View source for Great Red Spot

{{Short description|Persistent storm in Jupiter's atmosphere}}
{{Use dmy dates|date=September 2025}}
{{coord|22|S|55|W|globe:jupiter_type:landmark|display=title}}
[[File:Jupiter - Great Red Spot - PJ7-60 61 62 - Balanced (49803032983).png|300px|thumb|alt=|upright=1.5|Close up view of the Great Red Spot by [[Juno (spacecraft)|''Juno'']]]]

The '''Great Red Spot''' is a persistent [[high-pressure area|high-pressure region]] in the [[atmosphere of Jupiter]], producing an [[anticyclonic storm]] that is the largest in the [[Solar System]]. It is the most recognizable feature on [[Jupiter]], owing to its red-orange color whose origin is still unknown. Located 22 [[Degree (angle)|degrees]] south of Jupiter's [[equator]], it produces wind-speeds up to {{convert|432|km/h|mph|abbr=on}}. It was first observed in September 1831, with 60 recorded observations between then and 1878, when continuous observations began.<ref name="Denning" /><ref>{{cite news |last=Chang |first=Kenneth |title=The Great Red Spot Descends Deep Into Jupiter |url=https://www.nytimes.com/2017/12/13/science/jupiter-great-red-spot-juno.html |date=2017-12-13 |newspaper=[[The New York Times]] |access-date=2017-12-15 }}</ref><ref>{{cite encyclopedia |entry=Great Red Spot |entry-url=https://www.britannica.com/place/Great-Red-Spot |encyclopedia=[[Encyclopædia Britannica]] |access-date=2018-12-04}}</ref> A similar spot was observed from 1665 to 1713; if this is the same storm, it has existed for at least {{#expr: ({{CURRENTYEAR}} - 1665)}} years,<ref>{{cite web |author=Staff |year=2007 |url=https://www.space.com/3134-jupiter-data-sheet.html |title=Jupiter Data Sheet – SPACE.com |publisher=Imaginova |access-date=2008-06-03}}</ref><ref>{{cite web |url=http://csep10.phys.utk.edu/astr161/lect/jupiter/redspot.html | url-status=dead |archive-url=https://web.archive.org/web/20040610075946/http://csep10.phys.utk.edu/astr161/lect/jupiter/redspot.html |archive-date=2004-06-10 |title=The Solar System - The Planet Jupiter – The Great Red Spot |publisher=Dept. Physics & Astronomy – [[University of Tennessee]] |access-date=2015-08-30}}</ref> but a study from 2024 suggests this is not the case.<ref name="Sánchez-Lavega2024"/>

==Observation history==

=== First observations ===
[[File:Le osservazioni astronomiche - Giove.jpg|thumb|right|[[Donato Creti]]'s 1711 painting "Jupiter", the first depiction of a large spot on Jupiter as red]]
[[File:Jupiter Great Red Spot Elger November 1881.png|thumb|A sketch of Jupiter made by [[Thomas Gwyn Elger]] in November 1881, showing the Great Red Spot]]
The Great Red Spot may have existed before 1664, but it could be that the present spot was first seen only in 1830, and was well studied only after a prominent appearance in 1879. The storm that was seen in the 17th century may have been different from the storm that exists today.<ref>{{cite web |url=https://www.nasa.gov/feature/goddard/jupiter-s-great-red-spot-a-swirling-mystery |author=Karl Hille |date=2015-08-04 |title=Jupiter's Great Red Spot: A Swirling Mystery |website=[[NASA]] |access-date=2017-11-18}}</ref> A long gap separates its period of current study after 1830 from the 17th century discovery. It is unknown whether the original spot dissipated and reformed, whether it faded away, or whether observers simply failed to study and record it.{{sfnp|Beebe|1997|pp=38–41}}

The first sighting of the Great Red Spot is often credited to [[Robert Hooke]], who described a spot on the planet in May 1664.<ref name="aps-hooke-cassini"/> However, it is likely that Hooke's spot was not only in another belt altogether (the North Equatorial Belt, as opposed to the current Great Red Spot in the [[South Equatorial Belt]]), but also that it was in the shadow of a transiting moon, most likely [[Callisto (moon)|Callisto]].<ref name="aps-hooke-cassini">{{Cite web |title=May 1664: Hooke vs. Cassini: Who Discovered Jupiter's Red Spot? {{!}} This Month in Physics History |url=http://www.aps.org/publications/apsnews/202005/history.cfm |access-date=2021-12-29 |website=[[American Physical Society]] }}</ref> In the following year, [[Giovanni Cassini]] describes a "a permanent [spot] which was often seen to return in the same place with the same size and shape", calculating its rotation period to be {{nowrap|9 h 56 min}}.<ref name="aps-hooke-cassini"/>{{sfnp|Rogers|1995|p=6}} With fluctuations in visibility, Cassini's spot was observed from 1665 to 1713, but the 48-year observational gap makes the identity of the two spots inconclusive. Because of the older spot's shorter observational history and slower motion than the modern spot, it is difficult to conclude that they are the same.{{sfnp|Rogers|1995|p=188}}

A minor mystery concerns a Jovian spot depicted in a 1711 canvas by [[Donato Creti]], which is exhibited in the [[Vatican City|Vatican]].<ref>{{cite web |author=Staff |year=2003 |url=https://www.museivaticani.va/content/museivaticani/en/collezioni/musei/la-pinacoteca/sala-xv---secolo-xviii/donato-creti--osservazioni-astronomiche.html |title=Donato Creti, Astronomical observations |publisher=[[Vatican Museums]] |access-date=2019-12-16 }}</ref>{{sfnp|Hockey|1999|pp=40–41}} Part of a series of panels in which different (magnified) heavenly bodies serve as backdrops for various [[Italy|Italian]] scenes, and all overseen by the astronomer [[Eustachio Manfredi]] for accuracy, Creti's painting is the first known depiction of a large spot on Jupiter as red (albeit raised to the Jovian northern hemisphere due to an optical inversion inherent to the era's telescopes). No Jovian feature was explicitly described in writing as red before the late 19th century.{{sfnp|Hockey|1999|pp=40–41}}

