Editing Definition of planet (section)

=== Planets in the Middle Ages ===
[[File:Copernican heliocentrism diagram-2.jpg|thumb|Sketch of the heliocentric model of the Solar System by Copernicus]]
Medieval and Renaissance writers generally accepted the idea of seven planets. The standard medieval introduction to astronomy, [[Sacrobosco]]'s ''[[De sphaera mundi|De Sphaera]]'', includes the Sun and Moon among the planets,<ref>Sacrobosco, "On the Sphere", in Edward Grant, ed. ''A Source Book in Medieval Science,'' (Cambridge: Harvard University Press, 1974), p. 450.  "every planet except the sun has an epicycle."</ref> the more advanced ''Theorica planetarum'' presents the "theory of the seven planets,"<ref>Anonymous, "The Theory of the Planets," in Edward Grant, ed. ''A Source Book in Medieval Science,'' (Cambridge: Harvard University Press, 1974), p. 452.</ref>  while the instructions to the ''[[Alfonsine Tables]]'' show how "to find by means of tables the mean ''motuses'' of the sun, moon, and the rest of the planets."<ref>[[John of Saxony (astronomer)|John of Saxony]], "Extracts from the Alfonsine Tables and Rules for their use", in Edward Grant, ed. ''A Source Book in Medieval Science,'' (Cambridge: Harvard University Press, 1974), p. 466.</ref>  In his ''[[Confessio Amantis]]'', 14th-century poet [[John Gower]], referring to the planets' connection with the craft of [[Classical planets in Western alchemy|alchemy]], writes, "Of the planetes ben begonne/The gold is tilted to the Sonne/The Mone of Selver hath his part...", indicating that the Sun and the Moon were planets.<ref>{{cite journal|author=P. Heather|title=The Seven Planets|journal=Folklore|year=1943|pages=338–361|doi=10.1080/0015587x.1943.9717687|volume=54|issue=3}}</ref> Even [[Nicolaus Copernicus]], who rejected the geocentric model, was ambivalent concerning whether the Sun and Moon were planets. In his ''[[De Revolutionibus]]'', Copernicus clearly separates "the sun, moon, planets and stars";<ref name=koper>{{cite web|title=The text of Nicholas Copernicus' De Revolutionibus (On the Revolutions), 1543 C.E.|author=Edward Rosen (trans.)|work=Calendars Through the Ages|url=http://webexhibits.org/calendars/year-text-Copernicus.html|access-date=February 28, 2007}}</ref> however, in his Dedication of the work to Pope Paul III, Copernicus refers to, "the motion of the sun and the moon... and of the five other planets."<ref>{{cite web|title=Dedication of the Revolutions of the Heavenly Bodies to Pope Paul III|author=Nicolaus Copernicus|work=The Harvard Classics. 1909–14|url=http://www.bartleby.com/39/12.html|access-date=February 23, 2007}}</ref>