Hartmann's Astrolabe - Key Ring Fashioned of brass with a

Fashioned of brass with a brass key ring and featuring a compass rose on the reverse

The Spanish astronomer and mathematician Juan de Rojas presented to the European public the Orthographic Projection (1550)

Miniature nautical astrolabe

Hand crafted of brass and wood with green paint finish accented with a brass clasp and hinge

It's used by measuring the height of a star using the back of the instrument

Hartmann's Astrolabe - Key Ring Fashioned of brass with aPlanispheric (Catholic or European) astrolabe, set for 50 North latitude. Stars and other features updated to make it functional. This beautiful astrolabe is based on the work of Georg Hartman a sixteenth century astronomer from Nuremberg, Germany. The astrolabe is an astronomical calculating device used from ancient times into the eighteenth century. It's used by measuring the height of a star using the back of the instrument, and knowing the