The Great Red Spot has been frequently observed since 5 September 1831, with over 60 observations recorded by 1879, when it came into popular prominence.<ref name="Denning">{{cite journal |last1=Denning |first1=William Frederick |title=Early history of the great red spot on Jupiter |journal=Monthly Notices of the Royal Astronomical Society |date=June 1899 |volume=59 |issue=10 |page=574 |doi=10.1093/mnras/59.10.574 |publisher=Royal Astronomical Society |bibcode=1899MNRAS..59..574D|doi-access=free }}</ref> Since then, it has been under continuous observation.

A 2024 study of historical observations suggests that the "permanent spot" observed from 1665 to 1713 may not be the same as the modern Great Red Spot observed since 1831. It is suggested that the original spot disappeared, and later another spot formed, which is the one seen today.<ref name="Sánchez-Lavega2024"/>

===Late 20th and 21st centuries===
[[Image:Great Red Spot From Voyager 1.jpg|thumb|left|A wide view of Jupiter and the Great Red Spot as seen from ''[[Voyager 1]]'' in 1979]]
On 25 February 1979,{{sfnp|Smith|1979|pp=951–972}} when the ''[[Voyager 1]]'' spacecraft was {{convert|9200000|km|mi|abbr=on}} from Jupiter, it transmitted the first detailed image of the Great Red Spot. Cloud details as small as {{convert|160|km|mi|-1|abbr=on}} across were visible. The colorful, wavy cloud pattern seen to the left (west) of the Red Spot is a region of extraordinarily complex and variable wave motion.

In the 21st century, the major diameter of the Great Red Spot has been observed to be shrinking. In 2004 its length was about half that of a century earlier, when it reached a size of {{convert|40,000|km|mi|abbr=on}}, about three times the diameter of Earth. At the present rate of reduction, it will become circular by 2040. 
[[File:Jupiter GRS Changes.png|thumb|A sequence of images of Jupiter showing the shrinking and rounding of the GRS, between 2021 and 2025. Captured with an 8" untracked Dobsonian telescope.]]
It is not known how long the spot will last, or whether the change is a result of periodic fluctuations.<ref>{{cite journal |last=Beatty |first=J. Kelly |year=2002 |title=Jupiter's Shrinking Red Spot |url=http://www.saburchill.com/HOS/astronomy/034.html |journal=Sky and Telescope |volume=103 |issue=4 |page=24 |bibcode=2002S&T...103d..24B |access-date=2007-06-21 |archive-date=2011-05-27 |archive-url=https://web.archive.org/web/20110527081602/http://www.saburchill.com/HOS/astronomy/034.html |url-status=dead }}</ref> In 2019, the spot began "flaking" at its edge, with fragments of the storm spinning off and dissipating.<ref name="disintegrating">{{cite web |author=Paul Scott Anderson |date=10 June 2019 |title=Is Jupiter's Great Red Spot disintegrating? |url=https://earthsky.org/space/is-jupiters-great-red-spot-disintegrating |access-date=2 July 2019 |publisher=EarthSky}}</ref> The shrinking and "flaking" fueled speculation from some astronomers that the spot could dissipate within decades.<ref>{{cite web |last1=Urrutia |first1=Doris Elin |title=Jupiter's Great Red Spot Could Disappear Within 20 Years |website=[[Space.com]] |date=21 February 2018 |url=https://www.space.com/39764-jupiter-great-red-spot-could-disappear.html |access-date=30 April 2023}}</ref> However, other astronomers believe the apparent size of the spot reflects its cloud coverage and not the size of the underlying vortex, and also that the flaking events can be explained by interactions with other cyclones or anticyclones, including incomplete absorptions of smaller systems; this might mean that the Great Red Spot is not in danger of dissipating.<ref name="may not">{{cite web |author=Philip Marcus |date=26 November 2019 |title=Jupiter's Great Red Spot may not be disappearing |url=https://astronomy.com/news/2019/11/jupiters-great-red-spot-is-not-disappearing |access-date=25 December 2020 |publisher=Astronomy}}</ref>

A smaller spot, designated [[Oval BA]], which formed in March 2000 from the merging of three white ovals,<ref>{{cite journal | url=https://www.sciencedirect.com/science/article/abs/pii/S0019103500965485 |first1=Agustín |last1=Sanchez-Lavega  |display-authors=etal |date=February 2001 |title=The Merger of Two Giant Anticyclones in the Atmosphere of Jupiter |journal=[[Icarus (journal)|Icarus]] |volume=149 |issue=2 |pages=491–495 |bibcode=2001Icar..149..491S |doi=10.1006/icar.2000.6548|url-access=subscription }}</ref> has turned reddish in color. Astronomers have named it the ''Little Red Spot'' or ''Red Jr''. As of 5 June 2006, the Great Red Spot and Oval BA appeared to be approaching convergence.<ref>{{cite web |last=Phillips |first=Tony |title=Huge Storms Converge |url=https://science.nasa.gov/headlines/y2006/05jun_redperil.htm |archive-url=https://web.archive.org/web/20070202190145/https://science.nasa.gov/headlines/y2006/05jun_redperil.htm |archive-date=2007-02-02 |access-date=2007-01-08 |publisher=Science@NASA}}</ref> The storms pass each other about every two years, but the passings of 2002 and 2004 were of little significance.{{cn|date=March 2025}} [[Amy Simon|Amy Simon-Miller]], of the [[Goddard Space Flight Center]], predicted the storms would have their closest passing on 4 July 2006.{{cn|date=March 2025}} She worked with [[Imke de Pater]] and Phil Marcus of [[University of California, Berkeley|UC Berkeley]] as well as a team of professional astronomers beginning in April 2006 to study the storms using the [[Hubble Space Telescope]]; on 20 July 2006, the two storms were photographed passing each other by the [[Gemini Observatory]] without converging.<ref>{{cite news |last=Michaud |first=Peter |title=Gemini Captures Close Encounter of Jupiter's Red Spots |publisher=Gemini Observatory |url=http://www.gemini.edu/index.php?option=content&task=view&id=196 |access-date=2007-06-15}}</ref> In May 2008, a third storm turned red.<ref>{{cite magazine |last=Shiga |first=David |title=Third red spot erupts on Jupiter |url=https://www.newscientist.com/article/dn13963-third-red-spot-erupts-on-jupiter/ |magazine=New Scientist |access-date=2008-05-23}}</ref>

