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{{Short description|Body that enters the Earth's atmosphere}} {{Redirect-several|Meteor|Falling star|Shooting star}} [[File:Cosmic Fireball Falling Over ALMA.jpg|thumb|250px|Meteor seen from the site of the [[Atacama Large Millimeter Array]] (ALMA)<ref>{{cite news |title=Cosmic Fireball Falling Over ALMA |url=http://www.eso.org/public/images/potw1414a/ |access-date=10 April 2014 |newspaper=ESO Picture of the Week}}</ref>]] A '''meteor''', known colloquially as a '''<dfn>shooting star</dfn>''', is a glowing streak of a small body (usually [[meteoroid]]) going through Earth's atmosphere, after being heated to incandescence by collisions with air molecules in the upper atmosphere,<ref name="IMO-meteoroid">{{cite web|title=Glossary International Meteor Organization|publisher=[[International Meteor Organization]] (IMO)|url=http://www.imo.net/glossary#letterm|access-date=2011-09-16 }}</ref><ref name="M-W">{{cite dictionary|entry=meteor|dictionary= Merriam-Webster Dictionary |entry-url = http://www.merriam-webster.com/dictionary/meteor | access-date = 2014-09-21}} </ref><ref>{{cite book | last = Bronshten | first = V. A. | title = Physics of Meteoric Phenomena | publisher = Springer Science & Business Media | series = Science | year=2012 | page = 358 | url =https://books.google.com/books?id=snL8CAAAQBAJ&q=meteor+adiabatic+heating&pg=PA5 | isbn = 978-94-009-7222-3 }}</ref> creating a streak of light via its rapid motion and sometimes also by shedding glowing material in its wake. Although a meteor may seem to be a few thousand feet from the Earth,<ref>Bob King. (2016). ''Night Sky With Naked Eye: How to Find Planets, Constellations, Satellites and Other Night Sky Wonders Without a Telescope''{{ISBN?}}{{page needed|date=December 2021}}</ref> meteors typically occur in the [[mesosphere]] at altitudes from {{convert|76|to|100|km|ft|abbr=on|-4}}.<ref name="MIT-pje">{{cite web |url=http://www.haystack.mit.edu/~pje/meteors/ |title=Millstone Hill UHF Meteor Observations: Preliminary Results |first=Philip J. |last=Erickson |archive-url=https://web.archive.org/web/20160305073442/http://www.haystack.mit.edu/~pje/meteors/ |archive-date=2016-03-05 }}</ref><ref name="AMS-2">{{cite web |title=Meteor FAQs: How high up do meteors occur? |publisher=[[American Meteor Society]] (AMS) |url = https://www.amsmeteors.org/meteor-showers/meteor-faq/#2 |access-date=2021-04-16 }}</ref> The root word ''meteor'' comes from the [[Ancient Greek|Greek]] ''meteōros'', meaning "high in the air".<ref name="M-W" /> Millions of meteors occur in Earth's atmosphere daily. Most meteoroids that cause meteors are about the size of a grain of sand, i.e. they are usually millimeter-sized or smaller. Meteoroid sizes can be calculated from their mass and density which, in turn, can be estimated from the observed meteor trajectory in the upper atmosphere.<ref name="AJ-18">{{cite journal| last=Subasinghe | first=Dilini | journal=Astronomical Journal | title=Luminous Efficiency Estimates of Meteors | volume=155 | issue=2 | page=88 | year=2018 | doi=10.3847/1538-3881/aaa3e0| arxiv=1801.06123 | s2cid=118990427 | doi-access=free }}</ref> Meteors may occur in [[meteor shower|showers]], which arise when Earth passes through a stream of debris left by a comet, or as "random" or "sporadic" meteors, not associated with a specific stream of [[space debris]]. A number of specific meteors have been observed, largely by members of the public and largely by accident, but with enough detail that orbits of the meteoroids producing the meteors have been calculated. The atmospheric velocities of meteors result from the movement of Earth around the Sun at about {{cvt|30|km/s|mph|}},<ref name="NASA-earthfact">{{cite web |last=Williams |first=David R. |date=2004-09-01 |url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html |title=Earth Fact Sheet |publisher=NASA |access-date=2010-08-09 }}</ref> the orbital speeds of meteoroids, and the [[gravity well]] of Earth. Meteors become visible between about {{convert|75 to 120|km|mi||abbr=on}} above Earth. They usually disintegrate at altitudes of {{convert|50 to 95|km|mi|||abbr=|}}.