Editing Cassini–Huygens (section)

== Selected events and discoveries ==
{{Main|Cassini–Huygens timeline}}
[[File:Animation of Cassini trajectory.gif|thumb|right|Animation of ''Cassini''{{'s}} trajectory from October 15, 1997, to May 4, 2008. {{hlist|{{legend2|magenta|''Cassini–Huygens''}}|{{legend2|Gold|[[Jupiter]]}}|{{legend2|lime|[[Saturn]]}}|{{legend2|Royalblue|[[Earth]]}}|{{legend2|Cyan|[[Venus]]}}|{{legend2| OrangeRed| 2685 Masursky}}}}]]
[[File:Animation of Cassini trajectory around Saturn.gif|thumb|right|Animation of '' Cassini''{{'s}} trajectory around Saturn from May 1, 2004, to September 15, 2017.{{hlist|{{legend2|magenta|'' Cassini''}}|{{legend2| Lime |[[Saturn]]}}|{{legend2|OrangeRed|[[Enceladus]]}}|{{legend2| Gold |[[Titan (moon)|Titan]]}}|{{legend2|Cyan|[[Iapetus (moon)|Iapetus]]}}}}]]

=== Venus and Earth fly-bys and the cruise to Jupiter ===
[[File:Fullbl.jpg|thumb|Picture of the [[Moon]] during flyby]]

The ''Cassini'' space probe performed two [[gravity assist|gravitational-assist flybys]] of [[Venus]] on April 26, 1998, and June 24, 1999. These flybys provided the space probe with enough momentum to travel all the way out to the [[asteroid belt]], while the Sun's gravity pulled the space probe back into the inner Solar System.

On August 18, 1999, at 03:28&nbsp;UTC, the craft made a gravitational-assist flyby of the Earth. One hour and 20&nbsp;minutes before closest approach, ''Cassini'' made its closest approach to the Earth's Moon at 377,000 kilometers, and it took a series of calibration photos.

On January 23, 2000, ''Cassini'' performed a flyby of the [[asteroid]] [[2685 Masursky]] at around 10:00 UTC. It took photos<ref name=NASA-20000211/> in the period five to seven hours before the flyby at a distance of {{cvt|1.6|e6km|e6mi}} and a diameter of {{cvt|15|to|20|km|mi}} was estimated for the asteroid.

=== Jupiter flyby ===
{{more citations needed|section|date=October 2018}}<!--only first paragraph has a citation-->
[[File:Portrait of Jupiter from Cassini.jpg|thumb|right|A [[Jupiter]] flyby picture]]
''Cassini'' made its closest approach to Jupiter on December 30, 2000, at 9.7 million kilometers, and made many scientific measurements. About 26,000 images of Jupiter, its [[Jupiter's rings|faint rings]], and its [[Jupiter's moons|moons]] were taken during the six-month flyby. It produced the most detailed global color portrait of the planet yet (see image at right), in which the smallest visible features are approximately {{convert|60|km|mi|abbr=on}} across.<ref name=Hansen_2004/>

[[File:PIA02879 - A New Year for Jupiter and Io.jpg|thumb|left|''Cassini'' photographed Io [[Transit (astronomy)|transiting]] Jupiter on January 1, 2001.]]
A major finding of the flyby, announced on March 6, 2003, was of Jupiter's atmospheric circulation. Dark "belts" alternate with light "zones" in the atmosphere, and scientists had long considered the zones, with their pale clouds, to be areas of upwelling air, partly because many clouds on Earth form where air is rising. But analysis of ''Cassini'' imagery showed that individual storm cells of upwelling bright-white clouds, too small to see from Earth, pop up almost without exception in the dark belts. According to [[Anthony Del Genio]] of NASA's [[Goddard Institute for Space Studies]], "the belts must be the areas of net-rising atmospheric motion on Jupiter, [so] the net motion in the zones has to be sinking".

Other atmospheric observations included a swirling dark oval of high atmospheric haze, about the size of the [[Great Red Spot]], near Jupiter's north pole. Infrared imagery revealed aspects of circulation near the poles, with bands of globe-encircling winds, with adjacent bands moving in opposite directions.

