[meteorite-list] "Meteorite and meteoroid: New comprehensive definitions" the whole artical
Hello Larry, Dirk and List Here is the whole artical Meteorite and meteoroid: New comprehensive definitions by Alan E. RUBIN1* and Jeffrey N. GROSSMAN2 1Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California 90095–1567, USA 2U.S. Geological Survey, 954 National Center, Reston, Virginia 20192, USA *Corresponding author. E-mail: aeru...@ucla.edu (Received 05 May 2009; revision accepted 14 September 2009) INTRODUCTION Since Chladni (1794) published On the Origin of the Pallas Iron and Others Similar to it, and on Some Associated Natural Phenomena and made plausible the hypothesis that rocks could fall from the sky, the definition of the word meteorite has remained essentially unchanged, as reflected in the ten quotations given above. Nearly all modern reference works use a similar definition. Meteorites are almost always defined to be solid bodies that have fallen through the Earth’s atmosphere and landed on the Earth’s surface. Nineteenth-century definitions tend to leave open the origin of the falling material, whereas later definitions specify that the material came from space. Many recent definitions of meteorite, including the one adopted by the International Astronomical Union (IAU), specify that meteorites originated as meteoroids. The latter term was defined by the IAU as ‘‘a solid object moving in interplanetary space, of a size considerably smaller than an asteroid and considerably larger than an atom or molecule’’ (Millman 1961). Beech and Steel (1995) suggested modifying this definition to include only natural objects in the size range 100 lm to 10 m. Because modern usage frequently ties these two terms together, with meteoroids forming the pre-impact precursors of meteorites, it is imperative that the definitions be consistent. With the advent of the Space Age and the discovery of new sources of extraterrestrial material, it is clear that most existing definitions of the term meteorite are too restrictive. Indeed, there are already three objects recognized by the Meteoritical Society’s Committee on Meteorite Nomenclature (NomCom) that violate most traditional definitions of meteorite (with the exception of the one given in Gomes and Keil 1980) because they were not found on Earth’s surface. Two millimeter-size chondrites discovered among samples returned from the Moon during the Apollo missions have been described and named as meteorites: Bench Crater (McSween 1976; Zolensky et al. 1996) and Hadley Rille (Haggerty 1972; Grossman 1997; Rubin 1997). A IAB-complex iron identified on the surface of Mars by the Opportunity rover was recently given a formal meteorite name: Meridiani Planum (Connolly et al. 2006; Schro¨ der et al. 2008). The existence of these objects, combined with other probable meteorites from the Moon and Mars that have not yet been formally named (as well as other conceivable examples), has led us to re-examine the term meteorite and the related term meteoroid in a search for precise, comprehensive definitions. The NomCom is responsible for approving a unique name for every properly described meteorite. Meteorites are traditionally named for a geographic feature in the vicinity of the place where they were found. Thus, any change in the definition of meteorite will have practical consequences for how they are named. PROBLEMS WITH THE DEFINITIONS OF METEORITE AND METEOROID Where Do Meteorites Occur? Meteorites are Not Restricted to Earth The discoveries of the Bench Crater carbonaceous chondrite and Hadley Rille enstatite chondrite among returned lunar samples and the identification of the Meridiani Planum iron on Mars demonstrate that foreign objects, analogous to meteorites found on Earth, can arrive intact on the surfaces of other planetary bodies. The literature designations of these objects as meteorites have been widely accepted in the meteorite research community. The two meteorites found on the Moon were not derived from objects that produced meteors, a phenomenon that requires the presence of an atmosphere.1 Although the words meteor and meteorite share a common Greek root meaning ‘‘high in the air,’’ there is no reason to link these terms in a modern definition by requiring meteorites to have produced meteors during an atmospheric transit. If the chondrites found on the Moon or irons found on Mars are considered meteorites, then it is reasonable that a comprehensive definition of meteorite would allow for their presence on other planets as well as airless bodies such as asteroids and comets, or the natural satellites of any of these bodies. Thus, the first refinement needed for a comprehensive definition of meteorite is: Meteorites can occur on any celestial body, not just Earth. Meteoroids may Hit Spacecraft and Other Artificial Targets Another difficult situation arises when considering projectiles that strike a spacecraft. For example, publications reporting on the Long Duration Exposure Facility (LDE
