Meteoroid - Wikipedia

Sand- to boulder-sized particle of debris in the Solar System Not to be confused with Metroid or Matroid.

A meteoroid (/ˈmiːtiərɔɪd/ MEE-tee-ə-royd)[1] is a small body in outer space. Meteoroids are distinguished as objects significantly smaller than asteroids, ranging in size from grains to objects up to one meter (3.28 feet) wide.[2] Objects smaller than meteoroids are classified as micrometeoroids or space dust.[2][3][4] Many are fragments from comets or asteroids, whereas others are collision impact debris ejected from bodies such as the Moon or Mars.[5][6][7]

The visible passage of a meteoroid, comet, or asteroid entering Earth's atmosphere is called a meteor, and a series of many meteors appearing seconds or minutes apart and appearing to originate from the same fixed point in the sky is called a meteor shower.

An estimated 25 million meteoroids, micrometeoroids and other space debris enter Earth's atmosphere each day,[8] which results in an estimated 15,000 tonnes (16,535 short tons) of that material entering the atmosphere each year.[9] A meteorite is the remains of a meteoroid that has survived the ablation of its surface material during its passage through the atmosphere as a meteor and has impacted the ground.

Meteoroids

[edit] See also: Micrometeoroid

In 1961, the International Astronomical Union (IAU) defined a meteoroid as "a solid object moving in interplanetary space, of a size considerably smaller than an asteroid and considerably larger than an atom".[10][11] In 1995, Beech and Steel, writing in the Quarterly Journal of the Royal Astronomical Society, proposed a new definition where a meteoroid would be between 100 μm and 10 meters across.[12] In 2010, following the discovery of asteroids below 10 m in size, Rubin and Grossman proposed a revision of the previous definition of meteoroid to objects between 10 μm and one meter in diameter in order to maintain the distinction.[2] According to Rubin and Grossman, the minimum size of an asteroid is given by what can be discovered from Earth-bound telescopes, so the distinction between meteoroid and asteroid is fuzzy. Some of the smallest asteroids discovered (based on absolute magnitude H) are 2008 TS26 with H = 33.2[13] and 2011 CQ1 with H = 32.1[14] both with an estimated size of one meter.[15] In April 2017, the IAU adopted an official revision of its definition, limiting size to between 30 μm (0.0012 in) and one meter in diameter, but allowing for a deviation for any object causing a meteor.[16]

Objects smaller than meteoroids are classified as micrometeoroids and interplanetary dust. The Minor Planet Center does not use the term "meteoroid".

Composition

[edit]

Almost all meteoroids contain extraterrestrial nickel and iron. They have three main classifications: iron, stone, and stony-iron. Some stone meteoroids contain grain-like inclusions known as chondrules and are called chondrites. Stony meteoroids without these features are called "achondrites", which are typically formed from extraterrestrial igneous activity; they contain little or no extraterrestrial iron.[17] The composition of meteoroids can be inferred as they pass through Earth's atmosphere from their trajectories and the light spectra of the resulting meteor. Their effects on radio signals also give information, especially useful for daytime meteors, which are otherwise very difficult to observe. From these trajectory measurements, meteoroids have been found to have many different orbits, some clustering in streams (see meteor showers) often associated with a parent comet, others apparently sporadic. Debris from meteoroid streams may eventually be scattered into other orbits. The light spectra, combined with trajectory and light curve measurements, have yielded various compositions and densities, ranging from fragile snowball-like objects with density about a quarter that of ice,[18] to nickel-iron rich dense rocks. The study of meteorites also gives insights into the composition of non-ephemeral meteoroids.

In the Solar System

[edit]

Most meteoroids come from the asteroid belt, having been perturbed by the gravitational influences of planets, but others are particles from comets, giving rise to meteor showers. Some meteoroids are fragments from bodies such as Mars or the Moon, that have been thrown into space by an impact.

Meteoroids travel around the Sun in a variety of orbits and at various velocities. The fastest move at about 42 km/s through space in the vicinity of Earth's orbit. This is escape velocity from the Sun, equal to the square root of two times Earth's speed, and is the upper speed limit of objects in the vicinity of Earth, unless they come from interstellar space. Earth travels at about 29.6 km/s, so when meteoroids meet the atmosphere head-on (which only occurs when meteors are in a retrograde orbit such as the Leonids, which are associated with the retrograde comet 55P/Tempel–Tuttle) the combined speed may reach about 71 km/s (see Specific energy#Astrodynamics). Meteoroids moving through Earth's orbital space average about 20 km/s,[19] but due to Earth's gravity meteors such as the Phoenicids can make atmospheric entry at as slow as about 11 km/s.

