Since ancient times, astronomers around the world have used models of the sky to make calculations. With the advent of the armillary sphere, stargazers were given a physical model to better visualize the lines of celestial longitude and latitude. Created independently in ancient Greece and ancient China, these armillary spheres consisted of spherical rings centered on either the Earth or the Sun. During the 16th and 17th centuries, these astronomy tools were sized down to become fashionable finger rings that moved just like regular armillary spheres. Throughout Chinese history, astronomers have created celestial globes ( Chinese: 渾象) to assist the observation of the stars. The Chinese also used the armillary sphere in aiding calendrical computations and calculations.

This ring is sometimes engraved with the months on one side and corresponding zodiac signs on the outside; very similar to an astrolabe. The equatorial ring occupies a plane parallel to the celestial equator, at right angles to the meridian. It is aligned byThe flag of Portugal features an armillary sphere. The armillary sphere is also featured in Portuguese heraldry, associated with the Portuguese discoveries during the Age of Exploration. Manuel I of Portugal, for example, took it as one of his symbols where it appeared on his standard, and on early Chinese export ceramics made for the Portuguese court. In the flag of the Empire of Brazil, the armillary sphere is also featured. In the end of the 15th century, the armillary sphere became the personal heraldic badge of the future King Manuel I of Portugal, when he was still a Prince. The intense use of this badge in documents, monuments, flags and other supports, during the reign of Manuel I, transformed the armillary sphere from a simple personal symbol to a national one that represented the Kingdom of Portugal and in particular its Overseas Empire. As a national symbol, the armillary sphere continued in use after the death of Manuel I. Armillary sphere rings like the ones in the British Museum’s collection and the Swedish Historical Museum (top) serve a more benign purpose. Folded together, the two-part outer hoop and three interior hoops give the illusion of a simple gold band. Slipped off the wearer’s finger, they can fan out into a physical model of celestial longitude and latitude. The three rings are oriented with respect to the local meridian, the planet's equator, and a celestial object. The instrument itself can be used as a plumb bob to align it with the vertical. The instrument is then rotated until a single light beam passes through two points on the instrument. This fixes the orientation of the instrument in all three axes. a b Savage-Smith, Emilie (2017). "Of Making Celestial Globes There Seems No End" (PDF). Bulletin of the Scientific Instrument Society. No. 132: 1–9.

The whole fabric is supported on a pedestal N, and may be elevated or depressed upon the joint O, to any number of degrees from 0 to 90, by means of the arc P, which is fixed in the strong brass arm Q, and slides in the upright piece R, in which is a screw at r, to fix it at any proper elevation. The armillary sphere was reintroduced in the national arms and in the national Flag of Portugal in 1911.The Beijing Capital International Airport Terminal 3 features a large armillary sphere metal sculpture as an exhibit of Chinese inventions for international and domestic visitors. Handmade with extra attention to detail, this ring is the perfect gift for a jewelry collector or budding fashionista in your life. The Arctic Circle E, and the Antarctic Circle F, each 23 1⁄ 2 degrees from its respective pole at N and S. Often equipped with a graduated scale, it can be used to measure right ascension. On the traveller's sundial shown above, it is the inner ring. Williams, Henry Smith (2004). A History Of Science. Whitefish, MT: Kessinger Publishing. ISBN 1-4191-0163-3.

Dirk L. Couprie, Robert Hahn, Gerard Naddaf: Anaximander in Context: New Studies in the Origins of Greek Philosophy, 2003, ISBN 978-0-7914-5537-1, p. 179 With the Earth as center, an armillary sphere is known as Ptolemaic. With the Sun as center, it is known as Copernican. [1] First ever Heritage Flame lit at Stoke Mandeville in a historic moment for Paralympic Movement". www.paralympic.org. 3 January 2014. In the 17th century, the armillary sphere was used by astronomers to study and make calculations, so to our designers, this sphere was a symbol of knowledge and wisdom. We believe that magical feeling should be given to everyone, so we designed this ring with this sphere concept – so everyone (and anyone) can feel smart and sharp every time they wear this ring. The armillary sphere survives as useful for teaching, and may be described as a skeleton celestial globe, the series of rings representing the great circles of the heavens, and revolving on an axis within a horizon. With the earth as center such a sphere is known as Ptolemaic; with the sun as center, as Copernican. [1]A representation of an armillary sphere is present in the modern flag of Portugal and has been a national symbol since the reign of Manuel I. The declination ring is moveable, and rotates on pivots set in the meridian ring. An imaginary line connecting these pivots is parallel to the Earth's axis. The declination "ring" of the traveller's sundial above is not a ring at all, but an oblong loop with a slider for setting the season. The equinoctial A, which is divided into 360 degrees (beginning at its intersection with the ecliptic in Aries) for showing the sun's right ascension in degrees; and also into 24 hours, for showing its right ascension in time. Armillary spheres were among the first complex mechanical devices. Their development led to many improvements in techniques and design of all mechanical devices. Renaissance scientists and public figures often had their portraits painted showing them with one hand on an armillary sphere, which represented the zenith of wisdom and knowledge. The equinoctial colure G, passing through the north and south poles of the heaven at N and S, and through the equinoctial points Aries and Libra, in the ecliptic.

The meridian ring is placed vertically, then rotated (relative to the celestial object) until it is parallel to the local north-south line. The whole ring is thus parallel to the circle of longitude passing through the place where the user is standing. Kern, Ralf: Wissenschaftliche Instrumente in ihrer Zeit. Vom 15. – 19. Jahrhundert. Verlag der Buchhandlung Walther König 2010, ISBN 978-3-86560-772-0 The solstitial colure H, passing through the poles of the heaven, and through the solstitial points Cancer and Capricorn, in the ecliptic. Each quarter of the former of these colures is divided into 90 degrees, from the equinoctial to the poles of the world, for showing the declination of the sun, moon, and stars; and each quarter of the latter, from the ecliptic as e and f, to its poles b and d, for showing the latitude of the stars. It can be used as a sun dial to tell time, if the approximate latitude and season is known, or to tell latitude, if the time is known or observed (at solar noon). It may be considered to be a simplified, portable armillary sphere, or a more complex form of astrolabe. The tropic of Cancer C, touching the ecliptic at the beginning of Cancer in e, and the tropic of Capricorn D, touching the ecliptic at the beginning of Capricorn in f; each 23 1⁄ 2 degrees from the equinoctial circle.

a b c d Editors of Encyclopædia Britannica. (16 November 2006). " Armillary Sphere." Encyclopædia Britannica. Accessed 14 October 2017. The British Museum has a collection of several armillary sphere rings that are incredibly well-crafted and detailed. When closed, they look like any other ring, but as the different bands are fanned out, the rings take on a unique quality. Built with anywhere between two to eight moving bands, these intricate pieces of jewelry would need to have been executed by skilled craftsmen. The angle between the vertical and the light beam gives the solar elevation. The solar elevation is a function of latitude, time of day, and season. Any one of these variables can be determined using astronomical rings, if the other two are known. Astronomical rings ( Latin: annuli astronomici), [1] also known as Gemma's rings, are an early astronomical instrument. The instrument consists of three rings, representing the celestial equator, declination, and the meridian.