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ring

ring

The Columbia Encyclopedia, 6th ed. | 2008 | Copyright

ring in astronomy, relatively thin band of rocks and dust and ice particles that orbit around a planet in the planet's equatorial plane. All four of the giant planets in the solar system— Jupiter , Saturn , Uranus , and Neptune — have rings, although only those of Saturn are easily visible. The origin of the rings is unknown. One theory is that they may have been formed from moons that were shattered by the impact of comets and meteoroids. Another holds that they might be the remnants of moons or comets that came within the planet's Roche limit and were broken up by gravitational forces.

Saturn has seven rings designated alphabetically as A through G in the order of their discovery; two additional rings, designated as R/2004 S1 and R/2004 S2 were discovered in images returned to earth from the Cassini space probe in 2004. From the planet outward, the rings are D, C, B, A, R/2004 S1, R/2004 S2, F, G, and E. With named gaps occupying the space between several of the rings, Saturn's rings are a highly complex structure stretching almost 167,770 mi (270,000 km) from the planet's center to the farthest edge of ring E. The rings are not perfectly circular, and the gaps are not completely empty. The Columbo and Maxwell Gaps separate the C and B rings, the Cassini Division and Huygens Gap separate the B and A rings, and the Encke Division and Keeler Gap separate the A and R/2004 S1 rings. Except for the A and B rings, which are separated primarily by the 2,920-mi-wide (4,700-km) Cassini Division, the rings are relatively close to one another. The rings appear to be composed of small pieces of water ice mixed with a small amount of rocky material in a wide range of particle sizes, from 1 in. (2.5 cm) to 33 ft (10 m)—although there may be an occasional object as large as a mile (1.6 km) in diameter. Data returned by Cassini indicates that the rings are not uniform; for example, the B ring is very different from the A and C rings (which are similar to one another) found on either side of it. Several of Saturn's small moons appear to be shepherd satellites, maintaining the shape of the rings through gravitational interactions.

Jupiter's rings are similar to those of Saturn but much smaller and fainter. The main ring is about 4,300 mi (7,000 km) wide and has an abrupt outer boundary 80,000 mi (128,940 km) from the center of the planet. The inner main ring is formed from dust and ice particles kicked up when meteoroids collide with the small Jovian satellites Metus and Adrastea. The particles then spiral slowly in toward Jupiter. At its inner edge the main ring merges into the halo. A broad, faint band of dust and particles, the halo is about 6,200 mi (10,000 km) thick and stretches halfway from the main ring down to the top of Jupiter's atmosphere. A pair of broad, faint gossamer rings are located just outside the main ring, one bounded by the orbit of the Jovian shepherd satellite Amalthea and the other by the orbit Thebe.

Uranus has a thin elliptical band of eleven faint, narrow rings composed of ice, rock, and dust. Stretching outward from the planet, the rings are named 1986 U2R, Six, Five, Four, Alpha, Beta, Eta, Gamma, Delta, 1986 U1R, and Epsilon; the distance from the planetary center to the Epsilon ring is 31,750 mi (51,140 km). The rings are distinctly different from those of Jupiter and Saturn. A tenuous distribution of fine dust is scattered throughout the ring system, and the rings all are the same flat, dark color (perhaps from methane or black-carbon ice coating the rock), unlike Saturn's bright rings. The nine main rings consist of a single layer of particles, the monolayer, which had not previously been seen in planetary rings; the particles are kept from drifting away by several shepherd satellites. Because there are ringlets and incomplete rings and a varying opacity in several rings, it is believed that the Uranian ring system may be the remnants of a small moon.

Neptune has four almost circular faint rings composed of small rocks and dust. The rings are not uniform in density and thickness; the thicker parts of the rings are called ring arcs. Stretching outward from the planet, the rings are named Galle, Leverrier (whose outer extension is called Lassel), Arago, and Adams (which includes the ring arcs Liberty, Equality, and Fraternity); the distance from the planetary center to the Adams ring is 39,000 mi (62,930 km). The forces responsible for the development of ring arcs and ring extensions are not well understood, but shepherd satellites and gravitational forces attributable to Neptune's moons are thought to play a significant role. Earth-based observations indicate that the rings are less stable than was originally believed.