[meteorite-list] "Meteorite and meteoroid: New comprehensive definitions" the whole artical
Hello Larry, Dirk and List Here is the whole artical Meteorite and meteoroid: New comprehensive definitions by Alan E. RUBIN1* and Jeffrey N. GROSSMAN2 1Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California 90095–1567, USA 2U.S. Geological Survey, 954 National Center, Reston, Virginia 20192, USA *Corresponding author. E-mail: aeru...@ucla.edu (Received 05 May 2009; revision accepted 14 September 2009) INTRODUCTION Since Chladni (1794) published On the Origin of the Pallas Iron and Others Similar to it, and on Some Associated Natural Phenomena and made plausible the hypothesis that rocks could fall from the sky, the definition of the word meteorite has remained essentially unchanged, as reflected in the ten quotations given above. Nearly all modern reference works use a similar definition. Meteorites are almost always defined to be solid bodies that have fallen through the Earth’s atmosphere and landed on the Earth’s surface. Nineteenth-century definitions tend to leave open the origin of the falling material, whereas later definitions specify that the material came from space. Many recent definitions of meteorite, including the one adopted by the International Astronomical Union (IAU), specify that meteorites originated as meteoroids. The latter term was defined by the IAU as ‘‘a solid object moving in interplanetary space, of a size considerably smaller than an asteroid and considerably larger than an atom or molecule’’ (Millman 1961). Beech and Steel (1995) suggested modifying this definition to include only natural objects in the size range 100 lm to 10 m. Because modern usage frequently ties these two terms together, with meteoroids forming the pre-impact precursors of meteorites, it is imperative that the definitions be consistent. With the advent of the Space Age and the discovery of new sources of extraterrestrial material, it is clear that most existing definitions of the term meteorite are too restrictive. Indeed, there are already three objects recognized by the Meteoritical Society’s Committee on Meteorite Nomenclature (NomCom) that violate most traditional definitions of meteorite (with the exception of the one given in Gomes and Keil 1980) because they were not found on Earth’s surface. Two millimeter-size chondrites discovered among samples returned from the Moon during the Apollo missions have been described and named as meteorites: Bench Crater (McSween 1976; Zolensky et al. 1996) and Hadley Rille (Haggerty 1972; Grossman 1997; Rubin 1997). A IAB-complex iron identified on the surface of Mars by the Opportunity rover was recently given a formal meteorite name: Meridiani Planum (Connolly et al. 2006; Schro¨ der et al. 2008). The existence of these objects, combined with other probable meteorites from the Moon and Mars that have not yet been formally named (as well as other conceivable examples), has led us to re-examine the term meteorite and the related term meteoroid in a search for precise, comprehensive definitions. The NomCom is responsible for approving a unique name for every properly described meteorite. Meteorites are traditionally named for a geographic feature in the vicinity of the place where they were found. Thus, any change in the definition of meteorite will have practical consequences for how they are named. PROBLEMS WITH THE DEFINITIONS OF METEORITE AND METEOROID Where Do Meteorites Occur? Meteorites are Not Restricted to Earth The discoveries of the Bench Crater carbonaceous chondrite and Hadley Rille enstatite chondrite among returned lunar samples and the identification of the Meridiani Planum iron on Mars demonstrate that foreign objects, analogous to meteorites found on Earth, can arrive intact on the surfaces of other planetary bodies. The literature designations of these objects as meteorites have been widely accepted in the meteorite research community. The two meteorites found on the Moon were not derived from objects that produced meteors, a phenomenon that requires the