Astronomy:Glossary of meteoritics

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Short description: Wikipedia glossary

This is a glossary of terms used in meteoritics, the science of meteorites.

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A

  • Ablation – the process of a meteorite losing mass during the passage through the atmosphere.
  • Acapulcoite – a group of primitive achondrites.
  • Accretion – the process in which matter of the protoplanetary disk coalesces to form planetesimals.
  • Achondrite – a differentiated meteorite (meaning without chondrules).
  • Aerolite – an old term for stony meteorites.
  • ALH – an abbreviation used for meteorites from Allan Hills.
  • Allan Hills 84001 – is an exotic meteorite from Mars that does not fit into any of the SNC groups and was thought to contain evidence for life on Mars.
  • Allende meteorite – is the largest carbonaceous chondrite ever found on Earth.
  • Amphoterite – an obsolete classification of chondritic meteorites that are now classified as LL.
  • Angrite – a basaltic meteorite.
  • ANSMET – the Antarctic Search for Meteorites is a scientific program that looks for meteorites in the Transantarctic Mountains.
  • Asteroidal achondrite – an achondrite that differentiated on an asteroid or planetesimal (see planetary achondrite)
  • Asteroid spectral types – classification of asteroids according to their spectra.
  • Ataxite – an iron meteorite that has no visible structures when etched.

B

  • Basaltic achondrite – a grouping of basalt meteorites (HED meteorites + Angrite)
  • Brachinite – either a primitive achondrite or an asteroidal achondrite
  • Bolide – is an extremely bright meteor, especially one that explodes in the atmosphere

C

  • C – can refer to carbonaceous chondrite or to an iron meteorite designation (Roman numeral and letter).
  • Carbonaceous chondrite
  • CAI – an abbreviation of Calcium-aluminium-rich inclusion
  • Calcium-aluminium-rich inclusion
  • Chassignite
  • Chondrite – stony meteorites unmodified by melting or differentiation of the parent body
  • Chondrule – millimetre-scale round grains found in chondrites
  • Clan – meteorites that are not similar enough to form a group, but are also not too different from each other to be put in separate classes.[1]
  • Class – two or more groups that have a similar chemistry and oxygen isotope ratios.[1]
  • Compositional type – a classification based on overall composition, for example stony, iron, stony-iron (as introduced by Maskelyne). Can also refer to the composition deduced from spectroscopy of asteroids.
  • Condensation – the process of chemicals changing from the gaseous to the solid phase during the cooling of the protoplanetary disk.
  • Condensation sequence – the sequence of minerals that changes from the gaseous to the solid state while the protoplanetary disk cools.
  • Cosmic dust – small interplanetary and interstellar particles that are similar to meteorites (See Micrometeorite).
  • Cosmochemistry – the science of the chemistry of the Solar System, which is based in part on the chemistry of meteorites.

D

  • Dar al Gani – a meteorite field in the Libyan Sahara.
  • Desert glass – natural glass found in deserts formed from the silica in sand as a result of lightning strikes or meteor impacts.
  • Differentiated – a meteorite that has undergone igneous differentiation. (See: achondrite)
  • Differentiation – usually the process of a planetesimal forming an iron core and silicate mantle.
  • Duo – a grouping of two meteorites that share similar characteristics (see Grouplet).

E

  • E – can refer to enstatite chondrite or to an iron meteorite designation (Roman numeral and letter).
  • Eagle Station grouplet – a set of pallasite meteorite specimen that do not fit into any of the defined pallasite groups.
  • Electrophonic bolide – a meteoroid which produces a measurable discharge of electromagnetic energy (EMP) during its passage through the atmosphere.
  • Enstatite achondrite – a meteorite that is mostly composed of enstatite. Usually part of the aubrite group.
  • Enstatite chondrite – a rare form of meteorite thought to comprise only 2% of chondrites.

F

  • Fall – a meteorite that was seen while it fell to Earth and found.
  • Find – a meteorite that was found without seeing it fall.
  • Fossil meteorite – a meteorite that was buried under layers of sediment before the start of the Quaternary period. Some or all of the original cosmic material has been replaced by diagenetic minerals.[2]:320 (It is, however, not a fossil).
  • Fusion crust – a coating on meteorites that forms during their passage through the atmosphere.

