Michiel Florent van Langren and Lunar Naming

Abstract

Michiel Florent van Langren produced a lunar map in 1645 in order to present a way to mariners to find their position at sea by observing which craters were either illuminated by solar rays or obscured during the waxing or waning of the moon. This required a detailed map of the moon and in order to be able to refer to lunar objects these had to be named. The lunar map he produced in 1645 bore over 300 names, following the system of subdividing lunar topography into land masses and seas (a distinction based on Plutarch), and craters or peaks. He is therefore the pioneer of both selenography and selenonymy. His nomenclature had no lasting impact, although some 50 names he introduced are still used for other craters. The same negative result was obtained by Johannes Hevelius who introduced in 1647 his own naming system based on geographical names. It was the nomenclature proposed by a third astronomer, Giovanni Riccioli, shown on his lunar map produced in 1651 that won the day. From the 244 names Riccioli proposed on his lunar map, 201 are still in use. Nevertheless, despite Van Langren’s lack of success, from a toponymical point of view his methodology is interesting as it provides insight into the contemporary world view of a seventeenth century scientist who was dependant on sponsors to allow him to carry out his work and transform his theories into practical instructions.