presence of an atmosphere.1 Although the words meteor and meteorite share a common Greek root meaning ‘‘high in the air,’’ there is no reason to link these terms in a modern definition by requiring meteorites to have produced meteors during an atmospheric transit. If the chondrites found on the Moon or irons found on Mars are considered meteorites, then it is reasonable that a comprehensive definition of meteorite would allow for their presence on other planets as well as airless bodies such as asteroids and comets, or the natural satellites of any of these bodies. Thus, the first refinement needed for a comprehensive definition of meteorite is: Meteorites can occur on any celestial body, not just Earth. Meteoroids may Hit Spacecraft and Other Artificial Targets Another difficult situation arises when considering projectiles that strike a spacecraft. For example, publications reporting on the Long Duration Exposure Facility (LDE
Re: [meteorite-list] "Meteorite and meteoroid: New comprehensive definitions"
I agree. There's no reason that "meteoroid" and "asteroid" can't overlap, as well. That is, all meteoroids are asteroids, but not all asteroids are meteoroids. A meteoroid is simply an asteroid (whether a few centimeters or a few kilometers) that is destined to pass through the atmosphere. (A complete description would be a little more complex, but you get the idea .) I also encourage a slightly broader use of "meteorite", by extending the term backwards in time to the point that the body is actually finished developing. Thus, the material that survives ablation or other entry processes should reasonably be called meteoritic during the period it is falling (cold), but before it actually makes contact with the ground. That distinction probably isn't important to most here, but to somebody like myself, focused on meteors as opposed to meteorites, it is useful to have a term like that, and I don't think we need something new. Chris * Chris L Peterson Cloudbait Observatory http://www.cloudbait.com - Original Message - From: To: "Galactic Stone & Ironworks" Cc: "Shawn Alan" ; Sent: Sunday, April 04, 2010 10:46 AM Subject: Re: [meteorite-list] (no subject) Hi Mike: These are good definitions for things on Earth (meteorites, etc.), but once one talks about things in orbit around the Sun, this is in the purview of the IAU and they already have (not so perfect) definitions for small Solar System bodies. As I said previously, I would be hard-pressed to call anything larger than 1 meter an asteroid. Larry __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] "Meteorite and meteoroid: New comprehensive definitions"
Hello Larry and all, Thanks for this. Where was this published? Some of the numbers did not Maybe in the next (2010 Jan.) issue of MAPS? Katsu OHTSUKA Tokyo, JAPAN __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
[meteorite-list] "Meteorite and meteoroid: New comprehensive definitions" second part of the artical
Hello List Here is the second part of the artical Meteorite and meteoroid: New comprehensive definitions by Alan E. RUBIN1* and Jeffrey N. GROSSMAN2 1Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California 90095–1567, USA 2U.S. Geological Survey, 954 National Center, Reston, Virginia 20192, USA *Corresponding author. E-mail: aerubin at ucla.edu (Received 05 May 2009; revision accepted 14 September 2009) There are more practical reasons that can be used to select the best upper size cutoff for micrometeorites and micrometeoroids. Meteorites have long been recognized as rare, special kinds of rocks. The practice of naming individual meteorites after the places where they were found is based on this special status. Generally, to receive a name, a meteorite must be well classified and large enough to provide material for curation and research. Much of the material that forms meteorites in the inner solar system is relatively coarse grained. Many chondrites and nearly all achondrites and iron-rich meteorites have mineral grain sizes that exceed 100 lm. Although in many cases it is possible to classify small particles of meteoritic material at least tentatively, this process is greatly hindered when the particle size is significantly smaller than the parental rock’s grain size. To allow for proper classification, 2 mm is a more useful size cutoff than 100 lm. In addition, the number of objects that accrete to the Earth (and other bodies) varies exponentially with the inverse of mass (e.g., Brown 1960, 1961; Huss 1990; Bland et al. 1996). Single expeditions