G

  • Group – a collection of five or more meteorites sharing similar characteristics.[1]
  • Grouplet – a collection of fewer than five meteorites sharing similar characteristics.[1]

H

  • Hammer Stone – a specific individual meteorite that has hit either a human, man-made object, and/or an animal.
  • HED – abbreviation for three basaltic achondrite groups howardite, eucrite and diogenite.
  • HED meteorite – a clan of basaltic achondrites.
  • Hexahedrite – a structural class of iron meteorites having a relatively low nickel content
  • Hunter – a person who searches for meteorites.

I

  • Impact breccia – rock composed of fragments of terrestrial, extraterrestrial or mixed origin fused by the energy of impact
  • Impactite – informal term for a terrestrial rock resulting from the shocking impact of a meteor.
  • Iron–nickel alloy – an alternative expression for meteoric iron.
  • Iron meteorite – a meteorite that is mainly composed of meteoric iron.

K

  • Kakangari chondrite – a group of chondrite meteorites.
  • Kamacite – a native metal (mineral) found in meteorites.

L

  • Lodranite – member of a small group of primitive achondrites thought to derive from deeper within the same parent body as acapulcoites

M

  • Main group pallasite – a pallasite belonging to the main group.
  • Main mass – the largest/heaviest piece of a fragmented meteorite, typically found in a strewn field.
  • Magmatic meteorite
  • Maskelynite – a natural glass found in meteorites.
  • Matrix – the mineral assemblage surrounding chondrules.
  • Mesosiderite – a grouping of stony-iron meteorite that are breccias.
  • Meteoric iron – a native metal found in meteorites and a mixture of different mineral phases. Compare telluric iron.
  • Meteorite Observation and Recovery Program – a scientific program that was centered in Canada.
  • Meteoriticist – a scientist working on meteorites, meteors, and meteoroids.
  • Meteoritics – the science of meteorites, meteors, and meteoroids.
  • MORP – abbreviation for Meteorite Observation and Recovery Program.
  • Micrometeorite – microscopic meteorites derived from Cosmic dust.

N

  • Nakhlite – a group of Martian meteorites
  • Neumann lines (or Neumann bands) – a pattern of fine parallel lines seen in some iron meteorites, thought to be due to impact events on the parent body
  • Nonmagmatic meteorite – (deprecated) iron meteorites that were thought to have not formed by igneous processes.

O

  • O – usually refers to ordinary chondrite
  • Observed fall – a meteorite that was seen when it fell to Earth.
  • Octahedrite – the most common structural class of iron meteorites.
  • Ordinary chondrite – a chondrite meteorite, where 'ordinary' means that it is the most common found

P

  • PAC – abbreviation for primitive achondrite.
  • Pallasite – a class of stony–iron meteorite.
  • Panspermia – the hypothesis that life could reach other planets by the means of meteorites and/or comets.
  • Parent body – the celestial body from which originates a meteorite or a class of meteorites.
  • Petrologic type – a classification scheme that expresses the degree to which a meteorite has been affected by the secondary processes of thermal metamorphism and aqueous alteration on the parent asteroid.
  • Pitts grouplet – a grouplet of meteorites that is part of the IAB meteorites.
  • Planetary achondrite – an achondrite that was differentiated on a planet and not a planetesimal or asteroid (See asteroidal achondrite).[3]
  • Plessite – a fine grained intergrowth found in meteoric iron consisting of kamacite, taenite and tetrataenite lamella.[4]
  • Presolar grains – interstellar solid matter in the form of tiny solid grains from a time before the Sun was formed.
  • Primitive meteorite
  • Primitive achondrite – a meteorite that has similarities to achondrites and chondrites.
  • Protoplanetary disk – a circumstellar disk from which all solids in the Solar System formed.
  • Pyroxene pallasite grouplet

