An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

A selection effect in observational astronomy. If a sample of objects (galaxies, quasars, stars, etc.) is flux-limited, then the observer will see an increase in average luminosity with distance, because the less luminous sources at large distances will not be detected.

Named after the Swedish astronomer Gunnar Malmquist (1893-1982); → bias.

A correction introduced into star counts distributed by apparent magnitude.

→ Malmquist bias; → correction.

If the light wave entering an → analyzer is → linearly polarized, the intensity of the wave emerging from the analyzer is I = k I₀ cos²φ, where k is the coefficient of transmission of the analyzer, I₀ is the intensity of the incident light, and φ is the angle between the planes of → polarization of the incident light and the light emerging from the analyzer.

Named after Etienne Louis Malus (1775-1812), French physicist who also discovered polarization by reflection at a glass surface (1808); → law.

A method for deriving the Earth's size based on measuring a length of meridian between two points corresponding to the difference between the respective latitudes. The Abbasid caliph al-Ma'mun (ruling from 813 to 833 A.D.), appointed two teams of surveyors to this task. They departed from a place in the desert of Sinjad (nineteen farsangs from Mosul and forty-three from Samarra), heading north and south, respectively. They proceeded until they found that the height of the Sun at noon had increased (or decreased) by one degree compared to that for the starting point. Knowing the variation of the Sun's → declination due to its apparent → annual motion, they could relate the length of the arc of meridian to the difference between the latitudes of the two places. They repeated the measurement a second time, and so found that the length of one degree of latitude is somewhat between 56 and 57 Arabic miles (Biruni, Tahdid). 360 times this number yielded the Earth's circumference, and from it the radius was deduced.
See also: → Eratosthenes' method, → Biruni's method.

The seventh Abbasid caliph Abu Ja'far Abdullâh al-Ma'mûn, son of Hârûn al-Rashîd (786-833 A.D.); → method.

1) An adult male person.
2) A member of the species Homo sapiens. See also → human, → anthropo-.

M.E., from O.E. man, mann "human being, person" (O.S., O.H.G. man, Ger. Mann, O.N. maðr, Goth. manna "man"), from PIE base *man-; cf. Skt. mánu-, más- "man, person, husband;" Av. manu- in proper noun Manus-ciθra- (Pers. Manucehr); O.C.S. moži, Russ. muž "man, male."

(Mid.Pers./Mod.Pers.) mard "man," mardom "mankind, people," cognate with mordan "to die," → death; Sogd. martu, marti "man, human;" O.Pers. martiya-; Av. marəta- "mortal, man," maša- "mortal;" cf. Skt. márta- "mortal, man;" Gk. emorten "died;" L. mortalis "subject to death;" PIE base *merto-, *morto-. Ensân, loan from Ar.

To direct or control the use of; to exercise executive, administrative, and supervisory direction of.

Probably from It. maneggiare "to handle, train (a horse)," from L. manus "hand."

Gonârdan, from Mid.Pers vinârtan, variant vinâristan "to organize, arrange, put in order," from vi- "apart, away from" (Av. vi- "apart, away from, out;" O.Pers. viy- "apart, away;" cf. Skt. vi- "apart, asunder, away, out;" L. vitare "to avoid, turn aside") + âristan, ârâstan "to arrange, adorn;" O.Pers. râs- "to be right, straight, true," râsta- "straight, true" (Mod.Pers. râst "straight, true"), râd- "to prepare," Av. râz- "to direct, put in line, set," Av. razan- "order," Gk. oregein "to stretch out," L. regere "to lead straight, guide, rule," p.p. rectus "right, straight," Skt. rji- "to make straight or right, arrange, decorate," PIE base *reg- "move in a straight line."

The act or manner of managing; handling, direction, or control.

Verbal noun of → manage.

A person who manages; a person who has controls or directs an institution, a team, a division, or part it.

Agent noun of → manage.

A set of points in the complex plane, the boundary of which forms a fractal with varying shapes at different magnifications. Mathematically, it is the set of all C values for which the iteration z_n+1 = z_n² + C, starting from z₀ = 0, does not diverge to infinity.

Discovered by Benoît Mandelbrot (1924-) a Polish-born French mathematician, best known as the "father of fractal geometry;" → set.

A movement or action to accomplish a change of position.

From Fr. manoeuvre "manipulation, maneuver," from O.Fr. manovre "manual work," from M.L. manuopera, from manuoperare "work with the hands," from L. manu operari, from manu ablative of manus "hand" + operari "to work," → operate.

Metallic chemical element; symbol Mn. Atomic number 25; atomic weight 54.938; melting point about 1,244°C; boiling point about 1,962°C.

