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


Even during Tycho's life time there were those who  toyed with geo-heliocentric variations.  Indeed, Tycho became embroiled in a bitter dispute about authorship of his model with the astronomer Ursus (AKA 'The Bear'), eventually trying to enlist the support of young Kepler to come to his defense.


In the model above it is again easy to see earth at the center of the celestial sphere and, again, the Moon and Sun revolving around the stationary earth.  All of the other planets in turn revolve around the Sun, and here again, it is assumed that the sphere of fixed stars revolves daily, thus accounting for the First Motion.  The diagram above derives from a contemporary of Tycho, Christopher Rothmann, who seems to have proposed a planetary scheme very similar to that associated with the Tychonic geo-heliocentric model, which was first announced in 1588.  Evidence suggests that Rothmann privately proposed his model at least one year before Tycho, and further, that other contemporaries had similar variations.  One of the more obvious differences between the model of Rothmann and Tycho is the position of the orbits of Mars and the Sun, which do not appear to intersect in the diagram above.  Finally, it should be noted that other variations (though there are a limited number) also appeared.  One of Tycho's students, Longomontanus, suggested a model virtually identical to that of Tycho but which assumed that earth rotated daily west to east, thus negating the need for the sphere of fixed stars to rotate daily east to west.  I know of no illustration of the model of Longomontanus, though it look, on paper (flat and static), precisely like that of the Lord of Uraniborg, the Prince of Astonomers.  The best source on geo-heliocentric models is, without question, the work of Christine [Schofield] Jones.


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