View source for 2009 Jupiter impact event

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{{Infobox news event
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|caption = [[Hubble Space Telescope|Hubble]] image of the scar taken on July 23 showing a blemish of about {{convert|8,000|km|mi}} long<ref>{{cite news|author=Dennis Overbye|title=Hubble Takes Snapshot of Jupiter's 'Black Eye' |url=https://www.nytimes.com/2009/07/25/science/space/25hubble.html?ref=science|date=2009-07-24|work=[[The New York Times]]|access-date=2009-07-25}}</ref><ref name="hubblesite"/>
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|place = [[Jupiter]]
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[[File:Jupiter impact jul2009.jpg|thumb|A picture of the 2009 impact mark captured by [[NASA Infrared Telescope Facility]] in [[Mauna Kea]], [[Hawaii]]]]

[[File:The Keck Subaru and Infrared obervatories.JPG|thumb|[[W. M. Keck Observatory|Keck Observatory]] (the two in the middle) and [[NASA Infrared Telescope Facility]] (right) at [[Mauna Kea Observatory|Mauna Kea]], [[Hawaii]]]]

The '''2009 Jupiter impact event''', occasionally referred to as the '''Wesley impact''', was a July 2009 [[impact event]] on [[Jupiter]] that caused a black spot in the planet's atmosphere.  The impact area covered 190 million square kilometers, similar in area to the planet's [[Atmosphere of Jupiter#Oval BA|Little Red Spot]] and approximately the size of the [[Pacific Ocean]].<ref name="berkeleypr">[http://www.berkeley.edu/news/media/releases/2009/07/21_bruise.shtml Jupiter pummeled, leaving bruise the size of the Pacific Ocean]. University of California, Berkeley press release, July 21, 2009.</ref> The impactor is estimated to have been about 200 to 500 meters in diameter.<ref name="PR2011"/> (For comparison, the one for the [[Tunguska event]] was estimated to be in the 60–190 meters range.)

==Discovery==
[[amateur astronomy|Amateur astronomer]] [[Anthony Wesley]] discovered the impact at approximately 13:30 [[Coordinated Universal Time|UTC]] on 19 July 2009 (exactly 15 years after the Jupiter impacts of [[comet Shoemaker–Levy 9]], or SL9). He was at his home [[observatory]] just outside [[Murrumbateman, New South Wales|Murrumbateman]], [[New South Wales]], [[Australia]], using stacked images on a {{convert|14.5|in|cm|adj=on|1}} diameter [[reflecting telescope]] equipped with a low light machine vision video camera attached to the telescope.<ref>{{cite news|author=Mackey, Robert|title=Amateur Finds New Earth-Sized Blot on Jupiter|url=http://thelede.blogs.nytimes.com/2009/07/21/amateur-astronomer-finds-new-earth-size-impact-mark-on-jupiter/|date=July 21, 2009|work=The New York Times|access-date=2009-07-21}}</ref> Wesley stated that:

{{blockquote|When first seen close to the limb (and in poor conditions) it was only a vaguely dark spot, I [thought] likely to be just a normal dark polar storm. However as it rotated further into view, and the conditions improved I suddenly realised that it wasn't just dark, it was ''black'' in all channels, meaning it was truly a black spot.<ref>{{cite web |author=Wesley, Anthony |title=Impact mark on Jupiter, 19th July 2009 |url=http://jupiter.samba.org/jupiter-impact.html |archive-url=https://web.archive.org/web/20090724151242/http://jupiter.samba.org/jupiter-impact.html |archive-date=2009-07-24 |url-status=live |publisher=(jupiter.samba.org) |access-date=2009-07-21 }}</ref>}}

Wesley sent an e-mail to others including the [[NASA]] [[Jet Propulsion Laboratory]] in [[Pasadena, California]] reporting his observations.<ref>{{cite news|author=O'Loughlin, Toni and agencies|title=Amateur astronomer spots Earth-size scar on Jupiter|url=https://www.theguardian.com/science/2009/jul/21/jupiter-scar-comet-asteroid-crash|work=The Guardian|access-date=2009-07-21 | location=London | date=2009-07-21| archive-url= https://web.archive.org/web/20090729221115/http://www.guardian.co.uk/science/2009/jul/21/jupiter-scar-comet-asteroid-crash| archive-date= 29 July 2009 | url-status= live}}</ref>

