which a student of Tycho Brahe is transported 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. [41]

As a New Year's gift that year, 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 investigated 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. In Natural philosophy, atomism is the theory that all the objects in the universe are composed of very small indestructible building blocks - Atoms Or stated in In Mathematics, the Kepler conjecture is a Conjecture about Sphere packing in three-dimensional Euclidean space. [42]

### 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. Rudolf II ( July 18, 1552, Vienna, Austria - January 20, 1612, Prague, Bohemia, now part of This is a list of rulers of Bohemia. Bohemia, Moravia, Silesia, and Lusatia are territories which are or have Matthias ( February 24 1557 - March 20 1619) of the House of Habsburg reigned as Holy Roman Emperor from 1612-1619 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 were dim. [43]

Kepler postponed the move to Linz and remained in Prague until 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. [45]

## Linz and elsewhere (1612–1630)

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. The Eucharist, also called Holy Communion or Lord's Supper and other names is a Christian Sacrament by which in a common interpretation those 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 (though it would not be published until 1615). Pope Gregory XIII (January 7 1502 &ndash April 10 1585 born Ugo Boncompagni, was Pope from 1572 to 1585 The Gregorian calendar is the most widely used Calendar in the world today [46]

### Second marriage

On October 30, 1613, Kepler married the twenty-four-year-old Susanna Reuttinger. Events 637 - Antioch surrenders to the Muslim forces under Rashidun Caliphate after the Battle of Iron bridge. Following Barbara's death, Kepler had considered eleven different matches. 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. "[47] The first three children of this marriage (Margareta Regina, Katharina, and Sebald) died in childhood. Three more survived into adulthood: Cordula (b. 1621); Fridmar (b. 1623); and Hildebert (b. 1625). According to Kepler's biographers, this was a much happier marriage than his first. [48]

### Epitome of Copernican Astronomy, calendars, and the witch trial of Kepler's mother

Since completing the Astronomia nova, Kepler had intended to compose an astronomy textbook. [49] In 1615, he completed the first of three volumes of Epitome astronomia 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. Epitome became Kepler's most influential work. It contained all three laws of planetary motion and attempted to explain heavenly motions through physical causes. In Astronomy, Kepler's Laws of Planetary Motion are three mathematical laws that describe the motion of Planets in the Solar System. [50] 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. The Galilean moons are the four moons of Jupiter discovered by Galileo Galilei. [51]

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. An ephemeris (plural ephemerides; from the Greek word ἐφήμερος ephemeros "daily" is a table of values that gives the positions of 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 Graz. [52]

Geometrical harmonies in the regular polygons from Harmonices Mundi (1619)

In 1615, Ursula Reingold, a woman in a financial dispute with Kepler's brother Cristoph, 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. European Witchcraft is Witchcraft and magic that is practised primarily in the locality of Europe. 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, along with a distorted, second-hand version of Kepler's Somnium, in which a woman mixes potions and enlists the aid of a demon. However, 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. Torture, according to the United Nations Convention Against Torture, is "any act by which severe pain or suffering, whether physical or mental is intentionally 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 Worlds"). Harmonices Mundi ( Latin: The Harmony of the Worlds, 1619) is a book by Johannes Kepler. [53]

### Harmonices Mundi

Main article: Harmonices Mundi

Kepler was convinced "that the geometrical things have provided the Creator with the model for decorating the whole world. Harmonices Mundi ( Latin: The Harmony of the Worlds, 1619) is a book by Johannes Kepler. "[54] 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 Pythagoras, 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 theory. "Pythagoras of Samos" redirects here For the Samian statuary of the same name see Pythagoras (sculptor. Claudius Ptolemaeus ( Greek: Klaúdios Ptolemaîos; after 83 &ndash ca Robert Fludd, also known as Robertus de Fluctibus (1574 Bearsted Kent &ndash September 8 1637, London) was a prominent [55]

Kepler began by exploring regular polygons and regular solids, including the figures that would come to be known as Kepler's solids. General properties These properties apply to both convex and star regular polygons In Geometry, a Platonic solid is a convex Regular polyhedron. The Kepler-Poinsot polyhedra is a popular name for the regular star polyhedra. 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. The orbital speed of a body generally a Planet, a Natural satellite, an artificial satellite, or a Multiple star, is the speed at which it 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 them. [56]

