(A work of astonishing originality, Astronomia Nova stands...)
A work of astonishing originality, Astronomia Nova stands, with Copernicus's De Revolutionibus and Newton's Principia as one of the founding texts of the scientific revolution. Kepler revolutionized astronomy by insisting that it be based upon physics rather than ideal geometrical models.
(Mysterium Cosmographicum, (lit The Cosmographic Mystery, ...)
Mysterium Cosmographicum, (lit The Cosmographic Mystery, alternately translated Cosmic Mystery, The Secret of the World, or some variation) is an astronomy book by the German astronomer Johannes Kepler, published at Tübingen in 1596 and in a second edition in 1621. The full title being Forerunner of the Cosmological Essays, Which Contains the Secret of the Universe; on the Marvelous Proportion of the Celestial Spheres, and on the True and Particular Causes of the Number, Magnitude, and Periodic Motions of the Heavens; Established by Means of the Five Regular Geometric Solids.
(According to Carl Sagan and Isaac Asimov, Kepler´s "Somni...)
According to Carl Sagan and Isaac Asimov, Kepler´s "Somnium" ("The Dream"), written around 1611, should be considered the first science-fiction novel ever. The eminent astronomer Johannes Kepler imagines a trip to the moon and speculates about its inhabitants.
Epitome of Copernican Astronomy and Harmonies of the World
(This volume contains two of Kepler's most important works...)
This volume contains two of Kepler's most important works: The Epitome of Copernican Astronomy is a textbook of Copernican science, remarkable for the prominence given to physical astronomy, and for the extension to the Jovian system of the laws recently discovered to regulate the motions of the Planets. Harmonies of the World expounds an elaborate system of celestial harmonies depending on the varying velocities of the planets.
Johannes Kepler was a 17th-century German scientist, renowned for his numerous works on mathematics, astronomy, and astrology. He is a pivotal figure when talking about people who influenced the scientific revolution that took place in the 17th century. He formulated the laws of celestial mechanics, known as Kepler's laws of planetary motion.
Background
Johannes Kepler was born on December 27, 1571, at Weil der Stadt, Germany, of which his grandfather was a burgomaster. He was the eldest child of an ill-assorted union. His father, Henry Kepler, was a reckless soldier of fortune; his mother, Catherine Guldenmann, the daughter of the burgomaster of Eltingen, was undisciplined and ill-educated. She was a healer and herbalist. Her husband found campaigning in Flanders under Alva a welcome relief from domestic life; and, after having lost all he possessed by forfeited security and tried without success the trade of tavern-keeping in the village of Elmendingen, he finally, in 1589, deserted his family.
The misfortune and misconduct of his parents were not the only troubles of Kepler's childhood. He recovered from small-pox in his fourth year with crippled hands and eyesight permanently impaired; and a constitution enfeebled by premature birth had to withstand successive shocks of severe illness.
Education
As was typical during those days, Kepler went through grammar school, progressed to Latin school and finally, because of his religious interest pursued studies at the Maulbronn seminary, from which he graduated in 1589, discovering outstanding abilities. The city authorities appointed him a scholarship to help in further education. In 1591, he entered the University of Tübingen, first to the Faculty of Arts, to which mathematics and astronomy were also listed, then he transferred to the theological faculty. It is here that he first manifests himself as a competent mathematician and skilled astrologer. In the seminary, he also studies philosophy and theology under the leadership of the outstanding personalities of his time – Vitus Mueller and Jacob Heerbrand. At Tübingen University Kepler gets acquainted with the planetary systems of Copernicus and Ptolemy. Bending to the Copernican system, Kepler assumes the Sun as the main source of the driving force in the universe.
After graduating from university, Johannes Kepler dreams of getting a public post, but after the offer to become a professor of mathematics and astronomy at the Protestant school of Graz, he immediately renounces his political ambitions. The post of Professor Kepler took in 1594 when he was only 23 years old.
In 1596, the scientist wrote his first, and perhaps the most controversial of his work on astronomy, "The Mystery of the Universe." By this work, he conquers the reputation of a skillful astronomer. In the future, in his work, Kepler will make only minor amendments and will accept it as the basis for a number of his future works.
