The Man In The Moon:

Johannes Kepler

(1571 - 1630)



John W. Cowart

Honored in modern physics books primarily for his three laws of planetary and satellite motion, mathematician Johannes Kepler also invented a vacuum cleaner, discovered how the human eye works, developed a mechanical calculator, applied logarithms to measuring astronomical distances, wrote the first science fiction novel, improved the telescope, invented a method for determining the volume of irregular shapes, championed religious tolerance, defended his mother in a witchcraft trial, and advanced the Christian faith.

Instruments of torture.

Black iron pliers designed to pinch soft body parts. Cruel probes for orifices never meant to receive them. Manacles. Chains. Spikes. Pulleys. Weights. Leather restraints. Gags. Fire and water.

Tools to make a witch confess.


In the early 1600s, when German astronomer Johannes Kepler  wrote a novel predicting future space travel, his scientific, religious and political enemies responded by placing his 74-year-old mother on trial for her life charged with witchcraft.

During the four-year-long  trial, her accusers delighted in frightening the old woman into a gibbering husk by dangling before her eyes the instruments of torture which they would use on her  -- unless her son's scientific defense against the charges succeeded.

Kepler's mother stood in great danger. The magistrates showed her two thumbs which the woman before her had left torn off in the rack. In her hometown of Leonberg, Germany, six women had been burned as witches in 1615. In the district, Weil der Stadt, 38 other witches were burned to death between 1615 and 1629. cq - 1 -

Kepler began his book describing a trip to the moon, Somnium, Sive Astronomia Lunaris, "Dream on the Astronomy of the Moon", in 1593; it was not actually published until after his death, but an advance manuscript copy fell into the hands of his enemies and, since they could not strike at him directly because of his influential position in the Emperor's court, they used it to attack him through his mother.

Charges against her included 49 "points of disgrace" citing specific instances of her dabbling in "forbidden arts".

While the elderly Mrs. Kepler may not actually have been a witch, she was not a very nice person either.

A tavern keeper's daughter, she had been a army camp-follower in her younger days, settling down to marry one of the mercenary soldiers who retired to open -- and then drink out of business -- his own tavern. Both parents periodically according to drink, whim and the fortunes of war, had abandoned Kepler several times during his youth.

As an old woman, Mrs. Kepler proved to be a quarrelsome, meddlesome busybody who argued, fought, bickered, and aggravated both neighbors and family. She lived with one of her other sons, a pewter craftsman, until the night of August 7, 1620, when authorities crashed into the house,  bundled the shrieking old woman up in bedsheets, stuffed her into a linen chest to restrain her and carted her off inside the box to a windowless stone room inside the town wall.

Her other children just about disowned her, but they did write to Kepler who was living in Linz, Austria,  concerning her plight. And the astronomer, motivated by filial duty, Christian charity and a desire to clear the family name, immediately came to her defense.

Unknown to him, this move may have saved Kepler's own life.

While he was in Germany defending his mother, on June 21, 1621, Catholic authorities in Austria executed 27 Protestant leaders. And Kepler was a leading Protestant; had he been there, he also would have been executed by the Catholics. Yet, it was Lutheran officials in Germany who were persecuting his mother.

Kepler's science and his stand for Christ got him in trouble with both sides during those early days of science and the Reformation.

Yet his contributions to science enable modern astrophysicists to send probes to other planets, and the modern ecumenical movement often echoes his Sixteenth Century religious views.

Albert Einstein wrote, "Kepler won the foundation for the determination of the three fundamental laws that will remain linked to his name for all time. How much inventive power, how much tireless, obstinate work was necessary to reveal these laws, and to establish their certainty with great precision -- naturally, can hardly be evaluated by anyone...

"He belonged, nevertheless, to those few who cannot do otherwise than openly acknowledge their convictions on every subject...

"Kepler was a pious Protestant, who made no secret of the fact that he did not approve all decisions of the church; he was, for this reason, looked on as a sort of moderate heretic, and treated accordingly". cq - 2 -

As a boy, Kepler's brilliance, particularly in mathematics and languages,  came to the attention of the Duke of Wuerttemberg who paid for his early education. Outstanding work at Latin school lead to a scholarship at the University of Tuebinger where he studied to become a Lutheran minister. There, a professor gave him a copy of Nicolaus Copernicus' book De Revolutionibus Orbium Coelestium, "The Revolutions of The Spheres".

This book argued that the earth is not the center of the universe but that planets revolve in perfect circles around the sun.

Astronomy fascinated Kepler.

"If God has any interest in astronomy-- a belief which demands piety-- I hope that I shall achieve something in this field," he said. cq - 3 -

A vision of order ruling the universe and of worlds majestically circling in geometric harmony captured Kepler's mind.

"God, like a human architect, approached the founding of the world according to order and rule and measured everything in the course of His creation," Kepler said. cq - 4 With this idea at the foundation of his thinking, Kepler renewed his vigorous studies concentrating on mathematics, astronomy and Scripture.

"There is nothing I want to find out and long to know with greater urgency than this," Kepler wrote, "Can I find God -- whom I can almost grasp with my own hands in looking at the universe -- also in myself?" cq - 5 -

His quest to find God in the universe and in himself lead him to discoveries which give his name prominence in modern physics textbooks, and which  brought him great joy -- though his family wanted him to study something more practical, something to earn a good income.