The [[Juno (spacecraft)|''Juno'' spacecraft]], which entered into a polar orbit around Jupiter in 2016, flew over the Great Red Spot upon its close approach to Jupiter on 11 July 2017, taking several images of the storm from a distance of about {{convert|5000|mi|km|abbr=on|order=flip}} above the surface.<ref name="junospots"/><ref>{{cite web |last=Chang |first=Kenneth |date=2016-07-05 |title=NASA's Juno Spacecraft Enters Into Orbit Around Jupiter |url=https://www.nytimes.com/2016/07/05/science/juno-enters-jupiters-orbit-capping-5-year-voyage.html |access-date=2017-07-12 |website=[[The New York Times]]}}</ref> Over the duration of the ''Juno'' mission, the spacecraft continued to study the composition and evolution of Jupiter's atmosphere, especially its Great Red Spot.<ref name="junospots" />

The Great Red Spot should not be confused with the Great Dark Spot, a feature observed near the northern pole of Jupiter in 2000 with the ''[[Cassini–Huygens]]'' spacecraft.<ref>{{cite news |last=Phillips |first=Tony |title=The Great Dark Spot |publisher=Science at NASA |url=https://science.nasa.gov/headlines/y2003/12mar_darkspot.htm |access-date=2007-06-20 |archive-url=https://web.archive.org/web/20070615100054/https://science.nasa.gov/headlines/y2003/12mar_darkspot.htm |archive-date=2007-06-15}}</ref> There is also a feature in the atmosphere of [[Neptune]] called the [[Great Dark Spot]]. The latter feature was imaged by ''[[Voyager 2]]'' in 1989 and may have been an atmospheric hole rather than a storm.{{cn|date=March 2025}} It disappeared by 1994, although a similar spot had appeared farther to the north.{{cn|date=March 2025}}

==Mechanical dynamics==
[[File:790106-0203 Voyager 58M to 31M reduced.gif|thumb|upright=1.25|Time-lapse sequence from the approach of ''Voyager 1'' to Jupiter in 1979, showing the motion of atmospheric bands, and the circulation of the Great Red Spot. The momentary black spots are shadows cast by [[Moons of Jupiter|Jupiter's moons]].]]
Jupiter's Great Red Spot rotates counterclockwise, with a period of about 4.5 Earth days,<ref>{{cite journal |last1=Rogers |first1=John |title=The accelerating circulation of Jupiter's Great Red Spot |journal=Journal of the British Astronomical Association |date=2008 |volume=118 |issue=1 |pages=14–20 |bibcode=2008JBAA..118...14R |url=https://ui.adsabs.harvard.edu/abs/2008JBAA..118...14R/abstract |access-date=2022-08-28}}</ref> or 11 Jovian days, as of 2008. Measuring {{convert|16350|km|mi|abbr=on}} in width as of 3 April 2017, the Great Red Spot is 1.3 times the diameter of Earth. It has been shrinking for about a century, making it now slightly smaller than Earth.<ref name="junospots">{{Cite news|url=http://www.nasa.gov/feature/jpl/nasa-s-juno-spacecraft-spots-jupiter-s-great-red-spot|title=NASA's Juno Spacecraft Spots Jupiter's Great Red Spot|last=Perez|first=Martin|date=2017-07-12|work=NASA|access-date=2017-07-16|language=en|archive-date=2017-07-15|archive-url=https://web.archive.org/web/20170715181311/https://www.nasa.gov/feature/jpl/nasa-s-juno-spacecraft-spots-jupiter-s-great-red-spot/|url-status=dead}}</ref> The cloud-tops of this storm are about {{convert|8|km|mi|0|abbr=on}} above the surrounding cloud-tops.<ref>{{cite book |url=https://books.google.com/books?id=KuBYXLt4K9MC&pg=PA5 |title=The Voyager Mission: Jupiter, the Giant of the Solar System |date=1979 |publisher=NASA |page=5}}</ref> The storm has continued for centuries because there is no planetary surface (only a mantle of [[hydrogen]]) to cause friction; circulating atmospheric eddies persist because there is nothing to oppose their angular momentum.<ref>{{cite web |date=November 24, 2004 |title=Jupiter's Atmosphere and Great Red Spot |url=http://www.astrophysicsspectator.com/topics/planets/JupiterGreatRedSpot.html |publisher=www.astrophysicsspectator.com}}</ref>