Among many other harmonies, Kepler articulated what came to be known as the third law of planetary motion. In Astronomy, Kepler's Laws of Planetary Motion are three mathematical laws that describe the motion of Planets in the Solar System. 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. " However, the wider significance for planetary dynamics of this purely kinematical law was not realized until the 1660s. For when conjoined with Christian 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. Christiaan Huygens (ˈhaɪgənz in English ˈhœyɣəns in Dutch) ( April 14, 1629 &ndash July 8, 1695) was a Dutch Sir Isaac Newton, FRS (ˈnjuːtən 4 January 1643 31 March 1727) Biography Early years See also Isaac Newton's early life and achievements Edmond Halley FRS (ˈɛdmənd ˈhɔːlɪ ( November 8, 1656 &ndash January 14, 1742) was an English Astronomer Sir Christopher Wren ( 20 October 1632 &ndash 25 February 1723) was a 17th century English Designer, Astronomer Robert Hooke, FRS (18 July 1635 – 3 March 1703 was an English Natural philosopher and Polymath who played an important role in the [57] 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 celestial mechanics. [58]

### Rudolphine Tables and Kepler's last years

The iconic frontispiece to the Rudolphine Tables celebrates the great astronomers of the past: Hipparchus, Ptolemy, Copernicus, and most prominently, Tycho Brahe. Hipparchus ( Greek; ca 190 BC &ndash ca 120 BC was a Greek Astronomer, Geographer, and Mathematician of the Hellenistic Claudius Ptolemaeus ( Greek: Klaúdios Ptolemaîos; after 83 &ndash ca Tycho Brahe, born Tyge Ottesen Brahe ( December 14 1546 &ndash October 24 1601) was a Danish nobleman

In 1623, Kepler at last completed the Rudolphine Tables, which at the time was considered his major work. The Rudolphine Tables ( Latin: Tabulae Rudolphinae) consist of a Star catalog and planetary tables published by Johannes Kepler in 1627 However, due to the publishing requirements of the emperor and negotiations with Tycho Brahe's heir, it would not be printed until 1627. Tycho Brahe, born Tyge Ottesen Brahe ( December 14 1546 &ndash October 24 1601) was a Danish nobleman In the meantime religious tension — the root of the ongoing Thirty Years' War — once again put Kepler and his family in jeopardy. For the Mauritanian Thirty Years' War see Char Bouba war. For the band see The 30 Years War. 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. The Counter-Reformation (also Catholic Reformation denotes the period of Catholic revival from the pontificate of Pope Pius IV in 1560 to the close of the Kepler moved to Ulm, where he arranged for the printing of the Tables at his own expense. Ulm (ˈʊlm is a City in the German Bundesland of Baden-Württemberg, situated on the River Danube. [59]

In 1628, following the military successes of the Emperor Ferdinand's armies under General Wallenstein, Kepler became an official adviser to Wallenstein. In Astrology, a horoscope is a chart or diagram representing the positions of the Sun Moon planets the Astrological aspects, and sensitive angles Ferdinand II Holy Roman Emperor ( July 9, 1578 &ndash February 15, 1637) of the House of Habsburg, reigned as Ferdinand II 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 court in Prague to Linz and Ulm to a temporary home in Sagan, and finally to Regensburg. Żagań ( French and Sagan is a Town in western Poland, with 26665 inhabitants (2004 Regensburg ( also Ratisbon, Ratisbona Řezno originally Castra Regina) is a City (population 131000 in 2007 in Bavaria, Germany 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 army of Gustavus Adolphus destroyed the churchyard. Events 655 - Battle of Winwaed: Penda of Mercia is defeated by Oswiu of Northumbria. For the other Swedish kings known as Gustavus Adolphus see Gustav IV Adolf of Sweden or Gustav VI Adolf of Sweden [60]