"What is the good of the knowledge of nature, of all astronomy, to a hungry stomach," he wrote? "Painters are allowed to go on with their work because they give joy to the eyes, musicians because they bring joy to the ears... He who fights against such joy fights against nature... Do we ask what profit the little bird hopes for in singing? We know that singing in itself is a joy to him because he was created for singing... Many types of living creatures... are capable of providing for themselves more ably than we. But our Creator wished us to push ahead from the appearance of the things which we see with our eyes to the first causes of their being in growth, although this may be of no immediate practical avail to us. The other creatures and the body of man are kept alive by taking food and drink. But man's soul is something quite different from the other part of man, and the soul is kept alive, enriched and grows by that food called knowledge. The man who does not long for these things is therefore more of a corpse than a living being. We are therefore well justified in saying that the variety of the phenomena of nature is so great, the hidden treasures in the dome of the universe so rich, that nature should never run short in material for the human spirit". cq- 6 -

In 1594, Kepler's final year at Tuebinger, the mathematics professor at the University of Graz, in Austria, died. Kepler, then age 23,  was appointed to replace him.

At the time, the great Ottoman Empire of the Turks sought to expand into Europe through Austria, seat of the Holy Roman Empire. Vicious wars erupted between the two world powers.

One horror of the conflict:

When the Turks captured Christian prisoners of war, they would load the hapless men into the mouths of great cannon and fire them back at the Christian armies. Intended to demoralize the Christians, this act of terrorism had the opposite effect. Seeing their buddies splat against the city walls, made the European soldiers feel a bit reluctant about surrendering and  being taken prisoner.

Seeing living men shot out of cannon barrels impressed Kepler's mind also; it dwelt in his memory -- to surface in a different form years later.

In 1596, when Kepler was only 25 years old, he published Prodomus Dissertationum Cosmographicarum Contines Mysterium Cosmographicum, "Harbinger of Inquires Concerning the Structure of the Universe and Concerning the Worldmystery". It provided a mathematical basis for Copernicus' argument that the earth and planets revolve around the sun. It was the first of 88 books Kepler was to write. cq - 7 -

In addition to teaching mathematics at the university, Kepler held the post of District Mathematician, which put him  in charge of surveying land, insuring merchants used honest weights and measures, setting the dates for religious holidays, forecasting weather and writing an almanac, Prognosticum Meterologicum, for farmers and businessmen.

Writing this almanac required the talents of an astrologer.

In later years, telling about poverty in his life, Kepler said, "In order to raise money... I wrote a cheap calendar with prognostications; this seemed at least a bit more decent than begging". cq - 8 -

When Kepler asked Michael Mastlin, his old professor at Tuebinger, about how to predict the future, he was advised, "Always predict disaster; it is certain to come true!"

 Kepler did cast astrological charts for his patrons; but he also wrote disclaimers such as this:

  "Truly in all my knowledge of astrology, I know not enough with certainty that I should dare predict with confidence any specific thing. Astrology is the foolish little daughter of mother astronomy...

“In the Bible, in Jeremiah we are told that we need in no way fear the signs of the heavens. In the tenth chapter of the same wise prophet we read: 'Be not dismayed at the signs of heaven; for the heathen are dismayed by them'...

 “Do not depend upon astrology. The heavens cannot do much harm to the stronger of two enemies, nor help the weaker much. He who strengthens himself with good advice and courage, also brings heaven on his side, and if the stars are unfavorable to him, he conquers them." cq - 9 -

While Kepler taught mathematics at Graz, geometric figures fascinated him, especially as they related to astronomy. He envisioned combining the relationships between the six solid geometric figures (the tetrahedron, a four-sided pyramid; the six-sided cube; the eight-sided octahedron; the 12-sided dodecahedron; the 20-sided icosahedron; and the sphere) within the orbits of the six planets known in his day.

He figured that if each geometric solid were nested within the others like a Chinese box, then the ratios between these would correspond to the ratios and distances between the planets and the sun within a perfect sphere.

Kepler’s Mysterium Cosomographicum ,  a mechanical model of the universe.

As a gift to the Duke of  Wuerttemberg, Kepler made a mechanical model of the known universe proportioned within the six geometric solids; he made it in the form of a urn which would dispense wine -- a different wine from a spout on each planet!

This curious devise, along with his skill at making calendars, brought him great notoriety.

Remember that in those days a patron's financial support paid a scientist's wages; therefore, many researchers had to prove their worth by great mental and inventive agility aside from their direct field of studies.

Seeing God's hand in the order of the created universe brought Kepler great satisfaction. "I thank Thee, my Creator and my Lord, that Thou hast given me this joy in thy creation, this thrill in the works of Thy hand," he said.cq - 10 -

Kepler's book on the structure of the universe was published the same year he married a young widow who already had several children.

His book brought him letters of commendation from the two greatest astronomers in the world: Galileo Galilei of Italy and Tycho Brahe of Denmark.

Kepler was now solidly launched in his new career as an astronomer.

"I had the intention of becoming a theologian," he wrote, "For a long time I was restless because my duties at Graz prevented me from becoming a preacher of the Gospel. But now I see how God is, by my endeavors, also glorified in astronomy." cq - 11 -

His marriage soon brought him his own first baby son.

When the infant fell ill, the physician used a new invention, a disk with a nail driven through the center and a string attached to the nail; it was a pulsilogia, or pulse counter, a device just invented by Galileo! cq - 12 -

But even with the aid of the new medical invention, the baby died. Although over the years Kepler was to father many other children, his firstborn's death hurt him deeply.

Shortly after the baby's death, Archduke Ferdinand, a staunch Catholic, became ruler of Austria. He gave all Protestants eight days to settle their affairs and leave the country.

