Editing Johannes Kepler (section)

== Early life ==
=== Childhood (1571–1590) ===
[[File:Kepler-Geburtshaus.jpg|thumb|left|upright=0.7|Kepler's birthplace, in [[Weil der Stadt]], Germany]]
Kepler was born on 27 December 1571, in the [[Free Imperial City]] of [[Weil der Stadt]] (now part of the [[Stuttgart Region]] in the German state of [[Baden-Württemberg]]). His grandfather, Sebald Kepler, had been Lord Mayor of the city. By the time Johannes was born, the Kepler family fortune was in decline. His father, Heinrich Kepler, earned a precarious living as a [[mercenary]], and he left the family when Johannes was five years old. He was believed to have died in the [[Eighty Years' War]] in the Netherlands. His mother, [[Katharina Kepler|Katharina Guldenmann]], an innkeeper's daughter, was a [[healer (alternative medicine)|healer]] and [[herbalist]]. Johannes had six siblings, of which two brothers and one sister survived to adulthood. Born prematurely, he claimed to have been weak and sickly as a child. Nevertheless, he often impressed travelers at his grandfather's inn with his phenomenal mathematical faculty.<ref>Caspar. ''Kepler'', pp. 29–36; Connor. ''Kepler's Witch'', pp. 23–46.</ref>

[[File:Von einem Schrecklichen vnd Wunderbarlichen Cometen so sich den Dienstag nach Martini dieses lauffenden M. D. Lxxvij. Jahrs am Himmel erzeiget hat (grayscale).png|thumb|As a child, Kepler witnessed the [[Great Comet of 1577]], which attracted the attention of astronomers across Europe.]]
He was introduced to astronomy at an early age and developed a strong passion 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."<ref name = Koestler234 /> In 1580, at age nine, he observed another astronomical event, a [[lunar eclipse]], recording that he remembered being "called outdoors" to see it and that the [[Moon]] "appeared quite red".<ref name=Koestler234>Koestler. ''The Sleepwalkers'', p. 234 (translated from Kepler's family horoscope).</ref> However, childhood [[smallpox]] left him with weak vision and crippled hands, limiting his ability in the observational aspects of astronomy.<ref>Caspar. ''Kepler'', pp.&nbsp;36–38; Connor. ''Kepler's Witch'', pp.&nbsp;25–27.</ref>

In 1589, after moving through grammar school, [[Latin school]], and [[Evangelical Seminaries of Maulbronn and Blaubeuren|seminary at Maulbronn]], Kepler attended [[Tübinger Stift]] at the [[University of Tübingen]]. There, he studied philosophy under Vitus Müller<ref>Connor, James A. ''Kepler's Witch'' (2004), p. 58.</ref> and [[theology]] under [[Jacob Heerbrand]] (a student of [[Philipp Melanchthon]] at [[Wittenberg]]), who also taught [[Michael Maestlin]] while he was a student, until he became Chancellor at Tübingen in 1590.<ref name="Kepler's Astronomy Author 2001 p. 96">Barker, Peter; Goldstein, Bernard R. "Theological Foundations of Kepler's Astronomy", Osiris, 2nd Series, Vol. 16, Science'' in Theistic Contexts: Cognitive Dimensions'' (2001), p. 96.</ref> He proved himself to be a superb mathematician and earned a reputation as a skillful astrologer, casting [[horoscope]]s for fellow students. Under the instruction of Michael Maestlin, Tübingen's professor of mathematics from 1583 to 1631,<ref name="Kepler's Astronomy Author 2001 p. 96" /> he learned both the [[Ptolemaic system]] and the [[Copernican heliocentrism|Copernican system]] of planetary motion. He became a [[Nicolaus Copernicus|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.<ref>Westman, Robert S. "Kepler's Early Physico-Astrological Problematic," ''[[Journal for the History of Astronomy]]'', '''32''' (2001): 227–236.</ref> Despite his desire to become a minister in the Lutheran church, he was denied ordination because of beliefs contrary to the [[Formula of Concord]].<ref>{{Cite journal |last1=Barker |first1=Peter |last2=Goldstein |first2=Bernard R. |date=January 2001 |title=Theological Foundations of Kepler's Astronomy |url=http://dx.doi.org/10.1086/649340 |journal=Osiris |volume=16 |pages=88–113 |doi=10.1086/649340 |s2cid=145170215 |issn=0369-7827}}</ref> Near the end of his studies, Kepler was recommended for a position as teacher of mathematics and astronomy at the Protestant school in Graz. He accepted the position in April 1594, at the age of 22.<ref>Caspar. ''Kepler'', pp.&nbsp; 38–52; Connor. ''Kepler's Witch'', pp.&nbsp; 49–69.</ref>