## Reception of Kepler's astronomy

Classical mechanics
$\vec{F} = \frac{\mathrm{d}}{\mathrm{d}t}(m \vec{v})$
Newton's Second Law
History of ...
Scientists
Galileo · Kepler · Newton
Laplace · Hamilton · d'Alembert
Cauchy · Lagrange · Euler
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Kepler's laws were not immediately accepted. Classical mechanics is used for describing the motion of Macroscopic objects from Projectiles to parts of Machinery, as well as Astronomical objects Newton's laws of motion are three Physical laws which provide relationships between the Forces acting on a body and the motion of the Early Ideas on Motion The Greek philosophers, and Aristotle in particular were the first to propose that there are abstract principles governing nature Galileo Galilei (15 February 1564 &ndash 8 January 1642 was a Tuscan ( Italian) Physicist, Mathematician, Astronomer, and Philosopher Sir Isaac Newton, FRS (ˈnjuːtən 4 January 1643 31 March 1727) Biography Early years See also Isaac Newton's early life and achievements Sir William Rowan Hamilton (4 August 1805 &ndash 2 September 1865 was an Irish Mathematician, Physicist, and Astronomer who Several major figures such as Galileo and 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. Michael Maestlin (also Mästlin Möstlin or Moestlin ( 30 September 1550 in Göppingen, Germany - 20 October 1631) was a Some adopted compromise positions. Ismael Boulliau 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 equant. Ismaël Bullialdus ( September 28, 1605 - November 25, 1694 (age 89 was a French Astronomer. Seth Ward (1617 &ndash 6 January 1689) was an English Mathematician, Astronomer, and Bishop. Equant (or Punctum aequans) is a Mathematical concept developed by Claudius Ptolemy in the 2nd century AD to account for the observed [61][62][63]

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 predicted date. Pierre Gassendi observed the transit on the date predicted, a confirmation of Kepler's prediction. Pierre Gassendi ( January 22, 1592 &ndash October 24, 1655) was a French Philosopher, priest, Scientist [64] 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. A transit of Venus across the Sun takes place when the Planet Venus passes directly between the Sun and Earth, obscuring a small portion of the Gassendi did not realize that it was not visible from most of Europe, including Paris. Paris (ˈpærɨs in English; in French) is the Capital of France and the country's largest city [65] 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. Jeremiah Horrocks (1618 &ndash January 3, 1641) sometimes given as Jeremiah Horrox (the Latinised version that he used on the Emmanuel College register He remained a firm advocate of the Keplerian model. [66][67][68]

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. Between 1630 and 1650, it was the most widely used astronomy textbook, winning many converts to ellipse-based astronomy. [69] However, few adopted his ideas on the physical basis for celestial motions. In the late seventeenth century, a number of physical astronomy theories drawing from Kepler's work — notably those of 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. Giovanni Alfonso Borelli ( Pisa January 28, 1608 - December 31, 1679) was a Renaissance Italian Physiologist Robert Hooke, FRS (18 July 1635 – 3 March 1703 was an English Natural philosopher and Polymath who played an important role in the The vis insita or innate force of matter is a power of resisting by which every body as much as in it lies endeavors to preserve in its present state whether it be of rest or of moving 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. Sir Isaac Newton, FRS (ˈnjuːtən 4 January 1643 31 March 1727) Biography Early years See also Isaac Newton's early life and achievements The Philosophiæ Naturalis Principia Mathematica ( Latin: "mathematical principles of natural philosophy" often Principia Newton 's law of universal Gravitation is a physical law describing the gravitational attraction between bodies with mass [70]

## Kepler's historical and cultural legacy

Monument to Tycho Brahe and Johannes Kepler in Prague, Czech Republic
The GDR stamp featuring Johannes Kepler. Prague (ˈprɑːg Praha (ˈpraɦa see also other names) is the Capital and Largest city of the Czech Republic. The Czech Republic ( ˈt͡ʃɛskaː ˈrɛpuˌblɪka short form in Česko ˈt͡ʃɛskɔ also called Czechia, The German Democratic Republic ( GDR; Deutsche Demokratische Republik DDR; commonly known in English as East Germany) was a Socialist state

Beyond his role in the historical development of astronomy and natural philosophy, Kepler has loomed large in the philosophy and historiography of science. Philosophy of science is the study of assumptions foundations and implications of Science. The Historiography of Science usually refers to the study of History of Science in its disciplinary aspects and practices (methods theories schools and Kepler and his laws of motion were central to early histories of astronomy such as Jean Etienne Montucla’s 1758 Histoire des mathématiques and Jean-Baptiste Delambre's 1821 Histoire de l’astronomie moderne. Jean-Étienne Montucla ( September 5, 1725 &ndash December 18, 1799) was a French Mathematician. Jean Baptiste Joseph chevalier Delambre ( September 19, 1749 Amiens - August 19, 1822 Paris) was a French 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. The Age of Enlightenment or The Enlightenment is a term used to describe a phase in Western philosophy and cultural life centered upon the eighteenth century Romanticism, also known as the “Age of Reflexion” describes the intellectual movement from 1800-1840 that originated in Western Europe as a counter-movement to the 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. William Whewell ( May 24, 1794 &ndash March 6, 1866) was an English Polymath, Scientist, Anglican Priest Scientific method refers to bodies of Techniques for investigating phenomena 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". Ernst Friedrich Apelt (1812 &ndash 1859 was a German philosopher and entrepreneur Catherine II, called Catherine the Great (Екатерина II Великая Yekaterina II Velikaya;) reigned as Empress of Russia for 34 years 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 work. [71]

