JUNTEN Astronomical Ring Men Women Armillary Sphere Ring for Couple Lovers Foldable Cosmic Finger Rings, Size 5-12

Product Information

Kern, Ralf: Wissenschaftliche Instrumente in ihrer Zeit. Vom 15. – 19. Jahrhundert. Verlag der Buchhandlung Walther König 2010, ISBN 978-3-86560-772-0 In its simplest form, consisting of a ring fixed in the plane of the equator, the armilla is one of the most ancient of astronomical instruments. Slightly developed, it was crossed by another ring fixed in the plane of the meridian. The first was an equinoctial, the second a solstitial armilla. Shadows were used as indices of the sun's positions, in combinations with angular divisions. When several rings or circles were combined representing the great circles of the heavens, the instrument became an armillary sphere. [1] Tropic of Cancer: This small circle (also called the Northern Tropic) forms the northernmost latitude on earth at which the noontime sun can cross the zenith. This occurs around June 21 and is called the summer solstice in the northern hemisphere. A corresponding circle, also called the Tropic of Cancer, is formed by the projection of the earth’s Tropic of Cancer onto the celestial sphere. In ancient times, the sun passed through the zodiacal constellation of Cancer at this time of year — thus its name Cancer. The word “tropic” derives from the Greek word meaning turn — referring to the point on the sky where the sun changes direction and begins moving south as winter approaches in the northern hemisphere. Today, while precession (the wobble of the earth on its axis) has shifted the summer solstice into the constellational of Taurus, the solstitial sun remains in the astrological sign of Cancer, which is unaffected by precession. The Tropic of Cancer is currently at latitude 23 o 26.2’ N (23.44 o N). Like the obliquity, the latitude of the Tropic of Cancer varies from22.1 o Nand 24.5 o Nover about 41,000 years. The Tropic of Cancer is moving south toward the equator at about 50 feet per year. An armillary sundial also called an armillary sphere is a representation of both the terrestrial globe and celestial sphere. Often highly decorated, these are beautiful sundials. 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 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.

Inscriptions or zodiac symbols were often used as decorative elements on the bands.

Savage-Smith, Emilie (1985), Islamicate Celestial Globes: Their History, Construction, and Use, Smithsonian Institution Press, Washington, D.C. And so, by this construction, the machine is equally fitted to show either the real motion of the earth, or the apparent motion of the heavens. An armillary sphere (variations are known as spherical astrolabe, armilla, or armil) is a model of objects in the sky (on the celestial sphere), consisting of a spherical framework of rings, centered on Earth or the Sun, that represent lines of celestial longitude and latitude and other astronomically important features, such as the ecliptic. As such, it differs from a celestial globe, which is a smooth sphere whose principal purpose is to map the constellations. It was invented separately, in ancient China possibly as early as the 4th century BC and ancient Greece during the 3rd century BC, with later uses in the Islamic world and Medieval Europe. The 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. About it rotate a set of rings representing the heavens – the celestial sphere – with one complete revolution approximating 24 hours.

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 b c d Editors of Encyclopædia Britannica. (16 November 2006). " Armillary Sphere." Encyclopædia Britannica. Accessed 14 October 2017. An armillary sphere is ideally suited as a sundial. With its hour face inscribed on the inner circular surface of the Equatorial ring—also known as the Equinoctial—the gnomon’s shadow sweeps uniformly along with time, allowing the hour markings to be equally spaced along the equinoctial ring. Very few examples of the instrument survive from earlier than the 16th century. This may be due to their fragile nature and the materials used to construct them. Delicate spheres composed of rings, even when these were made of brass, are less likely to have been preserved than flat instruments such as astrolabes. First ever Heritage Flame lit at Stoke Mandeville in a historic moment for Paralympic Movement". www.paralympic.org. 3 January 2014.

Cookie Control

Equinoctial colure: meridian or great circle that passes through the celestial poles and the two equinoxes (first point of Aries and first point of Libra). Colure is one of two principal meridians (great circles) on the celestial sphere—equinoctial colure and solstitial colure. The concept of the celestial sphere was fundamental to astronomy from Antiquity through the Middle Ages and into the early Modern era. Williams, Henry Smith (2004). A History Of Science. Whitefish, MT: Kessinger Publishing. ISBN 1-4191-0163-3. Lindberg, David C.; Shank, Michael H. (7 October 2013). The Cambridge History of Science: Volume 2, Medieval Science. Cambridge University Press. p.173. ISBN 978-1-316-02547-5 . Retrieved 15 May 2018.