Why mapping the Moon?
As a fascinating object related to beliefs, observed for million years, the Moon is present under different shapes in many cultures. Each myth has projected through those lunar spots some familiar figures: faces, animals, vegetation, and objects.[1]
Somehow, if some prehistoric traces of lunar representations exists, which are partially readable, no ancient cartography or medieval maps were discovered.[2] Knowledge about the Moon was nevertheless major. Its phases, its eclipses recorded time and structured the social and religious life.
During the third and second century B.C., two Greek astronomers and mathematicians, Aristarchus of Samos and Hipparchus of Nicaea, determined the distance between the Earth and the Moon.[3] Ptolemy, the Greco-Roman mathematician and astronomer, during the 1st century A.D. and Al-Battani (858-929) have determined the satellite’s orbit.[4] Observations and calculations continues to extend after those discoveries. However, it is only at the beginning of the Renaissance period, when the Moon’s surface is revealed through a topography and cartography.
Jacques Lieutaud, La Connoissance des temps pour l'année 1702, 1702.
The determination of longitudes will accelerate the creation of a lunar cartography. Indeed, until the 17th century, the calculation of longitudes remains uncertain and complex. There were shipwrecks or a number got lost due to the uncertainty of borders.
During the 1620s, a young Dutch astronomer named Michael van Langren (1598-1675) suggested a solution: by surveying in different areas for the exact moment when the lunar surface is visible through the sunlight, it would be possible to determine the times’ division between these observations and the longitudes.
Pierre Charles Le Monnier, Astronomie nautique lunaire, 1771.
The cartography of the Moon is becoming a political and economic issue, notably for the main nautical powers, such as Spain and England.[5] Furthermore, the conquest of the Moon by cartography offers a unique occasion for astronomers and its sponsors to see their names marked for eternity on a topography that all humankind would contemplate.