Editing Orrery (section)

===Early Modern===
[[File:Astronomical clock (Venus-Mercury side), Eberhard Baldewein et al, Marburg-Kassel, 1563-1568 - Mathematisch-Physikalischer Salon, Dresden - DSC08057.jpg|thumb|Astronomical clock (Venus-Mercury side) by Eberhard Baldewein, 1563&ndash;1568. Exhibit in the [[Mathematisch-Physikalischer Salon]] of [[Dresden, Germany]].]]
In 1348, [[Giovanni Dondi dell'Orologio|Giovanni Dondi]] built the first known clock driven mechanism of the system. It displays the [[Ecliptic coordinate system|ecliptic position]] of the Moon, Sun, [[Mercury (planet)|Mercury]], [[Venus]], [[Mars]], [[Jupiter]] and [[Saturn]] according to the complicated [[Geocentric model|geocentric]] Ptolemaic planetary theories.<ref>{{cite book|last1=King|first1=Henry C.|last2=Millburn|first2=John R.|title=Geared to the stars : the evolution of planetariums, orreries, and astronomical clocks|date=1978|publisher=[[University of Toronto Press]]|location=Toronto|isbn=0-8020-2312-6|pages=[https://archive.org/details/gearedtostarsevo00king/page/28 28–41]|url-access=registration|url=https://archive.org/details/gearedtostarsevo00king/page/28}}</ref><ref name=Lloyd>{{cite book|last1=Lloyd|first1=H. Alan|title=Some Outstanding Clocks Over Seven Hundred Years|date=1958|publisher=Leonard Hill Books Limited|location=London|pages=9–24}}</ref> The clock itself is lost, but Dondi left a complete description of its astronomic [[gear train]]s.

As late as 1650, P. Schirleus built a geocentric [[planetarium]] with the Sun as a planet, and with Mercury and Venus revolving around the Sun as its [[Natural satellite|moon]]s.<ref name="EE">{{cite book|last=Brewster|first=David|title=The Edinburgh Encyclopedia |publisher=William Blackwood et al.|location=Edinburgh|date=1830|volume=16|pages=624|chapter=Planetary Machines|chapter-url=https://books.google.com/books?id=q2tTt_NNr2YC&pg=PA646}}</ref>

At the court of [[William IV, Landgrave of Hesse-Kassel]] two complicated astronomic clocks were built in 1561 and 1563–1568. These use four sides to show the ecliptical positions of the Sun, Mercury, Venus, Mars, Jupiter, Saturn, the Moon, Sun and Dragon (Nodes of the Moon) according to [[Ptolemy]], a calendar, the sunrise and sunset, and an automated [[celestial sphere]] with an animated Sun symbol which, for the first time on a celestial globe, shows the real position of the Sun, including the [[equation of time]].<ref name=Lloyd2>Lloyd (1958), pp. 46–57.</ref><ref>{{cite book|last1=Poulle|first1=Emmanuel|author1-link=Emmanuel Poulle|last2=Sändig|first2=Helmut|last3=Schardin|first3=Joachim|last4=Hasselmeyer|first4=Lothar|title=Die Planetenlaufuhr : ein Meisterwerk der Astronomie und Technik der Renaissance geschaffen von Eberhard Baldewein 1563 - 1568|date=2008|publisher=Dt. Gesellschaft für Chronometrie|location=Stuttgart|isbn=978-3-89870-548-6|edition=1ª|ref=Poulle}}</ref> The clocks are now on display in [[Kassel]] at the Astronomisch-Physikalisches Kabinett and in [[Dresden]] at the [[Mathematisch-Physikalischer Salon]].

In ''[[De revolutionibus orbium coelestium]]'', published in Nuremberg in 1543, [[Nicolaus Copernicus]] challenged the Western teaching of a geocentric universe in which the Sun revolved daily around the [[Earth]]. He observed that some Greek philosophers such as [[Aristarchus of Samos]] had proposed a heliocentric universe. This simplified the apparent [[epicycle|epicyclic]] motions of the planets, making it feasible to represent the planets' paths as simple circles. This could be modeled by the use of gears. [[Tycho Brahe]]'s improved instruments made precise observations of the skies (1576–1601), and from these [[Johannes Kepler]] (1621) deduced that planets orbited the Sun in [[ellipse]]s. In 1687 [[Isaac Newton]] explained the cause of elliptic motion in his [[Newton's law of universal gravitation|theory of gravitation]].<ref name="Ronan">{{cite book|last=Ronan|first=Colin |title=The Practical Astronomer|publisher=Bloomsbury Books|location=London|orig-year=First published 1981|date=1992|pages=108–112|isbn=1-85471-047-8}}</ref>