=== Graz (1594–1600) ===
{{multiple image|perrow=1
| image1 = Barbara Müller and Johannes Kepler.jpg
| caption1 = Oil on copper portraits of Kepler and his wife, {{circa|1600}}
| image2 = House of Johannes Kepler.JPG
| caption2 = House of Kepler and Barbara Müller in [[Gössendorf]], near Graz (1597–1599)}}
Before concluding his studies at Tübingen, Kepler accepted an offer to teach mathematics as a replacement to Georg Stadius at the Protestant school in Graz (now in Styria, Austria).<ref>Caspar, ''Kepler''. pp.&nbsp;50–51.</ref> During this period (1594–1600), he issued many official calendars and prognostications that enhanced his reputation as an astrologer. Although Kepler had mixed feelings about astrology and disparaged many customary practices of astrologers, he believed deeply in a connection between the cosmos and the individual. He eventually published some of the ideas he had entertained while a student in the ''Mysterium Cosmographicum'' (1596), published a little over a year after his arrival at Graz.<ref>Caspar, ''Kepler''. pp.&nbsp;58–65.</ref>

In December 1595, Kepler was introduced to Barbara Müller, a 23-year-old widow (twice over) with a young daughter, Regina Lorenz, and he began courting her. Müller, an heiress to the estates of her late husbands, was also the daughter of a successful mill owner. Her father Jobst initially opposed a marriage. Even though Kepler had inherited his grandfather's nobility, Kepler's poverty made him an unacceptable match. Jobst relented after Kepler completed work on ''Mysterium'', but the engagement nearly fell apart while Kepler was away tending to the details of publication. However, Protestant officials—who had helped set up the match—pressured the Müllers to honor their agreement. Barbara and Johannes were married on 27 April 1597.<ref>Caspar, ''Kepler''. pp.&nbsp;71–75.</ref>

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).<ref>Connor. ''Kepler's Witch'', pp.&nbsp;89–100, 114–116; Caspar. ''Kepler'', pp.&nbsp;75–77</ref>

=== Other research ===
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.<ref>Caspar. ''Kepler'', pp.&nbsp;85–86.</ref>

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 [[Rudolf II, Holy Roman Emperor|Rudolf II]] and a bitter rival of [[Tycho Brahe]]. Ursus did not reply directly, but republished Kepler's flattering letter to pursue his priority dispute over (what is now called) the [[Tychonic system]] with Tycho. Despite this black mark, Tycho also began corresponding with Kepler, starting with a harsh but legitimate critique of Kepler's system; among a host of objections, Tycho took issue with the use of inaccurate numerical data taken from Copernicus. Through their letters, Tycho and Kepler discussed a broad range of astronomical problems, dwelling on lunar phenomena and Copernican theory (particularly its theological viability). But without the significantly more accurate data of Tycho's observatory, Kepler had no way to address many of these issues.<ref>Caspar, ''Kepler'', pp.&nbsp;86–89</ref>

Instead, he turned his attention to [[chronology]] and "harmony," the [[numerology|numerological]] relationships among music, [[mathematics]] and the physical world, and their [[astrology|astrological]] consequences. 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 [[meteorology|weather]] and other earthly phenomena. By 1599, however, he again felt his work limited by the inaccuracy of available data—just as growing religious tension was also threatening his continued employment in Graz. In December of that year, Tycho invited Kepler to visit him in [[Prague]]; on 1 January 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.<ref>Caspar, ''Kepler'', pp.&nbsp;89–100</ref>