[[Infrared]] data has long indicated that the Great Red Spot is colder (and thus higher in altitude) than most of the other clouds on the planet.{{sfnp|Rogers|1995|p=191}} The upper atmosphere above the storm, however, has substantially higher temperatures than the rest of the planet.{{cn|date=March 2025}} [[Acoustic wave|Acoustic waves]] rising from the turbulence of the storm below have been proposed as an explanation for the heating of this region.<ref name="Heating of Jupiter's upper atmosphere">{{cite journal |last1=O'Donoghue |first1=J. |last2=Moore |first2=L. |last3=Stallard |first3=T. S. |last4=Melin |first4=H. |title=Heating of Jupiter's upper atmosphere above the Great Red Spot |journal=Nature |date=27 July 2016 |volume=536 |issue=7615 |pages=190–192 |doi=10.1038/nature18940|pmid=27462811 |bibcode=2016Natur.536..190O |hdl=2381/38554 |s2cid=4462322 |url=https://figshare.com/articles/journal_contribution/10122821 |hdl-access=free }}</ref> The acoustic waves travel vertically up to a height of {{cvt|800|km}} above the storm where they break in the upper atmosphere, converting wave energy into heat. This creates a region of upper atmosphere that is {{convert|1600|K}}—several hundred kelvins warmer than the rest of the planet at this altitude.<ref name="Heating of Jupiter's upper atmosphere" /> The effect is described as like "crashing [...] ocean waves on a beach".<ref>{{cite web |date=27 July 2016 |title=Jupiter's Great Red Spot Likely a Massive Heat Source |url=https://www.nasa.gov/feature/jupiter-s-great-red-spot-likely-a-massive-heat-source |access-date=23 December 2018 |website=[[NASA]] |archive-date=12 June 2019 |archive-url=https://web.archive.org/web/20190612134857/https://www.nasa.gov/feature/jupiter-s-great-red-spot-likely-a-massive-heat-source/ |url-status=dead }}</ref>

[[File:Jupiter, Earth size comparison.jpg|left|thumb|upright=1.2|Size of the Earth compared to the Great Red Spot]]
Careful tracking of atmospheric features revealed the Great Red Spot's counterclockwise circulation as far back as 1966, observations dramatically confirmed by the first time-lapse movies from the ''Voyager'' fly-bys.{{sfnp|Rogers|1995|pp=194–196}} The spot is confined by a modest eastward [[jet stream]] to its south and a very strong westward one to its north.{{sfnp|Beebe|1997|p=35}} Though winds around the edge of the spot peak at about {{convert|432|km/h|mph|abbr=on}}, currents inside it seem stagnant, with little inflow or outflow.{{sfnp|Rogers|1995|p=195}} The rotation of the spot has slowed with time, perhaps as a direct result of its steady reduction in size.<ref>{{cite web |last=Rogers |first=John |url=http://www.britastro.org/jupiter/2006report09.htm |title=Interim reports on STB (Oval BA passing GRS), STropB, GRS (internal rotation measured), EZ(S. Eq. Disturbance; dramatic darkening; NEB interactions), & NNTB |publisher=[[British Astronomical Association]] |access-date=2007-06-15 }}</ref>

The Great Red Spot's [[latitude]] has been stable for the duration of good observational records, typically varying by about a degree. Its [[longitude]], however, is subject to constant variation, including a 90-day longitudinal oscillation with an amplitude of ~1°.<ref>{{cite journal|author1=Reese, Elmer J.|author2=Solberg, H. Gordon|year=1966|title=Recent measures of the latitude and longitude of Jupiter's red spot|journal=Icarus|volume=5|issue=1–6|pages=266–273|bibcode=1966Icar....5..266R|doi=10.1016/0019-1035(66)90036-4|hdl-access=free|hdl=2060/19650022425}}<!--|access-date=2007-06-20 --></ref>{{sfnp|Rogers|1995|pp=192–193}}<ref>{{Cite journal |last1=Trigo-Rodriguez |first1=J.M |last2=Sánchez-Lavega |first2=A |last3=Gómez |first3=J.M |last4=Lecacheux |first4=J |last5=Colas |first5=F |last6=Miyazaki |first6=I |date=2000 |title=The 90-day oscillations of Jupiter's Great Red Spot revisited |url=https://linkinghub.elsevier.com/retrieve/pii/S0032063300000027 |journal=Planetary and Space Science |language=en |volume=48 |issue=4 |pages=331–339 |doi=10.1016/S0032-0633(00)00002-7|bibcode=2000P&SS...48..331T |s2cid=120883365 |url-access=subscription }}</ref> Because Jupiter's gaseous body does not rotate uniformly at all latitudes, astronomers have defined three different systems for defining longitude. System II is used for latitudes of more than 10 degrees and was originally based on the average rotational period of the Great Red Spot ({{nowrap|9 h 55 min 42 s}}).<ref>{{cite journal |last=Stone |first=Peter H. |title=On Jupiter's Rate of Rotation |journal=Journal of the Atmospheric Sciences |year=1974 |volume=31 |issue=5 |pages=1471–1472 |url=http://ams.allenpress.com/archive/1520-0469/31/5/pdf/i1520-0469-31-5-1471.pdf |access-date=2007-06-20 |doi=10.1175/1520-0469(1974)031<1471:OJROR>2.0.CO;2 |bibcode=1974JAtS...31.1471S}}</ref>{{sfnp|Rogers|1995|pp=48, 193}} Despite this, however, the spot has "lapped" the planet in System II at least 10 times since the early 19th century.{{cn|date=March 2025}} Its drift rate has changed dramatically over the years and has been linked to the brightness of the [[South Equatorial Belt]] and the presence or absence of a South Tropical Disturbance.{{sfnp|Rogers|1995|p=193}}

