Johannes Kepler was born on December 27, 1571 in Weil der Stadt, Germany.  Kepler’s father was a soldier and was not home for most of his life, and his mother was a quick tempered woman.  It was Kepler’s mother however who sparked Kepler’s interest in astronomy when she pointed out a passing comet to Kepler in 1577.   As a child Kepler was frail, and suffered from nearsighted and double vision (most likely caused by smallpox), abdominal problems, and “crippled” fingers.  Kepler earned a scholarship to Schreibschule in Leonburg where he was picked on for being handicapped, but this drove him to sanctuary in religion which always remained a source of motivation in his research.  In 1587 Kepler attended Tubingen University, where he studied theology and philosophy, and also studied mathematics and astronomy on the side.  Kepler was always a supporter of the Copernican heliocentric theory and would often engage in public debates on the topic.  At the age of 22 Kepler deserted the ministry school in order to pursue science, specifically mathematics and astronomy, at a Protestant school in Graz, Austria.

         In Graz Kepler created astrology calendars in order to earn money, because during his time astrology and astronomy were inseparable and it was expected from men in his field to create such calendars.  The first calendar Kepler printed predicted an unusually harsh winter and the Turkish incursion.  Since both of these events took place he was then hailed as a prophet.   However it is ironic that Kepler believed that astrology was the “foolish little daughter of astronomy.”  He also stated that, “If ever astrologers are correct, it ought to be credited to luck.”  So Kepler himself did not believe in his own predictions, he just created them for a source of income.

                     Kepler (right) and Barbara Muller (left)

        Also while in Graz, Kepler married Barbara Müller in April 1957.  Even though Kepler was not a believer in astrology he notedthat the wedding took place under an unfavorable constellation, which he attributed to the problems the marriage would encounter.  The first catastrophe of the marriage was that the first two children born died young, and this brought much grief to Kepler. He occupied himself with his work and tried to shut himself away, and during this time he wrote Mystery of the Cosmos.  Due to his constant occupation his wife described Kepler as, “fat, confused, and simple minded” in her diary.  In 1598 the Catholic archduke ordered that all Lutherans (Kepler was a Lutheran) to leave Graz in his effort to turn Austria into a Catholic country, so Kepler and his wife moved to Prague.

        In Prague Kepler visited Tycho Brache’s Benatky Castle where Tycho Brache, the imperial mathematician, offered him an assistant’s job.  Brache was also very wealthy and Kepler felt that he was “…superlatively rich, but he knows not how to make proper use of it, as is the case with most rich people.  Therefore, one must try to wrest his riches from him.”  Brache also had enormous amounts of data of the positions of the planets; however Brache lacked the mathematical and analytical skills to use it.  So Kepler was giving the job of analyzing and putting together a non-Copernican model of the planetary system.  This went against Kepler’s idea, as he supported a Copernican model, and so this assignment brought him much anger and frustration.  To calm his raging assistant, Brache assigned Kepler the task of determining the orbit of Mars, which had been perplexing Brache himself.  Although Kepler estimated this assignment would take 8 days, in reality it took him 8 years to finish the project.  Kepler concluded that the orbit of Mars was an ellipse, and this led Kepler to create his first and second laws of planetary motion.  These laws were published in 1609 in his book titled The New Astronomy.   After a year and a half passed since Kepler’s work with Brache, Brache developed a bladder infection and died within a few days.
Tycho Brache
        After Brache’s death Kepler was granted the position of imperial mathematician and Kepler took this opportunity to possess the data that Brache had recorded.  In his own words,

“I confess that when Tycho died, I quickly took advantage of the absence, or lack or circumspection, of the heirs, by taking the observations under my care, or perhaps usurping them.”

         Kepler took the 30 years of observations and published them in 1627 as Rudolphine Tables.  Kepler used this data and logarithms that he created to predict planetary positions, such as the transits of the sun by Mercury and Venus (sadly he did not live to witness them).  Kepler also witnessed a nova which would become known as “Kepler’s nova.”  In 1605 Kepler created the 1st Law of Planetary Motion, which stated that the planets moved in an ellipse with the sun at one focus.  Soon he also discovered that the Earth was closet to the sun in January and farthest in July.  Soon after the 1st Law, he established his 2nd Law of Planetary Motion or the law of equal squares.  This law stated that if a line were drawn from the sun to a planet it would divide the space into two equal areas in equal times.  It was at this time that he also began research in optics and published Dioptrices in 1611.  In the midst of gaining credit as a scientist, many tragedies would soon befall him.

        The first misfortune was that his marriage of 14 years ended when his wife died of typhus.  The second was that his favorite son also died around the same time.  In addition to the family problems he was forced to leave Prague due to religious upheavals and move to Linz.  Soon after the move Kepler was forced to defend his mother in court, who was being charged with witchcraft. In Linz he married his second wife Susanna Reuttinger, who was a 24 year old orphan, and gave birth to seven children, and only two survived to adulthood. After the upheaval in his life passed, Kepler wrote another book titled Harmonies of the World, which included his 3rd Law of Planetary motion.  This law stated that cubes of mean distances of the plants from the sun are proportional to the squares of their periods of revolution.  So basically Kepler deciphered how planets orbit, and this concept would be explained 60 years later by Isaac Newton and his laws of gravitation.

        The 30 Year War started in 1618 Kepler moved to Sagan, Silesia.  Here he wrote his final book which was a sort of science fiction novel called Dream of the Moon.  The story is an interview with an all knowing demon who explains how a protagonist could travel to the moon.  In 1630, Kepler was in poor financial situation and in pursuit of trying to collect an owed debt he became ill and died.  Kepler wrote his own epitaph as the following:
“I used to measure the heavens; now I shall measure the shadows of  the Earth. Although my soul was from heaven, the shadow of my body lies here.”