<ref name="meteorsandtheirparentcomets">{{Cite book |last=Jenniskens |first=Peter |title=Meteor Showers and their Parent Comets |year=2006 |publisher=Cambridge University Press |location=New York |isbn=978-0-521-85349-1 |page=372}}</ref> Meteors have roughly a fifty percent chance of a daylight (or near daylight) collision with Earth. Most meteors are, however, observed at night, when darkness allows fainter objects to be recognized. For bodies with a size scale larger than {{cvt|10|cm||}} to several meters meteor visibility is due to the atmospheric [[ram pressure]] (not friction) that heats the meteoroid so that it glows and creates a shining trail of gases and melted meteoroid particles. The gases include vaporised meteoroid material and atmospheric gases that heat up when the meteoroid passes through the atmosphere. Most meteors glow for about a second. == History == Meteors were not known to be an astronomical phenomenon until early in the nineteenth century. Before that, they were seen in the West as an atmospheric phenomenon, like lightning, and were not connected with strange stories of rocks falling from the sky. In 1807, [[Yale University]] chemistry professor [[Benjamin Silliman]] investigated a [[meteorite]] that fell in [[Weston meteorite|Weston, Connecticut]].<ref name="jefferson">{{cite web |last=Taibi |first=Richard |url=http://www.amsmeteors.org/about/ams-history/the-early-years-of-meteor-observations-in-the-usa/ |title=The Early Years of Meteor Observations in the USA |publisher=American Meteor Society }}</ref> Silliman believed the meteor had a cosmic origin, but meteors did not attract much attention from astronomers until the spectacular meteor storm of November 1833.<ref name="1833leonids">{{cite web |url=http://meteorshowersonline.com/showers/leonidhis.html |publisher=Meteorshowers Online |title=The Leonids and the Birth of Meteor Astronomy |first=Gary W. |last=Kronk |archive-url=https://web.archive.org/web/20090122195546/http://meteorshowersonline.com/showers/leonidhis.html |archive-date=January 22, 2009 }}</ref> People all across the eastern United States saw thousands of meteors, radiating from a single point in the sky. Careful observers noticed that [[Radiant (meteor shower)|the radiant]], as the point is called, moved with the stars, staying in the constellation Leo.<ref name="AJSA-1834">{{cite journal |url=https://books.google.com/books?id=HjcPAAAAYAAJ&pg=PA407 |journal=The American Journal of Science and Arts |volume=XXV |date=January 1834 |title=On the Meteors of Nov. 13, 1833 |first=Edward |last=Hitchcock }}</ref> The astronomer [[Denison Olmsted]] extensively studied this storm, concluding that it had a cosmic origin. After reviewing historical records, [[Heinrich Wilhelm Matthias Olbers]] predicted the storm's return in 1867, drawing other astronomers' attention to the phenomenon. [[Hubert Anson Newton|Hubert A. Newton]]'s more thorough historical work led to a refined prediction of 1866, which proved correct.<ref name="1833leonids" /> With [[Giovanni Schiaparelli]]'s success in connecting the [[Leonids]] (as they are called) with comet [[Tempel-Tuttle]], the cosmic origin of meteors was firmly established. Still, they remain an atmospheric phenomenon and retain their name "meteor" from the Greek word for "atmospheric".<ref name="AP-318">{{cite web|url=http://astroprofspage.com/archives/318 |publisher=Astro Prof |title=October's Orionid Meteors |archive-url=https://web.archive.org/web/20160304030333/http://astroprofspage.com/archives/318 |archive-date=March 4, 2016 }}</ref> == Fireball == {{main|List of bolides}} [[File:Взрыв метеорита над Челябинском 15 02 2013 avi-iCawTYPtehk.ogv|thumb|Camera recording of a [[Chelyabinsk meteor|superbolide]] passage above [[Chelyabinsk Oblast]], Russia on 15th February 2013. The object in this video is estimated to be {{Measurement converter|17 to 20|m|ft}} in diameter before atmospheric entry.]] A '''fireball''' is a brighter-than-usual meteor which can be also seen during daylight. The [[International Astronomical Union]] (IAU) defines a fireball as "a meteor brighter than any of the planets" ([[apparent magnitude]] −4 or greater).<ref name="meteor-13871">{{cite web |url=http://www.meteorobs.org/maillist/msg13871.html |first=George |last=Zay |title=MeteorObs Explanations and Definitions (states IAU definition of a fireball) |publisher=Meteorobs.org |date=1999-07-09 |access-date=2011-09-16 |archive-url=https://web.archive.org/web/20111001080446/http://www.meteorobs.org/maillist/msg13871.html |archive-date=2011-10-01 }}</ref> The [[International Meteor Organization]] (an amateur organization that studies meteors) has a more rigid definition. It defines a fireball as a meteor that would have at least magnitude of −3 if seen at [[zenith]]. This definition corrects for the greater distance between an observer and a meteor near the horizon. For example, a meteor of magnitude −1 at 5 degrees above the horizon would be classified as a fireball because, if the observer had been directly below the meteor, it would have appeared as magnitude −6.