ring compound: see aromatic compound.

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.

ring, small ornamental hoop usually worn on finger or thumb, but it may be attached to the ear or the nose. Finger rings made of bronze, gold, and silver from the period c.2500-1500 B.C. have been found in the Indus valley in India; in Egypt rings from c.1600 B.C. served as a symbol of status and were exchanged as a pledge or seal of faith. They were often also used as money. The signet ring grew from the custom of wearing a cylindrical seal suspended from the arm or neck, developed in Egypt, and was widely adopted as a seal of authority. Numerous rings were worn by Egyptian women, sometimes as many as three on a finger. In Greece gold bands were worn; later they were engraved with cameos or intaglios. Talismanic rings, endowed with many charms and powers, were also worn. In the middle and latter part of the Roman civilization the type of ring worn was governed by law. Iron rings were worn by the mass of the people; gold rings were reserved for those of civil or military rank. Later the gold ring was permitted to freeborn citizens, silver to freedmen, and iron to slaves. The Romans also used poison rings for assassination or suicide in the case of capture by an enemy. In addition there were key rings, which, worn by a matron, symbolized her authority to carry the keys of the house. The betrothal ring, used by Egyptians, Greeks, and Romans, was adopted by early Christians in the 2d cent. and later evolved into the wedding ring. The engagement ring set with a precious gem came into use in the Middle Ages; the diamond attained popularity in the 15th cent. and became customary c.1800. From the Middle Ages rings have figured in the coronation of kings and the consecration of bishops as emblems of authority or mystical significance. Since that time a gold seal ring (Fisherman's ring) with an intaglio of St. Peter in a fishing boat has been given each pope and is destroyed when he dies. By the 16th cent. the extravagant use of rings had reached its height. Highly decorated with enamel and jewels, they were sometimes worn on every finger and on several joints. At that time, too, the gold wedding band became popular, and signet rings were engraved with the family crest. Later, memorial rings and mourning rings became fashionable.

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.

Whiskey Ring, in U.S. history, a group of distillers and public officials who defrauded the federal government of liquor taxes. Soon after the Civil War these taxes were raised very high, in some cases to eight times the price of the liquor. Large distillers, chiefly in St. Louis, Milwaukee, and Chicago, bribed government officials in order to retain the tax proceeds. The Whiskey Ring was a public scandal, but it was considered impregnable because of its strong political connections. U.S. Secretary of the Treasury Benjamin H. Bristow resolved to break the conspiracy. To avoid warning the suspects, he assigned secret investigators from outside the Treasury Dept. to collect evidence. Striking suddenly in May, 1875, he arrested the persons and seized the distilleries involved. Over $3 million in taxes was recovered, and of 238 persons indicted 110 were convicted. Although President Grant's secretary, Orville E. Babcock, was acquitted through the personal intervention of the President, many persons believed that the Whiskey Ring was part of a plot to finance the Republican party by fraud.

Tweed Ring: see Tweed, William Marcy.

Ring nebula, planetary nebula in the northern constellation Lyra; cataloged as M57 or NGC 6720. It is perhaps the most famous and beautiful nebula of this type. Its name describes the appearance of the expanding shell of gas. The nebula is estimated to be more than 5,000 light-years distant.

Ring des Nibelungen, Der: see Nibelungen.

Lardner, Ring (Ringgold Wilmer Lardner), 1885-1933, American humorist and short-story writer, b. Niles, Mich. He was a sports reporter in Chicago, St. Louis, and Boston from 1907 to 1919. His first collection of short stories, You Know Me, Al (1916) revealed his talent for the racy sports idiom he made famous. Among his other early volumes of short stories are Gullible's Travels (1917) and Treat 'Em Rough (1918). With the publication of How to Write Short Stories (with Samples) (1924), Lardner's reputation as a satirist was established. Usually cynical and pessimistic, his stories are peopled by ordinary characters—baseball players, stenographers, barbers—who are stunningly revealed, often through their own conversation, as being stupid, dull, and vicious. His later story collections include What of It? (1925) and First and Last (1934). With George S. Kaufman he collaborated on the comedy June Moon (produced 1929).

Göring, Hermann Wilhelm: see Goering, Hermann Wilhelm.

In modern algebra, a set of elements with two operations, referred to as “addition” and “multiplication,” that conform to certain conditions. These specify that the set is closed under both operations, the associative law holds for both operations, the commutative law holds for addition, the distributive law holds, there is an additive identity (known as zero), and every element has an additive inverse (see inverse function). The set of integers is a ring. Seealso field theory.

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In a cross section of the stem of a woody plant, the amount of wood added during a single growth period. In temperate regions this period is usually one year, in which case the growth ring may be called an annual ring. In tropical regions growth rings may not be discernible or are not annual. Even in temperate regions growth rings are occasionally missing; and sometimes a second, or “false,” ring may be deposited during a single year (e.g., following defoliation by insects). Nevertheless, annual rings have been used in dating ancient wooden structures, especially those of American Indians in the dry U.S. Southwest. Changes in ring width are a source of information about ancient climates.

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(1875) Group of U.S. whiskey distillers who defrauded the government of taxes. The ring operated mainly in St. Louis, Milwaukee, and Chicago and kept liquor taxes after bribing Internal Revenue officials in Washington, D.C. A secret investigation by the U.S. Treasury Department resulted in 238 indictments and 110 convictions. While not involved, Pres. Ulysses S. Grant was tarnished by the scandal; his private secretary, Orville E. Babcock, was indicted but acquitted on Grant's testimony. The Republican Party allegedly received some of the illegally held tax money.

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(born March 6, 1885, Niles, Mich., U.S.—died Sept. 25, 1933, East Hampton, N.Y.) U.S. writer. He worked as a newspaper reporter, sportswriter, and columnist before he began publishing fiction. He won popular success with comic stories about a baseball player, some collected in You Know Me, Al (1916). Later collections, noted for their satire, narrative skill, and convincing vernacular language, include How to Write Short Stories (1924) and The Love Nest (1926). His son, the screenwriter Ring Lardner, Jr., was one of the Hollywood Ten and later wrote such hit movies as M*A*S*H (1970).

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