"It is a great comfort that we are not burned, but allowed to live," Kepler wrote. cq - 13 -.

The Kepler family left in a flood of other refuges -- but a guard stopped Kepler at the border and forced him to return to Graz; the Archduke had decided that even though Kepler was a Lutheran, his skill as a calendar maker made him too valuable an asset to lose.

        Refugees flee during the 30 Years War

Similar bouts of exile and return, persecution and restoration,  marked Kepler's whole career. Perhaps the Hapsburg bankers influenced these events; their shipping interests depended largely on efficient navigation and Kepler's reputation for accurate astronomical observations grew to the extent that astronomers and navigators from as far away as China wrote to him for information concerning global shipping. cq - 14 -

As a staunch Christian, Kepler tried to get along with both Catholics and Protestants. "Regarding something as true, I am, nevertheless, able to tolerate others who are not of the same opinion," he said. cq - 15 -

Nevertheless, religious persecution hovered over his head all his life.

Catholic military and church authorities often inspected the books in his library and at times illiterate men culled his collection for books which looked suspicious. Sometimes, they locked up his books,  allowing him to read only when a priest could be in the same room with him. Once, they forced him to watch as they publicly burned copies of his own works.cq-16 -

"It is impossible for me to give up my belief in the Lutheran faith," Kepler wrote. "Yet I am unwilling to take part in this terrible controversy... I cannot remain in Graz."

A ray of hope!

Tycho Brahe had moved from Denmark to Prague. He was now Imperial Mathematician to Rudolph II, Holy Roman Emperor of Hungary and Bohemia, and the great astronomer was seeking a new assistant.

Kepler applied and was accepted. He and his family moved to Prague.

They left Graz on the first day of a new century, January 1, 1600, an auspicious day to begin a new career.

The extremely wealthy and flamboyant Tycho Brahe, world's greatest astronomer -- if you didn't believe it, just ask him -- proved to be a trifle eccentric.

As a university student, Tycho Brahe had fought a sword duel -- over the correct answer to a math problem -- and his adversary sliced his nose off!

Undaunted, the astronomer made several artificial noses out of either  wax, brass, silver or gold. He wore these, changing several times a day according to his mood.

As a pet, Tycho kept a tame elk in the house. He let it drink beer from a bowl on his dinning room table.

The day Kepler arrived in Prague, Tycho's elk drank too much,  fell down a staircase, broke its legs and died --  an inauspicious event on which to begin a new career.! cq - 17 -

In spite of his eccentricities, Tycho Brahe's work as a scientist  changed mankind's perception of the sky. Before him, people believed Aristotle's idea that the heavens were unchangeable, but he observed and documented a super nova in the constellation of Cassiopeia, proving that even "fixed" stars are born and die.

Tycho designed and build an observatory where he assembled and refined the finest collection of astronomical instruments of his day. These included a brass globe five-feet across which pinpointed the positions of 777 stars, and a quadrant taller than a house which was so delicately balanced that it could be moved with a fingertip and so accurate that it could measure the distance between stars within one-sixth of a minute of arc.

While in Denmark, Tycho had marshaled a research team made up of Europe's brightest  astronomy students and lead them in recording precision measurements of astronomical phenomena every night for over 20 years!

Now in Prague, he assigned Kepler to the job of organizing these reams of raw data and abstracting information related to the orbit of Mars, a job which outlasted Tycho's lifetime.

Before Kepler could organize the information, he had to solve the problem of how a ray of light coming from a distant heavenly body located in the less dense regions of outer space is deflected when it enters earth's dense atmosphere. As he studied atmospheric refraction, Kepler analyzed the process of human vision. He published Concerning Optical Astronomy in 1604, providing the foundation for all further advances in the understanding of the structure and function of the human eye.

He also pioneered the use of logarithms in calculating astronomical observations and invented a mechanical calculating machine. Even with optical discoveries, the mechanical calculator and logarithms, it took Kepler 28 years to systematize Tycho Brahe's raw data. Kepler published this foundational navigational data as the Rudolphine Tables in 1628.

But, in 1600, while he still worked for Tycho Brahe, Kepler became friends with Rudolph II, Holy Roman Emperor.

He noticed that the Emperor's staff had a problem keeping the royal palace floors clean.

Kepler invented an odd machine, a billows with attached sections of leather hose. One servant pumped the billows, another stroked the end of the hose over the floor and Kepler's devise created a vacuum which sucked up dirt, dust and litter as if by magic! Shades of Electrolux!

The Emperor devoted much time to collecting art, studying  natural history oddities and discussing mental puzzles with his friends. Kepler's talent, good humor and quick wit impressed him.

When Tycho Brahe died one year after Kepler joined him, the Emperor appointed Kepler to the position of Imperial Mathematician of the Holy Roman Empire in Tycho's place -- but with only 1/5 of Tycho's salary. Tycho's relatives inherited his astronomical instruments but, after a legal battle with the heirs, the Emperor granted Kepler the right to keep the raw data Tycho had gathered.

Three years later Rudolph II was dethroned by his brother, Matthias, who plunged Europe into what history calls the Thirty Years War.

Kepler loyally maintained his friendship with the deposed Rudolph; yet the new Emperor reaffirmed Kepler in his office as Imperial Mathematician. Because of religious persecution in Prague, Kepler moved his family to the Catholic, but more tolerant, city of Linz, Austria.