R

Regmaglypts on Sikhote Alin

S

  • Shergottite – igneous rocks of mafic to ultramafic lithology, named after a meteorite that fell at Sherghati, India in 1865.
  • Shock stage – a measure of the degree of fracturing of the matrix of a common chondrite meteorite.
  • Shock metamorphism – the effects of shock-wave related deformation and heating during impact events.
  • Siderite – the old term for iron meteorite.
  • Siderolite – the old term for stony-iron meteorites.
  • SNC – abbreviation for shergottite, nakhlite and chassignite, the three main types of Martian meteorite.
  • Solar nebula – a synonym of the protoplanetary disk.
  • Spectral class
  • Stony meteorite – a meteorite composed mostly of silicates.
  • Stony-iron meteorite – a meteorite that is a mixture of meteoric iron and silicates.
  • Strewn field – a field of fragments from one meteorite fall.
  • Structural class – a subdivision of iron meteorites in ataxites, hexahedrites and octahedrites.
  • Superbolide – is a bolide that reaches an apparent magnitude of −17 or brighter, which is roughly 100 times brighter than the full moon. Recent examples of superbolides include the Sutter's Mill meteorite and the Chelyabinsk meteor.

T

  • Taenite – a native metal (mineral) found in meteorites.
  • Tamdakht – a meteorite that fell near Ouarzazate, Morocco on 2008-12-20 producing a strewn field of approximately 25 km (16 mi) by 2 km (1.2 mi) and two small impact craters.
  • Tektite – glassy terrestrial debris created by meteorite impacts.
  • Total known weight (TKW) – total known mass of a meteorite.
  • Trio – a grouping of three meteorites that share similar characteristics (see Grouplet).
  • Type – subdivision of meteorites. Loosely defined. Usually refers to chondrite, achondrite and sometimes primitive achondrite.[1]

U

  • Udei Station grouplet – a grouplet of meteorites that is part of the IAB meteorites.
  • Ungrouped – a meteorite that has not been assigned to a group or grouplet.
  • Undifferentiated
  • Ureilite

V

W

  • Widmanstätten pattern – a fine interleaving of kamacite and taenite bands/ribbons found in octahedrite irons and some pallasites.
  • Willamette meteorite – the largest meteorite discovered in North America, found in the Willamette Valley of Oregon.
  • Winonaite – a type of primitive achondrite meteorite.
  • Weston meteorite – a meteorite which fell to earth above the town of Weston, Connecticut on December 14, 1807.[6]

References

  1. 1.0 1.1 1.2 1.3 1.4 M. K. Weisberg; T. J. McCoy, A. N. Krot (2006). "Systematics and Evaluation of Meteorite Classification". in D. S. Lauretta. Meteorites and the early solar system II. Tucson: University of Arizona Press. pp. 19–52, 942. ISBN 978-0816525621. http://haroldconnolly.com/EES%20716%20Fall%2009%20Reading/Lecture%201/Background%20reading/Weisberg_etal_MESSII.pdf. Retrieved 15 December 2012. 
  2. Schmitz, B.; Tassinari, M. (2001), "Fossil Meteorites", in Peucker-Ehrenbrink, B.; Schmitz, B., Accretion of Extraterrestrial Matter Throughout Earth's History, New York: Springer, pp. 319–31, doi:10.1007/978-1-4419-8694-8_17, ISBN 978-1-4613-4668-5 
  3. Agee, C. B.; N.V. Wilson; F.M. McCubbin; Z.D. Sharp; K. Ziegler (2012). "Basaltic Breccia NWA 7034: New ungrouped planetary Achondrite". 43rd Lunar and Planetary Science Conference (1659): 2690. Bibcode2012LPI....43.2690A. http://www.lpi.usra.edu/meetings/lpsc2012/pdf/2690.pdf. Retrieved 4 January 2013. 
  4. Goldstein, J. I.; Michael, J. R. (1 April 2006). "The formation of plessite in meteoritic metal". Meteoritics & Planetary Science 41 (4): 553–70. doi:10.1111/j.1945-5100.2006.tb00482.x. Bibcode2006M&PS...41..553G. 
  5. "regmaglypts". Meteorite or Meteorwrong?. Department of Earth and Planetary Sciences, Washington University in St. Louis. http://meteorites.wustl.edu/id/regmaglypts.htm. 
  6. "The Weston Meteorite (Yale Peabody Museum)". 7 December 2010. http://www.peabody.yale.edu/collections/met/met_weston.html.