In the following year the archduke Ferdinand, on assuming the government of his hereditary dominions issued an edict of banishment against Protestant preachers and professors. Kepler immediately fled to the Hungarian frontier, but, by the favor of the Jesuits, was recalled and reinstated in his post. His refusal to subscribe unconditionally to the rigid formula of belief adopted by the theologians of Tübingen permanently closed against him the gates of his alma mater. His embarrassment was relieved however by an offer from Tycho Brahe of the position of assistant in his observatory near Prague, which, after a preliminary visit of four months, he accepted. The arrangement was made just in time; for in August 1600 he received definitive notice to leave Gratz, and, having leased his wife's property, he departed with his family for Prague.
Using the accurate data of Tycho Brahe, Johannes Kepler later discovered his three laws of planetary motion that describe the motion of planets around the Sun. Kepler’s 1609 work, Astronomia nova, records the discovery of the first two of the three planetary laws while the third law was first published in his 1619 work Harmonices Mundi.
By Tycho's unexpected death (October 24, 1601) a brilliant career seemed to be thrown open to Kepler. The emperor Rudolph II immediately appointed him to succeed his patron as an imperial mathematician; the invaluable treasure of Tycho's observations was placed at his disposal; and the laborious but congenial task was entrusted to him of completing the tables to which the grateful Dane had already affixed the title of Rudolphine.
He dedicated to the emperor in 1603 a treatise on the "great conjunction" of that year (Judicium de trigono igneo); and he published his observations on a brilliant star which appeared suddenly (September 30, 1604), and remained visible for seventeen months. A preliminary study of optics led to the publication, in 1604, of his Astronomiae pars optica, containing important discoveries in the theory of vision, and a notable approximation towards the true law of refraction. But it was not until 1609 that, the "great Martian labour" being at length completed, he was able, in his own figurative language, to lead the captive planet to the foot of the imperial throne.
Having been provided, in August 1610, by Ernest, archbishop of Cologne, with one of the new Galilean instruments, Kepler began, with unspeakable delight, to observe the wonders revealed by it. He had welcomed with a little essay called Dissertatio cum Nuncio Sidereo Galileo's first announcement of celestial novelties; he now, in his Dioptrice (Augsburg, 1611), expounded the theory of refraction by lenses, and suggested the principle of the "astronomical" or inverting telescope. Indeed the work may be said to have founded the branch of science to which it gave its name.
The year 1611 was marked by Kepler as the most disastrous of his life. His wife, who suffered from melancholy and several chronic diseases, died on the 3rd of July. Public calamity was added to private bereavement. In 1613 Kepler appeared with the emperor Matthias before the diet of Ratisbon as the advocate of the introduction into Germany of the Gregorian calendar; but the attempt was for the time frustrated by anti-papal prejudice. The abundant vintage of that year drew his attention to the defective methods in use for estimating the cubical contents of vessels, and his essay on the subject (Nova Stereometria Doliorum, Linz, 1615) entitles him to rank among those who prepared the discovery of the infinitesimal calculus.
His observations on the three comets of 1618 were published in De Comelis, contemporaneously with De Harmonice Mundi (Augsburg, 1619), of which the first lineaments had been traced twenty years previously at Gratz. This extraordinary production is memorable as having announced the discovery of the "third law" - that of the sesquiplicate ratio between the planetary periods and distances. But the main purport of the treatise was the exposition of an elaborate system of celestial harmonies depending on the various and varying velocities of the several planets, of which the sentient soul animating the sun was the solitary auditor.
Notwithstanding the distracted state of his own country, he refused to abandon it, as he had previously, in 1617, declined the post of successor to G.A. Magini in the mathematical chair of Bologna. The insurmountable difficulties presented by the lunar theory forced Kepler, after an enormous amount of fruitless labour, to abandon his design of comprehending the whole scheme of the heavens in one great work to be called Hipparchus, and he then threw a portion of his materials into the form of a dialogue intended for the instruction of general readers.
The Epitome Astronomiae Copernicanae (Linz and Frankfort, 1618-1621), a lucid and attractive textbook of Copernican science, was remarkable for the prominence given to "physical astronomy," as well as for the extension to the Jovian system of the laws recently discovered to regulate the motions of the planets. The first of a series of ephemerides, calculated on these principles, was published by him at Linz in 1617; and in that for 1620, dedicated to Baron Napier, he for the first time employed logarithms. This important invention was eagerly welcomed by him, and its theory formed the subject of a treatise entitled Chilias Logarithmorum, printed in 1624, but circulated in manuscript three years earlier, which largely contributed to bring the new method into general use in Germany.
