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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

   Homepage   
   


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

<< < -me mac mag mag mag mag mai man Mar mas mas mat May mea mec mem mer mes met met Mic mic mig Mim Min mis mod mod mol mon mor mov mul Mus > >>

Number of Results: 672
metastable state
  حالت ِ متاپایدار   
hâlat-e matâpâydâr

Fr.: état métastable   

An excited state in an atom, which is at the origin of the spectral lines called → forbidden lines. The time duration of the excited state being relatively long, under laboratory conditions the atom cannot pass directly to the ground state by emitting radiation. In the extremely rarefied interstellar medium, however, such highly improbable transitions do occur.

meta-; → stable; → state.

meteor
  شهاب   
šahâb (#)

Fr.: météore   

A streak of light caused when a → meteoroid enters Earth's → atmosphere and becomes incandescent, mostly from → friction with the air at high speed. Meteors are also referred to as shooting stars. Very bright meteors are called → fireball or → bolide. Most of visible meteors arise from particles ranging in size from about that of a small pebble down to a grain of sand, and generally weigh less than 1-2 grams. The brilliant flash of light from a meteor is mainly caused by the → meteoroid's high level of → kinetic energy as it collides with the atmosphere at high speeds (11-72 km/s). The increase in the number of meteors visible toward the end of the night results from the fact that the Earth rotates about its axis in the same direction as it orbits the Sun. This means that the leading edge (morning side) of the Earth encounters more meteoroids than the trailing edge (evening side). In general, 2 to 3 times as many meteors can be seen in the hour or so just before morning twilight, than can be seen in the early evening. Moreover, the numbers of random, or sporadic, meteors vary from season to season, due to the tilt of the Earth on its axis and other factors. See also → meteor shower.

From M.Fr. meteore, from M.L. meteorum (nom. meteora), from Gk. ta meteora "the celestial phenomena," pl. of meteoron, literally "thing high up," neuter of meteoros (adj.) "high up," from → meta- "over, beyond" + -aoros "lifted, hovering in air," related to aeirein "to raise."

Šahâb, from Ar. Šihâb.

Meteor Crater
  لاوک ِ شهاب‌سنگ، کندال ِ ~، ~ آسمان‌سنگ   
lâvak-e šahâbsang, kandâl-e ~, ~ âsmânsang

Fr.: Meteor Crater   

A → meteorite impact crater located about 55 km east of Flagstaff, near Winslow in the northern Arizona desert of the United States. Meteor Crater is about 1,200 m in diameter and some 170 m deep. It is thought to have formed between 20,000 to 50,000 years ago, by the impact of a small → asteroid about 25 m in diameter. Same as → Barringer Crater.

meteor; → crater.

meteor echo
  پژواک ِ شهاب   
pažvâk-e šahâb

Fr.: écho de météore   

The reflection of → radio waves from transmitters located on the ground by a → meteor or by the corresponding trail left behind. When a meteor enters the Earth's upper atmosphere it excites the air molecules, producing a streak of light and leaving a trail of ionization behind it tens of kilometers long. This ionized trail occurs typically at a height of about 85 to 105 km, and may persist for less than 1 second up to several minutes.

meteor; → echo.

meteor shower
  باران ِ شهابی، رگبار ِ ~، تندبار ِ ~   
bârân-e šahâbi, ragbâr-e ~, tondbâr-e ~ (#)

Fr.: averse de météores, pluie de ~   

An increased number of → meteors all appearing to → diverge from the direction of a single point, called → radiant. Meteor showers occur → annually on the same dates, when the Earth crosses through a → meteoroid stream. Meteor showers are named after the → constellation in which the radiant is located. For example, the → Perseids's radiant lies near the top of the constellation Perseus. Most meteor showers are caused by → comets. As a comet orbits the Sun it sheds an icy, dusty → debris stream along its orbit. When the Earth's orbit intersects the dust trail, more meteors are seen as the cometary debris encounters our planet's → atmosphere. In the case of the → Geminids and → Quadrantids, those meteor showers come from the debris scattered by orbiting → asteroids. Typical meteor showers show 15 to 100 meteors per hour at their peak. On very rare occasions, during a → meteor storm, thousands of meteors fall per hour. Prominent meteor showers are: → Quadrantids, → Lyrids, → Eta Aquariids, → Delta Aquariids, → Perseids, → Orionids, → Taurids, → Leonids, → Geminids, → Ursids, → Alpha Capricornids.

meteor; → shower.

meteor storm
  توفان ِ شهابی   
tufân-e šahâbi (#)

Fr.: orage de météorites   

An extremely intense → meteor shower, in which hundreds or even many thousands of → meteors per hour may be observed. During the great → Leonids meteor storm of 1833 an estimated number of about 150,000 meteors fell per hour.

meteor; → storm.

meteoric ionization
  یونش ِ شهاب‌سنگی، ~ ِ آسمان‌سنگی   
yoneš-e šahâbsangi, ~ âsmânsangi