==Findings==
[[Paul Kalas]] and collaborators confirmed the sighting. They had time on the [[W. M. Keck Observatory|Keck II]] telescope in [[Hawaii]], and had been planning to observe [[Fomalhaut b]], but they spent some of their time looking at the Jupiter impact.<ref name="keckpr">[http://keckobservatory.org/index.php/news/jupiters_adds_a_feature/ Jupiter adds a feature] {{webarchive|url=https://web.archive.org/web/20110720180242/http://keckobservatory.org/index.php/news/jupiters_adds_a_feature/ |date=2011-07-20 }}. Keck Observatory observations, July 21, 2009</ref> Infrared observation by Keck and the [[NASA Infrared Telescope Facility]] (IRTF)<ref name="berkeleypr"/> at Mauna Kea showed a bright spot where the impact took place, indicating the impact warmed a 190 million square km area of the lower atmosphere at 305° west, 57° south near Jupiter's south pole.<ref name="berkeleypr"/>

The spot's prominence indicated that it was composed of high-altitude aerosols similar to those seen during the SL9 impact.<ref name="keckpr"/> Using [[Near-infrared#Different regions in the infrared|near-infrared]] wavelengths and the IRTF, Glenn Orton and his team detected bright upwelling particles in the planet's upper atmosphere and using mid-infrared wavelengths, found possible extra emission of [[ammonia]] gas.<ref name=Martinez>{{cite web|author=Martinez, Carolina|title=New NASA Images Indicate Object Hits Jupiter|url=http://www.nasa.gov/topics/solarsystem/features/jup-20090720.html|date=July 20, 2009|publisher=Jet Propulsion Laboratory|access-date=2009-07-21| archive-url= https://web.archive.org/web/20090727121804/http://www.nasa.gov/topics/solarsystem/features/jup-20090720.html| archive-date= 27 July 2009 | url-status= live}}</ref>

The force of the explosion on Jupiter was thousands of times more powerful than the suspected comet or asteroid that [[Tunguska event|exploded over the Tunguska]] River Valley in Siberia in June 1908.<ref name="hubblesite">{{cite web |title=Hubble Captures Rare Jupiter Collision |publisher=Hubblesite (STScI-2009-23) |url=http://hubblesite.org/newscenter/archive/releases/2009/23/full |date=2009-07-24 |access-date=2009-07-24}}</ref> (This would be approximately 12,500–13,000 megatons of TNT, over a million times more powerful than [[Atomic bombings of Hiroshima and Nagasaki|the bomb dropped on Hiroshima]]).<ref>{{Cite book | last = Longo | first = Giuseppe | chapter = 18: The Tunguska event | editor-last = Bobrowsky | editor-first = Peter T. | editor2-last = Rickman | editor2-first = Hans | title = Comet/Asteroid Impacts and Human Society, An Interdisciplinary Approach | pages = 303–330 | publisher = Springer-Verlag | place = Berlin Heidelberg New York | publication-date = 2007 | contribution-url = http://www-th.bo.infn.it/tunguska/Asteroids-Chapter-18.pdf | isbn = 978-3-540-32709-7 | year = 2007 | access-date = 2009-07-26 | archive-date = 2009-07-29 | archive-url = https://www.webcitation.org/5icderdjK?url=http://www-th.bo.infn.it/tunguska/Asteroids-Chapter-18.pdf | url-status = bot: unknown }}. Accessed 2009-07-27.   2009-07-29.</ref>

