Doppelmayr Celestial Chart Explaining Planetary (1 results)

Very good. Old mounting on thick paper for binding; attractive original hand color. Marginal soiling to lower corners; else excellent with no mends or tears. Size 19 x 22.5 Inches. This fascinating 1710 celestial chart is a collaboration between mathematician and astronomer Johan Gabriel Doppelmayr and Johann Baptist Homann. It was produced to explain Copernicus' theories of planetary motion and apparent retrograde motion using data from observations in 1708 and 1709. Ingeniously Composed The ingeniously composed chart is embellished with an allegorical depiction of the discovered planets: Earth is shown as a regal, winged Gaia with a cornucopia; the other planets are putti wearing the classical garb associated with them - Mercury with his winged sandals and caduceus; Venus with a torch (alluding the brightness of the morning star); Mars with sword, shield, and helm; lightning-spitting Jupiter, and Saturn with his scythe and hourglass. Both these latter are attended by their orbiting moons. A Closer Look The central, circular diagram depicts a simplified Copernican solar system with the sun at center. The diagram's scale prevents the inclusion of Mercury and Venus, and so the first depicted orbit is that of Earth, beyond which are the concentric orbits of Mars, Jupiter, and Saturn. Each orbit is marked with the observed, monthly positions of their respective planets for the years 1708 and 1709, as well as their projected positions throughout the rest of their orbit around the sun (as late as 1757 for Saturn, an overestimation: Saturn's year is only 29.4 of our own.) The purpose of the diagram is to explain the phenomenon of retrograde motion. From the perspective of an observer on Earth, the planets appear to move in a predictable manner - only to apparently reverse direction for a span of months before resuming their journey across the sky. This phenomenon is caused by the fact that while the observed planets move, Earth itself remains in motion, overtaking the slower outer planets (or being overtaken by the inner planets) and creating the illusion of the other planet's apparent reversal. Thus, in addition to the central chart of the solar system, there are diagrams showing the 1708-9 observations of the apparent retrograde motion of each of the planets, keyed to their actual positions on the diagram. Publication History and Census This is the first edition of this celestial, engraved for inclusion in the 1710 issue of Homann's Neuer Atlas . It remained in Homann and Homann Heirs atlases well into the 18th century. In its various editions, the map is represented in 18 institutional collections. References: OCLC 248598463. Rumsey 12499.044 (1716 state).