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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 12948 Search : far
maximum light
  نور ِ بیشینه   
nur-e bišiné

Fr.: maximum de lumière   

Of a → supernova, → peak luminosity.

maximum; → light.

maximum likelihood
  شدواری ِ بیشینه   
šodvâri-ye bišiné

Fr.: maximum de vraisemblance   

A statistical procedure based on choosing the value of the unknown parameter under which the probability of obtaining an observed sample is highest.

maximum; → likelihood.

maxwell (Mx)
  ماکسول   
maxwell (#)

Fr.: maxwell   

The unit of → magnetic flux. The flux through 1 square cm normal to a magnetic field of 1 → gauss. It is equal to 10-8 → weber (Wb)s.

After James Clerk Maxwell (1831-1879), British outstanding physicist, who made fundamental contributions to electromagnetic theory and the kinetic theory of gases.

Maxwell bridge
  پل ِ ماکسول   
pol-e Maxwell

Fr.: pont de Maxwell   

A type of → Wheatstone bridge used for measuring → inductance in terms of → resistance and → capacitance.

maxwell; → bridge.

Maxwell gap
  گاف ِ ماکسول   
gâf-e Mawxell

Fr.: division de Maxwell   

A division in Saturn's ring in the outer part of the C ring. It is about 87500 km from Saturn's center and is 500 km wide. The gap was discovered in 1980 by Voyager 1.

Not discovered by J. C. Maxwell, but named in his honor; → maxwell; → gap.

Maxwell's demon
  پری ِ ماکسول   
pari-ye Maxwell

Fr.: démon de Maxwell   

A → thought experiment meant to raise questions about the possibility of violating the → second law of thermodynamics. A wall separates two compartments filled with gas. A little "demon" sits by a tiny trap door in the wall. He is able to sort hot (faster) molecules from cold molecules without expending energy, thus bringing about a general decrease in → entropy and violating the second law of thermodynamics. The → paradox is explained by the fact that such a demon would still need to use energy to observe and sort the molecules. Thus the total entropy of the system still increases.

Named after James Clerk Maxwell (→ maxwell), who first thought of this experiment; → demon.

Maxwell's equations
  هموگش‌های ِ ماکسول   
hamugešhâ-ye Maxwell

Fr.: équations de Maxwell   

A set of four fundamental equations that describe the electric and magnetic fields arising from varying electric charges and magnetic fields, electric currents, charge distributions, and how those fields change in time. In their vector differential form, these equations are:
i) ∇.E = ρ/ε0 (→ Gauss's law for electricity),
ii) ∇.B = 0 (→ Gauss's law for magnetism),
iii) x E = -∂B/∂t (→ Faraday's law of induction),
iv) x B = μ0J + μ0ε0E/∂t (→ Ampere's law), with c2 = 1/(μ0ε0), where E is → electric intensity, B is → magnetic flux density, ρ is → charge density, ε0 is → permittivity, μ0 is → permeability, J is → current density, and c is → speed of light.

maxwell. It should be emphasized that the equations originally published by James Clerk Maxwell in 1873 (in A Treatise on Electricity and Magnetism) were 20 in number, had 20 variables, and were in scalar form. The German physicist Heinrich Rudolf Hertz (1857-1894) reduced them to 12 scalar equations (1884). It was the English mathematician/physicist Oliver Heaviside (1850-1925) who expressed Maxwell's equations in vector form using the notations of → gradient, → divergence, and → curl of a vector, thus simplifying them to the present 4 equations (1886). Before Einstein these equations were known as Maxwell-Heaviside-Hertz equations, Einstein (1940) popularized the name "Maxwell's Equations;" → equation.

Maxwell's rule
  رزن ِ ماکسول   
razan-e Maxwell

Fr.: règle de Maxwell   

Every part of a deformable electric circuit tends to move in such a direction as to enclose the maximum magnetic flux.

maxwell; → rule.

Maxwell-Boltzmann distribution
  واباژش ِ ماکسول-بولتسمان   
vibâžš-e Maxwell-Boltzmann

Fr.: distribution de Maxwell-Boltzmann   

The distribution law for kinetic energies (or, equivalently, speeds) of molecules of an ideal gas in equilibrium at a given temperature.

maxwell; → Boltzmann's constant; → distribution.