==Impactor==
The object that hit Jupiter was not identified before Wesley discovered the impact. A 2003 paper estimated comets with a diameter larger than 1.5 kilometers impact Jupiter about every 90 to 500 years,<ref>{{Cite journal |first1=Kevin |last1=Zahnle |first2=Paul |last2=Schenk |first3=Harold |last3=Levison |first4=Luke |last4=Dones |year=2003 |title=Cratering rates in the outer Solar System |journal=[[Icarus (journal)|Icarus]] |volume=163 |issue=2 |pages=263–289 |url=http://lasp.colorado.edu/~espoclass/homework/5830_2008_homework/Zahnle2003CrateringRates.pdf |bibcode=2003Icar..163..263Z |quote=1.5-km-diameter comets is currently N(d > 1.5&nbsp;km) = 0.005{{±|0.006|0.003}}&nbsp;per annum |archive-url=https://www.webcitation.org/5icdGOsFF?url=http://lasp.colorado.edu/~espoclass/homework/5830_2008_homework/Zahnle2003CrateringRates.pdf |archive-date=2009-07-29 |access-date=2009-07-27 |doi=10.1016/S0019-1035(03)00048-4 |citeseerx=10.1.1.520.2964 }}</ref> while a 1997 survey suggested that the astronomer [[Giovanni Domenico Cassini|Cassini]] may have recorded an impact in 1690.<ref>{{Cite journal |first1=Isshi |last1=Tabe |first2=Jun-ichi |last2=Watanabe |first3=Michiwo |last3=Jimbo |date=February 1997 |title=Discovery of a Possible Impact SPOT on Jupiter Recorded in 1690 |journal=Publications of the Astronomical Society of Japan |volume=49 |pages=L1–L5 |bibcode=1997PASJ...49L...1T |quote=Jupiter has been continuously monitored for almost 400 yr |doi=10.1093/pasj/49.1.l1|doi-access=free }}</ref>

Given the size of the SL9 impactors,<ref name="sl9-size">{{cite web |title=Comet Shoemaker-Levy 9 Fragment Size |publisher=Lunar and Planetary Institute |author=D. A. Crawford |url=http://www.lpi.usra.edu/meetings/lpsc97/pdf/1351.PDF |access-date=2009-07-22}}</ref> it is likely that this object was less than one kilometer in diameter.<ref name="hubblesite"/><ref name="gemini">{{cite web |title=Surprise Collision on Jupiter Captured by Gemini Telescope |date=23 July 2009 |publisher=Gemini Observatory |url=http://www.gemini.edu/node/11300 |access-date=2009-07-24}}</ref>
<!-- <ref name="Tedmanson">{{cite news|url=http://www.timesonline.co.uk/tol/news/uk/science/article6721504.ece|title=Backyard astronomer discovers black spot on Jupiter|last=Tedmanson|first=Sophie|date=2009-07-22|publisher=[[The Times]]|access-date=2009-07-22 | location=London}}{{dead link|date=September 2024|bot=medic}}{{cbignore|bot=medic}}</ref>
<ref>{{cite news|url=http://www.telegraph.co.uk/science/space/5882014/Planet-Jupiter-hit-by-object-which-left-a-dent-the-size-of-Earth.html|title=Planet Jupiter hit by object which left a dent the size of Earth |date=2009-07-21|source=[[The Daily Telegraph]]|access-date=2009-07-22 | location=London}}</ref>
<ref>{{cite news|url=http://uk.reuters.com/article/idUKTRE56K0ZV20090721|archive-url=https://archive.today/20120715221437/http://uk.reuters.com/article/idUKTRE56K0ZV20090721|url-status=dead|archive-date=July 15, 2012|title=Giant "scar" on Jupiter spotted by amateur stargazer |date=2009-07-21|source=[[Reuters]]|access-date=2009-07-22 | first=Rob | last=Taylor}}</ref>
<ref name="Than">{{cite news|url=http://news.nationalgeographic.com/news/2009/07/090721-jupiter-impact-spot.html|title=PHOTO: Jupiter Impact Creates Huge New Spot|last=Than|first=Ker|date=2009-07-21|publisher=[[National Geographic]]|access-date=2009-07-22}}</ref>
<ref name="Johnson">{{cite news|url=http://www.latimes.com/news/science/la-sci-jupiter22-2009jul22,0,5215362.story|title= 'Incredible' new scar is spreading on Jupiter|last=Johnson,  Jr.|first=John |publisher=[[Los Angeles Times]]|access-date=2009-07-22|date=2009-07-22}}
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Finding water at the site would indicate that the impactor was a comet,<ref name="perlman">Perlman, David. "[http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2009/07/23/MN5I18TT7U.DTL Glowing scar is revealing Jupiter's secrets]" ''San Francisco Chronicle'', 23 July 2009.</ref> as opposed to an asteroid or a very small, icy moon.<ref name="Grossman">{{cite news|url=https://www.newscientist.com/article/dn17491-jupiter-sports-new-bruise-from-impact.html|title= Jupiter sports new 'bruise' from impact |last=Grossman|first=Lisa|date=2009-07-21|publisher=[[New Scientist]]|access-date=2009-07-22| archive-url= https://web.archive.org/web/20090803010347/http://www.newscientist.com/article/dn17491-jupiter-sports-new-bruise-from-impact.html| archive-date= 3 August 2009 | url-status= live}}</ref> At first it was believed that the object was more likely to be a comet since comets generally have more planet-crossing orbits.<ref name="Hergenrother">{{cite web |title=More on the Jupiter Impact |author=Carl Hergenrother |url=http://transientsky.wordpress.com/2009/07/21/more-on-the-jupiter-impact/ |type=Blog |website=The Transient Sky |date=2009-07-21 |access-date=2009-07-24}}</ref> At the distance of Jupiter (5.2 AU) most small comets are not close enough to the Sun to be very [[Coma (cometary)|active]], and so would be hard to detect.<ref name="Hergenrother"/> Small kilometer-sized asteroids would also be hard to detect, however, and recent work by Orton et al. and Hammel et al. has strongly suggested the impactor was an asteroid, as it left only one impact site, did not reduce Jovian decametric radiation emission by contributing significant dust to the Jovian magnetosphere, and produced high altitude dusty debris full of silica, very different than what was produced by SL9.{{citation needed|date=April 2010}}

