Ancient Greek Models of the Universe Quiz

Ancient Greek Models of the Universe

• Anaximander imagined the Earth as a cylinder one-third as high as it is broad, fixed at the center of the universe, surrounded by fire, mist, and stars.
• The Greeks assumed the Earth was fixed in the universe due to the lack of stellar parallax, the change in apparent positions of objects against a backdrop.
• The Greeks lacked the technology to notice stellar parallaxes, which made it difficult to understand the true nature of the universe.
• Plato adopted the geocentric model with the Earth as a stationary sphere, surrounded by the Moon, Sun, and planets guided by the "Fates."
• Eudoxus explained celestial motion through uniform circular motion, while Aristotle described the heavenly bodies as attached to transparent spheres.
• Aristotle attributed the roundness of the Earth to the shadow it casts during lunar eclipses and observed phenomena like ship sails and the North Star.
• The Greek geocentric models could not account for retrograde motion, the apparent backward motion of planets in the sky.
• Claudius Ptolemy modified the geocentric model to account for retrograde motion by adding epicycles to the planets' orbits.
• Ptolemy's model was generally accepted despite challenges from Arabic astronomers due to its inability to explain the appearance of the Moon and planets' oscillations.
• It took another millennium and a half for retrograde motion to be explained accurately by Copernicus, Kepler, and Newton, by which time the heliocentric model was being adopted.
• The Ptolemaic model of the universe had the planets orbiting the Sun in circular orbits with epicycles.
• Ptolemy was a mathematician, astronomer, astrologer, and geographer who formulated a reasonably accurate system of predicting planetary positions.