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  2. Eudoxus of Cnidus - Wikipedia

    en.wikipedia.org/wiki/Eudoxus_of_Cnidus

    Eudoxus, son of Aeschines, was born and died in Cnidus (also transliterated Knidos), a city on the southwest coast of Anatolia. [3] The years of Eudoxus' birth and death are not fully known but Diogenes Laërtius gave several biographical details, mentioned that Apollodorus said he reached his acme in the 103rd Olympiad (368– 365 BC), and claimed he died in his 53rd year.

  3. Concentric spheres - Wikipedia

    en.wikipedia.org/wiki/Concentric_spheres

    The cosmological model of concentric (or homocentric) spheres, developed by Eudoxus, Callippus, and Aristotle, employed celestial spheres all centered on the Earth. [1] [2] In this respect, it differed from the epicyclic and eccentric models with multiple centers, which were used by Ptolemy and other mathematical astronomers until the time of Copernicus.

  4. Celestial spheres - Wikipedia

    en.wikipedia.org/wiki/Celestial_spheres

    The celestial spheres, or celestial orbs, were the fundamental entities of the cosmological models developed by Plato, Eudoxus, Aristotle, Ptolemy, Copernicus, and others. In these celestial models, the apparent motions of the fixed stars and planets are accounted for by treating them as embedded in rotating spheres made of an aetherial ...

  5. Timeline of cosmological theories - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_cosmological...

    Eudoxus emphasised that this is a purely mathematical construct of the model in the sense that the spheres of each celestial body do not exist, it just shows the possible positions of the bodies. [23] His model was later refined and expanded by Callippus. Geocentric celestial spheres; Peter Apian's Cosmographia (Antwerp, 1539)

  6. Sphere of influence (astrodynamics) - Wikipedia

    en.wikipedia.org/wiki/Sphere_of_influence_(astro...

    A sphere of influence (SOI) in astrodynamics and astronomy is the oblate spheroid-shaped region where a particular celestial body exerts the main gravitational influence on an orbiting object. This is usually used to describe the areas in the Solar System where planets dominate the orbits of surrounding objects such as moons , despite the ...

  7. Celestial sphere - Wikipedia

    en.wikipedia.org/wiki/Celestial_sphere

    According to Eudoxus, there were only 27 spheres in the heavens, while there are 55 spheres in Aristotle's model. Eudoxus attempted to construct his model mathematically from a treatise known as On Speeds (Ancient Greek: Περί Ταχών) and asserted the shape of the hippopede or lemniscate was associated with planetary retrogression ...

  8. Callippus - Wikipedia

    en.wikipedia.org/wiki/Callippus

    Callippus was born at Cyzicus, and studied under Eudoxus of Cnidus at the Academy of Plato. He also worked with Aristotle at the Lyceum, which means that he was active in Athens prior to Aristotle's death in 322 BC. He observed the movements of the planets and attempted to use Eudoxus' scheme of connected spheres to account for their movements.

  9. Fixed stars - Wikipedia

    en.wikipedia.org/wiki/Fixed_stars

    Eudoxus of Cnidus, in around 380 BC, devised a geometric-mathematical model for the movements of the planets based on (conceptual) concentric spheres centered on Earth, [24] and by 360 BC Plato claimed in his Timaeus that circles and spheres were the preferred shape of the universe, and that the Earth was at the centre and the stars forming the ...