The armillary sphere (also known as a spherical astrolabe) is an ancient instrument which models the position of the sun and other celestial bodies. It is thought that it was invented by the Greek astronomer Eratostenes around 255 BC. It was used throughout Antiquity, the Middle Ages, and the Renaissance to determine the celestial coordinates of the stars.
It is comprised of a certain number of circles ("armilla" means bracelet in Latin) which represent the celestial equator, the ecliptic, the horizon, the zodiac, etc., in such a way that, once directed towards a star, their celestial coordinates could be read on graduated scales.
The armillary sphere were used by the Arab astronomers, Hipparcus and Ptolemy, and had a great development in 15th and 16th centuries. This one is a reproduction of the one made by Danish astronomer Tycho Brahe (1576-1601).
It is made of wood and brass and is totally handmade. It comes accompanied by a booklet with history and instructions for use.