== Internal depth and structure ==
[[File:Telescopes and Spacecraft Join Forces to Probe Deep into Jupiter's Atmosphere (49892941386).png|thumb|400x400px|Clockwise from top left: [[Hubble Space Telescope|Hubble]] image of [[visible spectrum]]; [[infrared]] from the [[Gemini Observatory]];
multiwavelength composite of Hubble and Gemini data showing visible light in blue and thermal infrared in red; [[ultraviolet]] image from Hubble; visible light detail <ref>{{cite journal |last1=Wong |first1=Michael H. |last2=Simon |first2=Amy A. |last3=Tollefson |first3=Joshua W. |last4=de Pater |first4=Imke |last5=Barnett |first5=Megan N. |last6=Hsu |first6=Andrew I. |last7=Stephens |first7=Andrew W. |last8=Orton |first8=Glenn S. |last9=Fleming |first9=Scott W. |last10=Goullaud |first10=Charles |last11=Januszewski |first11=William |last12=Roman |first12=Anthony |last13=Bjoraker |first13=Gordon L. |last14=Atreya |first14=Sushil K. |last15=Adriani |first15=Alberto |last16=Fletcher |first16=Leigh N. |title=High-resolution UV/Optical/IR Imaging of Jupiter in 2016–2019 |journal=The Astrophysical Journal Supplement Series |date=1 April 2020 |volume=247 |issue=2 |pages=58 |doi=10.3847/1538-4365/ab775f|doi-access=free |bibcode=2020ApJS..247...58W }}</ref>]]
Jupiter's Great Red Spot (GRS) is an elliptical-shaped anticyclone, occurring at 22 degrees below the equator, in Jupiter's southern hemisphere.<ref name="gas-composition">{{Cite journal |last1=Bjoraker |first1=G. L. |last2=Wong |first2=M. H. |last3=Pater |first3=I. de |last4=Hewagama |first4=T. |last5=Ádámkovics |first5=M. |last6=Orton |first6=G. S. |date=2018-08-20 |title=The Gas Composition and Deep Cloud Structure of Jupiter's Great Red Spot |journal=The Astronomical Journal |volume=156 |issue=3 |page=101 |doi=10.3847/1538-3881/aad186 |arxiv=1808.01402 |bibcode=2018AJ....156..101B |s2cid=119365729 |issn=1538-3881 |doi-access=free }}</ref> The largest [[Anticyclone|anticyclonic]] storm ({{nowrap|~16,000 km}}) in the [[Solar System]], little is known about its internal depth and structure.<ref name="depth-grs-juno">{{Cite journal |last1=Parisi |first1=Marzia |last2=Kaspi |first2=Yohai |last3=Galanti |first3=Eli |last4=Durante |first4=Daniele |last5=Bolton |first5=Scott J. |last6=Levin |first6=Steven M. |last7=Buccino |first7=Dustin R. |last8=Fletcher |first8=Leigh N. |last9=Folkner |first9=William M. |last10=Guillot |first10=Tristan |last11=Helled |first11=Ravit |date=2021-11-19 |title=The depth of Jupiter's Great Red Spot constrained by Juno gravity overflights |url=https://www.science.org/doi/10.1126/science.abf1396 |journal=Science |language=en |volume=374 |issue=6570 |pages=964–968 |doi=10.1126/science.abf1396 |pmid=34709940 |bibcode=2021Sci...374..964P |s2cid=240153766 |issn=0036-8075|hdl=11573/1605351 |hdl-access=free }}</ref> Visible imaging and cloud-tracking from [[In situ|in-situ]] observation determined the velocity and vorticity of the GRS, which is located in a thin anticyclonic ring at 70–85% of the radius and is located along Jupiter's fastest westward moving jet stream.<ref name="thermal-structure">{{Cite journal |last1=Fletcher |first1=Leigh N. |last2=Orton |first2=G. S. |last3=Mousis |first3=O. |last4=Yanamandra-Fisher |first4=P. |last5=Parrish |first5=P. D. |last6=Irwin |first6=P. G. J. |last7=Fisher |first7=B. M. |last8=Vanzi |first8=L. |last9=Fujiyoshi |first9=T. |last10=Fuse |first10=T. |last11=Simon-Miller |first11=A. A. |date=2010-07-01 |title=Thermal structure and composition of Jupiter's Great Red Spot from high-resolution thermal imaging |url=https://www.sciencedirect.com/science/article/pii/S0019103510000084 |journal=Icarus |language=en |volume=208 |issue=1 |pages=306–328 |doi=10.1016/j.icarus.2010.01.005 |bibcode=2010Icar..208..306F |issn=0019-1035|url-access=subscription |hdl=10533/144286 |hdl-access=free }}</ref> During NASA's 2016 [[Juno (spacecraft)|''Juno'']] mission, gravity signature and thermal infrared data were obtained that offered insight into the structural dynamics and depth of the GRS.<ref name="velocity-vorticity">{{Cite journal |last1=Choi |first1=David S. |last2=Banfield |first2=Don |last3=Gierasch |first3=Peter |last4=Showman |first4=Adam P. |date=2007-05-01 |title=Velocity and vorticity measurements of Jupiter's Great Red Spot using automated cloud feature tracking |url=https://www.sciencedirect.com/science/article/pii/S0019103506004179 |journal=Icarus |language=en |volume=188 |issue=1 |pages=35–46 |doi=10.1016/j.icarus.2006.10.037 |arxiv=1301.6119 |bibcode=2007Icar..188...35C |s2cid=55114257 |issn=0019-1035}}</ref><ref name="depth-grs-juno"/><ref name="thermal-structure"/> During July 2017, the ''Juno'' spacecraft conducted a second pass of the GRS to collect [[Microwave Radiometer (Juno)|Microwave Radiometer]] (MWR) scans of the GRS to determine how far the GRS extended toward the surface of the condensed {{chem|H|2|O}} layer.<ref name="depth-grs-juno"/> These MWR scans suggested that the GRS vertical depth extended to about {{nowrap|240 km}} below cloud level, with an estimated drop in atmospheric pressure to {{nowrap|100 bar}}.<ref name="depth-grs-juno"/><ref name="thermal-structure"/> Two methods of analysis that constrain the data collected were the [[mascon]] approach, which found a depth of {{nowrap|~290 km}}, and the Slepian approach showing wind extending to {{nowrap|~310 km}}.<ref name="depth-grs-juno"/> These methods, along with gravity signature MWR data, suggest that the GRS zonal winds still increase at a rate of 50% of the velocity of the viable cloud level, before the wind decay starts at lower levels. This rate of wind decay and gravity data suggest the depth of the GRS is between 200 and {{nowrap|500 km}}.<ref name="depth-grs-juno"/>

