"…who had devoted himself passionately to the pursuit of deep insight into the nature of natural incidents, and who, despite all inner and outer difficulties also reached his high aim." Albert Einstein in a pretext of a book about Johannes Kepler, 1949 |

## Short life history: Johannes Kepler* December 27, 1571 Weil der Stadt, †November 15, 1630 Regensburg Johannes Kepler was born as child of protestant parents. He had six siblings, three of which died already at an early age. His father Heinrich Kepler, a learned merchant, hired out as mercenary soldier and scarcely was at home. When being a child Johannes fell ill with pocks, as a result of which he suffered from an eye illness and scars. In 1576 the family moved to Leonberg where Johannes attended first the German School and then the Latin School. In 1583 he passed the exam in Stuttgart and in 1584 he went to seminar Adelberg, a convent school. Two years later he was accepted at a higher seminar in Maulbronn, also a convent school. Made possible through a scholarship he began in 1589 with his studies in theology at the University of Tuebingen. At this university also In Graz the task of a
landscape mathematician was to write astrological calendars. Kepler
was very good in it and became quickly famous through his
horoscopes. He continued to study mathematics and was busy with
astronomical problems. In 1596 he published In April 1597 he married
Barbara Mueller. In the course of the counter-reformation in
September 1598, all protestant clerics and teachers were driven out
of Styria. Kepler had to leave the country. After some interim
stops, he went in 1600 to the mathematician and court astronomer Tycho Brahe was working for Emperor Rudolf II and had both the most exact empiric data and the most exact measuring instruments of his time. Kepler was assistant of Brahe and there he saw the possibility to test his astronomical theories empirically. As Brahe was more convinced of the geocentric world view and Kepler more of the heliocentric one their teamwork was disturbed. In the geocentric world view the earth, and not the sun is at the centre of the solar system. The deeply different characters of the two men added to this conflict. Thus for Kepler it was really difficult to get Brahe’s observation data, which were important for his work. Brahe and Kepler together began the work about new, exact planet tables (Rudolfinian tables). Brahe set Kepler also the task to define the motion of the planet Mars. Astronomical observations had produced that the motion of Mars differed from a circle. This task was godsend for Kepler as he here, in the course of his thoughts, put the circular motion of planets into question and thought about elliptic ones. But this work was to keep him busy for some more years. In 1601, after the death of
Tycho Brahe, Kepler became imperialistic mathematician. Now Brahe’s
astronomical observation data and his measuring instruments were at
his disposal. In 1604 he wrote a report on a supernova watched by
himself and worked on the
After In October 1613 he married
his second wife, Mrs Susanne Reuttinger. In Linz Kepler worked still
on the Rudolfinian tables. In his world harmony with which he also
worked in Linz Kepler searched for a harmonic model of the universe.
He worked out the theoretical basics of music. In July 1619 he
published his results concerning the world harmony in a five-volume
book. It was called In 1615 Kepler’s mother Katharina was accused of wizardry in Leonberg. Kepler himself defended her. But it took six years until she was absolved. In 1618 the Thirty Years’ War had begun. Kepler left Linz with his
family in 1626 because of the pressure of the counter-reformation
and went to Ulm. There he finished his work on the Rudolfinian
tables which were printed in 1627 ( In the year 1628 he went to
the Silesian town Sagan to work there as mathematician for his
protégé ## Kepler’s laws of planetary motion:
Kepler has as the first one rejected the complete circular motion in his tests on planetary motion. Only with the observation of elliptic orbits did he find the long looked for accordance with Tycho Brahe’s measured data.
Kepler published this law in his 1609 work
That means the planet moves faster when it is near the sun than away from the sun – its speed is not constant, it changes with its distance from the sun. Also this law Kepler published in his 1609 work Astronomia nova. ## Kepler’s Third Law
Kepler’s most important law. It shows the relationship between the period of the orbit of the planets and their average distances from the sun. This
law can be found in Kepler’s work
A visit to the Kepler-Museum in Weil der Stadt.
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