Maya calendar
  گاهشمار ِ مایا   
gâhšomâr-e Mâyâ

Fr.: calendrier Maya   

A complex calendar created by the ancient central American Mayas which uses three different dating systems in parallel: Long Count, Tzolkin, and Haab. Only Haab has a direct relationship with the length of the year. It is a solar → vague year consisting of 18 months of 20 days each, and an additional period of 5 → epagomenal days. Tzolkin is a calendar of 13 x 20 = 260 days running within Haab and is used for ritual purposes. A date is usually described by specifying its position in both the Tzolkin and Haab calendars. The least common multiple of the two calendars, called the Calendar Round, has 18,980 days, representing a cycle of 73 sacred years, or 52 vague years. The Long Count is the number of days since the start of the Maya era. There is disagreement about the beginning date of the Long Count. Most authorities agree, however, that the Long Count started in 3114 B.C., with several possible dates.

Maya, proper name; → calendar.

Möbius band
  باند ِ موی‌بیوس   
bând-e Möbius

Fr.: ruban de Möbius   

A surface with only one side, made by putting a simple twist in a long, rectangular strip of paper, then pasting the ends together.

After the German astronomer and geometer August Ferdinand Möbius (1790-1868); → band.

Mössbauer effect
  ا ُسکر ِ موسباؤر   
oskar-e Mössbauer

Fr.: effet Mössbauer   

The resonant and recoil-free emission and absorption of gamma rays by atoms bound in a solid form.

Named after Rudolf Mößbauer (1929-), a German physicist who studied gamma rays from nuclear transitions, and discovered this phenomenon in 1957; → effect.

mean
  ۱) میانگین؛ ۲) چماردن   
1) miyângin (#); 2) cemârdan

Fr.: 1) moyenne; 2) signifier, vouloir dire   

1a) General: A quantity having a value intermediate between the values of other quantities; an average.
1b) → arithmetic mean.
1c) → geometric mean.
1d) → harmonic mean.
1e) → weighted mean.
1f) → root mean square.
2) To have as its sense or signification; signify.

1) From O.Fr. meien, from L. medianus "of or that is in the middle," → median.
2) Verb of → meaning.

1) Miyângin "the middle; middle-sized; the middle pearl in a string," from miyân, → middle, + -gin a suffix forming adjectives of possession.
2) → meaning.

mean anomaly
  ناسانی ِ میانگین   
nâsâni-ye miyângin

Fr.: anomalie moyenne   

The angle between the periapsis of an orbit and the position of a hypothetical body that orbits in the same period as the real one but at a constant mean angular velocity.

mean; → anomaly.

mean catalog place
  جای ِ میانگین ِ کاتالوگی   
jâ-ye miyângin-e kâtâlogi

Fr.: position catalogue moyenne   

That point on the → celestial sphere at which an object would be seen from the solar system → barycenter affected by the → e-terms → aberration.

catalog; → mean; → place.

mean daily motion
  جنبش ِ روزانه‌ی ِ میانگین   
jenbeš-e ruzâne-ye miyângin (#)

Fr.: mouvement diurne moyen   

The average movement of a body along its orbit in one day, usually expressed in degrees.

mean; → diurnal; → motion.

mean element
  بن‌پار ِ میانگین   
bonpâr-e miyângin

Fr.: élément moyen   

An element of an adopted reference orbit that approximates the actual, perturbed orbit. Mean elements may serve as the basis for calculating perturbations.

mean; → element.

mean equator
  هموگار ِ میانگین   
hamugâr-e miyângin

Fr.: équateur moyen   

The orientation the Earth's equator would have if the nutation was subtracted.

mean; → equator.

mean equinox
  هموگان ِ میانگین   
hamugân-e miyângin

Fr.: équinoxe moyen   

A fictitious equinox whose position is that of the vernal equinox at a particular epoch with the effect of nutation removed.

mean; → equinox.

mean free path
  پویش ِ آزاد ِ میانگین   
puyeš-e âzâd-e miyângin (#)