As of 2012, the impactor is believed to have been an asteroid with a diameter of about 200 to 500 meters.<ref name="PR2011">{{cite web
  |date=January 26, 2011
  |title=Asteroids Ahoy! Jupiter Scar Likely from Rocky Body
  |publisher=News and Features @ NASA/JPL
  |author=Jia-Rui C. Cook
  |url=http://www.jpl.nasa.gov/news/news.cfm?release=2011-028
  |access-date=2011-01-26| archive-url= https://web.archive.org/web/20110127202427/http://www.jpl.nasa.gov/news/news.cfm?release=2011-028| archive-date= 27 January 2011 | url-status= live}}</ref>

===Visibility===
Assuming it was an inactive comet (or asteroid) about 1&nbsp;km in diameter, this object would have been no brighter than about [[apparent magnitude]] 25.<ref name="Hergenrother"/> (Jupiter shines about 130 [[1000000000 (number)|billion]] times brighter than a 25th magnitude object.)<ref><math>(\sqrt[5]{100})^{25-(-2.8)}=131</math> billion (1.3{{e|11}})</ref> Most asteroid surveys that use a wide field of view do not see fainter than about magnitude 22 (which is 16x brighter than magnitude 25).<ref name="Hergenrother"/>  Even detecting satellites less than 10&nbsp;km in diameter orbiting Jupiter is difficult and requires some of the best telescopes in the world.<ref name="Sheppard2003">{{cite web |title=New Satellites of Jupiter Discovered in 2003 |publisher=Carnegie Institution (Department of Terrestrial Magnetism) |author=Scott S. Sheppard |author-link=Scott S. Sheppard |url=http://www.dtm.ciw.edu/users/sheppard/satellites/jup2003.html |access-date=2009-07-23| archive-url= https://web.archive.org/web/20090608233946/http://www.dtm.ciw.edu/users/sheppard/satellites/jup2003.html| archive-date= 8 June 2009 | url-status= live}}</ref> It is only since 1999 with the discovery of [[Callirrhoe (moon)|Callirrhoe]] that astronomers have been able to discover many of [[Moons of Jupiter#List|Jupiter's smallest moons]].<ref name="moon1999">{{cite web |title=New moon of Jupiter found |publisher=SpaceFlight Now (University of Arizona News Release) |url=http://spaceflightnow.com/news/n0007/21jovianmoon/ |access-date=2009-07-23}}</ref>

==See also==
*[[Impact events on Jupiter]]
*[[List of Jupiter events]]

