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Dr Robert A. Hatch - University of Florida
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| There are a number of heliocentric (sun-centered) models of planetary motion, and an even larger number of non-earth-centered models. In antiquity the Pythagoreans suggested that the earth and Sun revolved around a Central Fire. Others ancients also suggested that earth moved. Heraclides of Pontus proposed a model where earth was at the center of planetary motion but rotated on its axis daily. Heraclides believed that the Sphere of Fixed Stars was at rest. A number of ancients followed Heraclides' suggestion, among them Hicetas, Ecphantus, Martianus Capella, and perhaps others. Best known was the 'Ancient Copernicus', Aristarchus of Samos. Aristarchus proposed a heliocentric model where the earth had a double motion, it rotated on its axis daily and revolved around the central Sun annually. Finally, it must be underscored that what is often called the 'Copernican System' took many forms during the Scientific Revolution. Arguably, in discussing the various Sun-Centered models of the 17th century, we might more accurately speak of the Copernican- Galilean Model, the Copernican- Keplerian Model, the Copernican- Boulliau Model, the Copernican- Cartesian Model, the Copernican- Newton Model. You get the idea. Each system was quite different though each shared an assumption. The Copernican adjective has led to confusion and misunderstanding about the details, assumptions, and motives of later heliocentric models. To illustrate variations on the heliocentric model, I supply the following Clicks. Enjoy. |
| Early & Later Heliocentric Models |
| Modern Diagrams - Copernicus' Model |
rah.jan.99
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Dr Robert A. Hatch - All Rights Reserved