Equatorium

The Equatorium (Latin: Equation device ) is a device for the mechanical- geometric determination of the Planets in the Zodiac based on the geocentric planetary system of Ptolemy.

Description

The old astronomy difference between fixed stars and Change stars ( planets): the Moon, Mercury, Venus, Sun, Mars, Jupiter and Saturn. While the fixed stars do not change their position to each other, the planets perform complex movements against the background of the starry sky. The calculation of the movements of the sun and moon was especially important for the era and for the creation of a calendar. The constellation of other planets was indispensable for the creation of the horoscope.

Claudius Ptolemy took about 150 AD along the ancient knowledge of the planetary movements and developed a method to calculate their positions for any period of time. Valid until the early modern conditions of his system were the assumptions that the Earth is immobile located in the center of the universe, and that each movement traced in the sky on a circular motion with uniform speed could.

Because Ptolemy derived the motion of a planet only from the uniform circular motion ( epicycle ), with its movement on a Aufkreis, the epicycle, which is not fixed in space, but on a second circle, the carrier circuit or deferent moves (left), is the computation very complicated.

To avoid these extremely complicated and error-prone computations with multiple variables, suggested Campanus of Novara in the middle of the 13th century a device before showing the Ptolemaic planetary theory in two-dimensional models of movable discs. Such devices are known from the 14th to 16th century, parchment, paper, wood or metal instruments, the latter also in conjunction with movements.

The units for the representation of planetary motions with small discs to large discs were very popular. Many are the rules governing their production; thereby also the necessary output angle were specified for a particular day. Such works have been preserved since the 14th century.