[[Galileo (spacecraft)|Galileo]] and [[Cassini–Huygens|Cassini's]] thermal infrared imaging and [[spectroscopy]] of the GRS were conducted during 1995–2008, in order to find evidence of thermal inhomogeneities within the internal structure vortex of the GRS.<ref name="thermal-structure"/> Previous thermal infrared temperature maps from the [[Voyager program|Voyager]], Galileo, and Cassini missions suggested the GRS is a structure of an anticyclonic vortex with a cold core within a upwelling warmer annulus; this data shows a gradient in the temperature of the GRS.<ref name="gas-composition"/><ref name="thermal-structure"/> Better understanding of Jupiter's atmospheric temperature, aerosol particle opacity, and ammonia gas composition was provided by thermal-IR imaging: a direct correlation of the visible cloud layers reactions, thermal gradient and compositional mapping to observational data were collected over decades.<ref name="gas-composition"/><ref name="thermal-structure"/> During December 2000, high spatial resolution images from Galileo, of an atmospheric turbulent area to the northwest of the GRS, showed a thermal contrast between the warmest region of the anticyclone and regions to the east and west of the GRS.<ref name="thermal-structure"/><ref>{{Cite journal |last1=Sánchez-Lavega |first1=A. |last2=Hueso |first2=R. |last3=Eichstädt |first3=G. |last4=Orton |first4=G. |last5=Rogers |first5=J. |last6=Hansen |first6=C. J. |last7=Momary |first7=T. |last8=Tabataba-Vakili |first8=F. |last9=Bolton |first9=S. |date=2018-09-18 |title=The Rich Dynamics of Jupiter's Great Red Spot from JunoCam: Juno Images |journal=The Astronomical Journal |volume=156 |issue=4 |page=162 |doi=10.3847/1538-3881/aada81 |bibcode=2018AJ....156..162S |s2cid=125185665 |issn=1538-3881|doi-access=free }}</ref>

[[File:Winds in Jupiter’s Great Red Spot.jpg|left|thumb|400x400px|Winds in the Great Red Spot as analyzed from Hubble's data. In the false-color image at right, red indicates faster wind, blue indicates slower.<ref>{{cite journal |last1=Wong |first1=Michael H. |last2=Marcus |first2=Philip S. |last3=Simon |first3=Amy A. |last4=de Pater |first4=Imke |last5=Tollefson |first5=Joshua W. |last6=Asay-Davis |first6=Xylar |title=Evolution of the Horizontal Winds in Jupiter's Great Red Spot From One Jovian Year of HST/WFC3 Maps |journal=Geophysical Research Letters |date=28 September 2021 |volume=48 |issue=18 |doi=10.1029/2021GL093982|bibcode=2021GeoRL..4893982W }}</ref>]]
The vertical temperature{{clarify|date=March 2025}} of the structure of the GRS is constrained to be between 100 and {{nowrap|600 mbar}}, with the vertical temperature{{clarify|date=March 2025}} of the GRS core at approximately {{nowrap|400 mbar}} of pressure{{clarify|date=May 2023}} being {{nowrap|1.0–1.5 K}}, much warmer than regions of the GRS to the east–west, and {{nowrap|3.0–3.5 K}} warmer than regions to the north–south of the structure's edge.{{clarify|date=March 2025}}{{Fix|text=This seems to imply that the latter are below absolute zero!}}<ref name="thermal-structure"/> This structure is consistent with the data collected by the VISIR (VLT Mid-Infrared Imager Spectrometer on the ESO Very Large Telescope) imaging obtained in 2006; this revealed that the GRS was physically present at a wide range of altitudes that occur within the atmospheric pressure range of {{nowrap|80–600 mbar}}, and confirms the thermal infrared mapping result.<ref name="thermal-structure"/><ref name="velocity-vorticity"/><ref>{{Cite journal |last1=Simon |first1=Amy A. |last2=Tabataba-Vakili |first2=Fachreddin |last3=Cosentino |first3=Richard |last4=Beebe |first4=Reta F. |last5=Wong |first5=Michael H. |last6=Orton |first6=Glenn S. |date=2018-03-13 |title=Historical and Contemporary Trends in the Size, Drift, and Color of Jupiter's Great Red Spot |journal=The Astronomical Journal |volume=155 |issue=4 |page=151 |doi=10.3847/1538-3881/aaae01 |bibcode=2018AJ....155..151S |s2cid=126147959 |issn=1538-3881|doi-access=free }}</ref> To develop a model of the internal structure of the GRS, the Cassini instrument Composite [[Infrared spectroscopy|Infrared Spectrometer]] (CIRS) and ground based spatial imaging mapped the composition of the [[phosphine]] and [[ammonia]] aerosols ({{chem|PH|3}}, {{chem|NH|3}}) and [[para-hydroxybenzoic acid]] within the anticyclonic circulation of the GRS.<ref name="thermal-structure"/><ref>{{Cite journal |last1=Cho |first1=James Y-K. |last2=de la Torre Juárez |first2=Manuel |last3=Ingersoll |first3=Andrew P. |last4=Dritschel |first4=David G. |date=2001-03-25 |title=A high-resolution, three-dimensional model of Jupiter's Great Red Spot |journal=Journal of Geophysical Research: Planets |language=en |volume=106 |issue=E3 |pages=5099–5105 |doi=10.1029/2000JE001287|bibcode=2001JGR...106.5099C |doi-access=free }}</ref> The images that were collected from the CIRS and ground-based imaging trace the vertical motion in the Jovian atmosphere by {{chem|PH|3}} and {{chem|NH|3}} spectra.<ref name="gas-composition"/><ref name="thermal-structure"/>