The constant swirl of wars in those years-- the Turkish invasion,  European factions fighting, Protestants versus Catholics, the Peasants' Rebellion --  brought out a different element in Kepler's character. Since he had once studied medicine, since he believed in Christian charity, and since so many horribly mangled soldiers surrounded him, Kepler began taking the wounded into his home and personally nursing them. The astronomer was assisted in this ministry of mercy by his wife and by a dwarf who had been the fool entertaining in Tycho's castle.

Christian belief, physical science and brotherly love in action all appear as different facets of the same diamond in Kepler's thinking; in his Harmony of the World he wrote:

“While I struggle to bring forth this process (the ratios of the spheres and the eccentricities of the single planets) into the light of human intellect by means of the elementary form customary with geometers, may the Author of the heavens be favorable, the Father of intellects, the Bestower of mortal senses, Himself immortal and superblessed, and may He prevent the darkness of our mind from bringing forth in this work anything unworthy of His Majesty, and may He effect that we, the imitators of God by the help of the Holy Ghost, should rival the perfection of His works in sanctity of life, for which He choose His church throughout the earth and, by the blood of His son, cleansed it from sins, and that we should keep at a distance all the discords of enmity, all contentions, rivalries, anger, quarrels, dissensions, sects, envy, provocations, and Text Box:  Victims of religious persecution in 30 Years War 1irritations arising through mocking speech and the other works of the flesh; and that along with myself, all who possess the spirit of Christ will not only desire but will also strive by deeds to express and make sure their calling, by spurning all crooked morals of all kinds... Holy father, keep us safe in the concord of our love for one another, that we may be one, just as Thou art one with thy Son, Our Lord, and with the Holy Ghost, and just as through the sweetest bonds of harmonies Thou hast made all Thy works one; and that from the bringing of Thy people into concord the body of Thy Church may be built up in the Earth, as Thou didst erect the heavens themselves out of harmonies. cq - 18 -

Kepler believed that God is a God of order; he saw order and planning in all aspects of the universe, he saw geometry and intelligence at work in everything from "the edges of leaves, the scales of fishes, the skins of beasts and their spots, the spiral of a snail's shell" to what he called "the dance of the worlds".

Thoughts about God's order in the universe thrilled Kepler.

"To God there are, in the whole material world, material laws, figures and relations of special excellency and of the most appropriate order," he said. "Those laws are within the grasp of the human mind; God wanted us to recognize them by creating us after his own image so that we could share in his own thoughts". cq - 19 -

His sense of awe at seeing what he called "God's footprints in creation" lead him to worship. He said he felt a "divine ravishment in investigating the works of God". cq - 20 -

Kepler saw world-forming relationships in musical harmony and rhythm, in blends of colors, in smells and tastes, in rules of architecture, painting and poetry, in the pedals of flowers, in the complexities of a honeycomb, in the cocoon of the silkworm, and in the orbits of planets.

"For He who is before the ages and on into the ages thus adorned the great things of His wisdom: nothing excessive, nothing defective, no room for any censure. How lovely are His works! He has strengthened the goods-- adornment and propriety-- of each and every one and established them in the best reasons. Who will be satiated seeing their glory?" he wrote. cq - 21 -

His attitude lead him to conclude: "There are physical laws of nature which the planets obey, and these laws can be used to predict their motion". cq - 22 - Therefore, Kepler introduced science to the idea of gathering data first, then seeing what common patterns develop.

Aristotle taught that Earth was the center of the universe and that the sun, stars  and planets revolved around it. Copernicus thought that the sun was the center and that planets revolved around it in perfect circles. Tycho combined these theories saying that the sun revolved around the earth while the other planets circled the sun.

Kepler credited God with more common sense than that. Using a quaint analogy from the kitchen, Kepler said that even the most stupid cook does not move the fire around the roast, he lights the fire in one place and rotates the meat!

 "The perfection of the world consists in light, heat, movement, and in harmony of movements," Kepler said.

 "For as regards light, since the sun is very beautiful with light and is as if the eye of the world, like a source of light or very brilliant torch, the sun illuminates, paints, and adorns the bodies of the rest of the world; the intermediate space is not itself light-giving, but light-filled and transparent and the channel through which light is conducted from its source, and there exists in this region the globes and the creatures upon which the light of the sun is poured and which make use of this light. The sphere of the fixed stars plays the role of the riverbed in which this river of light runs, and is as it were an opaque and illuminated wall, reflecting and doubling the light of the sun...

“As regards heat, the sun is the fireplace of the world; the globes in the intermediate space warm themselves at this fireplace, and the sphere of the fixed stars keeps the heat from flowing out, like a wall of the world, or a skin or a garment -- to use the metaphor of the Psalm of David...

“As regards movement, the sun is the first cause of movement of the planets and the first mover of the universe, even by reason of its own body...

“As regards the harmony of the movements, the sun occupies that place in which alone the movements of the planets give the appearance of magnitudes harmonically proportioned... Since the earth and its surface -- where the eye is -- are not situated at the center of each sphere; therefore if the spheres were solid, that is to say far more dense... then the rays of the stars would be refracted before they reached our air, as optics teaches, and so the planets would appear irregularly and in places far different from those which could be predicted by the astromomer.cq-23-

Kepler learned -- and taught others to the present day -- how to accurately find the precise location of a planet in its orbit.

In 1609, in Astronomia Nova (New Astronomy),  Kepler published his first two laws of planetary movement, cornerstones of modern astronomy.

John Lear, science editor of the Saturday Review, wrote:

 "Kepler saw that the speed with which a planet traversed its ellipse varied in a regular pattern, accelerating with approach to the sun and decelerating with departure from the sun. By refining the mathematics he used to determine those movements, Kepler could tell where any planet would be in relation to any other planet at any chosen moment, and consequently in what direction and how far an expedition from one planet to another would have to proceed...