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ring

A Dictionary of Computing | 2004 | | Copyright

ring
1. An algebraic structure R on which there are defined two dyadic operations, normally denoted by + (addition) and · or juxtaposition (multiplication). With respect to addition, R is an abelian group, 〈R, +〉 i.e. + is commutative and associative. With respect to multiplication, R is a semigroup,〈R, ·〉 i.e. · is associative. Further, multiplication is distributive over addition.

Certain kinds of rings are of particular interest:(a)if multiplication is commutative the ring is called a commutative ring;(b)if 〈R, ·〉 is a monoid, the ring is called a ring with an identity;(c)a commutative ring with an identity, and having no nonzero elements x and y with the property that x · y = 0, is said to be an integral domain;(d)a commutative ring with more than one element, and in which every nonzero element has an inverse with respect to multiplication, is called a field.The different identity elements and inverses, when these exist, can be distinguished by talking in terms of additive identities (or zeros), multiplicative identities (or ones), additive inverses, and multiplicative inverses.

The concept of a ring provides an algebraic structure into which can be fitted such diverse items as the integers, polynomials with integer coefficients, and matrices; on all these items it is customary to define two dyadic operations.

2. Another name for circular list, but more generally applied to any list structure where all sublists as well as the list itself are circularly linked.

3. In network topology, a ring network is a closed-loop network that does not require terminators. A token ring topology is physically cabled as a star, with a logical ring maintained at the hub. When a workstation connects to the hub, the ring is extended out to the workstation and back to the hub.
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ring

The Oxford Dictionary of Phrase and Fable | 2006 | | Copyright

ring a circle or circular space, especially a circular band worn on a finger as a token of marriage, engagement, or authority, a ring can also be seen as a particularly personal possession, as in the story of Polycrates and his attempt to avert ill-fortune. In traditional legends such as that of the Nibelungenlied a ring may be an object of power. A ring is the emblem of St Catherine of Alexandria, St Catherine of Siena, and St Edward the Confessor.
hold the ring monitor a dispute or conflict without becoming involved in it; the idea here is of being a spectator at a boxing match.
ring-a-ring o'roses a singing game played by children, in which the players hold hands and dance in a circle, falling down at the end of the song. It is said to refer to the inflamed (‘rose-coloured’) ring of buboes, symptomatic of the plague; the final part of the game is symbolic of death.
Ring Cycle an informal name for Wagner' cycle of operas based on the Nibelungenlied.
ring finger the finger next to the little finger, especially of the left hand, on which the wedding ring is worn.
ring fort a prehistoric earthwork, especially an Iron Age hill fort, defended by circular ramparts and ditches.
ring of iron the defensive cordon created around Bilbao by the Basques in the Spanish Civil War; the term is a translation of Spanish cinturón de hierro.
ring of steel a security cordon built around (part of) a city, typically as an anti-terrorist measure, employing roadblocks and surveillance procedures; in the UK, the possibility was raised of establishing a ring of steel round the City of London after the IRA's bombing of the Baltic Exchange in 1992.
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ELIZABETH KNOWLES. "ring." The Oxford Dictionary of Phrase and Fable. 2006. Encyclopedia.com. 10 Feb. 2012 <http://www.encyclopedia.com>.

