OLD ENGRAVING ARMILLARY SPHERE CUT 16 OR 17TH SPHERE DE COPERNIC C1223 Old cut engraving, armillary sphere dating from the 16th or 17th. Belonged to a collector, kept in plastic, opened for taking photos. Sold as presented in the photos a little damage see photo folds etc - Armillary spheres • Why is this object called an armillary sphere? Armillary comes from the Greek armilla which means ring (also circle, bracelet) .- Ptolemy (approx. 90-160 AD) proposes with Aristotle (384-322 BC) a geocentric model of the world. This was accepted as a reference model for more than one thousand three hundred years.- It was only in the 16th century that Copernicus (1473-1543) advanced another theory, that of the heliocentric system. • two spheres a geocentric model (the Earth is at the center, the stars whose Sun revolve around the Earth). A heliocentric model (the Sun is at the center, the stars, including the Earth, revolve around the Sun). The armillary sphere is a scientific instrument representing the Universe as it appears to us when we observe it from Earth. The name deriving from the Latin armilla (ring) refers to the rings, which materialize the volume of this instrument.In this exhibition we present two models testifying to the two visions of the world. On the geocentric model on the left, the Earth, stationary in the center, is surrounded by several mobile rings which illustrate the apparent movement of the stars and in particular of the Sun and the planets. Thus, it is possible to visualize the position of the Sun every day of the year. This type of instrument, already used in Antiquity, is based on a geocentric vision. Ptolemy (around 90-160 AD), author of the famous treatise on astronomy Almagest, gives the first description of an armillary sphere. Educational and demonstration instruments rather than measuring, these spheres nevertheless allow a certain number of calculations and observations if they are of the right size and equipped accordingly. For example, Tycho Brahé (1546-1601) had spheres several meters in diameter built for his famous Uraniborg observatory in Denmark; during the Renaissance, they became luxurious works of art intended for the cabinets of princes and emperors. Symbol of knowledge and study, the armillary sphere appears on many portraits of scholars and personalities. From the 17th century, the heliocentric system proposed by Copernicus (1473-1543) is widely disseminated, in particular thanks to demonstration spheres. like the one shown on the right. Nevertheless, the geocentric type spheres are still widely used for study and teaching, because they made it possible to carry out a number of calculations and measurements which could not be carried out on the heliocentric spheres. Explanations of some circles • EcuadorThe extension of the terrestrial equator gives, on the celestial vault, the celestial equator. • Meridian The meridian is an imaginary semicircle connecting the poles. It is graduated in degrees to identify the height of the stars in relation to the horizon. At solar noon, the Sun is in the meridian plane of the place of observation. • Ecliptical Seen from the Earth, the Sun seems to move, during the year, by its own movement on the celestial sphere. Its apparent annual path defines the circle of the ecliptic. The planets seem to travel in this same strip of the sky. As eclipses take place along this imaginary trajectory, it was named ecliptic. 5000 years ago, the Babylonians cut this strip of sky into 12 equal sectors, which gave birth to the zodiacs. locate the evolution of the course of the Sun and the stars throughout the year. Everything above the circle of the horizon is visible to the observer, everything below is invisible to the observer. It is possible to modify the latitude of the place of observation, by tilting more or less the axis of the poles. • Tropic of Cancer / Capricorn The tropics are imaginary lines which, on the Earth, mark the place where the sun is exactly vertically, at noon on the day of the solstice. Armillary spheres, planetary clocks and celestial globes ... the Musée du Temps has other objects in its collections that reflect the evolution of knowledge of the world. You are invited to continue this visit in the gallery on the 1st floor of the museum.The photos are an integral part of the description.Dimensions: Height: 13.5 cmWidth: 9.2 cm I remain at your disposal for any questions.