to recover micrometeorites have found thousands of particles in the sub-millimeter size range (Rochette et al. 2008), but very few that exceed 2 mm. The 2 mm divide also seems to form an approximate break between the smallest objects that have historically been called meteorites and the largest objects called micrometeorites. This leads to additional refinements to our definitions: Micrometeorites are meteorites smaller than 2 mm in diameter; micrometeoroids are meteoroids smaller than 2 mm in diameter; objects smaller than 10 lm are dust particles. By this definition, IDPs are particles smaller than 10 lm. We are not proposing a lower size limit for IDPs. Before it impacted the Earth, object 2008 TC3 was approximately 4 m across and was officially classified as an asteroid (Jenniskens et al. 2009). It is likely that when smaller interplanetary objects are observed telescopically, they will also be called asteroids, even if they are of sub-meter size. Thus, the boundary between meteoroids and asteroids is soft and will only shrink with improved observational capabilities. For the minimum asteroid size. We thus differ from Beech and Steel (1995) who suggested a 10 m cutoff between meteoroids and asteroids. The Relationship between Meteorites and Meteoroids It is tempting to include in our definition of meteorite a statement that meteorites originate as meteoroids, which, using our modified definition are natural solid objects moving in space, with a size less that 1 m, but larger than 10 lm; this was done in previous definitions such as that of McSween (1987). However, because the Hoba iron meteorite is larger than 1 m across, it represents a fragment of an asteroid, not a meteoroid, under our definition of meteoroid. If a mass of iron 12 m in diameter deriving from an asteroidal core were to be found on Earth or another celestial body, it would almost certainly be called a meteorite, despite the fact that it was too large to have originated as a meteoroid even under the Beech and Steel (1995) definition. In addition, the Canyon Diablo iron meteorites associated with the Barringer (Meteor) Crater in Arizona, are fragments of an impacting asteroid that was several tens of meters in diameter (e.g., Roddy et al. 1980); the Morokweng chondrite may be a fragment of a kilometer-size asteroid that created the >70 km Morokweng crater in South Africa (Maier et al. 2006). Comets, particularly Jupiter-family comets (JFCs), could also produce meteorites. A small fraction of JFCs evolve into near-Earth objects (Levison and Duncan 1997) and could impact main-belt asteroids at relatively low velocities (approximately 5 km s)1) (Campins and Swindle 1998). Meteorites could also be derived from moons around planetary bodies. Lunar meteorites are well known on Earth, and meteorites derived from Phobos may impact Mars, especially after the orbit of Phobos decays sufficiently (e.g., Bills et al. 2005). We see no simple way out of this semantic dilemma, so we add the refinement: Meteorites are created by the impacts of meteoroids or larger natural bodies. Additional Complications Fragments of Meteorites Meteorite showers result from the fragmentation of a meteoroid (or larger body) in the atmosphere. In the case of the L6 chondrite Holbrook, about 14,000 individual stones fell (Grady 2000). Each of these stones is conside
[meteorite-list] "Meteorite and meteoroid: New comprehensive definitions" first part of the artical
Hello Larry, Dirk and List Here is the first part of the artical and if I had posted this twice already I am sorry for some reason it wastn post after I emailed and if it didnt post twice then here is the first part of the artical. Meteorite and meteoroid: New comprehensive definitions by Alan E. RUBIN1* and Jeffrey N. GROSSMAN2 1Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California 90095–1567, USA 2U.S. Geological Survey, 954 National Center, Reston, Virginia 20192, USA *Corresponding author. E-mail: aeru...