His studies were interrupted by family trouble. Catherine Kepler, his mother, died on the 13th of April 1622. Kepler's whole attention was now devoted to the production of the new tables, but financial difficulties, combined with civil and religious convulsions, long-delayed the accomplishment of his desires.
From the 24th of June to the 29th of August 1626, Linz was besieged, and its inhabitants reduced to the utmost straits by bands of insurgent peasants. The pursuit of science needed a more tranquil shelter; and on the raising of the blockade, Kepler obtained permission to transfer his types to Ulm, where, in September 1627, the Rudolphine Tables were at length given to the world. Although by no means free from errors, their value appears from the fact that they ranked for a century as the best aid to astronomy. Appended were tables of logarithms and of refraction, together with Tycho's catalogue of 777 stars, enlarged by Kepler to 1005.
In July 1628 Kepler accordingly arrived with his family to Sagan in Silesia, where he applied himself to the printing of his ephemerides up to the year 1636, and whence he issued, in 1629, a Notice to the Curious in Things Celestial, warning astronomers of approaching transits. That of Mercury was actually seen by Gassendi in Paris on the 7th of November 1631; that of Venus, predicted for the 6th of December following, was invisible in western Europe. Wallenstein's promises to Kepler were but imperfectly fulfilled. In lieu of the sums due, he offered him a professorship at Rostock, which Kepler declined. An expedition to Ratisbon, undertaken for the purpose of representing his case to the diet, terminated his life. Shaken by the journey, which he had performed entirely on horseback, he was attacked with fever, and died at Ratisbon, on the 15th of November, 1630, in the fifty-ninth year of his age. An inventory of his effects showed him to have been possessed of no inconsiderable property at the time of his death.
Johannes Kepler was a Lutheran. Lutheranism is a major branch of Protestant Christianity. In 1600, when Kepler was seeking an appointment as assistant to Tycho, all Protestants in Graz were forced to convert to Catholicism or leave the province, as part of Counter-Reformation measures. As Kepler refused to convert, he and his family were banished from Graz. While he served as Imperial Mathematician under Rudolf II in Prague, he was allowed to practice his faith due to his position although the only acceptable religious doctrines were Catholic and Utraquist. Still he didn’t enjoy complete religious freedom. After the death of Rudolf II, Kepler moved to Linz in 1612. Though he enjoyed more religious freedom here, still he was excluded from the sacrament in the Lutheran church as he refused to sign a Lutheran statement of faith known as Formula of Concord. In 1618, Counter-Reformation measures put pressure on Protestants in Linz. Though Kepler was exempted from banishment, he still suffered persecution.
Johannes Kepler was deeply religious, wanted to be a theologian initially, and looked for God’s design in science and nature. Incorporated religious arguments and reasoning into his work. He believed that God had created the world according to an intelligible plan. He regarded his three laws of planetary motion as celestial harmonies that reflected God’s design for the universe. In his famous work Harmonices Mundi, he found harmonies in nature to claim that the Earth has a soul because it is subjected to astrological harmony.
Kepler was not alone in believing that nature was a book in which the divine plan was written. He differed, however, in the original manner and personal intensity with which he believed his ideas to be embodied in nature. One of the ideas to which he was most strongly attached - the image of the Christian Trinity as symbolized by a geometric sphere and, hence, the visible, created world - was literally a reflection of this divine mystery (God the Father: centre; Christ the Son: circumference; Holy Spirit: intervening space). One of Kepler’s favourite biblical passages came from John (1:14): “And the Word became flesh and lived among us.” For him, this signified that the divine archetypes were literally made visible as geometric forms (straight and curved) that configured the spatial arrangement of tangible, corporeal entities. Moreover, Kepler’s God was a dynamic, creative being whose presence in the world was symbolized by the Sun’s body as the source of a dynamic force that continually moved the planets. The natural world was like a mirror that precisely reflected and embodied these divine ideas. Inspired by Platonic notions of innate ideas in the soul, Kepler believed that the human mind was ideally created to understand the world’s structure.
Views
Johannes Kepler’s first major astronomical work, Mysterium Cosmographicum, was published in 1596. Here Kepler’s central idea was that the distance relationships between the six planets (only six were known at that time) could be represented by six spheres separated by the five Platonic solids. For each of these regular polyhedra, there is an inner and an outer sphere. The inner sphere is tangent to the center of each face and the outer sphere contains all the vertices of the polyhedron.
