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Johannes Kepler was a German astronomer, mathematician, astrologer, natural philosopher and writer on music.

Johannes Kepler was a German astronomer, mathematician, astrologer, natural philosopher and writer on music.

Johannes Kepler is a key figure in the 17th-century Scientific Revolution, best known for his laws of planetary motion, and his books Astronomia nova, Harmonice Mundi, and Epitome Astronomiae Copernicanae.

Johannes Kepler taught mathematics in Linz, and was an adviser to General Wallenstein.

Johannes Kepler lived in an era when there was no clear distinction between astronomy and astrology, but there was a strong division between astronomy and physics.

Johannes Kepler incorporated religious arguments and reasoning into his work, motivated by the religious conviction and belief that God had created the world according to an intelligible plan that is accessible through the natural light of reason.

Johannes Kepler was believed to have died in the Eighty Years' War in the Netherlands.

Johannes Kepler's mother, Katharina Guldenmann, an innkeeper's daughter, was a healer and herbalist.

Johannes Kepler was introduced to astronomy at an early age and developed a strong passion for it that would span his entire life.

Johannes Kepler proved himself to be a superb mathematician and earned a reputation as a skilful astrologer, casting horoscopes for fellow students.

Johannes Kepler eventually published some of the ideas he had entertained while a student in the Mysterium Cosmographicum, published a little over a year after his arrival at Graz.

Jobst relented after Johannes Kepler completed work on Mysterium, but the engagement nearly fell apart while Johannes Kepler was away tending to the details of publication.

Johannes Kepler planned four additional books: one on the stationary aspects of the universe ; one on the planets and their motions; one on the physical nature of planets and the formation of geographical features ; and one on the effects of the heavens on the Earth, to include atmospheric optics, meteorology, and astrology.

Johannes 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.

Political and religious difficulties in Graz dashed his hopes of returning immediately to Brahe; in hopes of continuing his astronomical studies, Johannes Kepler sought an appointment as a mathematician to Archduke Ferdinand.

Several months later, Johannes Kepler returned, now with the rest of his household, to Prague.

Johannes Kepler 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.

Around 1611, Johannes Kepler circulated a manuscript of what would eventually be published as Somnium [The Dream].

Also in that year, Barbara Johannes Kepler contracted Hungarian spotted fever, then began having seizures.

At the University of Tubingen in Wurttemberg, concerns over Johannes Kepler's perceived Calvinist heresies in violation of the Augsburg Confession and the Formula of Concord prevented his return.

Johannes Kepler postponed the move to Linz and remained in Prague until Rudolf's death in early 1612, though between political upheaval, religious tension, and family tragedy, Johannes Kepler could do no research.

That blow, happening only a few years after Johannes Kepler's excommunication, is not seen as a coincidence but as a symptom of the full-fledged assault waged by the Lutherans against Johannes Kepler.

Johannes Kepler participated in deliberations on whether to introduce Pope Gregory's reformed calendar to Protestant German lands.

Johannes Kepler was buried in a Protestant churchyard that was completely destroyed during the Thirty Years' War.

Johannes Kepler advocated for tolerance among Christian denominations, for example arguing that Catholics and Lutherans should be able to take communion together.

Johannes Kepler found a formula relating the size of each planet's orb to the length of its orbital period: from inner to outer planets, the ratio of increase in orbital period is twice the difference in orb radius.

However, Johannes Kepler later rejected this formula, because it was not precise enough.

Johannes Kepler thought the Mysterium had revealed God's geometrical plan for the universe.

Much of Johannes 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 them to the Holy Spirit.

Mysterium was published late in 1596, and Johannes Kepler received his copies and began sending them to prominent astronomers and patrons early in 1597; it was not widely read, but it established Johannes Kepler's reputation as a highly skilled astronomer.

In 1621, Johannes 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.

Johannes Kepler calculated and recalculated various approximations of Mars's orbit using an equant, eventually creating a model that generally agreed with Tycho's observations to within two arcminutes.

The wide array of traditional mathematical astronomy methods having failed him, Johannes Kepler set about trying to fit an ovoid orbit to the data.

Johannes Kepler supposed that the motive power radiated by the Sun weakens with distance, causing faster or slower motion as planets move closer or farther from it.

Johannes Kepler then set about calculating the entire orbit of Mars, using the geometrical rate law and assuming an egg-shaped ovoid orbit.

Since completing the Astronomia Nova, Johannes Kepler had intended to compose an astronomy textbook that would cover all the fundamentals of heliocentric astronomy.

Johannes Kepler spent the next several years working on what would become Epitome Astronomiae Copernicanae.

Originally intended as an introduction for the uninitiated, Johannes Kepler sought to model his Epitome after that of his master Michael Maestlin, who published a well-regarded book explaining the basics of geocentric astronomy to non-experts.

Johannes Kepler surmises that the Earth has "cycles of humors" as living animals do, and gives for an example that "the highest tides of the sea are said by sailors to return after nineteen years around the same days of the year".

Johannes Kepler was convinced "that the geometrical things have provided the Creator with the model for decorating the whole world".

Johannes Kepler began by exploring regular polygons and regular solids, including the figures that would come to be known as Johannes Kepler's solids.

Johannes Kepler extended his study of optics to the human eye, and is generally considered by neuroscientists to be the first to recognize that images are projected inverted and reversed by the eye's lens onto the retina.

Johannes Kepler argued that if a focus of a conic section were allowed to move along the line joining the foci, the geometric form would morph or degenerate, one into another.

Johannes Kepler assumed that if a straight line is extended to infinity it will meet itself at a single point at infinity, thus having the properties of a large circle.

Johannes Kepler 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, Johannes Kepler published his own telescopic observations of the moons in Narratio de Jovis Satellitibus, providing further support of Galileo.

Johannes Kepler started a theoretical and experimental investigation of telescopic lenses using a telescope borrowed from Duke Ernest of Cologne.

Johannes Kepler wrote the influential mathematical treatise Nova stereometria doliorum vinariorum in 1613, on measuring the volume of containers such as wine barrels, which was published in 1615.

Johannes Kepler contributed to the development of infinitesimal methods and numerical analysis, including iterative approximations, infinitesimals, and the early use of logarithms and transcendental equations.

Johannes Kepler remained a firm advocate of the Keplerian model.

Beyond his role in the historical development of astronomy and natural philosophy, Johannes Kepler has loomed large in the philosophy and historiography of science.

William Whewell, in his influential History of the Inductive Sciences of 1837, found Johannes Kepler to be the archetype of the inductive scientific genius; in his Philosophy of the Inductive Sciences of 1840, Whewell held Johannes Kepler up as the embodiment of the most advanced forms of scientific method.

Alexandre Koyre's work on Johannes Kepler was, after Apelt, the first major milestone in historical interpretations of Johannes Kepler's cosmology and its influence.

Since the 1960s, the volume of historical Johannes 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.

Johannes 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".

One of the most influential is Arthur Koestler's 1959 The Sleepwalkers, in which Johannes Kepler is unambiguously the hero of the revolution.

The reverse side of the coin has a portrait of Johannes Kepler, who spent some time teaching in Graz and the surrounding areas.

Johannes Kepler was acquainted with Prince Hans Ulrich von Eggenberg personally, and he probably influenced the construction of Eggenberg Castle.

The German composer Paul Hindemith wrote an opera about Johannes Kepler entitled Die Harmonie der Welt, and during the prolonged process of its creation, he wrote a symphony of the same name based on the musical ideas he developed for it.

Philip Glass wrote an opera called Johannes Kepler based on Johannes Kepler's life, with a libretto in German and Latin by Martina Winkel.