Johannes Kepler

Johannes Kepler was a German <a href="/facts/Astronomer/ronF8j4a">astronomer</a>, <a href="/facts/German_mathematician/ARhYwz5l">mathematician</a>, <a href="/facts/Astrologer/kFP09KjH">astrologer</a>, <a href="/facts/Natural_philosophy/CUAsDWdk">natural philosopher</a> and writer on music. He is a key figure in the 17th-century <a href="/facts/Scientific_Revolution/KdeJepMq">Scientific Revolution</a>, best known for his <a href="/facts/Kepler%27s_laws_of_planetary_motion/jYQoIBjM">laws of planetary motion</a>, and his books <a href="/facts/Astronomia_nova/5MdQcSD8">Astronomia nova</a>, <a href="/facts/Harmonice_Mundi/BDKcKU7Y">Harmonice Mundi</a>, and <a href="/facts/Epitome_Astronomiae_Copernicanae/hYNroSkD">Epitome Astronomiae Copernicanae</a>, influencing among others <a href="/facts/Isaac_Newton/4L7gTncN">Isaac Newton</a>, providing one of the foundations for his theory of <a href="/facts/Newton%27s_law_of_universal_gravitation/F6qH2XC3">universal gravitation</a>. The variety and impact of his work made Kepler one of the founders and fathers of modern <a href="/facts/Astronomy/0ArJVM1p">astronomy</a>, the <a href="/facts/Scientific_method/182j8RWE">scientific method</a>, <a href="/facts/Natural_science/8hg81Q2p">natural</a> and <a href="/facts/Modern_science/pdBLPwP0">modern science</a>. He has been described as the "father of <a href="/facts/Science_fiction/d9hE2Lwt">science fiction</a>" for his novel <a href="/facts/Somnium_(novel)/wCKffYCD">Somnium</a>.
Kepler was a mathematics teacher at a <a href="/facts/Seminary/nuSQmQpq">seminary</a> school in <a href="/facts/Graz/NVCdhqkU">Graz</a>, where he became an associate of <a href="/facts/Hans_Ulrich_von_Eggenberg/AGDlHD2w">Prince Hans Ulrich von Eggenberg</a>. Later he became an assistant to the astronomer <a href="/facts/Tycho_Brahe/HroPxnCq">Tycho Brahe</a> in <a href="/facts/Prague/txpRNTUE">Prague</a>, and eventually the imperial mathematician to <a href="/facts/Rudolf_II,_Holy_Roman_Emperor/XoKJsYAd">Emperor Rudolf II</a> and his two successors <a href="/facts/Matthias,_Holy_Roman_Emperor/8Bg0c2Fb">Matthias</a> and <a href="/facts/Ferdinand_II,_Holy_Roman_Emperor/AmQV0oob">Ferdinand II</a>. He also taught mathematics in <a href="/facts/Linz/FyYYw8h5">Linz</a>, and was an adviser to <a href="/facts/Albrecht_von_Wallenstein/WRDHAJto">General Wallenstein</a>.
Additionally, he did fundamental work in the field of <a href="/facts/Optics/p0vq4S1T">optics</a>, being named the father of modern optics, in particular for his Astronomiae pars optica. He also invented an improved version of the <a href="/facts/Refracting_telescope/JtCz5CvW">refracting telescope</a>, the Keplerian telescope, which became the foundation of the modern refracting telescope, while also improving on the telescope design by <a href="/facts/Galileo_Galilei/98VT2z3v">Galileo Galilei</a>, who mentioned Kepler's discoveries in his work. He is also known for postulating the <a href="/facts/Kepler_conjecture/5cFNDqwA">Kepler conjecture</a>.
Kepler lived in an era when there was no clear distinction between <a href="/facts/Astronomy/0ArJVM1p">astronomy</a> and <a href="/facts/Astrology/kFP09KjH">astrology</a>, but there was a strong division between astronomy (a branch of <a href="/facts/Quadrivium/Qm48ab6G">mathematics</a> within the <a href="/facts/Liberal_arts/YtUI0rgu">liberal arts</a>) and <a href="/facts/Physics/a7aH2y08">physics</a> (a branch of <a href="/facts/Natural_philosophy/CUAsDWdk">natural philosophy</a>). Kepler also incorporated religious arguments and reasoning into his work, motivated by the religious conviction and belief that God had created the world according to an intelligible plan that is accessible through the natural light of <a href="/facts/Reason/tcBImN8J">reason</a>. Kepler described his new astronomy as "celestial physics", as "an excursion into <a href="/facts/Aristotle/U2bDlBFW">Aristotle</a>'s <a href="/facts/Metaphysics_(Aristotle)/JMUeXs0l">Metaphysics</a>", and as "a supplement to Aristotle's <a href="/facts/On_the_Heavens/enkT8Pq3">On the Heavens</a>", transforming the ancient tradition of physical cosmology by treating astronomy as part of a universal mathematical physics.

Johannes Kepler open-in-new

Johannes Kepler