The name derives from the Latin magnes for "magnet" since pyrolusite (MnO₂) has magnetic properties. It was discovered by the Swedish pharmacist and chemist Carl-Wilhelm Scheele in 1774.

Manganez, loan from Fr.

1) Readily perceived by the eye or the understanding; evident; obvious; apparent; plain.
2) To make clear or evident to the eye or the understanding; show plainly (Dictionary.com).

M.E., from O.Fr. manifest "evident, palpable," or from L. manifestus "plainly apprehensible, clear, apparent, evident;" "proved by direct evidence;" "caught in the act," probably from manus "hand," + -festus "struck; (able to be) seized."

From Torbat-Heydariye-yi nemusâr "evident, conspicuous, visible," from nemu-, nemudan "to show, display" from Mid.Pers. nimūdan, from ne- "down; into;" O.Pers./Av. ni- "down; below; into," → ni-, + mu- (as in âz-mu-dan, â-mu-dan, far-mu-dan, pey-mu-dan, etc.); Av. mā(y)- "to measure," → display, + -sâr a suffix of state, position, similarity.

1) An act of manifesting.
2) The state of being manifested.
3) Outward or perceptible indication; materialization.
4. A public demonstration, as for political effect (Dictionary.com).

Verbal noun of → manifest; → -tion.

A → topological space in which every point has a → neighborhood which resembles → Euclidean space (Rⁿ), but in which the global structure may be different. An example of a one-dimensional manifold would be a circle; if you zoom around a point the circle looks locally like a line (R¹). An example of a two-dimensional manifold would be a sphere; a small portion looks locally like a plane (R²). See also → flat manifold.

O.E. monigfald (Anglian), manigfeald (W.Saxon) "varied in appearance," from manig "many" + -feald "fold."

Baslâ, from bas "many, much" (Mid.Pers. vas "many, much;" O.Pers. vasiy "at will, greatly, utterly;" Av. varəmi "I wish," vasô, vasə "at one's pleasure or will," from vas- "to will, desire, wish") + lâ "fold."

The fractional or the decimal part of a → common logarithm. For example, log₁₀ 4000 = 3.602, where the → characteristic is 3 and the mantissa 0.602.

From L. mantis "makeweight, addition," of unknown origin. Introduced by Henry Briggs (1561-1630).

→ makeweight.

1) General: Something that covers, envelops, or conceals. → grain mantle; → plasma mantle.
2) Geology: → Earth's mantle.

O.E. mentel "loose, sleeveless cloak," from L. mantellum "cloak," perhaps from a Celtic source.

1) Rupuš "over-garment, cloak," from ru "surface, face; aspect; appearance" (Mid.Pers. rôy, rôdh "face;" Av. raoδa- "growth," in plural form "appearance," from raod- "to grow, sprout, shoot;" cf. Skt. róha- "rising, height") + puš "covering, mantle," from pušidan "to cover; to put on" (Mid.Pers. pôšidan, pôš- "to cover; to wear;" cf. Mid.Pers. pôst; Mod.Pers. pust "skin, hide;" O.Pers. pavastā- "thin clay envelope used to protect unbaked clay tablets;" Skt. pavásta- "cover," Proto-Indo-Iranian *pauastā- "cloth").
2) Gušté, from gušt "flesh, meat, pulp of fruit;" Mid.Pers. gôšt "meat;" Av. gah- "to eat;" cf. Skt. ghas- "to eat, devour," ghásati "eats" + nuance suffix -é.

The mathematical problem of solving the equations of motions of any number of bodies which interact gravitationally. More specifically, to find their positions and velocities at any point in the future or the past, given their present positions, masses, and velocities.

Many, from M.E. mani, meni, O.E. monig, manig; → body; → problem.

1a) A representation usually on a flat surface of an area of the Earth or a portion of the sky, showing them in their respective forms, sizes, and relationships.
1b) Math.: Same as → mapping.
2) To make a map of; show or establish the features of, details of.

Shortening of M.E. mapemounde "map of the world," from M.L. mappa mundi "map of the world," first element from L. mappa "napkin, cloth" (said to be of Punic origin) + L. mundi "of the world," from mundus "universe, world."

Naqšé "map," from naqš "painting, embroidering, carving," variant of negâštan, negâridan "to paint," negâr "picture, figure," → graph.

The theory and method of transforming the features, geometry, and topology on a sphere surface (in particular the spherical Earth) onto a plane.

→ map; → projection.

Any tree of the genus Acer. The maple leaf is an emblem of Canada.

M.E. mapel, O.E. mapul-, related to O.N. möpurr, O.S. mapulder, M.L.G. mapeldorn.

Afrâ, of Tabari origin.