 "Three hundred and fifty-three years would have to pass before metals could be alloyed for spaceship hulls, fuels developed for propulsion of those hulls, and electric controls devised for guidance of an actual interplanetary passage from earth to Venus by the robot named Mariner II. But Kepler began to elucidate the scientific problems entailed in such voyages". cq - 24 -

By observing the orbit of Mars, Kepler calculated the distance between that planet and the sun at various times of the year.

"The matter is obviously this," he said, "The planetary orbit is no circle; to both sides it goes inward and then outward until in the perihelion the circle is reached again. Such a figure is called an oval". cq - 25 -

"The routes or single circuits of the planets are not arranged in a perfect circle but are ellipses," Kepler said. cq - 26 -

Modern physics books call this discovery Kepler's First Law of Planetary Motion: The paths of the planets are ellipses with the sun at one focus.cq-27 -

When Kepler realized that the orbit of Mars is an ellipse, he said, "It was as if I awoke from sleep and saw a new light!" cq - 28 -

Science historian Antonie Pannekoek said, "As the first triumph of the empirical study of nature, Kepler's result stands at the entrance of modern scientific research...

"In Tycho Brahe's and Kepler's work the new method of scientific research is embodied -- the method of collecting data from experiment and observation, and from them deriving rules and laws which form the body of science". cq - 29 –

Kepler's Laws of Planetary Motion. The three laws which explain the motion of objects in elliptical orbits, developed by Johannes Kepler  and announced by him in 1609 and in 1618. The rules apply to any body in circular or elliptical orbit around the Sun. Equally, the rules also apply to satellites, both natural and artificial, in orbit around a planet. The first rule states that planets move in elliptical orbits with the Sun placed at one focus. Rule two states that equal areas are swept out in equal times, so the planets must be traveling faster when they are closer to the Sun. Rule three states that the square of the planet's orbital period is proportional to the cube of its mean orbital radius from the Sun

Kepler's Second Law of Planetary Movement is that of the radius vector: that is that an imaginary  line from a planet's center to the sun takes the same amount of time to move over equal areas of the ellipse of its orbit. A straight line joining a planet with the sun sweeps out equal areas in equal intervals of time.

If t = time; and A = area, then t1 = t2 and A1 = A2

An imaginary line from earth to the sun sweeps out equal areas each second whether Earth is close to or far from the sun. cq - 30 -

Kepler's Third Law is called the law of period. Period is the time it takes a planet to orbit the sun and return to the same place. Earth's period is 365 days, one year.

Kepler's Third Law states that the square of a planet's period of revolution is proportionate to the cube of its mean distance from the sun.

The ratio of the squares of the periods of any two planets revolving about the sun is equal to the ratio of the cubes of their average distances from the sun. Thus if Ta and Tb are their periods and ra and rb are their average distances, then

Ta 2 = ra 3

Tb     rb

Kepler published his third law in Harmonice Mundi in 1619. It is used by modern astrophysicists to compare the distances and periods of the planets about the sun or the distances and periods of the moon and artificial satellites around the earth, or, in the case of probes to distant planets, around other worlds. cq - 31 -

Kepler's laws describe the behavior of every planet as well as every artificial satellite. In fact, he coined the word "satellite" to describe a body moving around a planet.

Kepler credited the mathematical precision found in the movement of bodies through space to God:

"The ratio of the periodic times seems to be the work of a mind and not of material necessity," he wrote. “The most accurately harmonic attunement of the extreme movements -- the slowest and the fastest movement in any given planet -- is the work of the highest and most adored creator Mind or Wisdom...

“Because it is apparent that in so far as any planet is more distant from the sun than the rest, it moves more slowly -- so that the ratio of the periodic times is the ratio of the 3/2th powers of the distances from the sun." cq - 32 -

But wouldn't measuring the enormous distances between the planets and between the stars, make any astronomer feel that mankind is only an insignificant dot in the scheme of things?

Not necessarily.

"We should feel less astonished at the huge and almost endless width of the heavens than at the smallness of us human beings, the smallness of this, our tiny ball of earth," Kepler said, "The world is not immeasurable to God; but to God we are puny, compared to this world... Yet one must not infer from bigness to special importance. For God who lives above, still looks down at the humble... Else, yes, the crocodile or the elephant would be closer to God's heart than man." cq - 33 -

In 1620, Kepler published his treatise on comets in which he noted that the tail of a comet always streams away from the sun. He said that this was caused by the material in the comet's head being pushed away by the sun's light, the pressure of radiation.

"Kepler was on the track of a form of energy that may possibly be used to power spacecraft in the not too distant future," said science historian Charles-Albert Reichen, "This great astronomer had replaced the rather vague Copernican scheme of planetary motions with a precise definition of the workings of the solar system which in many aspects is still valid today and plays its part in the intricate calculations of modern astronautically engineers". cq - 34 -

When Kepler lectured to groups about his complex ideas, he illustrated his talks with an odd devise:

"Whenever men or women came together to watch me, first while they were engaged in conversation, I used to hide myself from them in a nearby corner of the house, which had been chosen for this demonstration. I cut out the daylight, constructed a tiny window out of a very small opening, and hung a white sheet on the wall. Having finished these preparations, I called in the spectators... In capital letters I wrote with chalk on a black board what I thought suited the spectators. The shape of the letters was backwards as Hebrew is written. I hung this board with the letters upside down in the open air outside in the sunshine. As a result, what I had written was projected right side up on the white wall within. If a breeze disturbed the boards outside, the letters inside wiggled to and fro on the wall in an irregular motion. cq - 35 -

Kepler's visions of space travel and his  camera obscura with its "letters of fire" played a prominent part in his mother's witchcraft trials.

