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

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.

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.

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.

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.

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

→ meteorite, → ionization.

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.

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.

Of or pertaining to a → meteorite.

From → meteorite + → -ic.

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.

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

→ meteoritic; → impact.

The science or study of meteorites.

→ meteorite + → -ics.

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.

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

→ meteoroid; → stream.

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

→ meteoroid; → swarm.

Evaluation or measurement of one or more meteorological elements.

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

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.

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 Δν_Cs.

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.

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.