<ref name="IMO-fireball">{{cite web |url=http://www.imo.net/fireball |title=International Meteor Organization - Fireball Observations |publisher=imo.net |date=2004-10-12 |access-date=2011-09-16 }}</ref> Fireballs reaching apparent magnitude −14 or brighter are called [[bolide]]s.<ref name="Belton">{{cite book |last1=Di Martino |first1=Mario |last2=Cellino |first2=Alberto |chapter=Physical properties of comets and asteroids inferred from fireball observations |title=Mitigation of hazardous comets and asteroids |publisher=Cambridge University Press |year=2004 |page=156 |chapter-url=https://books.google.com/books?id=Dw0A7T0fy6AC&pg=PA156 |isbn=978-0-521-82764-5 |editor-last=Belton |editor1-first=Michael J. S. |editor2-last=Morgan |editor2-first=Thomas H. |editor3-last=Samarasinha |editor3-first=Nalin |display-editors = 3 |editor4-last=Yeomans |editor4-first=Donald K. }}</ref> The IAU has no official definition of "bolide", and generally considers the term synonymous with "fireball". Astronomers often use "bolide" to identify an exceptionally bright fireball, particularly one that explodes in a [[meteor air burst]].<ref>{{cite encyclopedia |title=bolide |editor-last=Ridpath |editor-first=Ian |editor-link=Ian Ridpath |encyclopedia=Oxford Dictionary of Astronomy |year=2018 |publisher=Oxford University Press |location= |isbn=978-0-19-185119-3 |url=https://www.oxfordreference.com/view/10.1093/acref/9780191851193.001.0001/acref-9780191851193-e-487 |access-date=2024-09-03 }}</ref> They are sometimes called detonating fireballs. It may also be used to mean a fireball which creates audible sounds. In the late twentieth century, bolide has also come to mean any object that hits Earth and explodes, with no regard to its composition (asteroid or comet).<ref name="Google-Book-jR84AAAAIAAJ">{{cite book |last=Rogers |first=John J. W. |url=https://books.google.com/books?id=jR84AAAAIAAJ&pg=PA251 |title=A History of the Earth |publisher=Cambridge University Press |year=1993 |page=251 |isbn=978-0-521-39782-7 }}</ref> The word ''bolide'' comes from the [[Greek language|Greek]] βολίς (''bolis'') <ref name="myet-bolide">{{cite web |url=http://www.myetymology.com/english/bolide.html |archive-url=https://web.archive.org/web/20120117162151/http://www.myetymology.com/english/bolide.html |url-status=usurped |archive-date=January 17, 2012 |publisher=MyEtymology |title=Bolide }}</ref> which can mean ''a missile'' or ''to flash''. If the magnitude of a bolide reaches −17 or brighter it is known as a [[superbolide]].<ref name="Belton" /><ref name="Google-Book-3Hd8Lw1hExUC">{{cite book |last1=Adushkin |first1=Vitaly |last2=Nemchinov |first2=Ivan |title=Catastrophic events caused by cosmic objects |publisher=Springer |date=2008 |page=133 |url=https://books.google.com/books?id=3Hd8Lw1hExUC |isbn=978-1-4020-6451-7 |bibcode=2008cecc.book.....A }}</ref> A relatively small percentage of fireballs hit Earth's atmosphere and then pass out again: these are termed [[Earth-grazing fireball]]s. Such an event happened in [[The Great Daylight 1972 Fireball|broad daylight over North America in 1972]]. Another rare phenomenon is a [[meteor procession]], where the meteor breaks up into several fireballs traveling nearly parallel to the surface of Earth. A steadily growing number of fireballs are recorded at the [[American Meteor Society]] every year.<ref name="AMS-Fireballs" /> There are probably more than 500,000 fireballs a year,<ref name="AMS-FAQ">{{cite web |title=Fireball FAQs |publisher=[[American Meteor Society]] |url=http://www.amsmeteors.org/fireballs/faqf/ |access-date=2013-03-21 }} </ref> but most go unnoticed because most occur over the ocean and half occur during daytime. A [[European Fireball Network]] and a NASA All-sky Fireball Network detect and track many fireballs.