Shadows Pro offers the Saphae Arzachelis, an ancient model invented during the 11th century by the Andalusian astronomer Arzaquiel. In this astrolabe, the stereographic projection is not done from a pole on the equatorial plane, but from the vernal point on a collure plane (passing through the poles).
1 - the throne, as on a planispheric astrolabe, allows the user to hold it vertically when pointing a star with the alidade.
2 - the limb is scaled in degrees.
3 - the plate shows meridians and parallels.
4 - the ecliptic is scaled in ecliptic longitude and marked with names of Zodiac constellations.
5 - the ruler rotates around the axis. It is scaled in ecliptic longitude.
6 - the point, also called brachiolus, is articulated and rotates with the ruler. Its end can be moved to a point on the plate at the intersection of a meridian and a parallel.
This drawing of universal astrolabe was made with Shadows Pro »
The universal astrolabe's main use is the conversion of astronomical coordinates, for example between equatorial and ecliptic coordinates.
Learn more on astrolabes in the User Manual »