Eudoxus of Cnidus: Difference between revisions

Add figures explaining his planetary model and a reference
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(Add figures explaining his planetary model and a reference)
 
The Sun is also assigned three spheres. The second completes its motion in a year instead of a month. The inclusion of a third sphere implies that Eudoxus mistakenly believed that the Sun had motion in latitude.
 
[[File:Animated Hippopede of Eudoxus.gif|thumb|Animation depicting Eudoxus' model of retrograde planetary motion. The two innermost homocentric spheres of his model are represented as rings here, each turning with the same period but in opposite directions, moving the planet along a figure-eight, or hippopede.]]
 
[[File:Eudoxus' Homocentric Spheres.png|thumb|Eudoxus' model of planetary motion. Each of his homocentric spheres is represented here as a ring which rotates on the axis shown. The outermost (yellow) sphere rotates once per day; the second (blue) describes the planat's motion through the zodiac; the third (green) and fourth (red) together move the planet along a figure-eight shape (or hippopede) to explain retrograde motion.]]
 
The five visible planets ([[Venus]], [[Mercury (planet)|Mercury]], [[Mars]], [[Jupiter]], and [[Saturn]]) are assigned four spheres each:
== External links ==
* [https://www.youtube.com/watch?v=_SFzDYSqR_4 Working model and complete explanation of the Eudoxus's Spheres]
* [https://www.thehistoryofphysics.org/2018/06/15/s1e4-eudoxus-and-plato Eudoxus (and Plato)], a documentary on Eudoxus, including a description of his planetary model
* [http://www.dioi.org/vols/wf0.pdf Dennis Duke, "Statistical dating of the Phaenomena of Eudoxus", ''DIO'', volume 15] ''see pages 7 to 23''
* [http://www.britannica.com/EBchecked/topic/195005/Eudoxus-of-Cnidus Eudoxus of Cnidus] Britannica.com