In Kepler’s model, each planet is on a sphere, the inner sphere of a polyhedron whose outer sphere contains the next planet. That is, until we come to the sixth sphere, representing Saturn, the outermost planet. The five regular solids thus rationalize the existence of six planets. The distances between the spheres can be calculated. With a particular ordering of the polyhedra, Kepler was able to achieve reasonable agreement with the observed spacings of the planets. He found the arrangement in best accord with the known orbits: the six planets from Mercury out to Saturn were separated by the solids in the sequence octahedron, icosahedron, dodecahedron, tetrahedron and cube. The Sun was at the centre of the six concentric spheres. In such an ideal construction of the world, Kepler saw the will of God. However, further observations and discoveries of Kepler disproved this model.
Later Kepler discovered and formulated three major laws of planetary motion, conventionally designated as follows: (1) the planets move in elliptical orbits with the Sun at one focus; (2) the time necessary to traverse any arc of a planetary orbit is proportional to the area of the sector between the central body and that arc (the “area law”); and (3) there is an exact relationship between the squares of the planets’ periodic times and the cubes of the radii of their orbits (the “harmonic law”). Kepler himself did not call these discoveries “laws,” as would become customary after Isaac Newton derived them from a new and quite different set of general physical principles. He regarded them as celestial harmonies that reflected God’s design for the universe.
Kepler’s discoveries turned Nicolaus Copernicus’s Sun-centered system into a dynamic universe, with the Sun actively pushing the planets around in noncircular orbits. And it was Kepler’s notion of physical astronomy that fixed a new problematic for other important 17th-century world-system builders, the most famous of whom was Newton.
Although Kepler’s scientific work was centred first and foremost on astronomy, that subject as then understood - the study of the motions of the heavenly bodies - was classified as part of a wider subject of investigation called “the science of the stars.” The science of the stars was regarded as a mixed science consisting of a mathematical and a physical component and bearing a kinship to other like disciplines, such as music (the study of ratios of tones) and optics (the study of light). It also was subdivided into theoretical and practical categories. Besides the theory of heavenly motions, one had the practical construction of planetary tables and instruments; similarly, the theoretical principles of astrology had a corresponding practical part that dealt with the making of annual astrological forecasts about individuals, cities, the human body, and the weather. Within this framework, Kepler made astronomy an integral part of natural philosophy, but he did so in an unprecedented way - in the process, making unique contributions to astronomy as well as to all its auxiliary disciplines.
During the creative burst of the early Prague period, he also wrote important treatises on the nature of light and on the sudden appearance of a new star. Kepler’s interest in light was directly related to his astronomical concerns: how a ray of light, coming from a distant heavenly body located in the outer regions of space, deflects when entering the denser atmosphere surrounding Earth; and then, in turn, what happens to light as it enters the relatively denser medium of the human eye. These problems had some medieval precedent, but, as usual, Kepler treated them in his own individual way. Although a court astronomer, Kepler chose a traditional academic form in which to compose his ideas on light. He called it Ad Vitellionem Paralipomena, Quibus Astronomiae Pars Optica Traditur (1604; “Supplement to Witelo, in Which Is Expounded the Optical Part of Astronomy”). Witelo had written the most important medieval treatise on optics. But Kepler’s analysis of vision changed the framework for understanding the behavior of light. Kepler wrote that every point on a luminous body in the field of vision emits rays of light in all directions but that the only rays that can enter the eye are those that impinge on the pupil, which functions as a diaphragm. He also reversed the traditional visual cone. Kepler offered a punctiform analysis, stating that the rays emanating from a single luminous point form a cone the circular base of which is in the pupil. All the rays are then refracted within the normal eye to meet again at a single point on the retina. For the first time the retina, or the sensitive receptor of the eye, was regarded as the place where “pencils of light” compose upside-down images. If the eye is not normal, the second short interior cone comes to a point not on the retina but in front of it or behind it, causing blurred vision. For more than three centuries eyeglasses had helped people see better. But nobody before Kepler was able to offer a good theory for why these little pieces of curved glass had worked.
