La Sfera del Mondo … Di nuouo da lui ripolita, accresciuta, & fino à Sei Libri, di Quattro che erano ampliata, & quasi per ogniparte rinouata, & riformata.

Venice: Giovanni Varisco, 1566. 4to, ([2], [12], 252, 48, [6], [2] pages, 93 [i.e. 69, illustrated with text woodcuts and the forty-seven woodcut full page star charts, small owners stamp to title, bound in contemporary limp vellum, manuscript title on spine and lower book block, in an excellent state of preservation.

This is the first printed star atlas.  This early edition marks an important development in the form in which celestial knowledge was conveyed. The work introduced the system of stellar nomenclature, which with the modification subsequently made by Bayer, remains in use today. Stars are identified by lower case letters for a given constellation, with tables conveniently listing magnitudes from first to fourth. The work proved wildly popular, with twelve editions in Italian and Latin within the 16th century. The De le Stelle Fisse is the companion volume to La Sfera del Mondo containing 47 maps of the different star patterns.

Piccolomini used Ptolemy’s system of star magnitudes, although he reduced it to four rather than five, and assigned different symbols to each one. The charts show only the shape of the constellations, rather than overlaying them with a pictorial map. The constellations are often not oriented to the north, but shown in their most recognisable position.