@ucla.edu (Received 05 May 2009; revision accepted 14 September 2009) INTRODUCTION Since Chladni (1794) published On the Origin of the Pallas Iron and Others Similar to it, and on Some Associated Natural Phenomena and made plausible the hypothesis that rocks could fall from the sky, the definition of the word meteorite has remained essentially unchanged, as reflected in the ten quotations given above. Nearly all modern reference works use a similar definition. Meteorites are almost always defined to be solid bodies that have fallen through the Earth’s atmosphere and landed on the Earth’s surface. Nineteenth-century definitions tend to leave open the origin of the falling material, whereas later definitions specify that the material came from space. Many recent definitions of meteorite, including the one adopted by the International Astronomical Union (IAU), specify that meteorites originated as meteoroids. The latter term was defined by the IAU as ‘‘a solid object moving in interplanetary space, of a size considerably smaller than an asteroid and considerably larger than an atom or molecule’’ (Millman 1961). Beech and Steel (1995) suggested modifying this definition to include only natural objects in the size range 100 lm to 10 m. Because modern usage frequently ties these two terms together, with meteoroids forming the pre-impact precursors of meteorites, it is imperative that the definitions be consistent. With the advent of the Space Age and the discovery of new sources of extraterrestrial material, it is clear that most existing definitions of the term meteorite are too restrictive. Indeed, there are already three objects recognized by the Meteoritical Society’s Committee on Meteorite Nomenclature (NomCom) that violate most traditional definitions of meteorite (with the exception of the one given in Gomes and Keil 1980) because they were not found on Earth’s surface. Two millimeter-size chondrites discovered among samples returned from the Moon during the Apollo missions have been described and named as meteorites: Bench Crater (McSween 1976; Zolensky et al. 1996) and Hadley Rille (Haggerty 1972; Grossman 1997; Rubin 1997). A IAB-complex iron identified on the surface of Mars by the Opportunity rover was recently given a formal meteorite name: Meridiani Planum (Connolly et al. 2006; Schro¨ der et al. 2008). The existence of these objects, combined with other probable meteorites from the Moon and Mars that have not yet been formally named (as well as other conceivable examples), has led us to re-examine the term meteorite and the related term meteoroid in a search for precise, comprehensive definitions. The NomCom is responsible for approving a unique name for every properly described meteorite. Meteorites are traditionally named for a geographic feature in the vicinity of the place where they were found. Thus, any change in the definition of meteorite will have practical consequences for how they are named. PROBLEMS WITH THE DEFINITIONS OF METEORITE AND METEOROID Where Do Meteorites Occur? Meteorites are Not Restricted to Earth The discoveries of the Bench Crater carbonaceous chondrite and Hadley Rille enstatite chondrite among returned lunar samples and the identification of the Meridiani Planum iron on Mars demonstrate that foreign objects, analogous to meteorites found on Earth, can arrive intact on the surfaces of other planetary bodies. The literature designations of these objects as meteorites have been widely accepted in the meteorite research community. The two meteorites found on the Moon were not derived from objects that produced meteors, a phenomenon that requires the presence of an atmosphere.1 Although the words meteor and meteorite share a common Greek root meaning ‘‘high in the air,’’ there is no reason to link these terms in a modern definition by requiring meteorites to have produced meteors during an atmospheric transit. If the chondrites found on the Moon or irons found on Mars are considered meteorites, then it is reasonable that a comprehensive definition of meteorite would allow for their presence on other planets as well as airless bodies such as asteroids and comets, or the natural satellites of any of these bodies. Thus, the first refinement needed for a comprehensive definition of meteorite is: Meteorites can occur on any celestial body, not just Earth. Meteoroids may Hit Spacecraft and Other Artificial Targets A
Re: [meteorite-list] "Meteorite and meteoroid: New comprehensive definitions"
