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A meteorite is a relatively small extra-terrestrial body that reaches the Earth's surface. While in space these bodies are called meteoroids. These are "small" asteroids, approximately boulder-sized or less, which are generally fragments resulting from the collision of two or more asteroids. Upon entering the atmosphere, air drag and friction cause the body to heat up and emit light, thus forming a fireball or shooting star.
Most meteors disintegrate in the atmosphere, making impact events ( Earth impacts) on the surface of Earth uncommon. About 500 baseball-sized rocks reach the surface each year. Large meteorites may strike the ground with considerable force, leaving behind a meteor crater. The kind of crater will depend on the size, composition, degree of fragmentation, and incoming angle of the meteor. The force of collision may cause widespread destruction. Occasional damage to property, livestock, and even people has been recorded in historic times. In the case of comet fragments, which are largely composed of ice, a considerable concussion may occur, even though no fragment of the original meteoroid survives; the famed Tunguska event is thought to have resulted from such an incident.
79% of meteorites are Chondrites - balls of maficMafic is a term used in geology for silicate minerals, magmas, volcanic, and intrusive igneous rocks that have relatively high concentrations of the heavier elements. The term is a combination of " magnesium" and ferric the Latin word for iron(III), but m mineralMinerals are natural compounds formed through geological processes. The term "mineral" encompasses not only the material's chemical composition but also the mineral structures. Minerals range in composition from pure elements and simple salts to very comps with small grain size indicative of rapid cooling. In most chondrites small spherules, called chondruleChondrules in the chondrite Grassland. A millimeter scale is shown. Many meteorites are full of tiny silicate spherules which are called chondrules (from Greek chondros grain). Meteorites which contain such chondrules are called chondrites . Chondrites cos, can be found. Chondrites are typically about 4.6 billion years old and are thought to represent material from the asteroid beltThe asteroid belt is a region of the solar system falling roughly between the planets Mars and Jupiter where the greatest concentration of asteroid orbits can be found. It is termed the main belt when contrasted with other concentrations of minor planets,. It is unknown how they formed. Carbonaceous Chondrites, thought to be unaltered solar nebulaIn cosmogony, the solar nebula is a gaseous cloud (or accretion disc), from which, solar systems are formed. This nebular hypothesis was first proposed, in 1755, by Kant; who argued that nebulae slowly rotate, gradually condensing (due to gravity) and fla material, constitute about 5% of meteorites and contain small amounts of organic materials, including amino acidIn chemistry, an amino acid is any molecule that contains both amino and carboxylic acid functional groups. In biochemistry, this shorter and more general term is frequently used to refer to alpha amino acids: those amino acids in which the amino and carbs. Also, presolar grainsPresolar grains are tiny crystalline grains which are found within the fine grained matrix of primitive meteorites and are assumed to be older than the solar system. They are probably formed in supernovae explosions or stellar outflows of red giant stars. are identified in carbonaceous chondrites. The isotope ratios of carbonaceous chondrites are similar to those of the Sun.
Achondrites are similar to terrestrial mafic igneous rocks and sometimes are brecciated. Achondrites constitute about 8% of the incoming material and are thought to represent crustal material of larger asteroids. About 6% of meteorites are iron meteorites with intergrowths of iron- nickel alloys, such as kamacite. Unlike chondrites, the crystals are large and appear to represent slow crystallization. Iron meteorites are thought to be the core material of one or more planets that subsequently broke up. Stony iron meteorites constitute the remaining 2%. They are a mixture of iron-nickel and silicate minerals. They are thought to have originated in the boundary zone above the core regions where iron meteorites originated. A small number of meteorites belong to additional groups or subgroups with unique chemical characteristics relative to other members of the larger groups, such as Lunar meteorites or Martian meteorites.
One theory stipulates that a large meteorite impact caused the mass extinction of the dinosaurs. It is also theorized that meteorites caused other mass extinction events as well throughout the history of the earth.
The Willamette Meteorite, the largest ever to fall on the United States
The only reported fatality from meteorite impacts is an Egyptian dog who was killed in 1911, although this report is disputed. The meteorites that struck this area were identified in the 1980s as Martian in origin. The first and, as of 2003, only known modern case of a human being hit by a space rock occurred on November 30, 1954 in Sylacauga, Alabama. There an 8.5 pound sulfide meteorite crashed through a roof and hit a Mrs. Elizabeth Hodges in her living room after it bounced off her radio. She was lightly bruised.
Whole and partial meteorites are valuable to collectors, with large fully intact pieces selling for prices above $20,000 USD at auction.
