what did johannes kepler accomplish?
Mathematician Astronomer Scientist Astrologer
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 As a spin @-@ off from the Rudolphine Tables and the related Ephemerides , Kepler published astrological calendars , which were very popular and helped offset the costs of producing his other work — especially when support from the Imperial treasury was withheld . In his calendars — six between 1617 and 1624 — Kepler forecast planetary positions and weather as well as political events ; the latter were often cannily accurate , thanks to his keen grasp of contemporary political and theological tensions . By 1624 , however , the escalation of those tensions and the ambiguity of the prophecies meant political trouble for Kepler himself ; his final calendar was publicly burned in Graz . 

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 Kepler postponed the move to Linz and remained in Prague until Rudolph 's death in early 1612 , though between political upheaval , religious tension , and family tragedy ( along with the legal dispute over his wife 's estate ) , Kepler could do no research . Instead , he pieced together a chronology manuscript , Eclogae Chronicae , from correspondence and earlier work . Upon succession as Holy Roman Emperor , Matthias re @-@ affirmed Kepler 's position ( and salary ) as imperial mathematician but allowed him to move to Linz . 

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 Kepler has acquired a popular image as an icon of scientific modernity and a man before his time ; science popularizer Carl Sagan described him as " the first astrophysicist and the last scientific astrologer " . 

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 Kepler was a mathematics teacher at a seminary school in Graz , Austria , where he became an associate of Prince Hans Ulrich von Eggenberg . Later he became an assistant to the astronomer Tycho Brahe , and eventually he was the imperial mathematician to Emperor Rudolf II and his two successors Matthias and Ferdinand II . He was also a mathematics teacher in Linz , Austria , and an adviser to General Wallenstein . Additionally , he did fundamental work in the field of optics , invented an improved version of the refracting telescope ( the Keplerian telescope ) , and was mentioned in the telescopic discoveries of his contemporary Galileo Galilei . 

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 In the years following the completion of Astronomia Nova , most of Kepler 's research was focused on preparations for the Rudolphine Tables and a comprehensive set of ephemerides ( specific predictions of planet and star positions ) based on the table ( though neither would be completed for many years ) . He also attempted ( unsuccessfully ) to begin a collaboration with Italian astronomer Giovanni Antonio Magini . Some of his other work dealt with chronology , especially the dating of events in the life of Jesus , and with astrology , especially criticism of dramatic predictions of catastrophe such as those of Helisaeus Roeslin . 