<ref>{{Cite web|last=Cook|first=Bill|title=NASA's All Sky Fireball Network|url=https://fireballs.ndc.nasa.gov|access-date=2021-03-04}}</ref> {| class="wikitable" style="text-align: center; margin: 0.1em auto;" |+ Fireball Sightings reported to the American Meteor Society <ref name="AMS-Fireballs">{{cite web |title=Fireball Logs |author=American Meteor Society |url=http://www.amsmeteors.org/fireballs/fireball-report/ |access-date=2016-09-28 }}</ref> |- ! Year ! width=55 | 2008 ! width=55 | 2009 ! width=55 | 2010 ! width=55 | 2011 ! width=55 | 2012 ! width=55 | 2013 ! width=55 | 2014 ! width=55 | 2015 ! width=55 | 2016 ! width=55 | 2017 ! width=55 | 2018 ! width=55 | 2019 ! width=55 | 2020 ! width=55 | 2021 |- | '''Number''' || 734 || 676 || 953 || 1,660 || 2,183 || 3,599 || 3,789 || 4,250 || 5,391 || 5,510 || 5,993 || 6,978 || 8,259 || 9,629 |} == Effect on atmosphere == {{redirect2|Ionization trail|Dark flight (astronomy)|the movie|Dark Flight}} [[File:P10220XX.01.49.MESZ.14.08.2019.Berlin.Perseiden.x1.0.gif|thumb|A meteoroid of the [[Perseids]] with a size of about ten millimetres entering the earth's atmosphere in real time. The meteoroid is at the bright head of the trail, and the ionisation of the [[mesosphere]] is still visible in the tail.]] The entry of meteoroids into Earth's atmosphere produces three main effects: ionization of atmospheric molecules, dust that the meteoroid sheds, and the sound of passage. During the entry of a meteoroid or asteroid into the [[upper atmosphere]], an '''ionization trail''' is created, where the air molecules are [[ionization|ionized]] by the passage of the meteor. Such ionization trails can last up to 45 minutes at a time. Small, [[sand-grain]] sized meteoroids are entering the atmosphere constantly, essentially every few seconds in any given region of the atmosphere, and thus ionization trails can be found in the upper atmosphere more or less continuously. When radio waves are bounced off these trails, it is called [[meteor burst communications]]. Meteor radars can measure atmospheric density and winds by measuring the [[decay rate]] and [[Doppler shift]] of a meteor trail. Most meteoroids burn up when they enter the atmosphere. The left-over debris is called ''meteoric dust'' or just meteor dust. Meteor dust particles can persist in the atmosphere for up to several months. These particles might affect climate, both by scattering electromagnetic radiation and by catalyzing chemical reactions in the upper atmosphere.<ref name="Nature-443141a">{{cite journal |first=Jeff |last=Kanipe |title=Climate change: A cosmic connection |journal=Nature |volume=443 |issue=7108 |pages=141–143 |date=14 September 2006 |doi=10.1038/443141a |pmid=16971922 |bibcode=2006Natur.443..141K |s2cid=4400113 |doi-access=free }}</ref> Meteoroids or their fragments achieve '''dark flight''' after deceleration to [[terminal velocity]].<ref name="IMO-meteorites">{{cite web |title=Fireballs and Meteorite Falls |publisher=International Meteor Organization |url = http://www.imo.net/fireball/meteorites |access-date=2013-03-05 }}</ref> Dark flight starts when they decelerate to about {{convert|2|–|4|km/s|mph|abbr=on}}. <ref name="AMS-Fireball">{{cite web |title=Fireball FAQS |publisher=American Meteor Society |url = http://www.amsmeteors.org/fireballs/faqf/#8 |access-date=2013-03-05 }}</ref> Larger fragments fall further down the [[strewn field]]. === Colours === [[File:Leonid Meteor.jpg|thumb|A meteor of the [[Leonid meteor shower]]; the photograph shows the meteor, afterglow, and wake as distinct components]] The visible light produced by a meteor may take on various hues, depending on the chemical composition of the meteoroid, and the speed of its movement through the atmosphere. As layers of the meteoroid abrade and ionize, the colour of the light emitted may change according to the layering of minerals. Colours of meteors depend on the relative influence of the metallic content of the meteoroid versus the superheated air plasma, which its passage engenders:<ref>{{cite web| title = Background facts on meteors and meteor showers. | publisher = NASA | url = http://leonid.arc.nasa.gov/meteor.html | access-date = 2014-02-24}} </ref> * Orange-yellow ([[sodium]]) * Yellow ([[iron]]) * Blue-green ([[magnesium]]) * Violet ([[calcium]]) * Red (atmospheric [[nitrogen]] and [[oxygen]]) === Acoustic manifestations === The sound generated by a meteor in the upper atmosphere, such as a [[sonic boom]], typically arrives many seconds after the visual light from a meteor disappears. Occasionally, as with the [[Leonid meteor shower]] of 2001, "crackling", "swishing", or "hissing" sounds have been reported,<ref name="find-87854873">{{cite news |url=http://findarticles.com/p/articles/mi_m1134/is_6_111/ai_87854873/pg_1 |work=Natural History |title=Psst! Sounds like a meteor: in the debate about whether or not meteors make noise, skeptics have had the upper hand until now |first=Alan |last=Burdick |year=2002 |archive-url=https://archive.today/20120715100344/http://findarticles.com/p/articles/mi_m1134/is_6_111/ai_87854873/pg_1 |archive-date=2012-07-15 }}</ref> occurring at the same instant as a meteor flare. These are sometimes called [[electrophonic sounds]].