On January 17, 2013, at 05:21 PST, a one meter comet from the Oort cloud entered Earth atmosphere over California and Nevada.[20] The object had a retrograde orbit with perihelion at 0.98 ± 0.03 AU. It approached from the direction of the constellation Virgo (which was in the south about 50° above the horizon at the time), and collided head-on with Earth's atmosphere at 72 ± 6 km/s[20] vaporising more than 100 km above ground over a period of several seconds.

Collision with Earth's atmosphere

[edit] Main article: Meteor

When meteoroids intersect with Earth's atmosphere at night, they are likely to become visible as meteors. If meteoroids survive the entry through the atmosphere and reach Earth's surface, they are called meteorites. Meteorites are transformed in structure and chemistry by the heat of entry and force of impact. A noted 4-meter (13 ft) asteroid, 2008 TC3, was observed in space on a collision course with Earth on 6 October 2008 and entered Earth's atmosphere the next day, striking a remote area of northern Sudan. It was the first time that a meteoroid had been observed in space and tracked prior to impacting Earth.[10] NASA has produced a map showing the most notable asteroid collisions with Earth and its atmosphere from 1994 to 2013 from data gathered by U.S. government sensors.[21]

Meteorites

[edit] Main article: Meteorite

A meteorite is a portion of a meteoroid or asteroid that survives its passage through the atmosphere and hits the ground without being destroyed.[22] Meteorites are sometimes, but not always, found in association with hypervelocity impact craters; during energetic collisions, the entire impactor may be vaporized, leaving no meteorites. Geologists use the term, "bolide", in a different sense from astronomers to indicate a very large impactor. For example, the USGS uses the term to mean a generic large crater-forming projectile in a manner "to imply that we do not know the precise nature of the impacting body ... whether it is a rocky or metallic asteroid, or an icy comet for example".[23]

Meteoroids also hit other bodies in the Solar System. On such stony bodies as the Moon or Mars that have little or no atmosphere, they leave enduring craters.

Impact craters

[edit] Main article: Impact crater

Meteoroid collisions with solid Solar System objects, including the Moon, Mercury, Callisto, Ganymede, and most small moons and asteroids, create impact craters, which are the dominant geographic features of many of those objects. On other planets and moons with active surface geological processes, such as Earth, Venus, Mars, Europa, Io, and Titan, visible impact craters may become eroded, buried, or transformed by tectonics over time. In early literature, before the significance of impact cratering was widely recognised, the terms cryptoexplosion or cryptovolcanic structure were often used to describe what are now recognised as impact-related features on Earth.[24] Molten terrestrial material ejected from a meteorite impact crater can cool and solidify into an object known as a tektite. These are often mistaken for meteorites. Terrestrial rock, sometimes with pieces of the original meteorite, created or modified by an impact of a meteorite is called impactite.

Gallery of meteorites

[edit]

• Two tektites, molten terrestrial ejecta from a meteorite impact
• A partial slice of the Esquel pallasite
• Willamette Meteorite, from Oregon, US
• Meteorite, which fell in Wisconsin in 1868
• Marília Meteorite, a chondrite H4, which fell in Marília, Brazil (1971)
• Children posing behind a replica of the Tucson Meteorite at the Arizona Museum of Natural History[25]
• Meteorite with brecciation and carbon inclusions from Tindouf, Algeria[26]

See also

[edit]

• Glossary of meteoritics

Relating to meteoroids

[edit]

• Interplanetary dust
• Micrometeoroid
• Near-Earth object

Relating to meteorites

[edit]

• Baetyl – Sacred stones possibly originating as meteorites
• Impact crater
• Impact event
• Interplanetary dust cloud § Collecting interplanetary dust on Earth
• Meteorite
• Micrometeorite
• Tektite

References

[edit]