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ring

The Concise Oxford Dictionary of English Etymology | 1996 | | Copyright

ring1 circle or circlet of metal, etc.; circular group OE.; various transf. and fig. uses esp. from XIV. OE. hring = OS., OHG. hring (Du., G. ring), ON. hringr :— Gmc. *χreŋgaz.
Hence vb. put a ring or circle around; from XV, with corr. formations in the cogn. langs.; cf. OE. be-, ymbhringan surround. Comps. ringdove wood-pigeon. XVI. prob. after LG. or Du. ringfinger third finger. OE. hringfinger. ringleader XVI. f. phr. lead the r. ringlet XVI. ringworm skin disease marked by circular patches. XV.
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T. F. HOAD. "ring." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. 10 Feb. 2012 <http://www.encyclopedia.com>.

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ring

The Columbia Encyclopedia, 6th ed. | 2008 | Copyright

ring in mathematics, system consisting of a set R of elements and two binary operations, such that addition makes R a commutative group and multiplication is associative and distributes over addition (see commutative law ; associative law ; distributive law ). A commutative ring is one in which the commutative law also holds for multiplication. Examples of commutative rings are the sets of integers (see number ) and real numbers. Square matrices (see matrix ) furnish examples of non-communtative rings.

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Ring

Dictionary of Collective Nouns and Group Terms | 1985 | Copyright

Ring

a circular arrangement or group. See also circle.

Examples : ring of disciples, 1732; of branching elms, 1784; of forts; of all iniquity, 1578; of jewellers—Lipton, 1970; of fair ladies, 1450; of mushrooms; of oaks, 1820.
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ring

The Concise Oxford Dictionary of English Etymology | 1996 | | Copyright

ring2 pt. rang (rung) pp. rung give out a resonant sound OE.; cause (a bell) to do this XII. OE. hringan, corr. to ON. hringja; orig. wk. (OE. pt. hringde, early ME. ringde), but strong forms appear in early XIII.
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ringing

A Dictionary of Computing | 2004 | | Copyright

ringing A damped oscillation that occurs in many electrical circuits when signals change rapidly, and is due often to unwanted capacitance and inductance in devices and connecting wires.
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Ring

A Dictionary of British Place-Names | 2003 | | Copyright

Ring (Rinn) Waterford. ‘Point’.
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A. D. MILLS. "Ring." A Dictionary of British Place-Names. 2003. Encyclopedia.com. 10 Feb. 2012 <http://www.encyclopedia.com>.

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ring

A Dictionary of Nursing | 2008 | Copyright

ring (ring) n. (in anatomy) see annulus.
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ringing

A Dictionary of Earth Sciences | 1999 | | Copyright

ringing See REVERBERATION.
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AILSA ALLABY and MICHAEL ALLABY. "ringing." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 10 Feb. 2012 <http://www.encyclopedia.com>.

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ring

Oxford Dictionary of Rhymes | 2007 | Copyright

ring •Beijing, bing, bring, Chungking, cling, ding, dingaling, fling, I Ching, king, Kunming, ling, Ming, Nanjing, Peking, ping, ring, sing, Singh, sling, spring, sting, string, swing, Synge, thing, ting, wing, wring, Xining, zing •saying, slaying •bricklaying • minelaying •being, far-seeing, unseeing •sightseeing • well-being •blackberrying •dairying, unvarying •unwearying •self-pitying, unpitying •belying, dying, lying, self-denying, tying, vying •unedifying • unsatisfying • outlying •drawing • underdrawing •easygoing, flowing, going, knowing, mowing, outgoing, showing, sowing, thoroughgoing, toing and froing •seagoing • ongoing • foregoing •theatregoing • churchgoing •following • borrowing • annoying •bluing, doing, misdoing •evil-doing • wrongdoing

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Free newspaper and magazine articles

RINGS OF GLORY.(General News)(Former UO football players are among the few...
Newspaper article from: The Register Guard (Eugene, OR); 2/6/2005
Piston rings.(SHOP TALK)
Magazine article from: Outdoor Power Equipment; 7/1/2005
Saturn's rings 'may be as old as solar system'.
News Wire article from: PTI - The Press Trust of India Ltd.; 12/14/2007

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ring. (Image by Flickr user Robyn Gallagher, CC)

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