Editing Impact event (section)

==== 21st-century impacts ====
{{main|List of bolides}}
<!-- DDMMYYYY sequence Put 21st-c. discoveries of earlier earth impacts under appropriate heading  -->
On 7 June 2006, a meteor was observed striking a location in the [[Reisadalen]] valley in [[Nordreisa Municipality]] in [[Troms]] County, Norway. Although initial witness reports stated that the resultant fireball was equivalent to [[Atomic bombings of Hiroshima and Nagasaki|the Hiroshima nuclear explosion]], scientific analysis places the force of the blast at anywhere from 100 to 500 [[tonne#Use of mass as proxy for energy|tonnes]] TNT equivalent, around three percent of Hiroshima's yield.<ref>[https://archive.today/20120629002618/http://skyandtelescope.com/news/article_1742_1.asp Norway Impact Gentler Than Atomic Bomb] (Sky & Telescope June 16, 2006)</ref>

On 15 September 2007, a chondritic [[Carancas impact event|meteor crashed near the village of Carancas]] in southeastern Peru near [[Lake Titicaca]], leaving a water-filled hole and spewing gases across the surrounding area. Many residents became ill, apparently from the noxious gases shortly after the impact.

On 7 October 2008, an approximately 4 meter asteroid labeled {{mpl|2008 TC|3}} was tracked for 20 hours as it approached Earth and as it fell through the atmosphere and impacted in Sudan. This was the first time an object was detected before it reached the atmosphere and hundreds of pieces of the meteorite were recovered from the [[Nubian Desert]].<ref>[https://www.wired.com/wiredscience/2009/03/meteorite/ First-Ever Asteroid Tracked From Space to Earth], Wired, March 25, 2009 {{webarchive |url=https://web.archive.org/web/20140321060157/http://www.wired.com/wiredscience/2009/03/meteorite/ |date=March 21, 2014 }}</ref>

[[File:Chelyabinsk meteor trace 15-02-2013.jpg|thumb|Trail left by the exploding Chelyabinsk meteor as it passed over the city.]]