1. ^ "meteoroid". Cambridge English Dictionary.
2. ^ a b c Rubin, Alan E.; Grossman, Jeffrey N. (January 2010). "Meteorite and meteoroid: New comprehensive definitions". Meteoritics & Planetary Science. 45 (1): 114–122. Bibcode:2010M&PS...45..114R. doi:10.1111/j.1945-5100.2009.01009.x. S2CID 129972426.)
3. ^ Atkinson, Nancy (2 June 2015). "What is the difference between asteroids and meteorites". Universe Today.
4. ^ "meteoroids". The Free Dictionary. Retrieved 1 August 2015.
5. ^ "Meteoroid". National Geographic. Archived from the original on 7 October 2015. Retrieved 24 August 2015.
6. ^ "Meteors & Meteorites". NASA. Archived from the original on 26 December 2003. Retrieved 1 August 2015.
7. ^ "Asteroid Fast Facts". NASA. 31 March 2014. Retrieved 1 August 2015.
8. ^ Lidz, Franz (2019-01-09). "The Oldest Material in the Smithsonian Institution Came From Outer Space". Smithsonian. Retrieved 2019-01-09.
9. ^ Gary, Stuart (2011-12-22). "Survey finds not all meteors the same". ABC Science. ABC.
10. ^ a b "Glossary International Meteor Organization". International Meteor Organization (IMO). Retrieved 2011-09-16.
11. ^ Millman, Peter M. (1961). "A report on meteor terminology". Journal of the Royal Astronomical Society of Canada. 55: 265–267. Bibcode:1961JRASC..55..265M.
12. ^ Beech, Martin; Steel, Duncan (September 1995). "On the Definition of the Term Meteoroid". Quarterly Journal of the Royal Astronomical Society. 36 (3): 281–284. Bibcode:1995QJRAS..36..281B.)
13. ^ "JPL Small-Body Database Search Engine: H > 29 (mag)". JPL Solar System Dynamics. Retrieved 2013-01-28.
14. ^ "JPL Small-Body Database Browser: (2011 CQ1)" (2011-02-04 last obs).
15. ^ Yeomans, Donald K.; Chodas, Paul; Chesley, Steve (November 9, 2009). "Small Asteroid 2009 VA Whizzes By the Earth". NASA's Near Earth Object Program Office. Archived from the original on November 12, 2009. Retrieved 2013-01-28.
16. ^ Vincent Perlerin (September 26, 2017). "Definitions of terms in meteor astronomy (IAU)". News. International Meteor Organization. Retrieved 2018-01-22.
17. ^ Notkin, Geoffrey. "Meteorite types and classification". Meteorwritings. Geology.com. Retrieved 2014-03-02.
18. ^ Povenmire, Harold (2000). "Physical Dynamics of the Upsilon Pegasid Fireball – European Network 190882A" (PDF). Lunar and Planetary Science Conference: 1183. Bibcode:2000LPI....31.1183P.
19. ^ Interagency Group (Space) Working Group on Orbital Debris (February 1989). "Report on Orbital Debris". NASA Technical Reports Server: 1. hdl:2060/19900003319. Archived from the original on 2023-05-31. Retrieved 2023-05-31.
20. ^ a b Jenniskens, Peter. "2013 January 17 Sierra Nevada fireball". SETI Institute. Retrieved 2014-11-16. | "Earth Collides Head-On with Small Comet". SETI Institute. Archived from the original on 2013-01-28. Retrieved 2013-01-25.
21. ^ "New Map Shows Frequency of Small Asteroid Impacts, Provides Clues on Larger Asteroid Population". NASA Jet Propulsion Laboratory (JPL). Retrieved 17 February 2025.
22. ^ The Oxford Illustrated Dictionary. 1976. Second Edition. Oxford University Press. p. 533
23. ^ "What is a Bolide?". woodshole.er.usgs.gov. Retrieved 2011-09-16.
24. ^ French, Bevan M. (1998). "Traces of Catastrophe: A Handbook of Shock-Metamorphic Effects in Terrestrial Meteorite Impact Structures". Washington, DC: Smithsonian Institution. p. 97.
25. ^ "Arizona Through Time". Arizona Museum of Natural History. Retrieved 2024-09-03.
26. ^ "Northwest Africa 869". Meteoritical Bulletin Database. The Meteoritical Society.

External links

[edit] Wikimedia Commons has media related to Meteor. Wikisource has original works on the topic: Meteoroids Look up meteoroid or meteor in Wiktionary, the free dictionary.

• A History of Meteors and Other Atmospheric Phenomena
• American Meteor Society
• British Astronomical Society meteor page
• International Meteor Organization
• Live Meteor Scanner
• Meteoroids Page at NASA's Solar System Exploration
• Meteor shower predictions Archived 2011-07-03 at the Wayback Machine
• Meteor Showers and Viewing Tips
• Society for Popular Astronomy – Meteor Section
• Minor Planet Center: Asteroid Hazards, Part 2: The Challenge of Detection on YouTube (min. 7:14)
• Earth Impact Effects Program Estimates crater size and other effects of a specified body colliding with Earth.

