THE 1645 LUNAR NOMENCLATURE OF JOHANNES HEVELIUS.

(presented at the Canadian Cartographic Association annual meeting, Victoria, B.C., 1990)

Johannes Hevelius (1611-1687), contemporary of Galileo and a Burgomaster of Gdansk, drew three lunar charts, one of which is described here (Figure 1). In it, the classical geography of the Mediterranean region is projected onto the Moon, individual lunar features being named after terrestrial regions which slightly resemble them in form or location. Only with considerable distortion could this scheme be applied at all, but comparisons of placenames with classical geography permit its reconstruction (Figure 2).

The numerous contradictions in the scheme suggest that Hevelius did not believe, as did some of his contemporaries, that the lunar markings were a true mirror image of terrestrial lands and seas, and intended it solely as a mnemonic device. Of particular interest are a 90 degree rotation between azimuths of the lunar disk and the mapping scheme (suggesting that the scheme was based on a view of a rising full moon), the identification of some linear features as rivers and the collapse of the scheme beyond the Mediterranean and Black Sea coasts.

Observations:

1. Names fall into 3 categories:

Terrestrial names conforming to the scheme

Terrestrial names misplaced relative to the scheme

Descriptive names

(also some not yet classified)

2. The scheme demands extreme distortion and dislocation of terrestrial geography.

Examples:

Propontis (Sea of Marmara) disconnected from Aegean.

Adriatic perpendicular to west coast of Italy.

Sea of Azov separated from Black Sea.

Nile delta enormously exaggerated in size.

North African coast greatly distorted.

3. Names which do not conform to the scheme further confuse its application. Examples:

Apollonia - shown on the south shore of the Black sea east of the Bosporus. This name was common in the classical world but the nearest example appears to be on the Black sea coast of Bulgaria.

Mons Trapezus - shown in the northwest part of the Crimean peninsula. Best fit appers to be Trapezus, now Trebizond in northeastern Turkey.

Alabastrinus Mons - shown in Mauritania. The real location was Egypt, southeast of the Nile delta.

Insula Menynx - shown between Sicilia and Insula Cercinna. The two 'insulae' are small islands off the east coast of Tunisia. In fact, Cercinna lies between Menynx and Sicily. The Balearic islands are similarly shuffled in position.

4. The naming scheme is rotated 90 degrees relative to the lunar disk (north on the Moon corresponds to west in the scheme).

5. Many descriptive names refer to position on the disk, but they refer to lunar directions, not those of the naming scheme, and so are rotated 90 degrees out of place.

Examples:

Sinus Hyperb., 'northern bay', is northerly on the Moon but in the west (Mauritania) in the scheme.

Paludes Orient., 'eastern marshes', are easterly (in the pre-space age sense) on the Moon but in the south-west (Mauritania) in the scheme.

Mons Meridionalis, 'southern mountain', is southerly on the Moon but in the east (Israel) in the scheme.

6. The orientation of the scheme suggests it is based on a rising full Moon. Hevelius may have based his scheme on a naked eye view of the rising Moon. Terrestrial features can be 'seen' on the Moon quite easily at naked eye scale, the southern highlands corresponding to Asia Minor surrounded by the neighbouring waters of the Black, Aegean and Mediterranean Seas (the lunar maria). When Hevelius observed the same features through a telescope the greater detail made the similarity far less obvious. He adhered to the simple scheme in its fundamentals but abandoned it for lesser details and took names from literature and/or maps without regard for consistency.

7. The many inconsistencies undoubtedly contributed to the fact that most of these names were never adopted by other scholars. Only the names of the principal mountain ranges remain as assigned by Hevelius. The names now in use were assigned by the jesuit astronomers Riccioli and Grimaldi in 1651, but their map does not include names for mountain ranges. The Taurus Montes appear to derive their name not from the terrestrial Taurus Mountains but from Taurica Chersonesus, the Crimean peninsula.

The scheme probably failed to be widely adopted in large part because of the numerous inconsistencies, possibly exacerbated because many of the most significant astronomers of the time lived in regions which were excessively distorted (e.g. Italy) or were missing altogether (Britain, Germany).