<ref>{{Cite journal |last1=Zgrablić |first1=Goran |last2=Vinković |first2=Dejan |last3=Gradečak |first3=Silvija |last4=Kovačić |first4=Damir |last5=Biliškov |first5=Nikola |last6=Grbac |first6=Neven |last7=Andreić |first7=Željko |last8=Garaj |first8=Slaven |date=2002 |title=Instrumental recording of electrophonic sounds from Leonid fireballs |url=https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2001JA000310 |journal=Journal of Geophysical Research: Space Physics |language=en |volume=107 |issue=A7 |pages=SIA 11–1–SIA 11-9 |doi=10.1029/2001JA000310 |bibcode=2002JGRA..107.1124Z |issn=2156-2202}}</ref> Similar sounds have also been reported during intense displays of Earth's [[Aurora (astronomy)|auroras]].<ref name="auroral-sounds">{{cite web |url=https://sites.google.com/site/auroralsound/ |first=Andris |last=Vaivads |year=2002 |title=Auroral Sounds |access-date=2011-02-27 }}</ref><ref name="auroral-acoustics">{{cite web |url=http://www.acoustics.hut.fi/projects/aurora/ |title=Auroral Acoustics |work=Laboratory of Acoustics and Audio Signal Processing, Helsinki University of Technology |access-date=2011-02-17 }}</ref><ref name="AG16-155">{{cite book |doi=10.1016/S0065-2687(08)60352-0 |first1=Sam M. |last1=Silverman |first2=Tai-Fu |last2=Tuan |year=1973 |title=Auroral Audibility |volume=16 |pages=155–259 |series=Advances in Geophysics |isbn=978-0-12-018816-1 |bibcode = 1973AdGeo..16..155S }}</ref><ref name="JRASC-373K">{{cite journal |first=Colin S. L. |last=Keay |year=1990 |title=C. A. Chant and the Mystery of Auroral Sounds |journal=Journal of the Royal Astronomical Society of Canada |volume=84 |pages=373–382 |bibcode= 1990JRASC..84..373K}}</ref> Theories on the generation of these sounds may partially explain them. For example, scientists at NASA suggested that the turbulent ionized wake of a meteor interacts with [[geomagnetic field|Earth's magnetic field]], generating pulses of [[radio wave]]s. As the trail dissipates, [[megawatt]]s of electromagnetic power could be released, with a peak in the [[power spectrum]] at [[audio frequencies]]. Physical [[vibration]]s induced by the electromagnetic impulses would then be heard if they are powerful enough to make grasses, plants, eyeglass frames, the hearer's own body (see [[microwave auditory effect]]), and other conductive materials vibrate.<ref name="NASA-ast26">{{cite web |url=https://science.nasa.gov/headlines/y2001/ast26nov_1.htm |title=Listening to Leonids |publisher=science.nasa.gov |access-date=2011-09-16 |archive-url=https://web.archive.org/web/20090908035648/http://science.nasa.gov/headlines/y2001/ast26nov_1.htm |archive-date=2009-09-08 }}</ref><ref>{{cite journal |last1=Sommer |first1=H. C. |last2=Von Gierke |first2=H. E. |title=Hearing sensations in electric fields |journal=Aerospace Medicine |date=September 1964 |volume=35 |pages=834–839 |pmid=14175790 }} [https://web.archive.org/web/20110629080138/http://homepages.tesco.net/~John.Dawes2/extract.htm Extract text archive.]</ref><ref>{{cite journal |last1=Frey |first1=Allan H. |title=Human auditory system response to modulated electromagnetic energy |journal=Journal of Applied Physiology |date=1 July 1962 |volume=17 |issue=4 |pages=689–692 |doi=10.1152/jappl.1962.17.4.689 |pmid=13895081 |s2cid=12359057 }} [https://web.archive.org/web/20110629121952/http://homepages.tesco.net/~John.Dawes2/frey.htm Full text archive.]</ref><ref>{{cite journal |last1=Frey |first1=Allan H. |last2=Messenger |first2=Rodman |title=Human Perception of Illumination with Pulsed Ultrahigh-Frequency Electromagnetic Energy |journal=Science |date=27 Jul 1973 |volume=181 |issue=4097 |pages=356–358 |doi=10.1126/science.181.4097.356 |pmid=4719908 |bibcode = 1973Sci...181..356F |s2cid=31038030 }} [https://web.archive.org/web/20110629122016/http://homepages.tesco.net/~John.Dawes2/frey2.htm Full text archive.]</ref> This proposed mechanism, although proven plausible by laboratory work, remains unsupported by corresponding measurements in the field. Sound recordings made under controlled conditions in Mongolia in 1998 support the contention that the sounds are real.