The same announcement also discussed the nature of Jupiter's [[planetary ring|rings]]. Light scattering by particles in the rings showed the particles were irregularly shaped (rather than spherical) and likely originate as ejecta from [[micrometeorite]] impacts on Jupiter's moons, probably [[Metis (moon)|Metis]] and [[Adrastea (moon)|Adrastea]].

=== Tests of general relativity ===

On October 10, 2003, the mission's science team announced the results of tests of [[Albert Einstein]]'s [[general theory of relativity]], performed by using [[radio wave]]s transmitted from the ''Cassini'' space probe.<ref name=Bertotti_2003/> The radio scientists measured a [[frequency]] shift in the radio waves to and from the spacecraft, as they passed close to the Sun. According to the general theory of relativity, a massive object like the [[Sun]] causes [[space-time]] to curve, causing a beam of radiowaves travelling out of its [[gravitational well]] to decrease in [[frequency]] and radiowaves travelling into the gravitational well to increase in frequency, referred to as [[gravitational redshift]] / blueshift.

Although some measurable deviations from the values calculated using the [[general theory of relativity]] are predicted by some unusual cosmological models, no such deviations were found by this experiment. Previous tests using radiowaves transmitted by the ''Viking'' and ''Voyager'' space probes were in agreement with the calculated values from general relativity to within an accuracy of one part in one thousand. The more refined measurements from the ''Cassini'' space probe experiment improved this accuracy to about one part in 51,000.{{efn|This is currently the best measurement of [[Parameterized post-Newtonian formalism|post-Newtonian parameter]] ''γ''; the result ''γ'' {{=}} 1 + (2.1 ± 2.3) × 10<sup>−5</sup> agrees with the prediction of standard General Relativity, ''γ'' {{=}} 1|name=post-newton}} The data firmly support Einstein's general theory of relativity.<ref name=Dume_2003/>

=== New moons of Saturn ===
[[File:PIA18078-PossibleBeginning-NewMoonOfPlanetSaturn-20130415.jpg|thumb|right|The possible formation of a new [[Natural satellite|moon]] was captured on April 15, 2013.]]
In total, the ''Cassini'' mission discovered seven new moons orbiting Saturn.{{sfn|Meltzer|2015|pp=346–351}} Using images taken by ''Cassini'', researchers discovered [[Methone (moon)|Methone]], [[Pallene (moon)|Pallene]] and [[Polydeuces (moon)|Polydeuces]] in 2004,<ref name=bbc6/> although [[precovery|later analysis]] revealed that [[Voyager 2]] had photographed Pallene in its 1981 flyby of the ringed planet.<ref name=Spitale_2006/>

[[File:Moon Daphnis S2005 S1.jpg|thumb|left|Discovery photograph of moon [[Daphnis (moon)|Daphnis]] ]]
On May 1, 2005, a new moon was discovered by ''Cassini'' in the [[Keeler gap]]. It was given the designation S/2005&nbsp;S&nbsp;1 before being named [[Daphnis (moon)|Daphnis]]. A fifth new moon was discovered by ''Cassini'' on May 30, 2007, and was provisionally labeled S/2007 S 4. It is now known as [[Anthe (moon)|Anthe]]. A press release on February 3, 2009, showed a sixth new moon found by ''Cassini''. The moon is approximately {{convert|500|m|mi|1|abbr=on}} in diameter within the G-ring of the ring system of Saturn, and is now named [[Aegaeon (moon)|Aegaeon]] (formerly S/2008 S 1).<ref name=NBC1/> A press release on November 2, 2009, mentions the seventh new moon found by ''Cassini'' on July 26, 2009. It is presently labeled [[S/2009 S 1]] and is approximately {{cvt|300|m|ft}} in diameter in the B-ring system.<ref name=ciclops.iau-circular9091/>

On April 14, 2014, NASA scientists reported the possible beginning of a new moon in Saturn's [[A Ring]].<ref name=NASA-20140414/>

=== Phoebe flyby ===
[[File:Phoebe arrival and departure mosaics.jpg|thumb|upright=1.364|''Cassini'' arrival (left) and departure mosaics of [[Phoebe (moon)|Phoebe]] (2004)]]

On June 11, 2004, ''Cassini'' flew by the moon [[Phoebe (moon)|Phoebe]].  This was the first opportunity for close-up studies of this moon ([[Voyager 2]] performed a distant flyby in 1981 but returned no detailed images). It also was ''Cassini's'' only possible flyby for Phoebe due to the mechanics of the available orbits around Saturn.<ref name=Porco_2005/>

The first close-up images were received on June 12, 2004, and mission scientists immediately realized that the surface of Phoebe looks different from asteroids visited by spacecraft. Parts of the heavily cratered surface look very bright in those pictures, and it is currently believed that a large amount of water ice exists under its immediate surface.

