Tycho Brahe - The Tychonic Model of Planetary Motions

Tycho Brahe - The Tychonic Model - Scientific Revolution - Dr Robert A. Hatch
GEO-HELIOCENTRIC PLANETARY MODELS
POST-COPERNICAN MODELS & VARIATIONS
Dr Robert A. Hatch - University of Florida

By the middle decades of the 17th century, following Galileo's condemnation, various geo-heliocentric models had become well known and widely accepted in universities, and in particular, by educated members of the Roman Catholic church. The illustration above comes from the frontispiece of Riccioli's New Almagest. A member of the Jesuit order, Riccioli was a competent astronomer and, on balance, seems to have favored the Tychonic model.

The illustration above also comes from the middle decades of the 17th century, notably from the Selenographia (1647) of Johannes Hevelius, the great Danzig astronomer.

Again, as in the diagram offered by Kircher, we see a number of options being considered, even by that late 17th century. The illustration above derives from the late 17th century, and it shows the primacy of the geocentric model (top) followed by a heliocentric (middle left), Cartesian (middle right), and finally, geo-heliocentric (bottom left). In the lower right corner are the vortices of Descartes. Descartes claimed that his vortex model, which allowed both an absolute and relative sense of motion, was more acceptable than the Tychonic. Although it was a sun-centered model, Descartes maintained that, yes, the earth clearly revolved around the sun. But in another sense it did not move. All the particles in the vortex revolve around the Sun but they tend to maintain the same relative position to each other and to the earth. In this sense, with respect to the surrounding medium, the earth does not move. Right René.

rah.jan.99

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