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One of the most ambitious plates in Johann Gabriel Doppelmayr’s Atlas Novus Coelestis, this striking chart visualizes the apparent irregularities in the motions of Venus and Mercury (direction, retrogradation, and station) during the year 1710 as seen from Earth, but rendered within a rigorously Copernican framework. The work was designed not only to track these phenomena in mathematical detail but to make the Copernican model intuitively persuasive by displaying its geometric harmony.
At center, a radiant Sun is surrounded by three concentric rings representing the orbits of Mercury (orange), Venus (yellow), and the Earth (green). Projected radially from the Sun are daily sightlines showing each planet’s longitudinal position as viewed from Earth throughout the year. The outer edge of the diagram is calibrated to the zodiac, and where the planetary lines intersect, each day’s position is labeled, allowing for a continuous reading of the apparent motion of both planets across the sky.
At the upper left of the chart, Doppelmayr presents a richly allegorical vignette that enacts the Copernican cosmos. Apollo sits enthroned on the Sun, radiating light and order, while Venus and Mercury orbit nearby, Venus with her naked form, Mercury with winged helmet and caduceus. Below, a six-horse chariot moves along the Earth’s orbital track, representing the Earth itself. Its large wheel is ingeniously rendered as a hemispheric map of the Southern Hemisphere. Below the chariot, lightning, rain, and snow signal the Earth’s changing seasons.
Inset diagrams at upper left and right (Figs. I and II) simplify the planetary geometry to its essential components, illustrating how the planets’ orbits and solar elongations give rise to their observed stations and retrogradations. Two more diagrams below (Figs. III and IV) depict the inclination of the planetary orbits to the ecliptic, highlighting the conditions under which transits occur. The flanking vertical ephemerides show the daily latitudinal positions of each planet across the year, with Mercury’s solar transit on 5 November 1710 clearly indicated.
A substantial Latin text curving through the lower right quadrant offers theoretical explanation and emphasizes the superiority of the Copernican system over the now-obsolete Tychonic model.
Johann Baptist Homann (1663-1724) was a mapmaker who founded the famous Homann Heirs publishing company. He lived his entire life in Bavaria, particularly in Nuremberg. Initially, Johann trained to become a priest before converting to Protestantism and working as a notary.
In 1702, Johann founded a publishing house that specialized in engravings. The firm flourished, becoming the leading map publisher in Germany and an important entity in the European map market. In 1715, Johann was named Imperial Geographer to the Holy Roman Empire by Charles VI and made a member of the Prussian Academy of Sciences. Most importantly for his business, his reputation and contacts gained him imperial printing privileges which protected his publications and recommended him to customers. Johann is best known for this Grosser Atlas ueber die ganze Welt, or the Grand Atlas of the World, published in 1716.
After Johann died in 1724, the business passed to his son, Christoph (1703-1730). Upon Christoph’s early death, the company passed to subsequent heirs, with the name of the company changing to Homann Erben, or Homann Heirs. The firm continued in business until 1848.
