Armillary spheres date back to antiquity, with the first dating back to 200 BC, and they were certainly used by the 2nd century astronomer and mathematician Claudius Ptolemy of Alexandria (100 AD). It was a mathematical instrument designed to demonstrate the motion of the celestial sphere around a stationary Earth at its center. The concept of the celestial sphere was fundamental to astronomy from antiquity to the Middle Ages and into the early modern period. At the center of the sphere is the Earth. Since the Earth is stationary in this model, it is the celestial sphere that rotates around it and acts as a frame of reference for determining the location of celestial bodies, particularly stars, from a geocentric perspective. The sphere is the skeleton of a celestial globe with circles divided into degrees for angular measurement and representing the great celestial circles, including in the most sophisticated instruments the horizon, meridian, equator, tropics, polar circles and the ring of the ecliptic. Each sign of the zodiac is engraved on the ecliptic ring, which is also calibrated to the calendar scale, allowing the instrument to be used to model the apparent movement of the sun and stars at any time of the year. The instrument could be used not only to model the movement and relative geometry of the sky, but also to perform all kinds of calculations, such as the times of sunrise and sunset, the length of the day, and the altitude of the sun or stars. Beautifully crafted, solid brass with wooden stand Please watch video to see rotation. Would make a great decorative addition for any enthusiast collector. Old item, not antique. Height: 22 cm Sphere diameter: 15 cm Base diameter: 11 cm Item weight: 750 g Use for Occasions Graduation Gift, Father's Day Gift, Gift for a Special Man, Anniversary Gift, Groomsman Gift, Valentine's Day Gift, Personalized Gift for Men, Christmas Gift, Nautical Decor, Camping Gift for Man and Woman, Promotion Day Gift. Karniproduction, we are the third generation creator, specialize in handcrafted items, nautical style and interior design.. Made of brass, copper, iron and wood. All items are handcrafted or created with simple tools.. We are the manufacturer, supplier and exporter of various nautical decorative and other gift items.. They are available in various designs to meet the needs of our customers.. Our goal is to be the unrivaled leader in providing products.. We believe that customer satisfaction is the most important factor. Which determines the access of a company. As a result, to satisfy our customers, we provide high quality products.. What We Do The Royal Handicraft brand was created to meet the need for high quality products at reasonable prices. One purchase from you makes our day brighter. We will be happy to bring a smile to the faces of our clients. Thank you for purchasing from us.