On 15 February 2013, an asteroid entered Earth's atmosphere over [[Russia]] as a [[Bolide|fireball]] and exploded above the city of [[Chelyabinsk]] during its passage through the [[Ural (region)|Ural Mountains region]] at 09:13 [[Yekaterinburg Time|YEKT]] (03:13 [[Coordinated Universal Time|UTC]]).<ref name=meteor>{{cite web|title=Russian Meteor|url=http://www.nasa.gov/topics/solarsystem/features/russianmeteor.html|publisher=NASA|access-date=15 February 2013|archive-date=18 February 2013|archive-url=https://web.archive.org/web/20130218034325/http://www.nasa.gov/topics/solarsystem/features/russianmeteor.html|url-status=dead}}</ref><ref>{{cite news|url=https://www.usatoday.com/story/news/world/2013/02/15/russia-meteorite/1921991/ |title=Meteor in central Russia injures at least 500 |work=[[USA Today]] |access-date=15 February 2013 |first1=Anna |last1=Arutunyan |first2=Marc |last2=Bennetts |date=15 February 2013}}</ref> The object's air burst occurred at an altitude between {{convert|30|and|50|km|mi|abbr=on}} above the ground,<ref>{{cite news |title=Meteor falls in Russia, 700 injured by blasts |url=http://bigstory.ap.org/article/meteorite-falls-russian-urals |agency=Associated Press |access-date=15 February 2013 |archive-date=18 February 2013 |archive-url=https://web.archive.org/web/20130218034039/http://bigstory.ap.org/article/meteorite-falls-russian-urals |url-status=dead }}</ref> and about 1,500 people were injured, mainly by broken window glass shattered by the shock wave. Two were reported in serious condition; however, there were no fatalities.<ref name="chelyabinsk">{{cite web |url=http://www.vesti.ru/doc.html?id=1033922|script-title=ru:Метеоритный дождь над Уралом: пострадали 1200 человек |language= ru |work= Vesti |date=15 February 2013|access-date=15 February 2013 | location = [[Russia|RU]]}}</ref> Initially some 3,000 buildings in six cities across the region were reported damaged due to the explosion's shock wave, a figure which rose to over 7,200 in the following weeks.<ref>{{cite news|last=Marson|first=James|title=Meteorite Hits Russia, Causing Panic|url=https://www.wsj.com/articles/SB10001424127887324162304578305163574597722?mod=WSJ_hpp_LEFTTopStories|newspaper=Wall Street Journal|access-date=15 February 2013|author2=Gautam Naik}}</ref><ref>{{cite magazine|last=Ewait|first=David|title=Exploding Meteorite Injures A Thousand People In Russia|url=https://www.forbes.com/sites/davidewalt/2013/02/15/exploding-meteorite-injures-a-thousand-people-in-russia/|magazine=Forbes|access-date=15 February 2013}}</ref> The Chelyabinsk meteor was estimated to have caused over $30 million in damage.<ref>{{cite news|url=http://in.reuters.com/article/russia-meteorite-idINDEE91E03320130215|title=Meteorite explodes over Russia, more than 1,000 injured|author=Andrey Kuzmin|work=Reuters|date=16 February 2013|access-date=16 February 2013|archive-date=6 March 2016|archive-url=https://web.archive.org/web/20160306214917/http://in.reuters.com/article/russia-meteorite-idINDEE91E03320130215|url-status=dead}}</ref><ref name="RBTH-23513">{{cite news | url=http://rbth.ru/news/2013/03/05/meteorite-caused_emergency_situation_regime_over_in_chelyabinsk_region_23513.html | title=Meteorite-caused emergency situation regime over in Chelyabinsk region | work=Russia Beyond The Headlines | publisher=Rossiyskaya Gazeta | date=5 March 2013 | agency=[[Interfax]] | access-date=6 March 2013 | archive-date=23 June 2013 | archive-url=https://archive.today/20130623230931/http://rbth.ru/news/2013/03/05/meteorite-caused_emergency_situation_regime_over_in_chelyabinsk_region_23513.html | url-status=dead }}</ref> It is the largest recorded object to have encountered the Earth since the 1908 Tunguska event.<ref>{{cite news|url=https://www.economist.com/blogs/babbage/2013/02/asteroid-impacts?fsrc=nlw%7Cnewe%7C2-15-2013%7C5019506%7C37104620%7C|title=Asteroid impacts – How to avert Armageddon
 |newspaper=[[The Economist]] |date=15 February 2013|access-date=16 February 2013}}</ref><ref>{{cite news|url=https://www.nytimes.com/2013/02/16/science/space/size-of-blast-and-number-of-injuries-are-seen-as-rare-for-a-rock-from-space.html?ref=science&_r=0|title=Size of Blast and Number of Injuries Are Seen as Rare for a Rock From Space|author=Kenneth Chang|work=[[The New York Times]]|date=15 February 2013|access-date=16 February 2013}}</ref> The meteor is estimated to have an initial diameter of 17–20 metres and a mass of roughly 10,000 tonnes. On 16 October 2013, a team from Ural Federal University led by Victor Grokhovsky recovered a large fragment of the meteor from the bottom of Russia's Lake Chebarkul, about 80&nbsp;km west of the city.<ref>{{cite magazine|last=Beatty|first=J. Kelly|title=Russian Fireball Fragment Found|magazine=Australian Sky & Telescope|date=February–March 2014|page=12|issn=1832-0457}}</ref>

On 1 January 2014, a 3-meter (10 foot) asteroid, [[2014 AA]] was discovered by the [[Mount Lemmon Survey]] and observed over the next hour, and was soon found to be on a collision course with Earth. The exact location was uncertain, constrained to a line between [[Panama]], the central Atlantic Ocean, [[The Gambia]], and Ethiopia. Around roughly the time expected (2 January 3:06 UTC) an infrasound burst was detected near the center of the impact range, in the middle of the Atlantic Ocean.<ref name="Farnocchia2016">{{cite journal|title=The trajectory and atmospheric impact of asteroid 2014 AA|first1=Davide|last1=Farnocchia|first2=Steven R.|last2=Chesley|first3=Peter G.|last3=Brown|first4=Paul W.|last4=Chodas|date=1 August 2016|journal=[[Icarus (journal)|Icarus]]|volume=274|pages=327–333|bibcode=2016Icar..274..327F|doi=10.1016/j.icarus.2016.02.056 }}</ref><ref name="Marcos2016">{{cite journal|title=Homing in for New Year: impact parameters and pre-impact orbital evolution of meteoroid 2014 AA|first1=C.|last1=de la Fuente Marcos|first2=R.|last2=de la Fuente Marcos|first3=P.|last3=Mialle|date=13 October 2016|journal=[[Astrophysics and Space Science]]|volume=361|issue=11|pages=358 (33 pp.)|arxiv=1610.01055|bibcode=2016Ap&SS.361..358D |doi=10.1007/s10509-016-2945-3|s2cid=119251345}}</ref> This marks the second time a natural object was identified prior to impacting earth after 2008 TC3.

