Changes

== Life and career ==

== Life and career ==

Kepler was born in Weil, Württemburg, in what was then known as the [[Holy Roman Empire]], and more particularly in that part of it now known as [[Germany]].<ref name=dao/><ref name=rice>Van Helden, Al. "[http://galileo.rice.edu/sci/kepler.html Johannes Kepler (1571-1630)]." ''The Galileo Project'', Rice University, 1995. Accessed March 2, 2008.</ref><ref name=nasa>"[http://kepler.nasa.gov/johannes/ Johannes Kepler: His Life, His Laws, and Times]." [[NASA]]. Accessed March 2, 2008.</ref> He observed his first [[comet]] at the age of six and his first [[eclipse]] of the [[Moon]] at the age of eight or nine.<ref name=dao/> Kepler overcame an enormous obstacle to become a great scientist, as he suffered from an attack of [[smallpox]] when he was only four years old. The disease left him with poor eyesight and crippled hands for the rest of his life.

Kepler was born in Weil der Stadt, Württemberg, in what was then known as the [[Holy Roman Empire]], and more particularly in that part of it now known as [[Germany]].<ref name=dao/><ref name=rice>Van Helden, Al. "[http://galileo.rice.edu/sci/kepler.html Johannes Kepler (1571-1630)]." ''The Galileo Project'', Rice University, 1995. Accessed March 2, 2008.</ref><ref name=nasa>"[http://kepler.nasa.gov/johannes/ Johannes Kepler: His Life, His Laws, and Times]." [[NASA]]. Accessed March 2, 2008.</ref> He observed his first [[comet]] at the age of six and his first [[eclipse]] of the [[Moon]] at the age of eight or nine.<ref name=dao/> Kepler overcame an enormous obstacle to become a great scientist, as he suffered from an attack of [[smallpox]] when he was only four years old. The disease left him with poor eyesight and crippled hands for the rest of his life.

Kepler entered the Lutheran seminary at Adelberg in 1584,<ref name=rice/> and in 1589 he won a scholarship to study theology at the University of Tübingen.<ref name=nasa/>

Kepler entered the Lutheran seminary at Adelberg in 1584,<ref name=rice/> and in 1589 he won a scholarship to study theology at the University of Tübingen.<ref name=nasa/>

In 1600, Kepler left his job at Graz on account of the [[Counter Reformation]]. Unwilling either to convert to Catholicism or to sign the Lutheran Formula of Concord, he decided to leave Graz and travel to Prague.<ref name=nasa/><ref name=rice/> There he became the assistant to [[Tycho Brahe]], court mathematician to Emperor Rudolf II.<ref name=dao/>. Tycho was also makng observations on the orbit of the planets. In 1601, Tycho died, and Kepler was named Imperial Mathematician in his place,<ref name=nasa/> the highest ranking in Europe at the time.<ref name=rice/> After reading and studying the data that Tycho had developed and researched, Kepler was able to resolve a nagging problem concerning the motion of [[Mars]], and in particular its apparent [[retrograde motion]] in relation to the [[Earth]]. Kepler went on to calculate Mars' orbit--as an [[ellipse]], not a [[circle]].

In 1600, Kepler left his job at Graz on account of the [[Counter Reformation]]. Unwilling either to convert to Catholicism or to sign the Lutheran Formula of Concord, he decided to leave Graz and travel to Prague.<ref name=nasa/><ref name=rice/> There he became the assistant to [[Tycho Brahe]], court mathematician to Emperor Rudolf II.<ref name=dao/>. Tycho was also makng observations on the orbit of the planets. In 1601, Tycho died, and Kepler was named Imperial Mathematician in his place,<ref name=nasa/> the highest ranking in Europe at the time.<ref name=rice/> After reading and studying the data that Tycho had developed and researched, Kepler was able to resolve a nagging problem concerning the motion of [[Mars]], and in particular its apparent [[retrograde motion]] in relation to the [[Earth]]. Kepler went on to calculate Mars' orbit--as an [[ellipse]], not a [[circle]].

Kepler remained as Imperial Mathematician until 1612, when Rudolf II was deposed.<ref name=rice/> In the next year (1613) he accepted a teaching position in Linz, the last semi-permanent position he ever held. He held this job until 1626, when the pressures of the [[Thirty Years' War]] forced him to leave. Now out of a job and with no salary, he tried in vain to seek employment and to sue for back payment of his salary as Imperial Mathematician.<ref name=rice/> He died in 1630, at Regensberg.<ref name=rice/><ref name=nasa/>

Kepler remained as Imperial Mathematician until 1612, when Rudolf II was deposed.<ref name=rice/> In the next year (1613) he accepted a teaching position in Linz, the last semi-permanent position he ever held. He held this job until 1626, when the pressures of the [[Thirty Years' War]] forced him to leave. Now out of a job and with no salary, he tried in vain to seek employment and to sue for back payment of his salary as Imperial Mathematician.<ref name=rice/> He died in 1630, at Regensburg.<ref name=rice/><ref name=nasa/>

== Kepler's contributions to astronomy ==

== Kepler's contributions to astronomy ==