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 twenty-first century), and Max Caspar's seminal Kepler biography was published in 1948. [72] However, Alexandre Koyré's work on Kepler was, after Apelt, the first major milestone in historical interpretations of Kepler's cosmology and its influence. Alexandre Koyré ( August 29, 1892, Taganrog &ndash April 28, 1964, Paris) sometimes anglicised as Alexander 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. The period which many historians of science call the Scientific Revolution can be roughly dated as having begun in 1543 the year in which Nicolaus Copernicus published 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. [73]

The debate over Kepler's place in the Scientific Revolution has also spawned 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. Arthur Koestler CBE ( September 5, 1905, Budapest &ndash March 3, 1983, London) was a [74] Influential 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. Charles Sanders Peirce (pronounced purse) (September 10 1839 &ndash April 19 1914 was an American Logician mathematician, philosopher Norwood Russell Hanson (1924 &ndash 1967 was a philosopher of science. Stephen Edelston Toulmin (born March 25, 1922) is a British Philosopher, Author, and Educator. Sir Karl Raimund Popper ( July 28 1902  &ndash September 17 1994) was an Austrian and British Philosopher and a professor This article is about incommensurability in philosophy of science Analogy is both the cognitive process of transferring Information from a particular subject (the analogue or source to another particular subject (the target and Falsifiability (or "refutability" is the logical possibility that an assertion can be shown false by an observation or a physical experiment Physicist Wolfgang Pauli even used Kepler's priority dispute with Robert Fludd to explore the implications of analytical psychology on scientific investigation. Robert Fludd, also known as Robertus de Fluctibus (1574 Bearsted Kent &ndash September 8 1637, London) was a prominent Analytical psychology (or Jungian psychology) refers to the school of Psychology originating from the ideas of Swiss psychiatrist Carl Jung, and then advanced [75] 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. John Banville (born 1945 is an Irish Novelist and Journalist. [76] Somewhat more fanciful is a recent work of nonfiction, Heavenly Intrigue (2004), suggesting that Kepler murdered Tycho Brahe to gain access to his data. Tycho Brahe, born Tyge Ottesen Brahe ( December 14 1546 &ndash October 24 1601) was a Danish nobleman [77] 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 astrologer. Carl Edward Sagan ( November 9 1934 &ndash December 20 1996) was an American Astronomer, astrochemist, author Astrophysics is the branch of Astronomy that deals with the Physics of the Universe, including the physical properties ( Luminosity, "[78]

In Austria, Johannes Kepler has left such a historical legacy behind, that he was motive of one of the most famous silver collectors coins: the 10 euro Johannes Kepler silver coin minted in September 10, 2002. Euro gold and silver commemorative coins are special Euro coins minted and issued by member states of the Eurozone. Euro gold and silver commemorative coins are special Euro coins minted and issued by member states of the Eurozone. Events 506 - The Bishops of Visigothic Gaul meet in the Council of Agde. See also 2002 (disambiguation Year 2002 ( MMII) was a Common year starting on Tuesday of the Gregorian calendar.

The reverse side of the coin has a portrait of Johannes Kepler, who spent some time teaching in Graz and the surrounding areas. Kepler was acquainted with Hans Ulrich von Eggenberg personally, and most probably he knew and influenced the construction of Eggenberg Castle (the main motive of the coin). Prince Hans Ulrich von Eggenberg (1568 – October 18, 1634) was an Austrian statesman a son of Siegfried von Eggenberg (died 1594 In front of him on the coin is a model of his masterpiece, the “Mysterium Cosmographicum”.