The highest concentrations of {{chem|PH|3}} and {{chem|NH|3}} were found to the north of the GRS peripheral rotation. They aided in determining the southward jet movement and showed evidence of an increase in altitude of the column of aerosols with pressures ranging from {{nowrap|200–500 mbar}}.<ref name="thermal-structure"/><ref>{{Cite journal |last1=Morales-Juberías |first1=Raúl |last2=Dowling |first2=Timothy E. |date=2013-07-01 |title=Jupiter's Great Red Spot: Fine-scale matches of model vorticity patterns to prevailing cloud patterns |url=https://www.sciencedirect.com/science/article/pii/S0019103513001425 |journal=Icarus |language=en |volume=225 |issue=1 |pages=216–227 |doi=10.1016/j.icarus.2013.03.026 |bibcode=2013Icar..225..216M |issn=0019-1035|url-access=subscription }}</ref> However, the {{chem|NH|3}} composition data shows that there is a major depletion of {{chem|NH|3}} below the visible cloud layer at the southern peripheral ring of the GRS; this lower opacity is relative to a narrow band of atmospheric subsidence.<ref name="thermal-structure"/> The low mid-IR aerosol opacity, along with the temperature gradients, the altitude difference, and the vertical movement of the zonal winds, are involved with the development and sustainability of the vorticity.<ref name="thermal-structure"/> The stronger atmospheric [[subsidence]] and compositional asymmetries of the GRS suggest that the structure exhibits a degree of tilt from the northern edge to the southern edge of the structure.<ref name="thermal-structure"/><ref>{{Cite journal |last1=Flasar |first1=F. Michael |last2=Conrath |first2=Barney J. |last3=Pirraglia |first3=Joseph A. |last4=Clark |first4=Patrick C. |last5=French |first5=Richard G. |last6=Gierasch |first6=Peter J. |date=1981-09-30 |title=Thermal structure and dynamics of the Jovian atmosphere 1. The great red spot |url=http://doi.wiley.com/10.1029/JA086iA10p08759 |journal=Journal of Geophysical Research: Space Physics |language=en |volume=86 |issue=A10 |pages=8759–8767 |doi=10.1029/JA086iA10p08759|bibcode=1981JGR....86.8759F |hdl=2060/19810016481 |hdl-access=free }}</ref> The GRS depth and internal structure has been constantly changing over decades;<ref name="depth-grs-juno"/> however there is still no logical reason that it is {{nowrap|200–500 km}} in depth, but the jet streams that supply the force that powers the GRS vortex are well below the structure base.<ref name="depth-grs-juno"/><ref name="thermal-structure"/>

==Color and composition==
It is not known what causes the Great Red Spot's reddish color. Hypotheses supported by laboratory experiments suppose that it may be caused by chemical products created by the solar ultraviolet irradiation of [[ammonium hydrosulfide]]<ref>{{cite web|url=https://www.nasa.gov/feature/goddard/jupiter-s-great-red-spot-a-swirling-mystery|title=Jupiter's Great Red Spot: A Swirling Mystery|publisher=[[NASA]]|quote=[[Goddard Institute for Space Studies|Goddard]] scientists Mark Loeffler and Reggie Hudson have been performing laboratory studies to investigate whether cosmic rays, one type of radiation that strikes Jupiter's clouds, can chemically alter ammonium hydrosulfide to produce new compounds that could explain the spot's color. |date=August 4, 2015}}</ref> and the organic compound [[acetylene]], which produces a reddish material—likely complex organic compounds called [[tholin]]s.<ref name="Hudson2018">{{cite journal |last1=Loeffer |first1=Mark J. |last2=Hudson |first2=Reggie L. |title=Coloring Jupiter's clouds: Radiolysis of ammonium hydrosulfide (NH4SH) |journal=Icarus |year=2018 |volume=302 |pages=418–425 |doi=10.1016/j.icarus.2017.10.041|bibcode=2018Icar..302..418L }}</ref> The high altitude of the compounds may also contribute to the coloring.<ref name="EarthSky">{{cite web |title=What makes Jupiter's Red Spot red? |date=2014-11-11 |url=https://earthsky.org/space/what-makes-jupiters-red-spot-red |access-date=2019-03-13 |publisher=[[EarthSky]]}}</ref>

The Great Red Spot varies greatly in hue, from almost brick-red to pale salmon or even white. The spot occasionally disappears, becoming evident only through the Red Spot Hollow, which is its location in the [[South Equatorial Belt]] (SEB). Its visibility is apparently coupled to the SEB: when the belt is bright white, the spot tends to be dark, and when it is dark, the spot is usually light. These periods when the spot is dark or light occur at irregular intervals: between 1947 and 1997, the spot was darkest in the periods 1961–1966, 1968–1975, 1989–1990, and 1992–1993.{{sfnp|Beebe|1997|pp=38–41}}