Fr.: ionisation météoritique   

The ionization of air molecules by the heat generated when a meteorite enters the atmosphere.

meteorite, → ionization.

meteorite
  شخانه، شهاب‌سنگ، آسمان‌سنگ   
šaxâné (#), šahâbsang (#), âsmânsang (#)

Fr.: météorite   

An object of → extraterrestrial origin that survives entry through the atmosphere to reach the Earth's surface. → Meteors become meteorites if they reach the ground. See also → stony meteorite, → iron meteorite, → stony-iron meteorite, → chondrite, → micrometeorite , → achondrite, → CAI meteorite, → differentiated meteorite, → undifferentiated meteorite, → Hoba meteorite, → Jilin meteorite, → Martian meteorite, → meteorite flux.

From → meteor + -ite a suffix of nouns.

Šaxâné "metor," may be from šaxudan, šaxânidan "to scratch, to thrust, to assail," as the meteor light scratches the dark night.
Šahâbsang, from šahâb, → meteor, + sang, → stone.
Âsmânsang, from âsmân, → sky, + sang, → stone.

meteorite flux
  شار ِ شخانه‌ای   
šâr-e šaxâne-yi

Fr.: flux de météorites   

The total mass of extraterrestrial objects that land on Earth during a given time period. The meteorite flux is currently estimated to be about 107 to 109 kg yr-1. Much of this material is dust-sized objects called → micrometeorites.

meteorite; → flux.

meteoritic
  شخانه‌ای، شهاب‌سنگی   
šaxâne-yi, šahâbsangi (#)

Fr.: météoritique   

Of or pertaining to a → meteorite.

From → meteorite + → -ic.

meteoritic abundance
  فراوانی ِ شخانه‌ای، ~ شهاب‌سنگی   
farâvâni-ye šaxâne-yi, ~ šahânsangi

Fr.: abondance météoritique   

The abundance of a chemical element as derived from meteorites. Meteoritic abundances measured from carbonaceous → CI chondrites are believed to represent → protosolar abundances.

meteoritic; → abundance.

meteoritic impact
  برخورد ِ شخانه‌ای   
barxord-e šaxâne-yi

Fr.: impact météoritique   

A striking of a meteorite against another body, especially the solar system planets or satellites.

meteoritic; → impact.

meteoritics
  شخانیک، شهاب‌سنگ‌شناسی، شهاب‌سنگیک   
šaxânik, šahâbsangšenâsi, šahâbsangik

Fr.: météoritiqu   

The science or study of meteorites.

meteorite + → -ics.

meteoroid
  شخانه‌وار   
šaxânevâr (#)

Fr.: météoroïde   

A solid object in → interplanetary space before it reaches the Earth's atmosphere. Meteoroids are of → silicate and/or → metallic matter having a size from tiniest grains up to that of the smallest → asteroids.

meteor; → -oid.

meteoroid stream
  رابه‌ی ِ شخانه‌وار   
râbeh-ye šaxânevâr

Fr.: courants de météoroïdes   

The meteoroids distributed all along an → orbit and diffused somewhat around it.

meteoroid; → stream.

meteoroid swarm
  غنگ ِ شخانه‌وار   
qang-e šaxânevâr

Fr.: essaim de météoroïdes   

A relatively dense collection of meteoroids at certain spots along some → meteoroid streams.

meteoroid; → swarm.

meteorological observation
  نپاهش ِ هواشناختی   
napâheš-e havâšenâxti

Fr.: observation météorologique   

Evaluation or measurement of one or more meteorological elements.

Meteorological, of or pertaining to → meteorology; → observation.

meteorological observatory
  نپاهشگاه ِ هواشناختی   
nepâhešgâh-e havâšenâxti

Fr.: observatoire météorologique   

A scientific establishment dedicated to making precise and detailed meteorological observations and to studying and forecasting atmospheric phenomena by means of special equipments.

Meteorological, of or pertaining to → meteorology; → observatory.

meteorology
  هواشناسی   
havâšenâsi (#)

Fr.: météorologie   

The study of the physics, chemistry, and dynamics of the Earth's atmosphere, including the related effects at the air-earth boundary over both land and the oceans.

From Gk. meteorologia "discussion of celestial phenomena," from meteoronmeteor + -logia, &rarr-logy.

Havâšenâsi, from havâ "weather, air," → air.

meter
  متر   
metr (#)

Fr.: mètre   

The fundamental unit of length in the metric system, now defined as 1/299,792,458 of the distance light travels in a vacuum in one second. Abbreviation: m.

From Fr. mètre, from Gk. metron "measure," from PIE base *me- "to measure" (cf. O.Pers., Av. mā- "to measure;" Skt. mati "measures;" L. metri "to measure").

Metr, loan from Fr.

<< < -me mac mag mag mag mag mai man Mar mas mas mat May mea mec mem mer mes met met Mic mic mig Mim Min mis mod mod mol mon mor mov mul Mus > >>