Editing Impact event (section)

====Jupiter====
[[File:Impact site of fragment G.png|thumb|[[Comet Shoemaker-Levy 9]]'s scar on Jupiter (dark area near Jupiter's [[wikt:limb#Etymology 2|limb]])]]
{{Main|Impact events on Jupiter}}
{{See also|List of Jupiter events}}

[[Jupiter]] is the most massive planet in the [[Solar System]], and because of its large mass it has a vast sphere of gravitational influence, the region of space where an [[asteroid capture]] can take place under favorable conditions.<ref>{{cite journal|first=G.A. |last=Chebotarev |title=Gravitational Spheres of the Major Planets, Moon and Sun |journal=Soviet Astronomy |volume=7 |page=620 |url= http://adsabs.harvard.edu/full/1964SvA.....7..618C |year=1964|bibcode=1964SvA.....7..618C }}</ref>

Jupiter is able to capture [[comet]]s in orbit around the Sun with a certain frequency. In general, these comets travel some revolutions around the planet following unstable orbits as highly elliptical and perturbable by solar gravity. While some of them eventually recover a [[heliocentric orbit]], others crash on the planet or, more rarely, on its satellites.<ref>{{cite journal|last=Tancredi |first=G. |year=1990 |title=Temporary Satellite Capture and Orbital Evolution of Comet P/Helin-Roman-Crockett |journal=Astronomy and Astrophysics |volume=239 |issue=1–2 |bibcode=1990A&A...239..375T |pages=375–380 |url=http://adsabs.harvard.edu/abs/1990A%26A...239..375T }}</ref><ref>{{cite journal|last=Ohtsuka |first=Katsuhito|title=Quasi-Hilda Comet 147P/Kushida-Muramatsu: Another long temporary satellite capture by Jupiter |journal=Astronomy & Astrophysics |year=2008|volume=489|issue=3|page=1355|doi=10.1051/0004-6361:200810321|arxiv=0808.2277|bibcode=2008A&A...489.1355O|s2cid=14201751|url=http://www.arm.ac.uk/preprints/2008/531.pdf |archive-url=https://web.archive.org/web/20130226040659/http://www.arm.ac.uk/preprints/2008/531.pdf|url-status=dead |archive-date=2013-02-26 }}</ref>

In addition to the mass factor, its relative proximity to the inner solar system allows Jupiter to influence the distribution of minor bodies there. For a long time it was believed that these characteristics led the gas giant to expel from the system or to attract most of the wandering objects in its vicinity and, consequently, to determine a reduction in the number of potentially dangerous objects for the Earth. Subsequent dynamic studies have shown that in reality the situation is more complex: the presence of Jupiter, in fact, tends to reduce the frequency of impact on the Earth of objects coming from the [[Oort cloud]],<ref>{{cite journal|url=http://adsabs.harvard.edu/abs/2010IJAsB...9....1H |title=Jupiter – friend or foe? III: the Oort cloud comets |first=J. |last=Horner |author2=Jones, B.W.; Chambers, J. |year=2010 |journal=International Journal of Astrobiology |volume=9 |number=1 |pages=1–10 |doi=10.1017/S1473550409990346 |arxiv=0911.4381 |bibcode=2010IJAsB...9....1H |s2cid=1103987 }}</ref> while it increases it in the case of asteroids<ref>{{cite journal |first=J. |last=Horner |author2=Jones, B.W. |title=Jupiter: Friend or foe? I: the asteroids |year=2008 |journal=International Journal of Astrobiology |volume=7 |number=3&4 |pages=251–261 |doi=10.1017/S1473550408004187 |arxiv=0806.2795 |bibcode=2008IJAsB...7..251H |s2cid=8870726 }}</ref> and short period comets.<ref>{{cite journal |first=J. |last=Horner |author2=Jones, B.W. |title=Jupiter – friend or foe? II: the Centaurs |year=2009 |journal=International Journal of Astrobiology |volume=8 |number=2 |pages=75–80 |doi=10.1017/S1473550408004357 |arxiv=0903.3305 |bibcode=2009IJAsB...8...75H |s2cid=8032181 |url=http://adsabs.harvard.edu/abs/2009IJAsB...8...75H }}</ref>

For this reason Jupiter is the planet of the Solar System characterized by the highest frequency of impacts, which justifies its reputation as the "sweeper" or "cosmic vacuum cleaner" of the Solar System.<ref name=Overbye>{{cite news |title=Jupiter: Our Cosmic Protector?|url=https://www.nytimes.com/2009/07/26/weekinreview/26overbye.html|author=Dennis Overbye|magazine=The New York Times|page=WK7|year=2009}}</ref> 2009 studies suggest an impact frequency of one every 50–350 years, for an object of 0.5–1&nbsp;km in diameter; impacts with smaller objects would occur more frequently. Another study estimated that comets {{convert|0.3|km|abbr=on}} in diameter impact the planet once in approximately 500 years and those {{convert|1.6|km|abbr=on}} in diameter do so just once in every 6,000 years.<ref>{{cite journal |last1=Roulston |first1=M.S. |date=March 1997 |title=Impact Mechanics and Frequency of SL9-Type Events on Jupiter |journal=[[Icarus (journal)|Icarus]] |volume=126 |issue=1 |pages=138–147 |doi=10.1006/icar.1996.5636 |last2=Ahrens |first2=T |bibcode=1997Icar..126..138R}}</ref>

In July 1994, [[Comet Shoemaker–Levy 9]] was a comet that broke apart and collided with Jupiter, providing the first direct observation of an extraterrestrial collision of Solar System objects.<ref name=NASA2005>{{cite web|url=http://nssdc.gsfc.nasa.gov/planetary/comet.html |title=Comet Shoemaker–Levy 9 Collision with Jupiter |access-date=2008-08-26 |publisher=[[National Space Science Data Center]] |date=February 2005}}</ref> The event served as a "wake-up call", and astronomers responded by starting programs such as [[Lincoln Near-Earth Asteroid Research]] (LINEAR), [[Near-Earth Asteroid Tracking]] (NEAT), [[Lowell Observatory Near-Earth Object Search]] (LONEOS) and several others which have drastically increased the rate of asteroid discovery.

The [[Jupiter 2009 impact event|2009 impact event]] happened on July 19 when a new black spot about the size of Earth was discovered in Jupiter's southern hemisphere by [[amateur astronomy|amateur astronomer]] [[Anthony Wesley]]. Thermal infrared analysis showed it was warm and spectroscopic methods detected ammonia. [[Jet Propulsion Laboratory|JPL]] scientists confirmed that there was another impact event on Jupiter, probably involving a small undiscovered comet or other icy body.<ref>{{cite news|url=http://www.cnn.com/2009/TECH/space/07/21/jupiter.nasa.meteor.scar/index.html|title=Mystery impact leaves Earth-sized mark on Jupiter|publisher=CNN | date=July 21, 2009}}</ref><ref>{{cite news|last=Overbye|first=Dennis|title=All Eyepieces on Jupiter After a Big Impact|url=https://www.nytimes.com/2009/07/22/science/space/22jupiter.html?hpw|newspaper=New York Times|date=July 22, 2009}}</ref><ref>[https://www.theguardian.com/science/2009/jul/21/jupiter-scar-comet-asteroid-crash Amateur astronomer spots Earth-size scar on Jupiter], Guardian, July 21, 2009</ref> The impactor is estimated to have been about 200–500 meters in diameter.

Later minor impacts were observed by amateur astronomers in 2010, 2012, 2016, and 2017; one impact was observed by ''[[Juno (spacecraft)|Juno]]'' in 2020.