April 17, 2009

Peru And the Moon

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

• Astronomical and Physical Observations Made in the Kingdom of Peru
  

Related Links
Paco's lunar website

---