v t e Small Solar System bodies
Minor planets	Designation Groups List Moon Meanings of names Asteroid Active Aten asteroid Asteroid belt Family Jupiter trojan Near-Earth Spectral types Distant minor planet Centaur Neptune trojan Damocloid Trans-Neptunian object Detached Kuiper belt Oort cloud Scattered disc
Comets	Extinct Great Halley-type Hyperbolic Long-period Lost Near-parabolic Periodic Sungrazing
Other	Cosmic dust Meteoroids Space debris

v t e Meteorites and meteoritics
Meteorite...	Glossary Fall bolide impactite statistics strewn field Find hunting Largest Micrometeorite Notable Parent body
Classification	By type, class,clan, group and grouplet Chondrite Carbonaceous CB CH CI CK CM CO CR CV C ungrouped Enstatite EH EL Kakangari Ordinary H L LL Rumuruti Achondrite Primitive Acapulcoite Brachinite IAB IIICD Lodranite Ureilite Winonaite Asteroidal Angrite Aubrite HED Diogenite Eucrite Howardite Lunar Impact breccia Mare basalts List Martian Basaltic Breccia NWA 7034 Chassignites Kaidun Nakhlites Orthopyroxenite ALH84001 Shergottites Martian meteorites list Meteorites on Mars list Iron IC IIAB IIC IID IIE IIG IIIAB IIIE IIIF IVA IVB Stony-iron Mesosiderite Pallasite Main group Eagle Station Pyroxene Structural Ataxite Hexahedrite Octahedrite Obsolete terms Amphoterite Nonmagmatic meteorite
Mineralogy and petrology	Characteristics shock TKW weathering Grains chondrule presolar Minerals Ca–Al-rich inclusion extraterrestrial materials meteoric iron Patterns Neumann lines Widmanstätten CI1 fossils
Lists	Meteorites by find location type Awards Journals Organizations
See also: Asteroid Atmospheric entry Comet Impact event Meteor shower Meteoroid Near-Earth object

v t e Modern impact events
On Earth	Pre-2000 1490 Qingyang 1783 Great Meteor 1860 Great Meteor 1908 Tunguska 1913 Great Meteor Procession 1930 Curuçá River 1938 Chicora meteor 1947 Sikhote-Alin meteor 1969 Murchison meteor 1972 Great Daylight Fireball 1990 Earth-grazing meteoroid Post-2000 2002 Eastern Mediterranean event 2007 Carancas impact event 2008 TC3 impact 2008 Buzzard Coulee meteor 2009 Sulawesi superbolide 2012 Sutter's Mill meteor 2012 United Kingdom meteoroid 2012 Novato meteor 2013 Chelyabinsk meteor Chelyabinsk meteorite 2013 Braunschweig meteor 2014 AA impact 2014 Ontario fireball CNEOS 2014-01-08 2015 Kerala meteoroid 2015 Thailand bolide WT1190F impact 2017 China bolide 2018 LA impact 2018 Kamchatka meteor 2019 MO impact 2020 China bolide 2021 Winchcombe meteor 2022 EB5 impact 2022 WJ1 impact 2023 CX1 impact 2024 BX1 impact 2024 RW1 impact 2024 UQ impact 2024 XA1 impact
On Mars	Impact events on Mars
On Jupiter	Impact events on Jupiter 1994 Comet Shoemaker–Levy 9 2009 Jupiter impact 2010 Jupiter impact
Lists	Predicted asteroid impacts on Earth Asteroid close approaches to Earth Comets Bolides Meteor air bursts Meteorite falls Minor planets Asteroids crossing Earth's orbit
See also	Asteroid impact prediction Asteroid impact avoidance Bolide Earth-grazing fireball Meteor procession Meteor shower Meteorite Meteoroid Near-Earth object Potentially hazardous object

v t e Planetary defense
Main topics	Asteroid Bolide Earth-grazing fireball Impact event Meteor air burst Meteor procession Meteor shower Meteorite Meteoroid Near-Earth object Potentially hazardous object Earth-crossing minor planets Asteroid close approaches
Defense	Asteroid impact avoidance Asteroid laser ablation Gravity tractor Ion-beam shepherd
Space probes	Dawn Deep Impact HAMMER AIDA Hera DART Halley Armada Hayabusa Hayabusa2 MASCOT NEAR Shoemaker NEA Scout New Horizons OSIRIS-REx PROCYON Rosetta Philae Stardust
NEO tracking	ATLAS Catalina Sky Survey LINEAR LONEOS NEAT NEODyS NEO Surveyor NEOSSat OGS Telescope Orbit@home Pan-STARRS SCAP Sentinel Space Telescope Sentry Spacewatch WISE
Organizations	B612 Foundation Japan Spaceguard Association The Meteoritical Society NEOShield Planetary Defense Coordination Office Spaceguard The Spaceguard Foundation Space Situational Awareness Programme United Nations Office for Outer Space Affairs
Hazard rating	Torino scale Palermo scale
Potential threats	1950 DA 101955 Bennu 2010 RF12 99942 Apophis 2024 YR4 List of objects with non-zero Torino ratings
Related categories	Impact events Fiction about meteoroids Fiction about impact events