Although his Somnium, Sive Astronomia Lunaris hardly rivals 2001: A Space Odyssey, literary critics view his book as the forerunner of the modern science fiction novel.

In it the hero, Duracotus, a fictional former  student of Tycho Brahe, travels to the moon where he makes astronomical observations.

Notice a few of Kepler's observations about astronauts and space travel:

"For men the passage is exceedingly difficult and made at grave risk to life. No inactive persons are accepted into our company; no fat ones... No Germans are suitable," he wrote. His footnote explains, "I had reference here to an epigram with which I made fun of the bodily type of Mastlin (his former physics professor in Germany)... "We Germans have a reputation for corpulence and gluttony."

Text Box: A giant artillery  shell fired to the moon; an Illustration from Verne's 1868 novel. 1A traveler to the moon would find, "The first getting into motion is very hard on him, for he is twisted and turned just as if shot from a cannon". Perhaps Kepler was remembering the effect of seeing Turks shoot Christian soldiers from cannon. Centuries later in 1868, science fiction writer Jules Verne also transported his American Civil War astronauts to the moon inside a shell fired from a giant cannon.

Kepler said the space traveler, "Must be arranged, limb by limb, so that the shock will be distributed over the individual members, lest the upper part of his body be carried away from the fundament, or his head be torn from his shoulders. Then comes a new difficulty: the terrific cold and difficulty in breathing."

Kepler suggests that his astronauts carry oxygen stored in "moistened sponges applied to the nostrils" and that they cushion their bodies by curling up on a couch for the trip.

He says that after the initial blast-off and escape from earth's gravity, the pull of the moon would eliminate the need for further propulsion: "As soon as the body approaches slightly closer to the moon, the body will follow the gravitational pull of the moon whose force has become predominant".

He foresaw weightlessness in space:

"That is certainly the case when the body has been carried so far beyond the region of earth's magnetic force that the lunar globe's magnetic force is already preponderant. When the magnetic forces of earth and moon are canceled out by the opposing attractions, it is as though nothing pulled the body in any direction." cq - 36 -

He foresaw need of a breaking force for lunar landings, "Lest some damage be inflicted by a very hard impact on the moon." cq - 37 -

He predicted a need for specialists in space medicine:

"Let the traveler see to it that he arrives in such an unharmed condition that he can awaken. The allegory here furnishes an approved medicine for those who are bound against natural motions". cq - 38 -

"Let somebody else look after the safety of the traveler, lest he be torn to pieces regardless of whether he is asleep or awake". cq - 39 -

Kepler assumed that the circular formations which we call meteor craters on the moon were constructed by intelligent moon creatures:

"In the year 1623, on July 17, the day being considered as starting at midnight, I watched the moon from 1 a.m. to 2 a.m. using Father Niccolo Zucchi's lenses, which have a very long range. Most of the hollows looked round. But in the upper and lower part of the moon they appeared almost elliptical, according as the convex globe vanished from view. Looking like the crescent moon, the shadows of the valleys in certain cases were clearly the result of ellipses turned sideways, so that from this circumstance you would readily recognize the convexity of the moon's sphere by mere inspection. Interspersed in the lower spotted parts were some bright circles, embracing hollows and shadows within themselves. Yet these circles were few. You would call them swampy or slimy parts of the moon." cq - 40 -

Kepler thought these circles might be dikes to hold back lunar seas. "The technique of getting rid of the water which was inside the rampart was taught to those moon-dwellers, I suppose, by our Dutchmen," he jokes.

But how did the moon-dwellers scribe these huge circles?

Again Kepler resorts to humor, "Do not say that a circle having a radius of five miles can be described with a continuous swing of one leg of a compass -- unless a draftsman at least 20-miles tall is available".cq- 41 -

The biggest problem in interplanetary travel that Kepler foresaw was the problem of propulsion across the space between planets. He suggested that light rays from the sun have force and might be harnessed to sail ships across the void. Shades of Arthur C. Clarke!

Writing to Galileo, Kepler said, "Provide ship or sails adapted to the heavenly breezes, and there will be some who will not fear even that void... So, for those who will come shortly to attempt this journey, let us establish the astronomy: Galileo, you of Jupiter; I of the moon... cq 42

"There will certainly be no lack of human pioneers when we have mastered the art of flight. In the meantime, we shall prepare for the brave sky-travelers maps of the celestial bodies". cq 43

But in writing his Somnium Kepler did not tell about light rays propelling a sun-riggers to the moon; in his story the mother of Duracotus is a witch who conjures up a demon to propel him on his journey.

Although Kepler clearly labels his story as a work of fiction not autobiography -- and lest anyone wonder about that, he illustrates the 76-page book with 223 explanatory footnotes -- nevertheless, his enemies interpreted the witch in their pirated copy of the story to be Kepler's own mother.

They arrested her after finding 49 specific complaints about her dabbling in witchcraft.

The 17th Century records reveal a bit of bias: "The accused appeared in court, accompanied, alas, by her son, Johannes Kepler, mathematician".cq- 44 -

He insisted that the magistrates use scientific method, gathering data and observing facts before drawing conclusions, in judging the case. He traveled all over the district gathering specific information on each one of the 49 charges.