<ref name="BBC-321596">{{cite news |url=http://news.bbc.co.uk/2/hi/science/nature/321596.stm |title=Sound of shooting stars |work=BBC News |first=Chris |last=Riley |date=1999-04-21 |access-date=2011-09-16 }}</ref> ''(Also see [[Bolide]].)'' == Meteor shower == {{Main|Meteor shower|List of meteor showers}} [[File:Meteor burst.jpg|thumb|Multiple meteors photographed over an extended [[exposure time]] during a [[meteor shower]]]] [[File:PSM V18 D201 Shower of perseids sept 6 and 7.jpg|thumb|[[Meteor shower]] on chart]] A [[meteor shower]] is the result of an interaction between a planet, such as Earth, and streams of debris from a [[comet]] or other source. The passage of Earth through cosmic debris from comets and other sources is a [[List of meteor showers|recurring event]] in many cases. Comets can produce debris by water vapor drag, as demonstrated by [[Fred Whipple]] in 1951,<ref name="Harvard-464W">{{cite journal |first=Fred |last=Whipple |author-link=Fred Lawrence Whipple |year=1951 |title=A Comet Model. II. Physical Relations for Comets and Meteors |journal=Astrophysical Journal |volume=113 |pages=464–474 |doi=10.1086/145416 |bibcode=1951ApJ...113..464W |doi-access=free }}</ref> and by breakup. Each time a comet swings by the Sun in its [[orbit]], some of its ice vaporizes and a certain amount of meteoroids are shed. The meteoroids spread out along the entire orbit of the comet to form a meteoroid stream, also known as a "dust trail" (as opposed to a comet's "dust tail" caused by the very small particles that are quickly blown away by solar radiation pressure). The frequency of [[Fireball (meteor)|fireball]] sightings increases by about 10–30% during the weeks of [[Equinox|vernal equinox]].<ref name="fireball season NASA">{{cite web |first=Tony |last=Phillips |url=https://science.nasa.gov/science-news/science-at-nasa/2011/31mar_springfireballs/ |title=Spring is Fireball Season |publisher=science.nasa.gov |access-date=2011-09-16 |archive-date=2011-04-03 |archive-url=https://web.archive.org/web/20110403023239/https://science.nasa.gov/science-news/science-at-nasa/2011/31mar_springfireballs/ |url-status=dead }}</ref> Even [[meteorite]] falls are more common during the [[Northern Hemisphere|northern hemisphere]]'s spring season. Although this phenomenon has been known for quite some time, the reason behind the anomaly is not fully understood by scientists. Some researchers attribute this to an intrinsic variation in the meteoroid population along Earth's orbit, with a peak in big fireball-producing debris around spring and early summer. Others have pointed out that during this period the ecliptic is (in the northern hemisphere) high in the sky in the late afternoon and early evening. This means that fireball radiants with an asteroidal source are high in the sky (facilitating relatively high rates) at the moment the meteoroids "catch up" with Earth, coming from behind going in the same direction as Earth. This causes relatively low relative speeds and from this low entry speeds, which facilitates survival of meteorites.<ref>Langbroek, Marco; ''Seizoensmatige en andere variatie in de valfrequentie van meteorieten'', Radiant (Journal of the Dutch Meteor Society), 23:2 (2001), p. 32</ref> It also generates high fireball rates in the early evening, increasing chances of eyewitness reports. This explains a part, but perhaps not all of the seasonal variation. Research is in progress for mapping the orbits of the meteors to gain a better understanding of the phenomenon.<ref name="camera network NASA">{{cite web |first=Dauna |last=Coulter |url=https://science.nasa.gov/science-news/science-at-nasa/2011/01mar_meteornetwork/ |title=What's Hitting Earth? |publisher=science.nasa.gov |date=2011-03-01 |access-date=2011-09-16 |archive-date=2020-05-25 |archive-url=https://web.archive.org/web/20200525193605/https://science.nasa.gov/science-news/science-at-nasa/2011/01mar_meteornetwork/ |url-status=dead }}</ref> == Notable meteors == {{See also|Near-Earth object#Notable objects}} <!-- formerly linked to #Planet Earth collision probability with near-Earth objects|l1=Planet Earth collision probability with near-Earth objects}}--> {{meteoroid_size_comparison.svg}} ; 1992{{snd}}Peekskill, New York : The [[Peekskill Meteorite]] was recorded on October 9, 1992 by at least 16 independent videographers.<ref name="uwo-peeks">{{Cite web|url=https://aquarid.physics.uwo.ca/~pbrown/Videos/peekskill.htm|title=The Peekskill Meteorite October 9|website=aquarid.physics.uwo.ca}}</ref> Eyewitness accounts indicate the fireball entry of the Peekskill meteorite started over West Virginia at 23:48 UT (±1 min). The fireball, which traveled in a northeasterly direction, had a pronounced greenish colour, and attained an estimated peak visual magnitude of −13. During a luminous flight time that exceeded 40 seconds the fireball covered a [[ground path]] of some {{cvt|700|to|800|km|order=flip}}.