Concentric spheres
Encyclopedia
The cosmological model of concentric or homocentric spheres, developed by Eudoxus
, Callippus
, and Aristotle
, employed celestial spheres
all of which had the same center, the Earth. 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.
Eudoxus
Eudoxus or Eudoxos was the name of two ancient Greeks:* Eudoxus of Cnidus , Greek astronomer and mathematician.* Eudoxus of Cyzicus , Greek navigator....
, Callippus
Callippus
Callippus or Calippus was a Greek astronomer and mathematician.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...
, and Aristotle
Aristotle
Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...
, employed celestial spheres
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...
all of which had the same center, the Earth. In this respect it differed from the epicyclic and eccentric models with multiple centers, which were used by Ptolemy
Ptolemy
Claudius Ptolemy , was a Roman citizen of Egypt who wrote in Greek. He was a mathematician, astronomer, geographer, astrologer, and poet of a single epigram in the Greek Anthology. He lived in Egypt under Roman rule, and is believed to have been born in the town of Ptolemais Hermiou in the...
and other mathematical astronomers until the time of Copernicus.