An Etymological Dictionary of Astronomy and Astrophysics
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A solid object with a mass about 10^-18-10^-15 kg in → interplanetary space that moves in hyperbolic orbit as a result of the solar → radiation pressure.

→ meteoroid.

A member of a group of tiny (millimeter to centimeter) light-colored meteorites found often with → chondrules. They consist of high vaporization minerals, including → silicates and → oxides of Ca, Al, and Ti, but are quite poor in Fe. Compared to common → chondrules, which are uniformly spherical, their shapes are less regular. They appear to be 2-3 million years older than chondrules. CAI meteorites are probably the oldest solid materials to have formed in the → solar nebula.

CAI, short for → Calcium, → Aluminium, and → Inclusion; → meteorite.

A → meteor exploded on February 15, 2013 over Chelyabinsk, southern Russia.The explosion occurred at a height of 20 km above Earth, releasing 500 kilotons → TNT equivalent of energy, approximately 30 times the yield of the nuclear bomb over Hiroshima. It caused a → shock wave that damaged 7,200 buildings in six Russian cities and injured some 1,500 people, mainly from flying glass. Later, about five tons of meteoritic material reached the ground, including a 650 kg → meteorite that was recovered by divers from the bottom of Lake Chebarkul, on the slopes of the southern Ural mountains. With an estimated initial mass of about 12,000-13,000 metric tons, and measuring about 20 m in diameter, it is the largest known natural object to have entered Earth's atmosphere since the 1908 → Tunguska event.

Chelyabinsk, a city in Russia, the capital of the Chelyabinsk region, on the eastern slope of the Ural Mountains on the Miass River, 200 km south of Ekaterinburg and 1,879 km east of Moscow. The population of Chelyabinsk is about 1,183,000 (2015), the area, 530 sq. km; → meteor.

A → meteor detected using → radar techniques during daylight or when skies are cloudy.

→ day; → light; → meteor.

A meteorite that has distinctly separated stone, metal, and glass. It is derived from a differentiated parent body and hence not primitive. The parent body accreted surrounding material until it was large enough to start melting in the middle. The denser metals sank to the center and the stones and glasses floated to the top. A differentiated meteorite made completely of metal comes from the center of a parent meteoroid which was broken apart. → undifferenciated meteorite.

Differentiated, p.p. of → differentiate; → meteorite.

The world's largest meteorite found in 1920, near Grootfontein, Namibia. It was discovered by Jacobus H. Brits while ploughing one of his fields with an ox. The meteorite is tabular in shape and measures 2.95 x 2.84 m; it has an average thickness of about 1 m (1.22 m maximum and 0.75 m minimum). The Hoba meteorite weighs about 65-70 tons. Its chemical composition is 82.4 % iron, 16.4 % nickel, 0.8 % Cobalt, and traces of other metals. No crater is present around the site of the meteorite, probably because it fell at a lower rate of speed than expected. The flat shape of the object may be responsible for its low velocity at impact.

Named after Hoba West, the farm it was discovered; → meteorite.

A meteorite which is composed mainly of iron mixed with smaller amounts of → nickel. Iron meteorites make up about 4.4% of all meteorites. See also → stony meteorite, → stony-iron meteorite.

→ iron; → meteorite.

The biggest meteorite ever witnessed falling and the largest stone meteorite known. It happened near Jilin, an industrial port city located northeastern China, on March 8, 1976. Of the four tons of fragments of the type H5 chondrite recovered, one piece weighs 1.774 tons and measures about 100 x 80 x 50 cm. The meteorite exploded in the sky and produced a shower covering an area of more than 500 square kilometers.

Jilin, from the name of the Chinese city, known also as Chi-lin City or Kirin City. → meteorite.

A piece of rock that was ejected from the Martian surface into space by the impact of an asteroid or comet, and landed on Earth. So far about 100 Martian meteorites have been collected. These meteorites have elemental and isotopic compositions that match those of the Martian crust as measured by NASA's Mars exploration missions.

→ Martian; → meteorite.

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.

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.