He discovered that the barber's wife had gotten pregnant while her husband was away and that she had an abortion -- witchcraft had nothing to do with her illness. The butcher's pain came from years of suffering from arthritis -- no witchcraft. The tailor's two children died of smallpox -- not witchcraft. cq - 45 -

Kepler traced down the source and circumstances for each individual charge. The magistrates reluctantly agreed that when the facts were fully known, witchcraft could not be the cause on any complaint against her.

The Lutheran authorities freed Mrs. Kepler on October 4, 1621, but she died soon afterwards as a result of privation during her ordeal.

That same year, the Catholic church listed Kepler's Epitome of Copernican Astronomy was listed for censorship in the Index of banned books. cq - 46 -

But Lutheran pastors refused to allow him to take communion because he refused to sign a document condemning Roman Catholics as non-Christian people.

In a letter to Michael Mastlin, his former teacher, Kepler wrote, "I will not take part in the fury of the theologians. I will not stand as a judge over my brethren; for whether they stand or fall, they are brethren of mine in the Lord. As I am not a teacher of the Church, it will suit me better to pardon others and think well of them rather than accuse and misinterpret them". cq - 47 -

In a letter to a Lutheran theologian, he wrote, "It is not sophistry but brotherly love if I do not want to condemn those who want to adhere to the old teachings but would follow them rather than the Formula of Concord in the article about Christ as person. I know that your adversaries have sinned against love; but that is not my concern. I know that we have to be good to our enemy and to love those who hate us, that is, that we should examine their dictum regardless of their having sinned against love". cq - 48 -

His personal faith in Christ and his tolerance of other Christians even when they persecuted him drew the ire of many enemies. But he refused to act hypocritically in order to gain favor.

When his faith was challenged, he said, "I am a Christian. I am earnest with my religion. I don't play with it."  cq - 49 -

"Whatever I profess outwardly, that I believe inwardly," he said.cq- 50 -

As a scientist and as a serious Bible scholar  Kepler saw no conflict between the two disciplines; like Galileo he believed, "The Holy Scriptures teach how to go to Heaven, not how the heavens go."

Kepler said, "I believe that together with the Holy Scriptures came the book of Nature."

A "new star"

Kepler, Johann, 1571-1630.
De stella nova in pede serpentarii, et qui sub ejus exortum de novo iniit, Trigono Igneo. Prague: Ex Officina calcographica Pauli Sessii, 1606.
First edition of a work dealing with the occurrence of a "new star" in 1604/5. Bound in 18th century half morocco and marbled paper boards. Gift of Lewis Strauss to the Lauinger Library, Georgetown University.

In his final years, Johannes Kepler, using his knowledge of optics, improved the design of the telescope (which Galileo had invented) by replacing the eyepiece with two matched convex lenses. His improved design became the preferred model for astronomical use.

He also calculated the weight of air and the value of refraction. He invented a method to measure the volume of liquids in irregularly shaped containers, such as wine kegs with tapered ends. But his most lasting contribution to science remain his three laws of planetary motion.

Most of his life, Kepler lived in poverty because although the emperors gave him an important-sounding title and the promise of comfortable income, they seldom actually paid his salary.

Yet, Kepler was a happy man.

His God and his science made him so.

"If there is anything that can bind the heavenly mind of man to this dusty exile of our earthly home and can reconcile us with our fate so that one can enjoy living -- then it is verily the enjoyment of the mathematical sciences and astronomy," he said. cq - 51 -

Kepler died on November 15, 1630 in Regensburg, Germany, while trying to collect back salary.

Lutheran pastor Christopher Donauer attended his death-bed. He recorded that when asked about his hope of salvation, Kepler said, "Only and alone in the service of Jesus Christ; in Him is all refuge, all solace".   cq 52

Kepler's last words to his son-in-law, who also attended his death, were, "Tell them that the laws of motion are the same for all bodies; the physics of the heavens and the physics of earth are the same" cq - 53 -

Johannes Kepler was buried on November 18, 1630 --

                The following night there was a total eclipse of the moon.

NASA astronomers named this impact crater on the moon “Kepler” in his honor.

Endnotes & Bibliography Follow


Thank you for visiting  
I welcome your comments at John’s Blog!
You can E-mail me at
Return to John’s Home Page
              You can view my published works at 



cq - 1 - Lear, John. Kepler's Dream, page 30.

cq - 2 - Baumgardt, Carola. Johannes Kepler: Life and Letters page 12.

cq - 3 - Baumgardt, Ibid, page 66.

cq - 4 - Baumgardt, Ibid, page 33.

cq - 5 - Baumgardt, Ibid, page 115.

cq - 6 - Baumgardt, Ibid, page 35.

cq - 7 - Reichen, Charles-Albert. A History of Astronomy. page  49.

cq - 8 - Baumgardt, Carola. Op Cit., page 130.

cq - 9 - Tiner, John. Johannes Kepler: Giant of Faith and Science. page 67-69.

cq- 10 - Rehwinkel, Alfred. The Flood, page i.

cq- 11 - Tiner, John. Op. Cit., page 85.

cq- 12 - Rosen, Sidney. The Harmonious World of Johann Kepler. page 84.

cq- 13 - Baumgardt, Carola. Op Cit., page 154.

cq- 14 - Lear, John. Op Cit.,  page 33.

cq- 15 - Baumgardt, Carola. Op Cit., page 85.

cq- 16 - Baumgardt, Ibid, page 150.

cq- 17 - Banville, John. Kepler, page 52.