## Writings by Kepler

The lunar crater Kepler
• Mysterium cosmographicum (The Sacred Mystery of the Cosmos) (1596)
• Astronomiae Pars Optica (The Optical Part of Astronomy) (1604)
• De Stella nova in pede Serpentarii (On the New Star in Ophiuchus's Foot) (1604)
• Astronomia nova (New Astronomy) (1609)
• Tertius Interveniens (Third-party Interventions) (1610)
• Dissertatio cum Nuncio Sidereo (Conversation with the Starry Messenger) (1610)
• Dioptrice (1611)
• De nive sexangula (On the Six-Cornered Snowflake) (1611)
• De vero Anno, quo aeternus Dei Filius humanam naturam in Utero benedictae Virginis Mariae assumpsit (1613)
• Eclogae Chronicae (1615, published with Dissertatio cum Nuncio Sidereo)
• Nova stereometria doliorum vinariorum (New Stereometry of Wine Barrels) (1615)
• Epitome astronomiae Copernicanae (Epitome of Copernican Astronomy) (published in three parts from 1618–1621)
• Harmonice Mundi (Harmony of the Worlds) (1619)
• Mysterium cosmographicum (The Sacred Mystery of the Cosmos) 2nd Edition (1621)
• Tabulae Rudolphinae (Rudolphine Tables) (1627)
• Somnium (The Dream) (1634)

### Named in Kepler's honour

• Kepler Space Observatory, a solar-orbiting, planet-hunting telescope due to be launched by NASA in 2009
• The Kepler Solids, a set of geometrical constructions, two of which were described by him
• Kepler's Star, Supernova 1604, which he observed and described
• Kepler, a crater on the moon
• Kepler, a crater on Mars
• 1134 Kepler, an asteroid
• In 1975, nine years after its founding, the College for Social and Economic Sciences Linz (Austria) was renamed Johannes Kepler University Linz in honor of Johannes Kepler, since he wrote his magnum opus Harmonice Mundi in Linz. Kepler is a young lunar Impact crater that lies between the Oceanus Procellarum to the west and Mare Insularum in the east Mysterium Cosmographicum, (lit The Cosmographic Mystery, alternately translated Cosmic Mystery, The Secret of the World or some variation Johannes Kepler 's Astronomia nova, published in 1609 contains the results of the astronomer's ten-year long investigation of the motion of Mars Harmonices Mundi ( Latin: The Harmony of the Worlds, 1619) is a book by Johannes Kepler. Mysterium Cosmographicum, (lit The Cosmographic Mystery, alternately translated Cosmic Mystery, The Secret of the World or some variation The Rudolphine Tables ( Latin: Tabulae Rudolphinae) consist of a Star catalog and planetary tables published by Johannes Kepler in 1627 Somnium ( Latin for The Dream) is a fantasy written between 1620 and 1630 by Johannes Kepler in which a student of Tycho Brahe is transported In Astronomy, heliocentrism is the theory that the Sun is at the center of the Solar System. Astronomy is the oldest of the Natural sciences dating back to antiquity, with its origins in the religious, Mythological, and Astrological The modern discipline of Physics emerged in the 17th century following in traditions of inquiry established by Galileo Galilei, René Descartes, Isaac In Mathematics, the Kepler conjecture is a Conjecture about Sphere packing in three-dimensional Euclidean space. The Kepler-Poinsot polyhedra is a popular name for the regular star polyhedra. In Astronomy, Kepler's Laws of Planetary Motion are three mathematical laws that describe the motion of Planets in the Solar System. A Kepler triangle is a right triangle with edge lengths in Geometric progression. In Astronomy, Kepler's Laws of Planetary Motion are three mathematical laws that describe the motion of Planets in the Solar System. The period which many historians of science call the Scientific Revolution can be roughly dated as having begun in 1543 the year in which Nicolaus Copernicus published The Kepler Mission is a Space Photometer being developed by NASA. The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program The Kepler-Poinsot polyhedra is a popular name for the regular star polyhedra. Supernova 1604, also known as Kepler's Supernova, Kepler's Nova or Kepler's Star, was a Supernova which occurred in the Milky Way, Kepler is a young lunar Impact crater that lies between the Oceanus Procellarum to the west and Mare Insularum in the east Kepler is a crater on Mars. Located at 468° S 1409° E Kepler is 233 km wide and was named in 1973 in honor of the astronomer Johannes Kepler. Asteroids, sometimes called Minor planets or planetoids', are bodies—primarily of the inner Solar System —that are smaller than planets but Johannes Kepler University of Linz (JKU Linz or just JKU -- the full German name is Johannes Kepler Universität Linz, the short version is Universität Linz, Magnum opus (sometimes Opus magnum, plural magna opera) from the Latin meaning great work, refers to the best the greatest
• Kepler College, Seattle, Washington
• Keplerstraße in Hanau near Frankfurt am Main
• Keplerstraße and Keplerbrücke in Graz, Austria
• Kepler Launch Site
• Keplerplatz, a station on the U1 line of the Vienna U-Bahn rapid transit (Metro) system
• The Kepler system in the game Freelancer
• Johannes Kepler Grammar School , Prague, Czech Republic near the place Kepler lived while in Prague
• The Kepler Verge, a star cluster in the game Mass Effect
• Kepler Mission, a NASA mission to observe extra-solar planets from space. Mass Effect is an Action role-playing game developed by BioWare for Xbox 360 and Microsoft Windows. The Kepler Mission is a Space Photometer being developed by NASA.