v t e Solar System
Sun Mercury Venus Earth Mars Ceres Jupiter Saturn Uranus Neptune Orcus Pluto Haumea Quaoar Makemake Gonggong Eris Sedna
Planets, dwarfs, minors Terrestrials Mercury Venus Earth Mars Giants Gas Jupiter Saturn Ice Uranus Neptune Dwarfs Ceres Orcus Pluto Haumea Quaoar Makemake Gonggong Eris Sedna Large Minor Planets Salacia Varuna Ixion List Moons Earth Moon Claimed Mars Phobos Deimos Jupiter Ganymede Callisto Io Europa all 97 Saturn Titan Rhea Iapetus Dione Tethys Enceladus Mimas Hyperion Phoebe all 274 Uranus Titania Oberon Umbriel Ariel Miranda all 29 Neptune Triton Proteus Nereid all 16 Pluto Charon Nix Hydra Kerberos Styx Orcus Vanth Haumea Hiʻiaka Namaka Quaoar Weywot Makemake S/2015 (136472) 1 Gonggong Xiangliu Eris Dysnomia Exploration(outline) Colonization Discovery astronomy historical models timeline Space probes timeline list Human spaceflight space stations list programs Mercury Venus Moon mining Mars Ceres Asteroids mining Comets Jupiter Saturn Uranus Neptune Pluto Deep space Hypothetical objects Bagby's moon Chiron Coatlicue Counter-Earth Chrysalis Fifth Giant Hyperion Lilith Mercury's moon Neith Nemesis Nibiru Petit's moon Phaeton Planet Nine Effects Planet Ten Planet V Planet X Subsatellites Synestia Theia Themis Tyche Vulcan Vulcanoids Waltemath's moons Lists Comets Possible dwarf planets Gravitationally rounded objects Minor planets Natural satellites Solar System models Solar System objects by size by discovery date Interstellar and circumstellar molecules Rings Planetary Jovian Saturnian (Rhean?) Uranian Neptunian Minor objects' Charikloan Chironean Haumean Quaoarian Formation,evolution, contents, and History Star formation Accretion Accretion disk Excretion Capture theory Capture of Triton Circumplanetary disk Circumstellar disc Circumstellar envelope Coatlicue Co-orbital configuration Trojan moons Co-orbital moons Cosmic dust Debris disk Detached object Disk instability EXCEDE Exozodiacal dust Extraterrestrial materials Curation Sample-return mission Frost/Ice/Snow line Giant-impact hypothesis Grand tack hypothesis Gravitational collapse Hills cloud Hill sphere Interplanetary dust cloud Interplanetary medium/space Interstellar cloud Interstellar medium Interstellar space Kuiper belt Kuiper cliff Late Heavy Bombardment Molecular cloud Nebular hypothesis Nice model Nice 2 model Five-planet Nice model Oort cloud Oort limit Outer space Planet Disrupted Migration System Planetesimal Formation Merging stars Protoplanetary disk Ring system Roche limit vs. Hill sphere Rubble pile Scattered disc SmallSolarSystembodies Asteroid belt Asteroids Ceres Vesta Pallas Hygiea active List families PHA exceptional Kirkwood gap Centaurs Comets Damocloids Meteoroids Minor planets names and meanings moons Planetesimal Planetary orbit-crossers Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Trojans Venus Earth Mars Jupiter Trojan camp Greek camp Saturn Uranus Neptune Near-Earth objects NEAs Trans-Neptunian objects Kuiper belt Cubewanos Plutinos Detached objects Sednoids Scattered disc Hills cloud Oort cloud Oort limit Related Double planet Lagrange point Moonlet Syzygy Tidal locking
Outline of the Solar System Solar System portal Astronomy portal Earth sciences portal Solar System → Local Interstellar Cloud → Local Bubble → Gould Belt → Orion Arm → Milky Way → Milky Way subgroup → Local Group → Local Sheet → Local Volume → Virgo Supercluster → Laniakea Supercluster → Pisces–Cetus Supercluster Complex → Local Hole → Observable universe → UniverseEach arrow (→) may be read as "within" or "part of".

Authority control databases
International	GND
National	United States Israel
Other	Encyclopedia of Modern Ukraine Yale LUX

Portals:

• Stars
• Spaceflight
• Outer space
• Science