Johannes Kepler and the Movement of the Planets [1]

Translated by xia23

Personal description:

Johannes Kepler

Birth: 12/27/1571 in Weil city, Germany

Death: 11/15/1630 in Gegensburg, Germany

Wives: Barbara Müller; Susanne Reuttinger

Children: 3 kids with Barbara; 6 kids with Susanne

Important day: the day on which he discovered the laws of the planet obits

Do you know who wrote the first scientific fiction novel? Who discovered the telescope which had developed into the modern telescope? Who discovered the moon’s influence on the sea? Who showed how the planets moved around the sun? All of these were accomplished by the German astronomer Johannes Kepler.

Johannes Kepler’s life was full of problems. He was two months premature as a baby and had lots of diseases as a kid. He could see very poorly as a grown-up. He could not understand his parents very well and lived with his grand-parents for several years. Besides Kepler (just like Albert Einstein) was a poor learner in schools. Anyhow this he studied. After Kepler finished his university, he became a professor for mathematics in Graz, in the Austrian province Steiermark. But it was the time of the Counter-Reformation. In 1600 Kepler had to leave Graz, because he was a Protestant and because the city Graz was supposed to be catholic. Kepler’s whole life had faced such a problem. As an astronomer he could not make enough money and he had to write horoscope often. In spite of the problems in his life Kepler made many important discoveries, which have changed the picture of our world and our planet systems forever.

The renaissance brought a new interest in the ancient knowledge. People like Erasmus von Rotterdam, Nikolaus Kopernikus, Albrecht Dürer and Tilman Riemenschneider had great influence on their era. In Kepler’s time, 100 years later, people wanted to understand the world objectively. Many new developments were linked with astronomy. The Greek astronomer Ptolemäus had claimed for many centuries that the sun is moving around the earth. Man named that as the geocentric system. In the renaissance in 1543 Kopernikus wanted to show that the earth moved around the sun. He called that as the heliocentric system. In Kepler’s time there were two other astronomers, Galilei in Italy and Tycho Brahe in Prag, who wanted to prove the Kopernikus’ ideas. In order to see the planets, stars and the sun more clearly, Galilei developed a telescope in Italy. Tycho Brahe had already tried to prove the heliocentric system even before the development of the telescope.

Because he showed so much talent as a mathematician, Kepler was invited by Tycho Brahe to work together with him. Brahe wanted that Kepler to investigate the orbit of planet Mars. Kepler said he would discover the planet orbit in 9 days, but then he needed 9 years for it! When Brahe died, Kepler took Brahe’s notes and worked further on the planet orbit.

After Brahe’s death Kepler became the imperial court mathematician in Prag, the most important position for a mathematician in the whole Europe. In that period many important works were published by Kepler. In 1604 he circulated the modern explanation of how eyes were functioning in “Astronomia pars Optica” (“Optics, a part of astronomy”, in Latin). In his book “Dioptik” (“optics”) (1611) he wrote more about it and utilized many concepts such as lens and prism, which are still being used nowadays.

In 1609 he published the book “Astronomia Nova” (“The New Astronomy”), in which he described the first two “Keplerian Laws”. Through the second law he had clarified what influence of the moon on the tide in the ocean. Kepler developed the three complete laws, which clarified that planet obits are elliptical and how the planets move around the sun.

When Kepler learned of Galilei’s discoveries with the telescope in1610, he built his own “Keplerian telescope”.  Through his early work with the eye he knew lots about lenses. He was able to develop a lens, with which people could see things larger. With his astronomic telescope he discovered 4 satellites around the planet Jupiter.  Other astronomers were able to work further with the Keplerian telescope. In the year 1611, for example, Galilei then discovered sunspots with the help of the Keplerian telescope.

Like Paracelsus’ discovery, Kepler’s ideas were not well-received by many scientists of his time. They had ignored his second law for almost 80 long years. But based on Kepler’s laws of the planetary movement, Sir Isaac Newton developed his law of the universal gravitation in 1687.

[1]. Johannes Kepler und die Bewegung der Planeten. p. 312-314, Deutsch Actuell 3. EMC/Paradigm Publishing, Saint Paul, Minnesota, 2005

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