Astronomer, born in Weil-der-Stadt, SW Germany. He studied at Tübingen, and in 1593 was appointed professor of mathematics at Graz. In c.1596 he commenced a correspondence with Tycho Brahe, who was then in Prague, and from 16001 worked with him, showing that planetary motions were far simpler than had been imagined. He announced his first and second laws of planetary motion in Astronomia nova (1609, New Astronomy), which formed the groundwork of Isaac Newton's discoveries. His third law was promulgated in Harmonice mundi (1619, Harmony of the World). He succeeded Brahe as court astronomer to Emperor Rudolf II, and in 1628 became astrologer to Albrecht von Wallenstein at Zagan in Silesia.
| Johannes Kepler | |
|---|---|
| Born |
December 27, 1571 Weil der Stadt near Stuttgart, Germany |
| Died |
November 15, 1630 Regensburg, Bavaria, Germany |
Johannes Kepler (December 27, 1571 – November 15, 1630), a key figure in the scientific revolution, was a German mathematician, astronomer, astrologer, and an early writer of science fiction stories.
Through his career Kepler was a mathematics teacher at a Graz seminary school (later the University of Graz, Austria), an assistant to Tycho Brahe, court mathematician to Emperor Rudolf II, mathematics teacher in Linz, Austria, and court astrologer to General Wallenstein.
He is sometimes referred to as "the first theoretical astrophysicist", although Carl Sagan also referred to him as the last scientific astrologer.
Life
Childhood and education (1571–1594)
Kepler was born on December 29, 1571 in the Free Imperial 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). His grandfather had been Lord Mayor of that town, but by the time Johannes was born, the Kepler family fortunes were in decline. Whether Kepler was born prematurely is disputable.
In 1589, after moving through grammar school, Latin school, and after passing the "Landexamen" (state-wide examination), Kepler attended the lower and higher seminary in the scholarship-based education system of the Duchy of Württemberg. Kepler enrolled in the University of Tübingen as a theology student, where he proved himself to be a superb mathematician and earned a reputation as a skillful astrologer. 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.
Early career (1594–1601)
In Graz, Kepler began developing an original theory of cosmology based on the Copernican system, which was published in 1596 as Mysterium Cosmographicum—The Sacred Mystery of the Cosmos.
In April 1597, Kepler married Barbara Müller.
In December 1599, Tycho Brahe wrote to Kepler, inviting Kepler to assist him at Benátky nad Jizerou outside Prague. Pressured to leave Graz by increasingly strict Counter-Reformation policies restricting the religious practices and political rights of Protestants, Kepler joined Tycho in 1600. After Tycho's death in 1601, Kepler was appointed Imperial Mathematician in his place, a post he would retain through the reigns of three Habsburg Emperors (from November 1601 to 1630).
Imperial Mathematician in Prague (1601–1612)
As Imperial Mathematician, Kepler inherited Tycho's responsibility for the Emperor's horoscopes as well as the commission to produce the Rudolphine Tables. Working with Tycho's extensive collection of highly accurate observational data, Kepler also set out to refine his earlier theories but was forced to abandon them.
In October 1604, Kepler observed the supernova which was subsequently named Kepler's Star (a term which may also refer to the stellated octahedron). In 1611, Kepler published (as a letter to a friend) a monograph on the origins of snowflakes, the first known work on the subject. To escape the growing religious tension in Prague, Kepler took the post of Provincial Mathematician in Linz.
Teaching in Linz and final years (1612–1630)
In 1615, Kepler married Susanna Ruettinger, with whom he would have several children.
In 1617, Kepler's mother Katharina was accused of being a witch in Leonberg. Thanks in part to the extensive legal defense drawn up by Kepler, she was released in October 1621 after failed attempts to convict her. Throughout the trial, Kepler postponed his other work (on the Rudolphine Tables and a multi-volume astronomy textbook) to focus on his "harmonic theory".
Kepler completed the last of seven volumes of his textbook Epitome of Copernican Astronomy in 1621, which brought together and extended his previous work and would become very influential in the acceptance of the Copernican system over the next century.
On November 15, 1630 Kepler died of a fever in Regensburg. Kepler had incidentally composed the epitaph for his own tombstone, which read:
I measured the skies, now the shadows I measure,Sky-bound was the mind, earth-bound the body rests
Work
Kepler lived in an era when there was no clear distinction between astronomy and astrology, while there was a strong division between astronomy/astrology (a branch of mathematics within the liberal arts) and physics (a branch of the more prestigious discipline of philosophy).
For instance, Kepler was explicit about the intellectual safeguards that, in his view, the Christian faith provided for scientific speculation.
Kepler was a Pythagorean mystic. In his attempt to discover universal laws, Kepler applied terrestrial physics to celestial bodies; Kepler was also convinced that celestial bodies influence terrestrial events.