<ref name="Nature-6464">{{cite journal |last1=Brown |first1=Peter |last2=Ceplecha |first2=Zedenek |last3=Hawkes |first3=Robert L. |last4=Wetherill |first4=George W. |last5=Beech |first5=Martin |last6=Mossman |first6=Kaspar |title=The orbit and atmospheric trajectory of the Peekskill meteorite from video records |journal=Nature |volume=367 |issue=6464 |pages=624–626 |year=1994 |bibcode=1994Natur.367..624B |doi=10.1038/367624a0 |s2cid=4310713 }}</ref> One meteorite recovered at [[Peekskill, New York]], for which the event and object gained their name, had a mass of {{convert|12.4|kg|lb|abbr=on|order=flip}} and was subsequently identified as an H6 monomict breccia meteorite.<ref name="MB-75">{{cite journal | doi=10.1111/j.1945-5100.1993.tb00641.x| title=The Meteoritical Bulletin, No. 75, 1993 December| journal=Meteoritics| volume=28| issue=5| pages=692–703| year=1993| last1=Wlotzka| first1=Frank}}</ref> The video record suggests that the Peekskill meteorite had several companions over a wide area. The companions are unlikely to be recovered in the hilly, wooded terrain in the vicinity of Peekskill. ; 2009{{snd}}Bone, Indonesia : A [[2009 Sulawesi superbolide|large fireball]] was observed in the skies near [[Watampone|Bone]], [[Sulawesi]], Indonesia on October 8, 2009. This was thought to be caused by an asteroid approximately {{cvt|10|m||}} in diameter. The fireball contained an estimated energy of 50 kilotons of TNT, or about twice the [[Fat Man|Nagasaki atomic bomb]]. No injuries were reported.<ref name="NEO165">{{cite web |date=October 23, 2009 |title=Asteroid Impactor Reported over Indonesia |publisher=NASA/JPL Near-Earth Object Program Office |first1=Donald K. |last1=Yeomans |first2=Paul |last2=Chodas |first3=Steve |last3=Chesley |url=http://neo.jpl.nasa.gov/news/news165.html |archive-url=https://web.archive.org/web/20091026095704/http://neo.jpl.nasa.gov/news/news165.html |archive-date=October 26, 2009 |access-date=2009-10-30 }}</ref> ; 2009{{snd}}Southwestern US : A large bolide was reported on 18 November 2009 over southeastern California, northern Arizona, Utah, Wyoming, Idaho and Colorado. At 00:07 local time a security camera at the high altitude [[Willard L. Eccles Observatory|W. L. Eccles Observatory]] ({{cvt|2930|m|order=flip|}} above sea level) recorded a movie of the passage of the object to the north.<ref name="YT-XiL1UGbHXSI">{{cite web |url=https://www.youtube.com/watch?v=XiL1UGbHXSI |title=W. L. Eccles Observatory, November 18, 2009, North Camera |publisher=YouTube |date=2009-11-18 |access-date=2011-09-16 }}</ref><ref name="YT-kE109bKQESw">{{cite web |url=https://www.youtube.com/watch?v=kE109bKQESw |title=W. L. Eccles Observatory, November 18, 2009, North West Camera |publisher=YouTube |date=2009-11-18 |access-date=2011-09-16 }}</ref> It had a spherical "ghost" image slightly trailing the main object (likely a lens reflection of the intense fireball), and a bright fireball explosion associated with the breakup of a substantial fraction of the object. An object trail continued northward after the fireball. The shock from the final breakup triggered seven seismological stations in northern Utah. The seismic data yielded a terminal location of the object at 40.286 N, −113.191 W, altitude {{cvt|27|km|ft|-4|order=flip}}.{{citation needed|date = January 2016}}<!---<ref>Wiggins, Patrick; private communication</ref>----> This is above the Dugway Proving Grounds, a closed Army testing base. ; 2013{{snd}}Chelyabinsk Oblast, Russia : The [[Chelyabinsk meteor]] was an extremely bright, exploding fireball, or [[superbolide]], measuring about {{cvt|17|to|20|m}} across, with an estimated mass of 11,000 tonnes as the relatively small [[asteroid]] entered Earth's atmosphere.<ref name="JPL20130301">{{cite web |date=1 March 2013 |title=Additional Details on the Large Fireball Event over Russia on Feb. 15, 2013 |publisher=NASA/JPL Near-Earth Object Program Office |first1=Don |last1=Yeomans |first2=Paul |last2=Chodas |url=http://neo.jpl.nasa.gov/news/fireball_130301.html |archive-url=https://web.archive.org/web/20130306002358/http://neo.jpl.nasa.gov/news/fireball_130301.html |archive-date=6 March 2013 |access-date=2 March 2013}}</ref><ref name="NASA-061">{{cite web |url=http://www.jpl.nasa.gov/news/news.php?release=2013-061 |author=JPL |title=Russia Meteor Not Linked to Asteroid Flyby |website=[[Jet Propulsion Laboratory]] |date=2012-02-16 |access-date=2013-02-19 }}</ref> It was