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.
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.
yoneš-e šahâbsangi, ~ âsmânsangi
Fr.: ionisation météoritique
The ionization of air molecules by the heat generated when a meteorite enters the atmosphere.
šaxâné (#), šahâbsang (#), âsmânsang (#)
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.
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.
šaxâne-yi, šahâbsangi (#)
Of or pertaining to a → meteorite.
farâvâni-ye šaxâne-yi, ~ šahânsangi
Fr.: abondance météoritique
Fr.: impact météoritique
A striking of a meteorite against another body, especially the solar system planets or satellites.
šaxânik, šahâbsangšenâsi, šahâbsangik
The science or study of meteorites.
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.
Fr.: courants de météoroïdes
The meteoroids distributed all along an → orbit and diffused somewhat around it.
Fr.: essaim de météoroïdes
A relatively dense collection of meteoroids at certain spots along some → meteoroid streams.
Fr.: observation météorologique
Evaluation or measurement of one or more meteorological elements.
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.
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 meteoron→ meteor + -logia, &rarr-logy.
Havâšenâsi, from havâ "weather, air," → air.
The → SI unit of length; symbol m. It is defined by taking the fixed numerical value of the → speed of light in vacuum, c, to be 299 792 458 when expressed in the unit m/s, where the → second is defined in terms of ΔνCs.
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.
A colorless, odorless, inflammable gas gas of formula CH4; the simplest hydrocarbon.
From meth- a combining form representing methyl + -ane a suffix used in names of hydrocarbons of the methane or paraffin series.
Fr.: méthanol, alcool méthylique
Alcohol, also known as methyl alcohol, formula CH3OH, formed in small quantities in the oxidation of methane. → methanol maser.
From → methane + -ol a suffix used in the names of chemical derivatives.
Fr.: maser méthanol
A maser source in which excited methanol molecules (CH3OH) produce → maser emission. Methanol masers are signposts of the early stages of star formation, many being associated with sources that have not developed an → H II region. There are more than 20 different methanol transitions that have been observed. They are divided into two categories: Class I, excited by collisions, and class II, excited by infrared radiation. The most important class I masers are at a frequency of 44.1 GHz, while he most important class II masers are at a frequency of 6.7 GHz.
A manner or mode of procedure, especially an orderly, logical, or systematic way of instruction, inquiry, investigation, experiment, and so on.
From M.Fr. méthode, from L. methodus "way of teaching or going," from Gk. methodus "scientific inquiry, method of inquiry," originally "following after," from → meta- "after" + hodos "way."
Raveš "mthod," originally "going, walking," from row "going," present stem of raftan "to go, walk;" Mid.Pers. raftan, raw-, Proto-Iranian *rab/f- "to go; to attack" + -eš a suffix of verbal nouns.