Astrolabium

The astrolabe is a universal instrument for astronomical measurements and for determining solar time and sidereal time. It was used from Aristotle (384 to 322 BC) until the 17th century. It consists of a large disc that is hung in the vertical position of use using a ring eyelet.
The Astrolab is a model of the sky. It is assumed that the Earth is the center of a spherical universe. A flat disk depicts the positions of the Sun and some major stars at a particular latitude at a particular time, as they would appear to an imaginary observer from outside the sphere. The Astrolab can be adjusted to show the positions of these celestial bodies at different times, at different dates and at different latitudes. It can solve tasks that depend on the movements of these bodies, such as the length of the day and night at any given time.
The Astrolab is equipped with a sighting device and a graduation for angle measurement. This can be used, for example, to carry out altitude and time of day calculations.