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Dr Robert A. Hatch - University of Florida |
| The illustration above derives from Copernicus' justly famous De Revolutionibus Orbium Coelestium published in 1543, perhaps the single most widely reproduced image of his heliocentric model. The second most widely reproduced diagram comes from Copernicus' handwritten draft (the holography copy) of the De Revolutionibus. In the diagram above, it is easy to see a sun-centered model with the planets arranged in concentric circles. The central Sun is followed by Mercury, Venus, earth (with the almost obtrusive Moon), followed by the superior planets, Mars, Jupiter, and Saturn. Curiously, Copernicus' hand-drawn illustration of this model, found in the manuscript draft mentioned above, does not graphically represent the earth's Moon, a small detail seldom mentioned by scholars. |
| The above diagram of the 'Copernican Hypothesis' was produced in the 16th century by Copernicus' friend and collaborator, G-J Rheticus, and later published by Kepler's mentor, Michael Maestlin (1596). |
| An important step in the history of cosmology was taken about forty years after Copernicus' De Revolutionibus by the Englishman, Thomas Digges. In his A Perfect Description of the Coelestiall Orbes (1576), Digges suggested that there was, in effect, no longer in use for the traditional sphere of fixed stars. The purpose of that sphere, since antiquity, had been to hold the stars in some coherent relation and, far more importantly, to rotate each day (carry all of the heavenly bodies with it) to account for the appearances. Digges suggested that the stars were distributed in 'empty' space not fixed to a redundant rotating sphere. This opened the way to speculations about an infinitely (or indefinitely) extend space. Some scholars, among them Alexandre Koyré, have suggest that this new view of space was central to the Scientific Revolution, that it brought a shift in perspective, from a Closed World to an Infinite Universe. The shift from Cosmos to Universe, according to Koyré, brought new concepts of matter, motion, and cause, a shift from a closed, qualitative, hierarchically arranged cosmos to an infinite, homogeneous, quantitative universe. |
| The above diagram of the 'Copernican Hypothesis' was published in the middle of the 17th century by Hevelius, the great Danzig astronomer. Although the details are not clear (even in the original print) the viewer can see moons around both Jupiter and Saturn, details unknown to Copernicus. This illustration derives from Hevelius Selenographia of 1647. |
| BY the late decades of the 17th century, natural philosophy ('science') was becoming well established, and by the 18th century, the period widely known as the Enlightenment, science had become fashionable. The above illustration derives from a fashionable, if not popular, publication, Entretiens sur la pluralité de mondes (1686, 1687), that is, Conversations on the Plurality of Worlds. The author was the long-time (indeed, perpetual) secretary of the French Académie des science, Bernard Fontenelle (1657-1757). Besides being a most precise centenarian, Fontenelle helped spread interest in the heliocentric world view. Above, a male teacher is depicted with his female student as they sat in a garden discussing the universe. Here the heliocentric model is depicted anew, again with the Sun at the center and the usual concentric circles representing the planets. But there are new additions. Although the details are not clear, it is possible to see that both Jupiter and Saturn are each shown with several moons. The four major moons of Jupiter were of course discovered by Galileo, the first major moon of Saturn was discovered by Huygens (Titan) and later, others were observed by Cassini. |
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Dr Robert A. Hatch - All Rights Reserved