Larry, Shawn and List, I have re-posted the abstract of Meteorite and meteoroid: New comprehensive definitions by Alan E. RUBIN and Jeffrey N. GROSSMAN at: http://lunarmeteoritehunters.blogspot.com/2010/04/meteorite-and-meteoroid-new.html Best Regards, Dirk Ross...Tokyo --- On Sun, 4/4/10, lebof...@lpl.arizona.edu wrote: > From: lebof...@lpl.arizona.edu > Subject: Re: [meteorite-list] "Meteorite and meteoroid: New comprehensive > definitions" > To: "Shawn Alan" > Cc: meteorite-list@meteoritecentral.com > Date: Sunday, April 4, 2010, 11:37 AM > Hi Alan: > > Thanks for this. Where was this published? Some of the > numbers did not > come though. This works fine with me other than,if read > this correctly, it > does not classify anything larger than a meter. What are > those objects? > > There was a discussion of this topic some time ago and one > needs to take > into account some that has been observed and has its orbit > determined. > Technically this is an asteroid since the IAU does not > number/name > meteoroids. This can be down to about 5 meters (not sure > what the smallest > NEO observed is). I would be hard pressed to call > everything larger than 1 > meter (if I read this right) an asteroid. > > My two cents. > > Larry > > > Hello Listers, > > > > Here is an intersting artical I found that explains > new comprehensive > > definitions about meteorites. Down below is an > abstract from the artical > > and a short introduction into the what is disussed > about new definitions. > > > > > > Meteorite and meteoroid: New comprehensive > definitions > > > > Alan E. RUBIN1* and Jeffrey N. GROSSMAN2 > > 1Institute of Geophysics and Planetary Physics, > University of California, > > Los Angeles, California 90095–1567, USA > > 2U.S. Geological Survey, 954 National Center, Reston, > Virginia 20192, USA > > *Corresponding author. E-mail: aeru...@ucla.edu > > (Received 05 May 2009; revision accepted 14 September > 2009) > >  > > Abstract–Meteorites have traditionally been > defined as solid objects > > that have fallen to Earthfrom space. This definition, > however, is no > > longer adequate. In recent decades, man-made objects > have fallen to Earth > > from space, meteorites have been identified on the > Moon andMars, and small > > interplanetary objects have impacted orbiting > spacecraft. Taking these > > factsand other potential complications into > consideration, we offer new > > comprehensive definitions of the terms > ‘‘meteorite,’’ > > ‘‘meteoroid,’’ and their > smaller counterparts: A meteoroid is a > > 10-lm to 1-m-size natural solid object moving in > interplanetary space. > > Amicrometeoroid is a meteoroid 10 lm to 2 mm in size. > A meteorite is a > > natural, solid object > > larger than 10 lm in size, derived from a celestial > body, that was > > transported by naturalmeans from the body on which it > formed to a region > > outside the dominant gravitational influence of that > body and that later > > collided with a natural or artificial body larger > than > > itself (even if it is the same body from which it was > launched). > > Weathering and other secondary processes do not affect > an object’s > > status as a meteorite as long as something > recognizable remains of its > > original minerals or structure. An object loses its > status as a > > meteorite if it is incorporated into a larger rock > that becomes a > > meteorite itself. A micrometeorite is a meteorite > between 10 lm and 2 mm > > in size. > >  > > Meteorite–‘‘a solid substance or > body falling from the high regions > > of the atmosphere’’(Craig 1849); > ‘‘[a] mass of stone and iron that > > ha[s] been directly observed to have fallen down to > the Earth’s > > surface’’ (translated from Cohen 1894); > ‘‘[a] solid bod[y] which > > came to the earth from space’’ > (Farrington 1915); ‘‘A mass of > > solid matter, too small to be > > considered an asteroid; either traveling through space > as an unattached > > unit, or having landed on the earth and still > retaining its identity’’ > > (Nininger 1933); ‘‘[a meteoroid] which has > reached the surface of the > > Earth without being vaporized’’ (1958 > International > > Astronomical Union (IAU) definition, quoted by Millman > 1961); ‘‘a > > solid body which has arrived on the Earth from outer > space’’ (Mason > > 1962); ‘‘[a] solid bod[y] which reach[es] > the
Re: [meteorite-list] "Meteorite and meteoroid: New comprehensive definitions"
Hi Alan: Thanks for this. Where was this published? Some of the numbers did not come though. This works fine with me other than,if read this correctly, it does not classify anything larger than a meter. What are those objects? There was a discussion of this topic some time ago and one needs to take into account some that has been observed and has its orbit determined. Technically this is an asteroid since the IAU does not number/name meteoroids. This can be down to about 5 meters (not sure what the smallest NEO observed is). I would be hard pressed to call everything larger than 1 meter (if I read this right) an asteroid. My two cents. Larry > Hello Listers, > > Here is an intersting artical I found that explains new comprehensive > definitions about meteorites. Down below is an abstract from the artical > and a short introduction into the what is disussed about new definitions. > > > Meteorite and meteoroid: New comprehensive definitions > > Alan E. RUBIN1* and Jeffrey N. GROSSMAN2 > 1Institute of Geophysics and Planetary Physics, University of California, > Los Angeles, California 90095â1567, USA > 2U.S. Geological Survey, 954 National Center, Reston, Virginia 20192, USA > *Corresponding author. E-mail: aeru...