Fr.: libre parcours moyen   

The mean distance which a particle moves between two successive collisions with other particles of the medium. Mean free path is inversely proportional to the number of particles per cm3 (n), and the collision → cross section (σ). In the case of a gas with molecules having a diameter of d, the cross section is equal to the area of a circle of radius d, i.e. σ = πd2, and the mean free path is given by: l = 1/(nσ). Taking into account the relative velocity distribution of the colliding molecules, l = 1/(√2 . nσ). For a gas at one atmosphere pressure and room temperature, the average distance between molecules is roughly 3.5 × 10-7 cm, that is some 35 times the diameter of a molecule. Taking the gas density n = 2.4 × 1014 molecules cm-3, and a typical diameter d = 2 × 10-8 cm for a molecule, the mean free path is 3.3 × 10-5 cm. This means that the average distance between collisions is about 95 times the average distance between molecules.

mean; → free; → path.

Puyeš, verbal noun of puyidan "to run, trot; wander," from Mid.Pers. pôy-, pwd- "to run;" cf. Gk. speudein "to hasten;" Lith. spudinti; âzâd, → free; miyângin, → mean.

<< < -es -iv -ti 21- A r abe abs abs acc acc acc act act ada adi adu aff age alc Alf ali all alp alt ama amp ana ang ang ann ano ant ant ape apo app aps arc Arg ari art ass ast ast ast atm ato att aur aut axi B r bac Bal Bar Bar Bay bec Ber Bet Bie bij bin bio bis bla bla blu blu bol Bor bou Bra bre bro Bug C-s cal Cam can car Car Cas cat cav cel cen cer Cha cha cha che cho cir cir cir cla clo clo clu coa coe coh col col col com com com com com com com com com con con con con con con con con con con con coo cor cor cor cos cos cos Cou cou Cra Cre cri cro cub cur cyc cyl dar dat daw de- Deb dec dec dee def deg del Den dep der det deu dew dic dif dif dil dip dir dis dis dis dis dis div dog Dop dou dra dua dus dwa dyn e-m ear ecl eco eff ein Ein elb ele ele ele ele Els emi emp ene enr env epi equ equ Eri est Euc eva evo exc exc exh exo exp exp ext ext f-n Fah fam fau fee Fer fib fil fin fir fix fle flu foc for for for fra fre fre fri fun fuz gal gal gal Gan gau GCN gen geo geo geo geo Gl glo gra gra gra gra gra gre gro GW1 hab hal han HAR haz hea hel hel Hen Her heu Hig Hil hol hop hor hou Hub Hum Hyd hyd hyd hyp hys ide ign ima imp imp inc inc ind ine inf inf inf inh INP ins ins int int int int Int int int int inv ion iri irr iso iso iso Jea Jos Jun K2 Kep key kin Kol lag lam Lan lar las lav lea leg len lev lig lim lin lin lin lis lob loc log lor low lum lun lun Lym Mac mag mag mag mag mag mai Mal mar mas mas mat max mea mea mee Men mer met met met mic mid Mil min Mir mix mod mod mol mon Mor mou mul muo mys nan nat nav nec Nep neu New New NGC nob nom non non nor not nuc nuc num Nyq obj obs obs oce oen OH omn opa ope opt opt opt orb ord Ori ort osc out ove oxy pal pan par Par par par pas pea Pen per per per per per pet pha pho pho pho phy pie Pit Pla pla pla pla ple Poi pol pol pol pol pop pos pos pow pre pre pre Pre pri pri pri pro pro pro pro pro pro Pro pub pul pyr qua qua qua qua Qui rad rad rad rad rad rad ram ran rat rea rec rec rec red ref ref reg reg rel rel rem rep res res res ret rev rho Rie rim riv rol Ros rot rul S a Sah san Sat sca Sch Sch scr sec sec sec sei sel sem sep set sha she sho sid sig sil sim sin sit sky slu sno sof sol sol sol sol sou sou spa spa spe spe spe sph spi spl spr sta sta sta sta sta ste ste sti sto str str sub sub sub sug sun sup sup sup sup sur syl syn sys tal Tay tel ten ter tex the the the thi tho thu tid tim tod top tot tra tra tra tra tri tri tro tru tur twi Typ UFO ult unc uni uni uni upg ura uti val var vec vel ver ver vig vir vis voc von wak Was wav wax wea wei whi Wie win WN6 wom X-r yel you zer zod > >>