=== Saturn rotation ===
In an announcement on June 28, 2004, ''Cassini'' program scientists described the measurement of the rotational period of Saturn.<ref name=NASA-20040627/> Because there are no fixed features on the surface that can be used to obtain this period, the repetition of radio emissions was used. This new data agreed with the latest values measured from Earth, and constituted a puzzle to the scientists. It turns out that the radio rotational period had changed since it was first measured in 1980 by ''[[Voyager 1]]'', and it was now 6 minutes longer. This, however, does not indicate a change in the overall spin of the planet. It is thought to be due to variations in the upper atmosphere and ionosphere at the latitudes which are magnetically connected to the radio source region.<ref name=Chowhury_2022/>

In 2019 NASA announced Saturn's rotational period as 10 hours, 33 minutes, 38 seconds, calculated using Saturnian ring seismology. Vibrations from Saturn's interior cause oscillations in its gravitational field. This energy is absorbed by ring particles in specific locations, where it accumulates until it is released in a wave.<ref name=NASA-20190118/> Scientists used data from more than 20 of these waves to construct a family of models of Saturn's interior, providing basis for calculating its rotational period.<ref name=Mankovich_2018/>

=== Orbiting Saturn ===
[[File:Saturn during Equinox.jpg|thumb|upright=1.364|left|Saturn reached equinox in 2008, shortly after the end of the prime mission.]]
On July 1, 2004, the spacecraft flew through the gap between the [[Rings of Saturn|F and G rings]] and achieved [[orbit]], after a seven-year voyage.<ref name=Porco_2007/> It was the first spacecraft to orbit Saturn.

The Saturn Orbital Insertion (SOI) maneuver performed by ''Cassini'' was complex, requiring the craft to orient its High-Gain Antenna away from Earth and along its flight path, to shield its instruments from particles in Saturn's rings. Once the craft crossed the ring plane, it had to rotate again to point its engine along its flight path, and then the engine fired to decelerate the craft by 622&nbsp;m/s to allow Saturn to capture it.<ref name=Doody_2003/> ''Cassini'' was captured by Saturn's gravity at around 8:54&nbsp;pm [[Pacific Daylight Time]] on June 30, 2004. During the maneuver ''Cassini'' passed within {{convert|20000|km|mi|abbr=on}} of Saturn's cloud tops.

When Cassini was in Saturnian orbit, departure from the Saturn system was evaluated in 2008 during end of mission planning.<ref name=spilker/>{{clarify|date=February 2016}}

=== Titan flybys ===
[[File:PIA21923-Titan-SaturnMoon-InfraredViews-20180718.jpg|thumb|right|<div class="center"> Titan – infrared views (2004 – 2017)</div>]]
<!---[[File:Titan globe.jpg|thumb|[[Titan (moon)|Titan's]] surface was imaged by looking through the atmosphere in 2004, but some clouds remain visible.]]--->
''Cassini'' had its first flyby of [[Saturn's]] largest moon, [[Titan (moon)|Titan]], on July 2, 2004, a day after orbit insertion, when it approached to within {{convert|339000|km|abbr=on}} of Titan. Images taken through special filters (able to see through the moon's global haze) showed south polar clouds thought to be composed of [[methane]] and surface features with widely differing brightness. On October 27, 2004, the spacecraft executed the first of the 45 planned close flybys of Titan when it passed a mere {{cvt|1200|km|mi}} above the moon. Almost four [[gigabit]]s of data were collected and transmitted to Earth, including the first radar images of the moon's haze-enshrouded surface. It revealed the surface of Titan (at least the area covered by radar) to be relatively level, with topography reaching no more than about {{cvt|50|m|ft}} in altitude. The flyby provided a remarkable increase in imaging resolution over previous coverage. Images with up to 100 times better resolution were taken and are typical of resolutions planned for subsequent Titan flybys. Cassini collected pictures of Titan and the lakes of methane were similar to the lakes of water on Earth.

