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: 3079 Search : on
Moon's prime meridian
  نیمروزان ِ نخستی ِ مانگ   
nimruzân-e naxosti-ye Mâng

Fr.: méridien origine de la lune   

The line connecting the Moon's north pole with its south pole, and passing through the center of the lunar disk. The longitude of the Moon's prime meridian is zero degrees.

Moon; → prime meridian.

moonbow
  ماه‌کمان   
mâhkamân

Fr.: arc en ciel lunaire   

A rainbow that arises from the refraction and reflection of moonlight on rain drops or mist.

moon; → bow.

moonlet
  مانگچه   
mângcé

Fr.: satellite mineur, lune mineure   

A very small natural or artificial satellite orbiting a planet. Saturn has dozens of moonlets often associated with its → planetary rings.

moon; → -let.

moonlet wake
  کل ِ مانگچه   
kel-e mângcé

Fr.: sillage de lune mineure   

Local disturbances in the ring structure caused by the gravitational influence of embedded satellites. If the satellite (moonlet) is large enough to clear a gap in the rings, the moonlet wakes become edge waves that precede the satellite on the inner edge and trail the satellite on the outer edge. For smaller satellites, the "gap-less" wakes have been nicknamed propellors (Ellis et al., 2007, Planetary Ring Systems, Springer).

moonlet; → wake.

moonlight
  مهتاب   
mahtâb (#)

Fr.: clair de lune   

The light of the Moon.

From → moon + → light.

Mahtâb (Gilaki mângtâb) from mah, mâh (mâng), → moon, + tâb "light," from tâbidan, tâftan "to shine," tafsidan "to become hot" (Av. tāp-, taf- "to warm up, heat," tafsat "became hot," tāpaiieiti "to create warmth;" cf. Skt. tap- "to spoil, injure, damage; to suffer; to heat, be/become hot," tapati "burns;" L. tepere "to be warm," tepidus "warm;" PIE base *tep- "warm").

moonquake
  مانگ-لرزه   
mâng-larze

Fr.: tremblement de lune   

A → seismic event occurring on the → Moon; the lunar equivalent of an → earthquake. Moonquakes were first detected by the → seismometers placed on the Moon by Apollo astronauts from 1969 through 1972. The instruments placed by the Apollo 12, 14, 15, and 16 missions were functional until 1977. Unlike earthquakes, moonquakes are not believed to be caused by → tectonic plate movement, but by → tidal forces between Earth and the Moon. There are at least four different kinds of moonquakes: (1) deep moonquakes about 700 km below the surface. They occur at monthly intervals at about 100 distinct sites, indicating that these moonquakes are caused by → stresses from changes in lunar tides as the Moon orbits the Earth; (2) vibrations from the impact of → meteorites; (3) thermal quakes caused by the expansion of the frigid crust when first illuminated by the morning sun after two weeks of deep-freeze lunar night; and (4) shallow moonquakes only 20 or 30 km below the surface (science.nasa.gov/science-news).

moon; → quake.

moonrise
  بر‌آمد ِ ماه   
barâmad-e mâh (#)

Fr.: lever de la lune   

The times at which the apparent upper limb of the ascending Moon is on the astronomical horizon.

moon; → rise.

moonset
  فروشد ِ مانگ   
forušod-e mâng (#)

Fr.: coucher de la lune   

The crossing of the visible horizon by the upper limb of the descending Moon.

moon; → set.

moonset lag
  لک ِ فروشد ِ مانگ   
lek-e forušod-e mâng

Fr.: retard du coucher de la lune   

The delay between → sunset and → moonset.

moonset; → lag.

Moreton wave
  موج ِ مورتون   
mowj-e Moreton

Fr.: onde de Moreton   

A large-scale → shock wave observed in Hα on the Sun's → chromosphere that is generated by the impact of a → solar flare. Moreton waves expand outward at about 1,000 km/s, and may travel for several hundred thousand kilometers. They are accompanied by meter-wave radio bursts.

Named after the American astronomer Gail E. Moreton (1960, A.J. 65, 494); → wave.

Morgan-Keenan classification
  رده‌بندی ِ مورگان-کینان   
radebandi-ye Morgan-Keenan (#)

Fr.: classification de Morgan-Keenan   

A system of → spectral classification introduced in 1943 by William W. Morgan (1906-1994), Philip C. Keenan (1908-2000), and Edith M. Kellman (1911-2007) at Yerkes Observatory. Also known as the MK (or MKK) classification or the → Yerkes system.