### Kepler in fiction, music, etc.

#### Music

• Kepler is the main character in Paul Hindemith's opera Die Harmonie der Welt (The Harmony of the World) (1956-57)
• Albert Guinovart's string quartet Kepler, based on the Harmonices Mundi theories, was premiered at Barcelona on 2007. Johannes Kepler (ˈkɛplɚ ( December 27 1571 &ndash November 15 1630) was a German Mathematician, Astronomer Paul Hindemith (16 November 1895 &ndash 28 December 1963 was a German Composer, Violist, violinist teacher music theorist and conductor. Harmonices Mundi ( Latin: The Harmony of the Worlds, 1619) is a book by Johannes Kepler.

#### Fiction

• John Banville's novel Kepler: a novel (1981). John Banville (born 1945 is an Irish Novelist and Journalist.

#### Cinema

• Johannes Kepler (1974), German film directed by Frank Vogel.
• První sekunda (1989), Czech TV film by Michael Havas, about Kepler and Rudolph II. Johannes Kepler (ˈkɛplɚ ( December 27 1571 &ndash November 15 1630) was a German Mathematician, Astronomer Rudolf II ( July 18, 1552, Vienna, Austria - January 20, 1612, Prague, Bohemia, now part of
• Unseen forces (2004), short film (40 min. ) directed by Ryan Junell.