@ucla.edu > (Received 05 May 2009; revision accepted 14 September 2009) > Â > AbstractâMeteorites have traditionally been defined as solid objects > that have fallen to Earthfrom space. This definition, however, is no > longer adequate. In recent decades, man-made objects have fallen to Earth > from space, meteorites have been identified on the Moon andMars, and small > interplanetary objects have impacted orbiting spacecraft. Taking these > factsand other potential complications into consideration, we offer new > comprehensive definitions of the terms ââmeteorite,ââ > ââmeteoroid,ââ and their smaller counterparts: A meteoroid is a > 10-lm to 1-m-size natural solid object moving in interplanetary space. > Amicrometeoroid is a meteoroid 10 lm to 2 mm in size. A meteorite is a > natural, solid object > larger than 10 lm in size, derived from a celestial body, that was > transported by naturalmeans from the body on which it formed to a region > outside the dominant gravitational influence of that body and that later > collided with a natural or artificial body larger than > itself (even if it is the same body from which it was launched). > Weathering and other secondary processes do not affect an objectâs > status as a meteorite as long as something recognizable remains of its > original minerals or structure. An object loses its status as a > meteorite if it is incorporated into a larger rock that becomes a > meteorite itself. A micrometeorite is a meteorite between 10 lm and 2 mm > in size. > Â > Meteoriteâââa solid substance or body falling from the high regions > of the atmosphereââ(Craig 1849); ââ[a] mass of stone and iron that > ha[s] been directly observed to have fallen down to the Earthâs > surfaceââ (translated from Cohen 1894); ââ[a] solid bod[y] which > came to the earth from spaceââ (Farrington 1915); ââA mass of > solid matter, too small to be > considered an asteroid; either traveling through space as an unattached > unit, or having landed on the earth and still retaining its identityââ > (Nininger 1933); ââ[a meteoroid] which has reached the surface of the > Earth without being vaporizedââ (1958 International > Astronomical Union (IAU) definition, quoted by Millman 1961); ââa > solid body which has arrived on the Earth from outer spaceââ (Mason > 1962); ââ[a] solid bod[y] which reach[es] the Earth (or the Moon, > Mars, etc.) from interplanetary space and [is] large enough to survive > passage through the Earthâs (or Marsâ, etc.) atmosphereââ (Gomes > and Keil 1980); ââ[a meteoroid] that survive[s] passage through the > atmosphere and fall[s] to earthââ (Burke1986); ââa recovered > fragment of a meteoroid that has survived transit through the > earthâsatmosphereââ (McSween 1987); ââ[a] solid bod[y] of > extraterrestrial material that penetrate[s] > the atmosphere and reach[es] the Earthâs surfaceââ (Krot et al. > 2003). > Â > INTRODUCTION > Since Chladni (1794) published On the Origin of the > Pallas Iron and Others Similar to it, and on Some > Associated Natural Phenomena and made plausible the > hypothesis that rocks could fall from the sky, the > definition of the word meteorite has remained essentially > unchanged, as reflected in the ten quotations given > above. Nearly all modern reference works use a similar > definition. Meteorites are almost always defined to be > solid bodies that have fallen through the Earthâs > atmosphere and landed on the Earthâs surface. > Â > Many recent definitions of meteorite, including the > one adopted by the International Astronomical Union > (IAU), specify that meteorites originated as meteoroids. > The latter term was def
[meteorite-list] "Meteorite and meteoroid: New comprehensive definitions"