Scientific work
Kepler's laws
Kepler inherited from Tycho Brahe a wealth of the most accurate raw data ever collected on the positions of the planets. Kepler concentrated on trying to understand the orbit of Mars, but he had to know the orbit of the Earth accurately first.
Unlike Brahe, Kepler had accepted Copernicus's heliocentric model of the solar system. Starting from that framework, Kepler made twenty years of painstaking trial-and-error attempts at making some sense out of the data. He finally arrived at his three laws of planetary motion:
Kepler's elliptical orbit law: The planets orbit the sun in elliptical orbits with the sun at one focus. Kepler's laws were the first clear evidence in favor of the heliocentric model of the solar system, because they only came out to be so simple under the heliocentric assumption. Kepler, however, never discovered the deeper reasons for the laws, despite many years of what would now be considered non-scientific mystical speculation.Kepler first discovered his distance-cubed-over-time-squared (or 'third') law of planetary motion on March 8, 1618 but rejected the idea until May 15, 1618, when he verified his result.
Supernova 1604
On October 17, 1604, Kepler observed that an exceptionally bright star had suddenly appeared in the constellation Ophiuchus. (It was first observed by several others on October 9.) The appearance of the star, which Kepler described in his book De Stella nova in pede Serpentarii ("On the New Star in Ophiuchus's Foot"), provided further evidence that the cosmos were not changeless; It has since been determined that the star was a supernova, the second in a generation, later called Kepler's Star or Supernova 1604.
Other scientific and mathematical work
Kepler also made fundamental investigations into combinatorics, geometrical optimization, and natural phenomena such as snowflakes, always with an emphasis on form and design. He was also one of the founders of modern optics, defining for example antiprisms and the Keplerian telescope (see Kepler's books Astronomiae Pars Optica—i.a. In addition, since he was the first to recognize the non-convex regular solids (such as the stellated dodecahedra), they are named Kepler solids in his honor.
Kepler also was in contact with Wilhelm Schickard, inventor of the first automatic calculator, whose letters to Kepler show how to use the machine for calculating astronomical tables.
Mysticism and astrology
Mysticism
Kepler discovered the laws of planetary motion while trying to achieve the Pythagorean purpose of finding the harmony of the celestial spheres.
In 1596 Kepler published Mysterium Cosmographicum, or The Sacred Mystery of the Cosmos. For, as I have proved next, the solids of the first group must lie beyond the earth's orbit, and those of the second group within… Thus I was led to assign the Cube to Saturn, the Tetrahedron to Jupiter, the Dodecahedron to Mars, the Icosahedron to Venus, and the Octahedron to Mercury…
To emphasize his theory, Kepler envisaged an impressive model of the universe which shows a cube, inside a sphere, with a tetrahedron inscribed in it;
In his 1619 book, Harmonice Mundi or Harmony of the Worlds, as well as the aforementioned Mysterium Cosmographicum, he also made an association between the Platonic solids with the classical conception of the elements: the tetrahedron was the form of fire, the octahedron was that of air, the cube was earth, the icosahedron was water, and the dodecahedron was the cosmos as a whole or ether.
His most significant achievements came from the realization that the planets moved in elliptical, not circular, orbits. Kepler's willingness to abandon his most cherished theory in the face of precise observational evidence also indicates that he had a very modern attitude to scientific research. Kepler also made great steps in trying to describe the motion of the planets by appealing to a force which resembled magnetism, which he believed emanated from the sun.
Astrology
Kepler disdained astrologers who pandered to the tastes of the common man without knowledge of the abstract and general rules, but he saw compiling prognostications as a justified means of supplementing his meager income. Yet, it would be a mistake to take Kepler's astrological interests as merely pecuniary. However, Kepler's views on astrology were quite unconventional for his time;
Kepler believed in astrology in the sense that he was convinced that astrological aspects physically and really affected humans as well as the weather on Earth. In The Intervening Third Man, or a warning to theologians, physicians and philosophers (1610), posing as a third man between the two extreme positions for and against astrology, Kepler advocated that a definite relationship between heavenly phenomena and earthly events could be established.
At least 800 horoscopes and natal charts drawn up by Kepler are still extant, several of himself and his family, accompanied by some unflattering remarks. As part of his duties as district mathematician to Graz, Kepler issued a prognostication for 1595 in which he forecast a peasant uprising, Turkish invasion and bitter cold, all of which happened and brought him renown. Kepler is known to have compiled prognostications for 1595 to 1606, and from 1617 to 1624. As court mathematician, Kepler explained to Rudolf II the horoscopes of the Emperor Augustus and the Prophet Muhammad, and Kepler gave astrological prognosis for the outcome of a war between the Republic of Venice and Paul V. In the On the new star (1606) Kepler explicated the meaning of the new star of 1604 as the conversion of America, downfall of Islam and return of Christ.
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