==See also==
{{portal|Solar System}}
* [[Extraterrestrial vortex]]
* [[Great Dark Spot]]
* [[Great White Spot]], a similar storm on [[Saturn]]
* [[Hypercane]]
* [[WISEP J190648.47+401106.8]]

==References==
{{Reflist|refs=
<ref name="Sánchez-Lavega2024">{{cite journal |last1=Sánchez-Lavega |first1=Agustín |last2=García-Melendo |first2=Enrique |last3=Legarreta |first3=Jon |last4=Miró |first4=Arnau |last5=Soria |first5=Manel |last6=Ahrens-Velásquez |first6=Kevin |date=June 2024 |title=The Origin of Jupiter's Great Red Spot |journal=[[Geophysical Research Letters]] |volume=51 |issue=12 |pages= |doi=10.1029/2024GL108993 |arxiv=2406.13222|bibcode=2024GeoRL..5108993S }}</ref>
}}

==Further reading==
*{{cite book
 |url=https://archive.org/details/newsolarsystem0000unse_z6a8
 |url-access=registration
 |author=[Numerous authors]
 |editor1=Beatty, Kelly J.
 |editor2=Peterson, Carolyn Collins
 |editor3=Chaiki, Andrew
 |year=1999
 |title=The New Solar System
 |edition=4th
 |publisher=Sky Publishing Corporation
 |location=Massachusetts
 |isbn=978-0-933346-86-4
}}
*{{cite book
 |url=https://archive.org/details/jupitergiantplan00beeb_0
 |url-access=registration
 |first=Reta |last=Beebe
 |year=1997
 |title=Jupiter the Giant Planet
 |edition=2nd
 |publisher=Smithsonian Books
 |location=Washington
 |isbn=978-1-56098-685-0
}}
*{{cite book
 |first=Thomas |last=Hockey
 |year=1999
 |title=Galileo's Planet: Observing Jupiter Before Photography
 |publisher=IOP Publishing
 |location=Bristol, Philadelphia
 |isbn=978-0-7503-0448-1
}}
*{{cite book
 |first=Bertrand M.
 |last=Peek
 |author-link=Bertrand Meigh Peek
 |year=1981
 |title=The Planet Jupiter: The Observer's Handbook
 |edition=Revised
 |publisher=Faber and Faber Limited
 |location=London
 |isbn=978-0-571-18026-4
 |url-access=registration
 |url=https://archive.org/details/planetjupiter00peek
 }}
*{{cite book
 |first=John H. |last=Rogers
 |year=1995
 |title=The Giant Planet Jupiter
 |publisher=Cambridge University Press
 |location=Cambridge
 |isbn=978-0-521-41008-3
}}
*{{cite journal
 |last=Smith |first=B. A.
 |display-authors=etal
 |year=1979
 |title=The Jupiter system through the eyes of Voyager 1
 |journal=Science
 |volume=204 |issue=4396|pages=951–957, 960–972
 |bibcode=1979Sci...204..951S
 |doi=10.1126/science.204.4396.951
 |pmid=17800430
|s2cid=33147728
 }}

==External links==
{{Commons category|Great Red Spot}}
* {{cite news
 |first=Sarah |last=Yang
 |title=Researcher predicts global climate change on Jupiter as giant planet's spots disappear
 |publisher=UC Berkeley News |date=April 21, 2004
 |url=http://www.berkeley.edu/news/media/releases/2004/04/21_jupiter.shtml
 |access-date=2007-06-14
}}
* {{cite news
 |first=Tony 
 |last=Phillips 
 |title=Jupiter's New Red Spot 
 |publisher=Science at NASA 
 |date=March 3, 2006 
 |url=https://science.nasa.gov/headlines/y2006/02mar_redjr.htm 
 |access-date=2007-06-14 
 |archive-url=https://web.archive.org/web/20081019024917/https://science.nasa.gov/headlines/y2006/02mar_redjr.htm 
 |archive-date=October 19, 2008 
}}
* {{cite news |first=Tony |last=Phillips |title=Huge Storms Converge |publisher=Science at NASA |date=June 5, 2006 |url=https://science.nasa.gov/headlines/y2006/05jun_redperil.htm?list56685 |access-date=2007-06-14 |archive-url=https://web.archive.org/web/20070505203040/http://science.nasa.gov/headlines/y2006/05jun_redperil.htm?list56685 |archive-date=May 5, 2007 |df=mdy-all }}
*{{cite journal
 |author1=Youssef, Ashraf
 |author2=Marcus, Philip S.
 |year=2003
 |title=The dynamics of jovian white ovals from formation to merger
 |journal=Icarus
 |volume=162 |issue=1 |pages=74–93
 |bibcode=2003Icar..162...74Y
 |doi=10.1016/S0019-1035(02)00060-X
}}
* {{cite web
 |last=Williams |first=Gareth P.
 |date=May 4, 2005
 |url=http://www.gfdl.noaa.gov/~gw
 |title=NOAA Web Page
 |publisher=Geophysical Fluid Dynamics Laboratory
 |access-date=2007-07-21
}}
* [https://www.flickr.com/photos/136797589@N04/35790218312/in/photostream/ Video based on Juno's Perijove 7 overflight] by Seán Doran (see [https://www.flickr.com/photos/136797589@N04/albums/72157684110532315 album] for more)

{{Jupiter}}
[[Category:1664 in science]]
[[Category:1831 in science]]
[[Category:Jupiter]]
[[Category:Planetary spots]]
[[Category:Anticyclones]]
[[Category:Vortices]]
[[Category:Storms]]
[[Category:Robert Hooke]]