In his work on optics, Kepler was the first to introduce into geometry the principle of continuity and the concept of a point at infinity - an important step towards the creation of projective geometry. His work on the theory of polygons and polyhedra was also noteworthy, particularly his discovery of the regular star-shaped polyhedra and of the space-filling property of these and other regular convex solids.
Quotations:
"I much prefer the sharpest criticism of a single intelligent man to the thoughtless approval of the masses."
"The diversity of the phenomena of nature is so great, and the treasures hidden in the heavens so rich, precisely in order that the human mind shall never be lacking in fresh nourishment."
"Without proper experiments I conclude nothing."
"Truth is the daughter of time, and I feel no shame in being her midwife."
"Nature uses as little as possible of anything."
"I demonstrate by means of philosophy that the earth is round, and is inhabited on all sides; that it is insignificantly small, and is borne through the stars."
"Geometry is one and eternal shining in the mind of God. That share in it accorded to humans is one of the reasons that humanity is the image of God."
"Geometry has two great treasures: one is the Theorem of Phythagoras, the other the division of a line in extreme and mean ratio. The first we can compare to a mass of gold; the other we may call a precious jewel."
Membership
Accademia dei Lincei
,
Italy
Personality
In private character Kepler was amiable and affectionate; his generosity in recognizing the merits of others secured him against the worst shafts of envy; and a life marked by numerous disquietudes was cheered and ennobled by sentiments of sincere piety.
Being a great scientist, Kepler was a poor lecturer, and the subject that he taught was not a popular one. He expected too much of his students, gabbled too much, and ventured down too many side streets away from the simple main road of the subject. His teaching was confused. Thus he attracted few students to his classes.
Quotes from others about the person
"Kepler was the first to discover the art of successfully inquiring [into] her laws of nature, since his predecessors merely constructed explanatory concepts which they endeavoured to apply to the course of nature." - Ernst Friedrich Apelt
"Kepler is the first who ventured here [into] an exact mathematical treatment of the problems (of astronomical science), the first to establish natural laws in the specific sense of the new science." - Rudolf Christoph Eucken
"Kepler was a brilliant thinker and a lucid writer, but he was a disaster as a classroom teacher. He mumbled. He digressed. He was at times utterly incomprehensible. He drew only a handful of students his first year at Graz; the next year there were none. He was distracted by an incessant interior clamour of associations and speculations vying for his attention. And one pleasant summer afternoon, deep in the interstices of one of his interminable lectures, he was visited by a revelation that was to alter radically the future of astronomy. Perhaps he stopped in mid-sentence. His inattentive students, longing for the end of the day, took little notice, I suspect, of the historic moment." - Carl Sagan
Interests
Philosophers & Thinkers
Nicolaus Copernicus
Connections
Kepler was introduced to his first wife, Barbara Müller von Mulek, in 1595. The two fell in love and Kepler began pursuing and courting the 23 year old widow. Müller had been married twice over and had one daughter by the name of Regina Lorenz. Their marriage was not at once approved by Müller’s parents who believed that Kepler was not a good match for their widowed daughter. The problem was that Barbara was destined to inherit a large fortune from her deceased husbands, while Kepler, although he had inherited his paternal grandfather’s nobility, was seen as nothing but a poor teacher. It wasn’t until he released his first book that Müller’s father agreed to the union of the pair. With Müller’s parent’s blessing and that of Kepler’s Protestant officials, the pair was married in 1597, on April 27. They had three biological children in total, two of whom died in their infancy, Friedrich and Susanna. Their only surviving biological child, Ludwig was born in 1607.
In 1611, disaster struck the Kepler household when Barbara suddenly contracted Hungarian spotted fever. A few days into the illness she started experiencing seizures. At one moment it appeared like she was recovering, but she once again relapsed and couldn’t keep fighting. Kepler had traveled to Austria where he was trying to arrange a teaching post as a mathematics teacher in Linz; upon arriving back home, his wife Barbara died. That was not the end of the tragic series of deaths that haunted the Kepler household in that year. Little Friedrich, 6 years old succumbed to smallpox.
After the death of his first wife, and after searching for a spouse for a period of 5 years, Kepler remarried again. He married Susanna Reuttinger on October 30, 1613. The couple had 6 children in total: three of them died in infancy, and the other three lived to adulthood. The three who survived were Cordula, Fridmar and Hildebert. This marriage was credited by Kepler’s biographers as being a very happy one.