Named after the two main astronomers, as above; → classification.

morphological classification
  رده‌بندی ِ ریخت‌شناختی   
radebandi-ye rixtšenâxti (#)

Fr.: classification morphologique   

A classification scheme of galaxies based on their apparent shape. → Hubble classification.

morphological; → classification.

morphology-density relation
  بازانش ِ ریخت-چگالی   
bâzâneš-e rixt-cagâli

Fr.: relation morphologie-densité   

An observationally determined relationship between the → morphological classification of galaxies and the → environments in which they are located. Specifically, the morphology-density relation indicates that early-type galaxies (→ ETG) are preferentially located in high density environments, whereas late-type galaxies (→ LTG) are preferentially found in low density environments. Hence, spiral galaxies are rare in the high densities of clusters and are common in the lower density group environments. Early-type galaxies, on the other hand, are common in clusters and are rarely found in isolation.

morphology; → density; → relation.

motion
  جنبش   
jonbeš (#)

Fr.: mouvement   

The action or process of moving or of changing place or position; movement.

Verbal noun of → move.

Mount Wilson Observatory
  نپاهشگاه ِ ماؤنت ویلسون   
nepâhešgâh-e Mount Wilson

Fr.: Observatoire du Mont Wilson   

An observatory situated on a mountain 1700 m above sea level near Pasadena, California. It was built in 1904 by American astronomer George Ellery Hale as a solar-observing station for the Yerkes Observatory, but it became an independent observatory funded by the Carnegie Institution of Washington. In 1908 a 60-inch (152-cm) reflector, then the largest in the world, was added for observations of stars and galaxies. Ten years later a 100-inch (254-cm) reflecting telescope was put into service. It was the most powerful telescope in the world until the construction of the Palomar 200-inch reflector in 1948. The 100-inch telescope's most important discovery was Edwin Hubble's determination of the distance to the Andromeda Nebula in 1924. He showed that the nebula lay beyond the bounds of the Milky Way Galaxy and hence was a galaxy in its own right. Then in 1929, following the work of Vesto Slipher, Hubble and his assistant Milton Humason demonstrated that galaxies were moving away from one another. This movement is the expansion of the Universe.

mountain; a peak of the San Gabriel Mountains, located in northern Los Angeles County, California, named after Benjamin D. Wilson (1811-1878) a California statesman and politician; → observatory .

multiplication
  بستایش   
bastâyeš

Fr.: multiplication   

In general, the process of repeatedly adding a quantity to itself a certain number of times, or any other process which has the same result.

Verbal noun of → multiply.

multiplication sign
  نشانه‌ی ِ بستایش   
nešâne-ye bastâyeš

Fr.: croix de multiplication   

The sign used to indicate multiplication, either a times sign (×), a centered dot (·), or an asterisk. The multiplication sign was introduced by William Oughtred in 1631.

multiplication; → sign.

multiwire proportional chamber
  اتاقک ِ بسیار-سیم ِ برپارشی   
otâqak-e besyâr-sim-e barpâreši

Fr.: chambre proportionnelle multifils   

Same as → Charpak's detector.

multi-; → wire; → proportional; → chamber.

muon
  موءون   
muon (#)

Fr.: muon   

A short-lived → elementary particle with negative → electric charge, represented by the symbol μ-. The muon was discovered in 1936 by Carl Anderson (1905-1991) in → cosmic rays. It shares several properties with the electron: it is a → lepton with the same charge and → spin as the electron. But it is heavier than the electron (105 MeV/c2), about 200 times more massive. The muon is instable and decays after 2.197 × 10-6 s into → electron, → neutrino, and → antineutrino-e- + νμ + anti νe) .

A shortening of mu meson, from mu the 12th letter of the Gk. alphabet, + → meson.

muon telescope
  تلسکوپ ِ موءونی   
teleskop-e muoni

Fr.: télescope muonique   

An → instrument used in → geophysics to determine the average → density of geological bodies by measuring the → attenuation produced by → rocks on the flux of → atmospheric muons. This density muon → radiography is or example used to study the physical conditions inside → volcanoes.

muon; → telescope.

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