## Notes and references

• The most complete biography of Kepler remains Max Caspar's Kepler, while many later studies have focused on particular elements of his life and work. Though there are a number of more recent biographies, most are based on Caspar's work with minimal original research; much of the information cited from Caspar can also be found in the books by Arthur Koestler, Kitty Ferguson, and James A. Connor. Owen Gingerich's The Eye of Heaven builds on Caspar's work to place Kepler in the broader intellectual context of early-modern astronomy. Kepler's mathematics, cosmological, philosophical and historical views have been extensively analyzed in books and journal articles, though his astrological work — and its relationship to his astronomy — remains understudied.
1. ^ On the change from orbs moving with circular motion to orbits derived from physical principles see Bernard R. Goldstein and Giora Hon, "Kepler’s Move from Orbs to Orbits: Documenting a Revolutionary Scientific Concept," Perspectives on Science, 13 (2005): 74-111.
2. ^ Barker and Goldstein, "Theological Foundations of Kepler's Astronomy", pp. 112–13.
3. ^ Kepler, New Astronomy, title page, tr. Donohue, pp. 26–7
4. ^ Kepler, New Astronomy, p. 48
5. ^ Epitome of Copernican Astronomy in Great Books of the Western World, Vol 16, p. 845
6. ^ Stephenson, Kepler's Physical Astronomy, pp. 1–2; Dear, Revolutionizing the Sciences, pp. 74–78
7. ^ Caspar, Kepler, pp 29–36; see also: Connor, Kepler's Witch, pp 23–46
8. ^ a b Quotation from Koestler, The Sleepwalkers, p 234, translated from Kepler's family horoscope
9. ^ Caspar, Kepler, pp 36–38; Connor, Kepler's Witch, pp 25–27.
10. ^ James A. Connor, Kepler's Witch (2004), p. 58.
11. ^ Robert S. Westman, "Kepler's Early Physico-Astrological Problematic," Journal for the History of Astronomy, 32 (2001): pp 227–36.
12. ^ Caspar, Kepler, pp 38–52; Connor, Kepler's Witch, pp 49–69.
13. ^ Caspar, Kepler, pp 60–65; see also: Barker and Goldstein, "Theological Foundations of Kepler's Astronomy. "
14. ^ Barker and Goldstein, "Theological Foundations of Kepler's Astronomy," pp 99–103, 112–113
15. ^ Caspar, Kepler, pp 65–71
16. ^ Field, Kepler's Geometrical Cosmology, Chapter IV p 73ff
17. ^ Caspar, Kepler, pp 71–75
18. ^ Connor, Kepler's Witch, pp 89–100, 114–116; Caspar, Kepler, pp 75–77
19. ^ Caspar, Kepler, pp 85–86
20. ^ Caspar, Kepler, pp 86–89
21. ^ Caspar, Kepler, pp 89–100
22. ^ Caspar, Kepler, pp 100–108
23. ^ Translation from Caspar, Kepler, p 110
24. ^ Caspar, Kepler, pp 108–111
25. ^ Caspar, Kepler, pp 111–122
26. ^ Caspar, Kepler, pp 149–153
27. ^ Caspar, Kepler, pp 146–148, 159–177
28. ^ Caspar, Kepler, pp 142–146
29. ^ Caspar, Kepler, pp 153–157
30. ^ Caspar, Kepler, pp 123–128
31. ^ On motive species, see: Lindberg, "The Genesis of Kepler's Theory of Light," pp 38–40
32. ^ "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.
33. ^ Koyré, The Astronomical Revolution, pp 199–202
34. ^ Caspar, Kepler, pp 129–132
35. ^ Caspar, Kepler, pp 131–140; Koyré, The Astronomical Revolution, pp 277–279
36. ^ Caspar, Kepler, pp 178–181
37. ^ Caspar, Kepler, pp 181–185. 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. "
38. ^ Caspar, Kepler, pp 192–197
39. ^ Koestler, The Sleepwalkers p 384
40. ^ Caspar, Kepler, pp 198–202
41. ^ Lear, Kepler's Dream, pp 1–78
42. ^ Schneer, "Kepler's New Year's Gift of a Snowflake," pp 531–545
43. ^ Caspar, Kepler, pp 202–204
44. ^ Connor, Kepler's Witch, pp 222–226; Caspar, Kepler, pp 204–207
45. ^ Caspar, Kepler, pp 208–211
46. ^ Caspar, Kepler, pp 209–220, 227–240
47. ^ Quotation from Connor, Kepler's Witch, p 252, translated from an October 23, 1613 letter from Kepler to an anonymous nobleman
48. ^ Caspar, Kepler, pp 220–223; Connor, Kepler's Witch, pp 251–254.
49. ^ Caspar, Kepler, pp 239–240, 293–300
50. ^ Gingerich, "Kepler, Johannes" from Dictionary of Scientific Biography, pp 302–304
51. ^ Wolf, A History of Science, Technology and Philosophy, pp 140–141; Pannekoek, A History of Astronomy, p 252
52. ^ Caspar, Kepler, pp 239, 300–301, 307–308
53. ^ Caspar, Kepler, pp 240–264; Connor, Kepler's Witch, chapters I, XI-XIII; Lear, Kepler's Dream, pp 21–39
54. ^ Quotation from Caspar, Kepler, pp 265–266, translated from Harmonices Mundi
55. ^ Caspar, Kepler, pp 264–266, 290–293
56. ^ Caspar, Kepler, pp 266–290
57. ^ Westfall, Never at Rest, pp 143, 152, 402–3; 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
58. ^ Koyré, The Astronomical Revolution, p 502
59. ^ Caspar, Kepler, pp 308–328
60. ^ Caspar, Kepler, pp 332–351, 355–361
61. ^ 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.
62. ^ Koyré, The Astronomical Revolution, pp 362–364
63. ^ North, History of Astronomy and Cosmology, pp. 355–360
64. ^ Albert van Helden, "The Importance of the Transit of Mercury of 1631," Journal for the History of Astronomy, 7 (1976): 1–10.
65. ^ HM Nautical Almanac Office (2004-06-10). "MMIV" redirects here For the Modest Mouse album see " Baron von Bullshit Rides Again " Events 1190 - Third Crusade: Frederick I Barbarossa drowns in the Sally River while leading an army to Jerusalem 1631 Transit of Venus. Retrieved on 28 August, 2006.
66. ^ Allan Chapman, "Jeremiah Horrocks, the transit of Venus, and the 'New Astronomy' in early seventeenth-century England," Quarterly Journal of the Royal Astronomical Society, 31 (1990): 333–357.
67. ^ North, History of Astronomy and Cosmology, pp. 348–349
68. ^ Wilbur Applebaum and Robert Hatch, "Boulliau, Mercator, and Horrock's Venus in sole visa: Three Unpublished Letters," Journal for the History of Astronomy, 14(1983): 166–179
69. ^ Gingerich, "Kepler, Johannes" from Dictionary of Scientific Biography, pp 302–304
70. ^ Kuhn, The Copernican Revolution, pp 238, 246–252
71. ^ Jardine, "Koyré’s Kepler/Kepler's Koyré," pp 363–367
72. ^ Gingerich, introduction to Caspar's Kepler, pp 3–4
73. ^ Jardine, "Koyré’s Kepler/Kepler's Koyré," pp 367–372; Shapin, The Scientific Revolution, pp 1–2
74. ^ Stephen Toulmin, Review of The Sleepwalkers in The Journal of Philosophy, Vol. 59, no. 18 (1962), pp 500–503
75. ^ Pauli, "The Influence of Archetypical Ideas"
76. ^ 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
77. ^ 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
78. ^ Quote from Carl Sagan, Cosmos: A Personal Voyage, episode III: "The Harmony of the Worlds". Cosmos A Personal Voyage is a thirteen-part television series written by Carl Sagan, Ann Druyan, and Steven Soter, with Sagan 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. The period which many historians of science call the Scientific Revolution can be roughly dated as having begun in 1543 the year in which Nicolaus Copernicus published