the largest natural object known to have entered Earth's atmosphere since the [[Tunguska event]] in 1908. Over 1,500 people were injured, mostly by glass from shattered windows caused by the [[Meteor air burst|air burst]] approximately {{cvt|25|to|30|km|ft|-4}} above the [[Chelyabinsk Oblast|environs of Chelyabinsk]], Russia on 15 February 2013. An increasingly bright streak was observed during morning daylight with a large contrail lingering behind. At no less than one minute and up to at least three minutes after the object peaked in intensity (depending on distance from trail), a large concussive blast was heard that shattered windows and set-off car alarms, which was followed by a number of smaller explosions.<ref name="guardian-20130215">{{cite news |title=Meteorite slams into Central Russia injuring 1100 - as it happened |url=https://www.theguardian.com/science/2013/feb/15/meteorite-explodes-over-russian-urals-live-updates |newspaper=Guardian |date=15 February 2013 |access-date=16 February 2013 <!-- traces at http://www.navbug.com/article64047559_arch20130219/meteorite_slams_into_central_russia_injuring_1100_as_it_happened_the_guardian.htm and http://vietnamtimesonline.com/2013/02/16/meteorite-slams-into-central-russia-injuring-1100-as-it-happened-the-guardian/ -->}}</ref> ; 2019{{snd}}Midwestern United States : On November 11, 2019, a meteor was spotted streaking across the skies of the [[Midwestern United States]]. In the [[St. Louis]] Area, security cameras, dashcams, webcams, and video doorbells captured the object as it burned up in the earth's atmosphere. The [[superbolide]] meteor was part of the [[Taurids|South Taurids]] meteor shower.<ref>{{Cite web|url=https://www.stltoday.com/news/local/stcharles/once-in-a-lifetime-bright-meteor-streaks-across-st-louis/article_ee432841-2fd7-5b11-9ad6-179af67c8670.html|title=Once in a lifetime: Bright meteor streaks across St. Louis nighttime skies|last=Staff|date=November 12, 2019|website=St. Louis Post Dispatch|language=en|access-date=2019-11-12}}</ref> It traveled east to west ending its flight somewhere near [[Wellsville, Missouri|Wellsville]], [[Missouri]].<ref>{{cite web |url=https://www.amsmeteors.org/2019/11/fireball-spotted-over-missouri-on-nov-11th-2019/ |title=Fireball spotted over Missouri on Nov. 11th, 2019 |last=Perlerin |first=Vincent |date=12 November 2019 |website=[[American Meteor Society]] |access-date=2024-09-19}}</ref><ref>{{Cite web|url=https://www.cnn.com/2019/11/12/us/meteor-sighting-midwest-louis-missouri-scn-trnd/index.html|title=A bright meteor streaks through the Midwest sky|author1=Elizabeth Wolfe |author2=Saeed Ahmed|date=November 12, 2019|website=CNN|access-date=2019-11-12}}</ref> == Monitoring == [[File:SmallAsteroidImpacts-Frequency-Bolide-20141114.jpg|thumb|World map of large meteoric events ''(also see [[#Fireball|Fireball]] below)'' <ref>{{cite news |title=We are not Alone: Government Sensors Shed New Light on Asteroid Hazards |first=Tim |last=Reyes |date=17 November 2014 |url=http://www.universetoday.com/116355/we-are-not-alone-government-sensors-shed-new-light-on-asteroid-hazards/ |access-date=12 April 2015 |newspaper=Universe Today }}</ref>]] In a range of countries networks of sky observing installations have been set up to monitor meteors. *[[FRIPON]] *[[North American Meteor Network]] *[[Desert Fireball Network]] *[[European Fireball Network]] == Gallery == <gallery mode="packed" heights="150"> File:Orionid meteor.jpg|[[Orionids|Orionid]] meteor File:Meteor Bolide.JPG|Sporadic bolide over the desert of Central Australia and a [[Lyrids|Lyrid]] (top edge) File:Looking Down on a Shooting Star.JPG|Meteor (center) seen from the [[International Space Station]] File:Earth Sol63A UFO-A067R1.jpg|Possible meteor (center) photographed from Mars, March 7, 2004, by [[Spirit rover|MER ''Spirit'']] File:SL9ImpactGalileo.jpg|[[Comet Shoemaker–Levy 9]] colliding with Jupiter: The sequence shows fragment W turning into a [[#Fireball|fireball]] on the planet's dark side </gallery> == See also == {{Div col|colwidth=16em}} * [[American Meteor Society]] * [[Bolide]] * [[Desert Fireball Network]] * [[Fireballs Aotearoa]] * [[Green fireballs]] * [[Hydrometeor]] * [[International Meteor Organization]] * [[Leonids]] * [[List of meteor showers]] * [[Lyrids]] * [[Meteor air burst]] * [[North American Meteor Network]] * [[Orionids]] * [[Perseids]] * [[Tollmann's hypothetical bolide]] {{Div col end}} ==References== {{reflist}} [[Category:Meteoroids]]
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