Nick Kanas, M.D., is a Professor Emeritus at the University of California San Francisco; a Fellow of the Royal Astronomical Society; and a past Vice President of the California Map Society. He has collected antiquarian celestial maps since 1982.

This map of the solar system captures the scope of astronomical knowledge in the early 1700s. 

Around 1720, two Germans, astronomer and mathematician Johann Doppelmayr and cartographer Johann Homann, collaborated to create this chart. They included several descriptions from the writings of the Dutch astronomer Christian Huygens.  

The map was later included in their 1742 Atlas Coelestis in quo Mundus Spectabilis.  For reference, see: Nick Kanas, Star Maps: History, Artistry, and Cartography, 3rd edition (Cham, Switzerland: Springer Nature Switzerland AG, 2019), 3-5, 235.

At its core, the map depicts a universe revolving not around the Earth but around the Sun. The Polish astronomer Nicholas Copernicus had introduced this heliocentric model two centuries earlier, prompting intense conflict with believers of the traditional Earth-centric model.

In Doppelmayr and Homann's model, the planets circle the Sun, accompanied by Huygens' descriptions. Saturn and its moons (to the right of crab-shaped Cancer at the top) mark the outer boundary of the solar system. 

(Uranus and Neptune would not be discovered until 1781 and 1846, respectively.)

Beyond Saturn lies the rest of the universe, depicted allegorically as the twelve zodiac constellations.

See Kanas, Star Maps, 3-5.

Here, Doppelmayr and Homann depict the planets' sizes relative to one another and to the Sun.

See Kanas, Star Maps, 5.

Here, Doppelmayr and Homann model a solar eclipse that took place on May 12, 1706.

See Kanas, Star Maps, 5.

Like many other early 18th-century terrestrial maps, the map of the Earth used in the eclipse model depicts California (just above this dot) as an island. 

See Kanas, Star Maps, 5.

In Dots 6, 7, and 8, our two Johanns depict the three primary competing models of the solar system in allegorical terms.

On the bottom left in Dot 6 is the classical Greek, geocentric model summarized by the 2nd-century mathematician Ptolemy. Doppelmayr and Homann were not fans of the once-dominant Ptolemaic system; they depict this model as cracked and decrepit and partly obscure it with modern tools to discredit geocentrism.

See Kanas, Star Maps, 5, 66-70.

Introduced by a putto, or baby angel, this is the Danish astronomer Tycho Brahe's (1546-1601) compromise model between geocentrism and heliocentrism.  

Nicolas Copernicus had published his theory of a Sun-centered universe back in 1543, but heliocentrism took a century to reach general acceptance. Universities and ecclesiastical leaders continued to teach the geocentric model and pushed back against the Copernicans, most famously with Galileo Galilei's 1633 heresy trial. 

As in the classical model, the Sun and Moon revolve around the Earth. In a concession to Copernicus, however, the non-Earth planets revolve around the Sun.

See Kanas, Star Maps, 5, 104-6.

Moving on to Dot 8, we find a dramatic image of Urania, the goddess of astronomy herself. 

She introduces the heliocentric Copernican system as if to allegorically say, "This is the true model of the universe." 

In addition, the label sic ratione ("according to reason") suggests that Doppelmayr and Homann preferred this model as well.

By the 1700s, the Copernican view was finally endorsed by most serious scientists. 

See Kanas, Star Maps, 5, 101-3.

Moving past the lunar eclipse shown above Urania, we see, in the top-right corner, other stars with their own planetary systems. 

In the early 18th century, this leveled a radical challenge against the importance of our solar system. In 1600, Giordano Bruno, a noted philosophical troublemaker in Italy, had been burned at the stake for fostering such a view. 

The fact that Doppelmayr and Homann could presage the existence of exoplanets (not observed until the late 1900s) highlights the monumental change in astronomy that had unfolded since Copernicus.

Created and Presented by Nick Kanas.

Scripted and edited by Andrew Gu, Pixeum Summer 2024 Intern.

Courtesy of the Nick and Carolynn Kanas collection; and Star Maps: History, Artistry, and Cartography, 3rd edition (Nick Kanas, Cham, Switzerland: Springer Nature Switzerland AG, 2019).

For more information on celestial maps, check out Nick Kanas' books on the subject:

• Star Maps: History, Artistry, and Cartography. 

• Solar System Maps: From Antiquity to the Space Age.

 

To see more of Nick Kanas' work, including his bio, go to https://nickkanas.com/.