Hello Listers, Here is an intersting artical I found that explains new comprehensive definitions about meteorites. Down below is an abstract from the artical and a short introduction into the what is disussed about new definitions. Meteorite and meteoroid: New comprehensive definitions Alan E. RUBIN1* and Jeffrey N. GROSSMAN2 1Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California 90095–1567, USA 2U.S. Geological Survey, 954 National Center, Reston, Virginia 20192, USA *Corresponding author. E-mail: aeru...@ucla.edu (Received 05 May 2009; revision accepted 14 September 2009) Abstract–Meteorites have traditionally been defined as solid objects that have fallen to Earthfrom space. This definition, however, is no longer adequate. In recent decades, man-made objects have fallen to Earth from space, meteorites have been identified on the Moon andMars, and small interplanetary objects have impacted orbiting spacecraft. Taking these factsand other potential complications into consideration, we offer new comprehensive definitions of the terms ‘‘meteorite,’’ ‘‘meteoroid,’’ and their smaller counterparts: A meteoroid is a 10-lm to 1-m-size natural solid object moving in interplanetary space. Amicrometeoroid is a meteoroid 10 lm to 2 mm in size. A meteorite is a natural, solid object larger than 10 lm in size, derived from a celestial body, that was transported by naturalmeans from the body on which it formed to a region outside the dominant gravitational influence of that body and that later collided with a natural or artificial body larger than itself (even if it is the same body from which it was launched). Weathering and other secondary processes do not affect an object’s status as a meteorite as long as something recognizable remains of its original minerals or structure. An object loses its status as a meteorite if it is incorporated into a larger rock that becomes a meteorite itself. A micrometeorite is a meteorite between 10 lm and 2 mm in size. Meteorite–‘‘a solid substance or body falling from the high regions of the atmosphere’’(Craig 1849); ‘‘[a] mass of stone and iron that ha[s] been directly observed to have fallen down to the Earth’s surface’’ (translated from Cohen 1894); ‘‘[a] solid bod[y] which came to the earth from space’’ (Farrington 1915); ‘‘A mass of solid matter, too small to be considered an asteroid; either traveling through space as an unattached unit, or having landed on the earth and still retaining its identity’’ (Nininger 1933); ‘‘[a meteoroid] which has reached the surface of the Earth without being vaporized’’ (1958 International Astronomical Union (IAU) definition, quoted by Millman 1961); ‘‘a solid body which has arrived on the Earth from outer space’’ (Mason 1962); ‘‘[a] solid bod[y] which reach[es] the Earth (or the Moon, Mars, etc.) from interplanetary space and [is] large enough to survive passage through the Earth’s (or Mars’, etc.) atmosphere’’ (Gomes and Keil 1980); ‘‘[a meteoroid] that survive[s] passage through the atmosphere and fall[s] to earth’’ (Burke1986); ‘‘a recovered fragment of a meteoroid that has survived transit through the earth’satmosphere’’ (McSween 1987); ‘‘[a] solid bod[y] of extraterrestrial material that penetrate[s] the atmosphere and reach[es] the Earth’s surface’’ (Krot et al. 2003). INTRODUCTION Since Chladni (1794) published On the Origin of the Pallas Iron and Others Similar to it, and on Some Associated Natural Phenomena and made plausible the hypothesis that rocks could fall from the sky, the definition of the word meteorite has remained essentially unchanged, as reflected in the ten quotations given above. Nearly all modern reference works use a similar definition. Meteorites are almost always defined to be solid bodies that have fallen through the Earth’s atmosphere and landed on the Earth’s surface. Many recent definitions of meteorite, including the one adopted by the International Astronomical Union (IAU), specify that meteorites originated as meteoroids. The latter term was defined by the IAU as ‘‘a solid object moving in interplanetary space, of a size considerably smaller than an asteroid and considerably larger than an atom or molecule’’ (Millman 1961). Beech and Steel (1995) suggested modifying this definition to include only natural objects in the size range 100 lm to 10 m. Because modern usage frequently ties these two terms together, with meteoroids forming the pre-impact precursors of meteorites, it is imperative that the definitions be consistent. With the advent of the Space Age and the discovery of new sources of extraterrestrial material, it is clear that most existing definitions of the term meteorite are too restrictive. Indeed, there are already three objects recognized by the Meteoritical Society’s Committee on Meteorite Nomenclature (NomCom) that violate most traditional definitions of meteorite (with the exception of the one given in Go
