Editing Comet Shoemaker–Levy 9 (section)

== Impacts ==
[[File:Hubble Space Telescope Image of Fragment BDGLNQ12R Impacts.png|left|thumb|Jupiter in [[ultraviolet]] (about 2.5 hours after R's impact). The black dot near the top is [[Io (moon)|Io]] transiting Jupiter.<ref>{{cite web|url=http://hubblesite.org/image/180/news_release/1994-35|title=Hubble Ultraviolet Image of Multiple Comet Impacts on Jupiter|work=News Release Number: STScI-1994-35|date=July 23, 1994|publisher=Hubble Space Telescope Comet Team|access-date=November 12, 2014|archive-url=https://web.archive.org/web/20171205042113/http://hubblesite.org/image/180/news_release/1994-35|archive-date=December 5, 2017|url-status=dead}}</ref>]]

Anticipation grew as the predicted date for the collisions approached, and astronomers trained terrestrial telescopes on Jupiter. Several space observatories did the same, including the [[Hubble Space Telescope]], the [[ROSAT]] [[X-ray]]-observing [[satellite]], the [[W. M. Keck Observatory]], and the [[Galileo (spacecraft)|''Galileo'' spacecraft]], then on its way to a rendezvous with Jupiter scheduled for 1995. Although the impacts took place on the side of Jupiter hidden from Earth, ''Galileo'', then at a distance of {{convert|1.6|AU|e6km+e6mi|abbr=unit}} from the planet, was able to see the impacts as they occurred. Jupiter's rapid rotation brought the impact sites into view for terrestrial observers a few minutes after the collisions.<ref name="Chodas">
{{cite journal
 |last=Yeomans
 |first=D.K.
 |date=December 1993
 |title=Periodic comet Shoemaker–Levy 9 (1993e)
 |journal=IAU Circular
 |issue=5909
 |url=http://www.cbat.eps.harvard.edu/iauc/05900/05909.html#Item2
 |access-date=July 5, 2011
}}</ref>

Two other space probes made observations at the time of the impact: the [[Ulysses (spacecraft)|''Ulysses'' spacecraft]], primarily designed for [[Sun|solar]] observations, was pointed toward Jupiter from its location {{convert|2.6|AU|e6km+e6mi|abbr=unit}} away, and the distant ''[[Voyager 2]]'' probe, some {{convert|44|AU|e9km+e9mi|abbr=unit}} from Jupiter and on its way out of the Solar System following its encounter with [[Neptune]] in 1989, was programmed to look for radio emission in the 1–390&nbsp;[[kHz]] range and make observations with its ultraviolet spectrometer.<ref name=williamsnasa>{{cite web |url=http://nssdc.gsfc.nasa.gov/planetary/others.html |last=Williams|first=David R.|title=Ulysses and Voyager 2 |access-date=August 25, 2008 |work=Lunar and Planetary Science |publisher=[[National Space Science Data Center]]}}</ref>

[[File:Impact fireball appears over the limb of Jupiter.jpg|thumb|150px|Hubble Space Telescope images of a [[Fireball (meteor)|fireball]] from the first impact appearing over the limb of the planet]]
[[File:Animation of Shoemaker-Levy 9's orbit around Jupiter.gif|thumb|Animation of Shoemaker-Levy 9's orbit around Jupiter<br>{{legend2|Lime|Jupiter}}{{·}}{{legend2| Magenta| Fragment A}}{{·}}{{legend2|RoyalBlue|Fragment D}}{{·}}{{legend2|Cyan|Fragment G}}{{·}}{{legend2|Gold|Fragment N}}{{·}}{{legend2|OrangeRed|Fragment W}}]]
Astronomer [[Ian Morison]] described the impacts as following:
<blockquote>The first impact occurred at 20:13&nbsp;[[Coordinated Universal Time|UTC]] on July 16, 1994, when fragment A of the [[comet nucleus|[comet's] nucleus]] slammed into Jupiter's southern hemisphere at about {{convert|60|km/s|abbr=on|round=5}}. Instruments on ''Galileo'' detected a [[Fireball (meteor)|fireball]] that reached a peak temperature of about {{convert|24,000|K|lk=in}}, compared to the typical Jovian cloud-top temperature of about {{convert|130|K|lk=in}}. It then expanded and cooled rapidly to about {{convert|1500|K}}. The plume from the fireball quickly reached a height of over {{convert|3000|km|abbr=on}} and was observed by the HST.<ref>{{cite book |last1=Morison |first1=Ian |title=A Journey through the Universe: Gresham Lectures on Astronomy |date=25 September 2014 |publisher=Cambridge University Press |isbn=978-1-316-12380-5 |page=110 |url=https://books.google.com/books?id=GZx7BAAAQBAJ&dq=sl9+jupiter+24000+k&pg=PA110 |access-date=12 January 2022 |language=en}}</ref><ref name="Martin">{{cite journal |last=Martin |first=Terry Z. |date=September 1996 |title=Shoemaker–Levy 9: Temperature, Diameter and Energy of Fireballs |journal=Bulletin of the American Astronomical Society |volume=28 |page=1085 |bibcode=1996DPS....28.0814M}}</ref></blockquote>