## Bibliography

• 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
• Banville, John: Kepler, Martin, Secker and Warburg, London, 1981 (fictionalised biography).
• 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 by Owen Gingerich and Alain Segonds. New York: Dover, 1993 ISBN 0-486-67605-6
• 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 1995 ISBN 0-691-03367-6.
• Dreyer, J. L. E.: A History of Astronomy from Thales to Kepler. John Louis Emil Dreyer ( February 13 1852 &ndash September 14 1926) was a Danish - Irish Astronomer. Dover Publications Inc, 1967 ISBN-10: 0486600793
• 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 ISBN 0-8027-1390-4)
• Field, J. V. : Kepler's geometrical cosmology. Chicago: 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 0385508441 ISBN 978-0385508445 Reviews [1][2]
• Gingerich, Owen: The Eye of Heaven: Ptolemy, Copernicus, Kepler. Events 1152 - Henry II of England marries Eleanor of Aquitaine. "MMIV" redirects here For the Modest Mouse album see " Baron von Bullshit Rides Again " Dr Owen Jay Gingerich (1930- is a former Research Professor of Astronomy and of the History of Science at Harvard University, and a senior Astronomer New York: 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
• Jardine, Nick: "Koyré’s Kepler/Kepler's Koyré," History of Science, Vol. 38 (2000), pp 363–376
• Kepler, Johannes: Johannes Kepler New Astronomy trans. W. Donahue, forward by O. Gingerich, Cambridge University Press 1993 ISBN 0-521-30131-9
• Kepler, Johannes, et al. Erlangen is a Middle Franconian City in Bavaria, Germany. It is located at the confluence of the river Regnitz and its large tributary Google Book Search is a tool from Google that searches the full text of books that Google scans OCRs, and stores in its digital database : 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. Arthur Koestler CBE ( September 5, 1905, Budapest &ndash March 3, 1983, London) was a This article concerns the nonfiction book by Arthur Koestler For the novel trilogy by Hermann Broch, see The Sleepwalkers (Broch. (1959). ISBN 0-14-019246-8
• Koyré, Alexandre: The Astronomical Revolution: Copernicus-Kepler-Borelli Ithaca, NY: Cornell University Press, 1973 ISBN 0-8014-0504-1; London: Methuen, 1973 ISBN 0-416-76980-2; Paris: Hermann, 1973 ISBN 2-7056-5648-0
• Kuhn, Thomas S.: The Copernican Revolution: Planetary Astronomy in the Development of Western Thought. Alexandre Koyré ( August 29, 1892, Taganrog &ndash April 28, 1964, Paris) sometimes anglicised as Alexander Thomas Samuel Kuhn (surname ˈkuːn July 18, 1922  &ndash June 17, 1996) was an American intellectual who wrote extensively 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, 1965.
• 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. ISBN 0486659941
• 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, concerning Johannes Kepler and Robert Fludd (1574–1637). Robert Fludd, also known as Robertus de Fluctibus (1574 Bearsted Kent &ndash September 8 1637, London) was a prominent ISBN 354-05685-9X, ISBN 978-354-05685-99.
• Schneer, Cecil: "Kepler's New Year's Gift of a Snowflake. " Isis, Volume 51, No. Isis is an Academic journal published by The University of Chicago Press devoted to the History of science, History of medicine 4. University of Chicago Press, 1960, pp 531–545.
• 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 Development of 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. Richard S Westfall ( April 22, 1924 &mdash August 21, 1996) was an American academic biographer and Historian of science 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.