Nearly two years later, on October 3, [[WT1190F]] was detected orbiting Earth on a highly eccentric orbit, taking it from well within the [[Geocentric orbit|Geocentric satellite ring]] to nearly twice the orbit of the Moon. It was estimated to be perturbed by the Moon onto a collision course with Earth on November 13. With over a month of observations, as well as precovery observations found dating back to 2009, it was found to be far less dense than a natural asteroid should be, suggesting that it was most likely an unidentified artificial satellite. As predicted, it fell over [[Sri Lanka]] at 6:18 UTC (11:48 local time). The sky in the region was very overcast, so only an airborne observation team was able to successfully observe it falling above the clouds. It is now thought to be a remnant of the [[Lunar Prospector]] mission in 1998, and is the third time any previously unknown object – natural or artificial – was identified prior to impact.

On 22 January 2018, an object, [[A106fgF]], was discovered by the [[Asteroid Terrestrial-impact Last Alert System]] (ATLAS) and identified as having a small chance of impacting Earth later that day.<ref>[https://groups.yahoo.com/neo/groups/mpml/conversations/messages/33680 Bill Gray MPML]{{dead link|date=December 2023|bot=medic}}{{cbignore|bot=medic}}</ref> As it was very dim, and only identified hours before its approach, no more than the initial 4 observations covering a 39-minute period were made of the object. It is unknown if it impacted Earth or not, but no fireball was detected in either infrared or infrasound, so if it did, it would have been very small, and likely near the eastern end of its potential impact area – in the western Pacific Ocean.

On 2 June 2018, the [[Mount Lemmon Survey]] detected {{mpl|2018 LA}} (ZLAF9B2), a small 2–5 meter asteroid which further observations soon found had an 85% chance of impacting Earth. Soon after the impact, a fireball report from [[Botswana]] arrived to the [[American Meteor Society]]. Further observations with ATLAS extended the observation arc from 1 hour to 4 hours and confirmed that the asteroid orbit indeed impacted Earth in southern Africa, fully closing the loop with the fireball report and making this the third natural object confirmed to impact Earth, and the second on land after {{mp|2008 TC|3}}.<ref name="orientation">{{cite journal
|last1=de la Fuente Marcos |first1=Carlos
|last2=de la Fuente Marcos |first2=Raúl
|date=18 June 2018
|title=On the Pre-impact Orbital Evolution of 2018 LA, Parent Body of the Bright Fireball Observed Over Botswana on 2018 June 2
|journal=[[Research Notes of the AAS]]
|volume=2
|issue=2
|page=57
|arxiv=1806.05164
|bibcode=2018RNAAS...2...57D
|doi=10.3847/2515-5172/aacc71|s2cid=119325928
|doi-access=free
}}</ref><ref name="pre-impact2">{{cite journal
|last1=de la Fuente Marcos |first1=Carlos
|last2=de la Fuente Marcos |first2=Raúl
|date=26 July 2018
|title=Pre-airburst Orbital Evolution of Earth's Impactor 2018 LA: An Update
|journal=[[Research Notes of the AAS]]
|volume=2
|issue=3
|page=131
|arxiv=1807.08322
|bibcode=2018RNAAS...2..131D
|doi=10.3847/2515-5172/aad551|s2cid=119208392
|doi-access=free
}}</ref><ref name="excess">{{cite journal |last1=de la Fuente Marcos |first1=C. |last2=de la Fuente Marcos | first2= R.|title=Waiting to make an impact: A probable excess of near-Earth asteroids in 2018 LA-like orbits |journal=[[Astronomy and Astrophysics]] |volume= 621|pages= A137|date=2019 |doi=10.1051/0004-6361/201834313
 |arxiv=1811.11845 |bibcode=2019A&A...621A.137D|s2cid=119538516 }}</ref>

On 8 March 2019, [[NASA]] announced the detection of a large airburst that occurred on 18 December 2018 at 11:48 local time off the eastern coast of the [[Kamchatka Peninsula]]. The [[Kamchatka superbolide]] is estimated to have had a mass of roughly 1600 tons, and a diameter of 9 to 14 meters depending on its density, making it the third largest asteroid to impact Earth since 1900, after the Chelyabinsk meteor and the Tunguska event. The fireball exploded in an airburst {{convert|25.6|km|mi}} above Earth's surface.