==References==
{{Reflist|colwidth=30em}}

==Further reading==
*{{Cite journal | last1 = Hammel | first1 = H. B. | last2 = Wong | first2 = M. H. | last3 = Clarke | first3 = J. T. | last4 = De Pater | first4 = I. | last5 = Fletcher | first5 = L. N. | last6 = Hueso | first6 = R. | last7 = Noll | first7 = K. | last8 = Orton | first8 = G. S. | last9 = Pérez-Hoyos | first9 = S. | last10 = Sánchez-Lavega | first10 = A. | last11 = Simon-Miller | first11 = A. A. | last12 = Yanamandra-Fisher | first12 = P. A. | doi = 10.1088/2041-8205/715/2/L150 | title = Jupiter After the 2009 Impact:hubble Space Telescopeimaging of the Impact-Generated Debris and Its Temporal Evolution | journal = The Astrophysical Journal | volume = 715 | issue = 2 | pages = L150 | year = 2010 |bibcode = 2010ApJ...715L.150H | doi-access = free }}.
*{{Cite journal | last1 = Sánchez-Lavega | first1 = A. | last2 = Wesley | first2 = A. | last3 = Orton | first3 = G. | last4 = Hueso | first4 = R. | last5 = Perez-Hoyos | first5 = S. | last6 = Fletcher | first6 = L. N. | last7 = Yanamandra-Fisher | first7 = P. | last8 = Legarreta | first8 = J. | last9 = De Pater | first9 = I. | last10 = Hammel | first10 = H. | last11 = Simon-Miller | first11 = A. | last12 = Gomez-Forrellad | first12 = J. M. | last13 = Ortiz | first13 = J. L. | last14 = García-Melendo | first14 = E. | last15 = Puetter | first15 = R. C. | last16 = Chodas | first16 = P. | title = The Impact of a Large Object on Jupiter in 2009 July | doi = 10.1088/2041-8205/715/2/L155 | journal = The Astrophysical Journal | volume = 715 | issue = 2 | pages = L155 | year = 2010 |arxiv = 1005.2312 |bibcode = 2010ApJ...715L.155S | s2cid = 119251280 }}.

==External links==
<!--Please do *not* add links here that are already used in the article itself. In particular, do *not* again link to [[comet Shoemaker-Levy 9]]! Whenever possible, instead of adding an external link here, create a cite at an appropriate place within the text of the article itself; it is both cleaner, and improves articles' accuracy.-->
{{wikinews|Black spot on Jupiter is impact site, says NASA}}
{{commons category}}
*{{cite web|url=http://jupiter.samba.org/AnthonyWesley.jpg|title=Photo of Anthony Wesley and his telescope|publisher=(jupiter.samba.org)|access-date=2009-07-21| archive-url= https://web.archive.org/web/20090726100856/http://jupiter.samba.org/AnthonyWesley.jpg| archive-date= 26 July 2009 | url-status= live}}
*[https://web.archive.org/web/20070523061638/http://alpo-j.asahikawa-med.ac.jp/Latest/Jupiter.htm Jupiter Section of ALPO-Japan with Latest Jupiter Observations]
*[https://web.archive.org/web/20090726003513/http://www.google.com/hostednews/ap/article/ALeqM5j6sEwe5hIfsw-mn8KJgZlvzU_LIQD99J311G0 Aussie stargazer spots scar from Jupiter collision]
*[http://palscience.com/2009/07/22/a-comet-or-meteoroid-hits-jupiter A comet or meteoroid hits Jupiter]
*[https://arxiv.org/abs/0806.2795 Jupiter - friend or foe?] (arXiv:0806.2795)
*[http://antwrp.gsfc.nasa.gov/apod/ap090908.html APOD 9/8/2009, Unexpected Impact on Jupiter] polar projection animation
*[http://www.physorg.com/news/2012-03-simulations-unravel-mysteries-jupiter-impact.html Simulations unravel mysteries of 2009 Jupiter impact] (physorg.com March 30, 2012)

{{Modern impact events}}
{{Jupiter}}

[[Category:2009 in science|Jupiter Impact Event, 2009]]
[[Category:Jupiter impact events]]
[[Category:2009 in outer space]]