How it began
Johannes Hevelius, born in 1611, built an observatory in Gdańsk, in present-day Poland. Before he turned to cataloguing stars he made his name as an observer and mapper of the Moon. He drew the appearance of the Moon for every day of the lunar cycle, engraved many of the plates himself, and dated each one. One plate shows the Moon as it appeared on November 4, 1643. He published the results in 1647 as the Selenographia, a tall, thick quarto.
Before it existed
The first map with lunar names had been published two years earlier by the Flemish cartographer Michael van Langren, who followed Galileo in naming craters and seas after patrons. It was printed as a broadside, did not circulate widely and never acquired a following.
How it works
Hevelius combined the details of his daily drawings into three double-page lunar maps. One showed the full Moon. A second showed the Moon as if every crater were lit by a mid-morning Sun, so that each cast the same defining shadow, a view that can never be seen in the sky. The third was a nomenclature map. Hevelius named lunar features after features of Earth they resembled, so that the large dark region became the Mediterranean Sea and a large crater within it became Sicilia, with its central peak named Mount Etna.
Who pushed back
Hevelius's naming system attracted adherents over the following century but ultimately faded. A competing system offered by a Jesuit astronomer in 1651 named craters after astronomers and natural philosophers and the dark seas after moods and weather. That is why the crater Hevelius called Sicilia is now called Copernicus.
What lasted
The Linda Hall Library calls the Selenographia the most elegant book on the Moon ever printed. The book also discussed cosmology and showed the telescopic faces of Mars, Jupiter with its four satellites, and Saturn. Hevelius went on to publish a widely used star catalog and a celestial atlas, and introduced seven constellations still in use, including Lacerta and Vulpecula.