A few minutes after the impact fireball was detected, ''Galileo'' measured renewed heating, probably due to ejected material falling back onto the planet. Earth-based observers detected the fireball rising over the limb of the planet shortly after the initial impact.<ref name="Weissman">{{cite journal |last1=Weissman |first1=P.R. |date=March 1995 |title=Galileo NIMS Direct Observation of the Shoemaker–Levy 9 Fireballs and Fall Back |journal=Abstracts of the Lunar and Planetary Science Conference |volume=26 |page=1483 |bibcode=1995LPI....26.1483W |last2=Carlson |first2=R. W. |last3=Hui |first3=J. |last4=Segura |first4=M. |last5=Smythe |first5=W. D. |last6=Baines |first6=K. H. |last7=Johnson |first7=T. V. |last8=Drossart |first8=P. |last9=Encrenaz |first9=T.|author9-link=Thérèse Encrenaz|last10=Leader |first10=F. |last11=Mehlman |first11=R. |display-authors=9 }}</ref>

Despite published predictions,<ref name="Boslough" /> astronomers had not expected to see the fireballs from the impacts<ref name="Fizzle">{{cite journal |last=Weissman |first=Paul |date=July 14, 1994 |title= The Big Fizzle is coming |journal=Nature |volume=370 |issue=6485 | pages=94–95 |doi=10.1038/370094a0|bibcode = 1994Natur.370...94W |s2cid=4358549 |doi-access=free }}</ref> and did not have any idea how visible the other atmospheric effects of the impacts would be from Earth. Observers soon saw a huge dark spot after the first impact; the spot was visible from Earth. This and subsequent dark spots were thought to have been caused by debris from the impacts, and were markedly asymmetric, forming crescent shapes in front of the direction of impact.<ref name="Hammel">{{Cite conference |last=Hammel |first=H.B. |date=December 1994 |title=The Spectacular Swan Song of Shoemaker–Levy 9 |conference=185th AAS Meeting |publisher=American Astronomical Society |volume=26 |pages=1425 |bibcode=1994AAS...185.7201H}}</ref>

Over the next six days, 21 distinct impacts were observed, with the largest coming on July 18 at 07:33 UTC when fragment G struck Jupiter. This impact created a giant dark spot over {{cvt|12000|km|disp=or}}<ref>{{cite web |title=Remembering Comet Shoemaker-Levy 9's Impact on Jupiter, 23 Years Ago This Week |url=https://www.americaspace.com/2017/07/17/remembering-comet-shoemaker-levy-9s-impact-on-jupiter-23-years-ago-this-week/ |website=AmericaSpace |access-date=12 January 2022 |date=17 July 2017}}</ref> (almost one [[Earth radius#Derived quantities: diameter, circumference, arc-length, area, volume|Earth diameter]]) across, and was estimated to have released an energy equivalent to 6,000,000&nbsp;[[TNT equivalent|megatons of TNT]] (600 times the world's nuclear arsenal).<ref>{{cite web |first=Dan |last=Bruton |url=http://www.physics.sfasu.edu/astro/sl9/cometfaq2.html#Q3.1 |title=What were some of the effects of the collisions? |work=Frequently Asked Questions about the Collision of Comet Shoemaker–Levy 9 with Jupiter |publisher=[[Stephen F. Austin State University]] |date=February 1996 |access-date=January 27, 2014 |archive-date=August 28, 2021 |archive-url=https://web.archive.org/web/20210828080844/http://www.physics.sfasu.edu/astro/sl9/cometfaq2.html#Q3.1 |url-status=dead }}</ref> Two impacts 12&nbsp;hours apart on July 19 created impact marks of similar size to that caused by fragment G, and impacts continued until July 22, when fragment W struck the planet.<ref>{{cite web |first=Don |last=Yeomans |author2=Chodas, Paul |url=http://www2.jpl.nasa.gov/sl9/impacts4.html | title=Comet Crash Impact Times Request |publisher=[[Jet Propulsion Laboratory]] |date=March 18, 1995 |access-date=August 26, 2008}}</ref>