Peru And the Moon

Originally published April 17, 2009
image by Paco Bellido, Spain

The 1748 book, Observaciones astronómicas y físicas hechas en los Reinos del Perú* published in Madrid by Jorge Juan and Antonio de Ulloa includes this map of the Moon. Juan and Ulloa joined the French expedition of La Condamine (he got a named crater out of it!) to measure the shape and size of the Earth. For this purpose they used a 16 foot focal length telescope to measure Moon eclipses; using a lunar map to identify landmarks for timing the progression of the eclipse shadow across the lunar surface (p 73 of their book). This appears to be a degraded copy of Cassini's 1692 map shown in Whitaker's Mapping and Naming the Moon, figure 48. The same named features are indicated on each map, with the endings changed on the 1748 map to match Spanish. It is possible that this derivative map has been relatively unknown, for few lunar historians may have looked in a book about Peru. The book is online so readers of Spanish can explore what Juan and Ulloa say about the origin of the map; I didn't find anything but did come across this nice illustration of their observing instruments and techniques:

Thanks to Paco for the photo of the map and for submitting it to LPOD!

Chuck Wood

Technical Details