[[2019 MO]], an approximately 4m asteroid, was detected by [[Asteroid Terrestrial-impact Last Alert System|ATLAS]] a few hours before it impacted the Caribbean Sea near Puerto Rico in June 2019.<ref>{{Cite web |date=25 June 2019 |title=Breakthrough: UH team successfully locates incoming asteroid |url=https://legacy.ifa.hawaii.edu/info/press-releases/ATLAS_2019MO/ |access-date=12 March 2023 |website=Institute for Astronomy – University of Hawaii}}</ref>

In 2023, a small meteorite is believed to have crashed through the roof of a home in Trenton, New Jersey. The metallic rock was approximately 4 inches by 6 inches and weighed 4 pounds. The item was seized by police and tested for radioactivity.<ref>{{Cite web |url=https://apnews.com/article/meteorite-hits-home-hopewell-new-jersey-fd8391f8c5daea1e596ed85ed3ae5a68 |title=Possible meteorite crashes into New Jersey home, no injuries |date=May 9, 2023 |publisher=[[AP News]] |access-date=May 10, 2023}}</ref> The object was later confirmed to be a meteorite by scientists at The College of New Jersey, as well as meteorite expert Jerry Delaney, who previously worked at Rutgers University and the American Museum of Natural History.<ref>{{Cite web |url=https://apnews.com/article/meteorite-hits-home-hopewell-new-jersey-91fecf2eb7e5ffb938bfb68920dc6011 |title=Experts: Metallic object that crashed into New Jersey home was a meteorite |date=May 11, 2023 |publisher=[[AP News]] |access-date=May 14, 2023}}</ref>

===== Asteroid impact prediction =====
{{main|Asteroid impact prediction}}

[[File:2018 LA-orbit.png|thumb|250px|[[Orbit]] and positions of [[2018 LA]] and Earth, 30 days before impact. The diagram illustrates how orbit data can be used to predict impacts well in advance. Note that in this particular instance the asteroid's orbit was not known until a few hours before impact. The diagram was constructed afterwards for illustration.]]

In the late 20th and early 21st century scientists put in place measures to detect [[Near Earth object]]s, and predict the dates and times of [[asteroids]] impacting Earth, along with the locations at which they will impact. The [[International Astronomical Union]] [[Minor Planet Center]] (MPC) is the global clearing house for information on asteroid orbits. [[NASA]]'s [[Sentry (monitoring system)|Sentry System]] continually scans the MPC catalog of known asteroids, analyzing their orbits for any possible future impacts.<ref>{{YouTube|id=53Js-_vo3mo|title=How Does NASA Spot a Near-Earth Asteroid?}}</ref> Currently none are predicted (the single highest probability impact currently listed is ~7 m asteroid {{mpl|2010 RF|12}}, which is due to pass earth in September 2095 with only a 5% predicted chance of impacting).<ref>{{cite web|title=Sentry: Earth Impact Monitoring|url=https://cneos.jpl.nasa.gov/sentry/|website=Jet Propulsion Laboratory|publisher=NASA|access-date=25 August 2018}}</ref>

Currently prediction is mainly based on cataloging [[asteroids]] years before they are due to impact. This works well for larger asteroids (> 1 [[kilometre|km]] across) as they are easily seen from a long distance. Over 95% of them are already known and their [[orbit]]s have been measured, so any future impacts can be predicted long before they are on their final approach to Earth. Smaller objects are too faint to observe except when they come very close and so most cannot be observed before their final approach. Current mechanisms for detecting asteroids on final approach rely on wide-field ground based [[telescopes]], such as the ATLAS system. However, current telescopes only cover part of the Earth and even more importantly cannot detect asteroids on the day-side of the planet, which is why so few of the smaller asteroids that commonly impact Earth are detected during the few hours that they would be visible.<ref name="JPL-2017-SDT-Update">{{cite news
  |title      = Update to Determine the Feasibility of Enhancing the Search and Characterization of NEOs
  |work       = Near-Earth Object Science Definition Team Report 2017
  |publisher  = NASA
  |url        = https://www.nasa.gov/sites/default/files/atoms/files/2017_neo_sdt_final_e-version.pdf
  |access-date = 7 July 2018}}</ref>
So far only four impact events have been successfully predicted, all from innocuous 2–5 m diameter asteroids and detected a few hours in advance.

{{wide image|SmallAsteroidImpacts-Frequency-Bolide-20141114.jpg|500px|align-cap=center|Ground based telescopes can only detect objects approaching on the night-side of the planet, away from the [[Sun]]. Roughly half of impacts occur on the day-side of the planet.}}