cq- 18 - Kepler, Johannes. The Harmonies of the World, page 1050.

cq- 19 - Baumgardt, Carola. Op Cit., page 50.

cq- 20 - Kepler, Johannes. Epitome of Copernican Astronomy, page 849.

cq- 21 - Kepler, Johannes. The Harmonies of the World, page 1071.

cq- 22 - Rosen, Sidney. Op. Cit., page 134.

cq- 23 - Kepler, Johannes. Epitome of Copernican Astronomy, pages 855-857.

cq- 24 - Lear, John. Op Cit.,  page 2.

cq- 25 - Pannekoek, Antonie. History of Astronomy, page 241.

cq- 26 - Kepler, Johannes. Epitome of Copernican Astronomy, page 929.

cq- 27 - Zitzewitz & Murphy. Physics: Principles and Problems, page 130.

cq- 28 - Pannekoek, Antonie. Op. Cit., page 241.

cq- 29 - Pannekoek, Antonie. Ibid, pages 241 - 242.

cq- 30 - Zitzewitz & Murphy, Op. Cit., page 130.

cq- 31 - Zitzewitz & Murphy, Ibid, page 131.

cq- 32 - Kepler, Johannes. Epitome of Copernican Astronomy, page 895.

cq- 33 - Baumgardt, Carola. Op Cit., page 49.

cq- 34 - Reichen, Charles-Albert. Op. Cit., page 45.

cq- 35 - Rosen, Edward. Kepler's Somnium, page 57.

cq- 36 - Rosen, Edward. Kepler's Somnium, page 73.

cq- 37 - Lear, John. Op Cit.,  page 108.

cq- 38 - Lear, John. Ibid,  page 109.

cq- 39 - Rosen, Edward. Kepler's Somnium, page 71.

cq- 40 - Rosen, Edward. Kepler's Somnium, page 166.

cq- 41 - Rosen, Edward. Kepler's Somnium, page 170.

cq- 42 - Lear, John. Op Cit.,  page 3.

cq- 43 - Tiner, John. Op. Cit., page 152.

cq- 44 - Tinner, John. Ibid,  page 180.

cq- 45 - Lear, John. Op Cit.,  page 29 - 37.

cq- 46 - Rosen, Sidney. Op. Cit., page 178.

cq- 47 - Baumgardt, Carola. Op Cit., page 107.

cq- 48 - Baumgardt, Ibid, page  109.

cq- 49 - Tiner, John. Op. Cit., page 114.

cq- 50 - Kepler, Johannes. Epitome of Copernican Astronomy, page 850.

cq- 51 - Baumgardt, Carola. Op Cit., page 190.

cq- 52 - Tiner, John. Op. Cit., page 193.

cq- 53 - Rosen, Sidney. Op. Cit. page 205.


              Banville, John. Kepler. Boston: David R. Godine Publisher, c.1983.

192 pages.

              Baumgardt, Carola. Johannes Kepler: Life and Letters with an introduction by Albert Einstein. New York: Philosophical Library, c.1951. 209 pages. Index.

              Kepler, Johannes. Epitome of Copernican Astronomy. Vol. XVI of Great Books of The Western World. Chicago:  Encyclopðdia Britannica Inc. c.1952.

              Kepler, Johannes. The Harmonies of the World. Vol. XVI of Great Books of The Western World. Chicago: Encyclopðdia Britannica Inc. c.1952.

              "Kepler, Johannes". Encyclopðdia Britannica, 15th Edition. c.1978.

              "Kepler, Johannes". New Encyclopedia of Science Fiction. Edited by James Gunn. New York: Viking Press. c.1988.

              Lear, John. Kepler's Dream: with the full text and notes of Somnium, Sive Astronomia Lunaris by Joannis Kepleri.  Translated by Patricia Frueh Kirkwood. Berkely: University of California Press, c.1965. 182 pages.

              Pannekoek, Antonie. A History of Astronomy. London: George Allen & Unwin Ltd., c.1969. Translated from De Groei van ons Wereldbeeld published by Wereld-Bibliotheck, Amsterdam. c.1951. 521 pages. Index. Illus.

              Rehwinkel, Alfred. The Flood. St. Louis, Missouri: Concordia Publishing House,  c.1951.

              Reichen, Charles-Albert. A History of Astronomy. New York: Hawthorn Books Inc., c.1968. 104 pages.

              Rosen, Edward (Translator) Kepler's Somnium: The Dream, or Posthumous Work on Lunar Astronomy. Madison, Wisc.: University of Wisconsin Press, c.1967. 255 pages. Index.

              Rosen, Edward. "Kepler and Witchcraft Trials". Historian (1966). Vol. 28: 447-450.

              Rosen, Sidney. The Harmonious World of Johann Kepler. Boston: Little, Brown and Company, c.1962. 212 pages. Index.

              Small, Robert An Account of the Astronomical Discoveries of Kepler: A reprinting of the 1804 text with a forward by William D. Stahlman. Madison, Wisconsin: University of Wisconsin Press, c.1963. (first published by T. Gillet, London, 1804). 386 pages. Index.

              Tiner, John Hudson. Johannes Kepler: Giant of Faith and Science. Milford, Michigan: Mott Media,  c.1977. 202 pages. Index.

              Zitzewitz, Paul W. and Murphy, James T. Physics: Principles and Problems. Columbus, Ohio: Merrill Publishing Co., c.1990. 590 pages. Index.



Thank you for visiting  
I welcome your comments at John’s Blog!
You can E-mail me at
Return to John’s Home Page
              You can view my published works at