Libros del saber de astronomía

The Libros del saber de astronomía (Old Spanish: Libro del saber de astrología), literally "book[s] of the wisdom of astronomy [astrology]", is a series of books of the medieval period, composed during the reign of Alfonso X of Castile.

[1] The collection is a group of treatises on astronomical instruments, like the celestial sphere, the spherical and plane astrolabe, saphea,[2] and universal plate for all latitudes, for uranography or star cartography that can be used for casting horoscopes.

The purpose of the rest of the instruments, the quadrant of the type called vetus, sundial, clepsydras, is to determine the time, which was also needed to cast the horoscope.

Use of the vernacular Castillian language was an innovation at the time, when most scientific texts were written in Latin.

Later Alfonso also decided to translate the works into Latin, as he expected to extend his influence and had aspirations to the imperial throne in Germany.