Mars Ancient Roman god of war and protector of Rome, second only to Jupiter in importance. His festivals occurred in the spring (March) and fall (October). Until the time of Augustus, Mars had only two temples in Rome. His sacred spears were kept in a sanctuary; on the outbreak of war, the consul had to shake the spears, saying “Mars vigila!” (“Mars, awake!”) Under Augustus, Mars became not only the guardian of Rome in its mili¬ tary affairs but the emperor’s personal guardian. He was identified with the Greek god Ares.
Mars Fourth planet from the Sun, named after the Roman god of war. Its mean distance from the Sun is 141 million mi (227 million km). Its day is 24.6 Earth hours and its year about 687 Earth days. It has two small moons, Phobos and Deimos. Mars’s equatorial diameter is 4,220 mi (6,792 km), about half that of Earth, and it is less dense than Earth. Its
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Mars ► Marshall I 1201
mass is about one-tenth of Earth’s and its surface gravity about one-third as strong. No magnetic field has been detected on Mars, suggesting, as does its low density, the absence of a substantial metallic core. Like Earth, it has seasons and an atmosphere, but its average daytime surface tem¬ perature is only -10 °F (-20 °C). Mars’s thin atmosphere is mainly car¬ bon dioxide, with some nitrogen and argon and traces of water vapour. Spacecraft images show a cratered surface, with volcanoes, lava plains, flood channels, and canyons, many large by Earth standards; Olympus Mons, for example, is the largest known volcano in the solar system. Wind is an important element on Mars, sculpting features such as dunes and occasionally causing global dust storms. In the distant past Mars appears to have had a denser, warmer atmosphere and much more water than at present. Images from the Mars Global Surveyor spacecraft suggest that some liquid water may have flowed near the planet’s surface in relatively recent times. No life has been detected on the planet.
Mars, canals of Apparent systems of straight-line markings on the surface of Mars, now known to be an illusion caused by the chance align¬ ment of large craters and other surface features. Giovanni Virginio Schi¬ aparelli (1835-1910) observed about 100 of what he described as channels. Percival Lowell called them canals and believed them to be evi¬ dence of intelligent life. Most astronomers could not see them, and many doubted their reality. The controversy was finally resolved only when pic¬ tures from Mariner spacecraft showed nothing resembling a network of channels.
Mars Pathfinder First spacecraft to land on Mars since the Viking 1976 missions. Launched in 1996 by NASA, Pathfinder descended to the Mar¬ tian surface in July 1997 using parachutes, rockets, and air bags. It then deployed instruments, including Sojourner, a small, six-wheeled robotic rover, which explored as far as 1,600 ft (500 m) from the lander and sent pictures back for over a month. The mission’s main objective was to show that low-cost Mars landings and exploration are feasible.
Marsalis \mar-'sa-l9s\, Wynton (b. Oct. 18, 1961, New Orleans, La., U.S.) U.S. trumpeter and composer. Marsalis was a trumpet prodigy and was recognized as an important soloist in both the classical and jazz tra¬ ditions at an early age. He joined Art Blakey’s Jazz Messengers (1980- 82) before leading his own groups. As a composer he has written ballet and concert works, and he won the 1997 Pulitzer Prize for his oratorio Blood on the Fields. He also worked on Ken Burns’s Jazz miniseries and was a catalyst in the revival of broad interest in jazz.
Marseille or Marseilles \mar-'sa\ City (pop., 1999: city, 797,486; metro, area, 1,349,772), southeastern France. One of the Mediterranean’s major seaports and the second largest city in France, it is located on the Gulf of Lion, west of the French Riviera. It was settled by Greeks during the 7th century bc and was annexed by the Romans, who called it Massilia, in 49 bc. It declined along with the Roman Empire but revived as a commer¬ cial port during the Crusades era; it passed to the French crown in 1481. The plague of 1720 killed half of its population. In the 19th century the devel¬ opment of France’s colonial empire added to the city’s importance. Fol¬ lowing World War II, rapid industrial growth took place around the port complex at Fos-sur-Mer and in suburbs such as Marignane and Vitrolles.
marsh Freshwater or marine wetland ecosystem characterized by poorly drained mineral soils and by plant life dominated by grasses. Fewer plant species grow in marshes than on well-watered but not waterlogged land; grasses, sedges, and reeds or rushes are most common. Commercially, rice is by far the most important freshwater marsh plant: it supplies a major portion of the world’s grain. Salt marshes are formed on intertidal land by seawater flooding and draining, and salt-marsh grasses will not grow on permanently flooded flats. See also swamp.
Marsh, Dame (Edith) Ngaio (b. April 23, 1895, Christchurch, N.Z.—d. Feb. 18, 1982, Christchurch) New Zealand writer of detective stories. Originally an artist, she later acted in and produced Shakespear¬ ean repertory theatre (1938-64). She is known for her mystery stories featuring Inspector Roderick Alleyn of Scotland Yard. With novels such as Overture to Death (1939), Final Curtain (1947), Death of a Fool (1956), and Dead Water (1963), she helped make the detective story a respectable literary genre.
Marsh, O(thniel) C(harles) (b. Oct. 29, 1831, Lockport, N.Y., U.S.—d. March 18, 1899, New Haven, Conn.) U.S. paleontologist. He spent his entire career at Yale University (1866-99) as the first professor of vertebrate paleontology in the U.S. From 1870 he led scientific expe¬
ditions to the West; in 1871 his party discovered the first pterodactyl found in the U.S. In 1882 he was placed in charge of the U.S. Geological Sur¬ vey’s work in vertebrate paleontology, aggravating a fierce rivalry between him and Edward D. Cope. Credited with discovering more than 1,000 fossil vertebrates and describing at least 500 more, Marsh published major works on toothed birds, gigantic homed mammals, and North American dinosaurs. His books include Fossil Horses in America (1874) and Introduction and Succession of Vertebrate Life in America (1877).
Marsh, Reginald (b. March 14, 1898, Paris, France—d. July 3, 1954, Bennington, Vt., U.S.) U.S. painter and printmaker. Bom to American parents in Paris and educated at Yale University, from 1922 to 1925 he produced a daily column of drawings of vaudeville acts for the New York Daily News. In 1925 he became an original member of the staff of The New Yorker magazine, for which he drew humorous illustrations and met¬ ropolitan scenes. In 1929 he began painting scenes of city life, including Coney Island crowds and Bowery derelicts. He taught at the Art Students League from 1934 until his death.
marsh gas See methane
marsh mallow Perennial herbaceous plant ( Althaea officinalis ) of the mallow family, native to eastern Europe and northern Africa and natural¬ ized in North America. Found usually in marshy areas near the sea, the marsh mallow has strongly veined, heart-shaped or oval leaves and pink¬ ish flowers borne on stalks about 6 ft (1.8 m) tall. The root was formerly processed to make marshmallows.
marsh marigold Perennial herbaceous plant ( Caltha palustris) of the buttercup family, native to wetlands in Europe and North America. It is grown in boggy wild gardens. The plant has a hollow stem, heart-shaped or round leaves, and glossy pink, white, or yellow flowers composed solely of sepals (petals are absent). The stems, leaves, and roots are some¬ times cooked and eaten as a vegetable, though the fresh plant is poison¬ ous. See also cowslip.