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

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With the Earth as center, an armillary sphere is known as Ptolemaic. With the Sun as center, it is known as Copernican. [1]

The armillary sphere is commonly used in heraldry and vexillology, being mainly known as a symbol associated with Portugal, the Portuguese Empire and the Portuguese discoveries. 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.I think what’s most interesting (to me anyway) about these rings is the fact that they were, for some, important tools to grasp advanced concepts of astronomy, but for others, they were almost a way to brag about their own accomplishments. I mean, being an astronomer several centuries ago surely took plenty of work and a whole lot of learning (as is still true today), but scientists aren’t typically known for being braggadocious. The instrument survived throughout the medieval period into the early modern era, and in many respects came to symbolise the queen of the sciences, astronomy. It wasn’t until the middle of the sixteenth-century that the basis of the instrument – a geocentric concept of the Universe – was seriously challenged by the Polish mathematician, Nicolaus Copernicus. Even then, the instrument still continued to serve a useful purpose as a purely mathematical instrument. A beautiful object called an armillary sphere appears mysteriously in the gardens of the sisters’ home on Lake Geneva and plays a key role in The Seven Sisters series.

Each of the signs of the zodiac is engraved upon the ecliptic ring which is also calibrated with a calendar scale enabling the instrument to be used to model the apparent motion of the sun and the stars at any time of the year. The instrument could be used not only to model the movements and relative geometry of the heavens, but to carry out all sorts of calculations such as the times of sunrise and sunset, the length of a day, and the altitude of the sun or stars. While there is a good deal of evidence suggesting that ancient and medieval armillary spheres existed, much of it is not straightforward. Medieval texts often refer to instruments that could be either armillary spheres or celestial globes. Texts that specifically mention the construction and use of armillary spheres seem to be less common than those that deal with other astronomical instruments. Spheres and globes Antarctic Circle: This small circle forms the southernmost latitude on earth at which the center of the sun’s disk travels completely around the horizon for a full 24 hours on the December solstice (summer solstice in the Southern hemisphere). Currently the latitude of the Antarctic Circleis 66 o 33.8’ S. The latitude of the Antarctic Circlevaries from67.9 o S and 65.5 o Sover about 41,000 years. The Antarctic Circleis moving north toward the equator at about 50 feet per year. In Renaissance Europe, the armillary sphere was amongst the first complex mechanical devices. Public figures often had their portraits painted showing them with one hand on an armillary sphere which represented the height of wisdom and knowledge. Each of the signs of the Zodiac is engraved upon the ecliptic ring, which is also calibrated with a calendar scale enabling the instrument to be used to model the apparent motion of the Sun and the stars at any time of the year. The instrument could be used not only to model the movements and relative geometry of the heavens, but to carry out all sorts of calculations, such as the times of sunrise and sunset, the length of a day, and the altitude of the Sun or stars.There is no evidence for the Hellenistic origin of the spherical astrolabe, but rather evidence so far available suggests that it may have been an early but distinctly Islamic development with no Greek antecedents." It wasn’t until the middle of the 1500s CE that the basis of the instrument – a geocentric concept of the Universe – was seriously challenged by the Polish mathematician Nicolaus Copernicus. Even then, the instrument still continued to serve a useful purpose as a purely mathematical instrument. How does an armillary sphere work? 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] Elements of the general description incorporate text from the Encyclopædia Britannica First Edition (1771). 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.

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 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. 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. Kern, Ralf: Wissenschaftliche Instrumente in ihrer Zeit. Vom 15. – 19. Jahrhundert. Verlag der Buchhandlung Walther König 2010, ISBN 978-3-86560-772-0Solstitial colure: meridian or great circle that passes through the celestial poles and the two solstices (first point of Cancer and first point of Capricorn). 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. The Arctic Circle E, and the Antarctic Circle F, each 23 1⁄ 2 degrees from its respective pole at N and S. This particular instrument is Italian, made in Rome in 1588, and is signed by Carlo Plato. It has a number of unusual features that make it rather special, such as the moon mounted on a separate ring within the sphere, and a number of stars represented by individual pointers.

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. 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] 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.It is believed that the Greek astronomer Hipparchus invented the armillary sphere around 200BC, to decipher how the heavens and stars moved around the earth. His sphere had a ball representing the earth in the centre, and four overlapping rings circling the globe. Obliquity: Earth's axial tilt or obliquity of the ecliptic is defined as the angle that its rotational axis makes with its orbital plane (ecliptic). The earth’s axial tilt is currently 23 o 26.2’ (23.44 o). Since the earth’s orbital plane is affected by the otherplanets in the solar system, its axial tilt varies over time. Data over the past 5 million years show that the obliquity varies from22.1 o and 24.5 o over about 41,000 years. Currently the earth’s obliquity is slowly decreasing towards the low values. There are other shorter-term variations in the obliquity, such as nutation, which is caused by the moon and varies over 18.6 years.