=== ''Huygens'' lands on Titan ===
{{Main|Huygens (spacecraft)}}
{{External media
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|image1=[http://esamultimedia.esa.int/docs/titanraw/index.htm Raw images from the ''Huygens'' probe descent on 14 January 2005 (37 pages)] <br /> ESA/NASA/JPL/University of Arizona <small>(ESA hosting)</small>}}
''Cassini'' released the ''Huygens'' probe on December 25, 2004, by means of a spring and spiral rails intended to rotate the probe for greater stability. It entered the atmosphere of Titan on January 14, 2005, and after a two-and-a-half-hour descent landed on solid ground.<ref name=NYT-20170914/> Although ''Cassini'' successfully relayed 350 of the pictures that it received from ''Huygens'' of its descent and landing site, a malfunction in one of the communications channels resulted in the loss of a further 350 pictures.<ref name=space.com3/>

=== Enceladus flybys ===
[[File:Enceladus PIA06191.jpg|thumb|right|View of Enceladus's [[Europa (moon)|Europa]]-like surface with the [[Labtayt Sulci]] fractures at center and the Ebony (left) and Cufa dorsa at lower left; imaged by ''Cassini'' on February 17, 2005]]
During the first two close flybys of the moon [[Enceladus]] in 2005, ''Cassini'' discovered a deflection in the local magnetic field that is characteristic for the existence of a thin but significant atmosphere. Other measurements obtained at that time point to ionized water vapor as its main constituent. ''Cassini'' also observed water ice geysers erupting from the south pole of Enceladus, which gives more credibility to the idea that Enceladus is supplying the particles of Saturn's E ring. Mission scientists began to suspect that there may be pockets of liquid water near the surface of the moon that fuel the eruptions.<ref name=NASA-20110705/>

On March 12, 2008, ''Cassini'' made a close fly-by of Enceladus, passing within 50&nbsp;km of the moon's surface.<ref name=NASA-20080310/> The spacecraft passed through the plumes extending from its southern geysers, detecting water, carbon dioxide and various hydrocarbons with its mass spectrometer, while also mapping surface features that are at much higher temperature than their surroundings with the infrared spectrometer.<ref name=NASA-20080325/> ''Cassini'' was unable to collect data with its cosmic dust analyzer due to an unknown software malfunction.

On November 21, 2009, ''Cassini'' made its eighth flyby of Enceladus,<ref name=PHYS-20091123/> this time with a different geometry, approaching within {{cvt|1600|km|mi}} of the surface. The Composite Infrared Spectrograph (CIRS) instrument produced a map of thermal emissions from the [[Tiger stripes (Enceladus)|Baghdad Sulcus 'tiger stripe']]. The data returned helped create a detailed and high resolution mosaic image of the southern part of the moon's Saturn-facing hemisphere.

On April 3, 2014, nearly ten years after ''Cassini'' entered Saturn's orbit, NASA reported evidence of a large salty internal ocean of liquid water in Enceladus. The presence of an internal salty ocean in contact with the moon's rocky core, places Enceladus "among the most likely places in the Solar System to host [[Astrobiology|alien microbial life]]".{{r|bbc5|Iess_2014|guardian1}} On June 30, 2014, NASA celebrated ten years of ''Cassini'' exploring Saturn and [[Moons of Saturn|its moons]], highlighting the discovery of water activity on Enceladus among other findings.<ref name=NASA-20140625/>

In September 2015, NASA announced that gravitational and imaging data from ''Cassini'' were used to analyze the [[libration]]s of Enceladus' orbit and determined that the moon's surface is not rigidly joined to its core, concluding that the underground ocean must therefore be global in extent.<ref name=NASA-20150915/>

On October 28, 2015, ''Cassini'' performed a close flyby of Enceladus, coming within  {{convert|49|km|mi|abbr=on}} of the surface, and passing through the [[Atmosphere of Enceladus|icy plume above the south pole]].<ref name=NASA-20151028/>

On December 14, 2023, astronomers reported the first time discovery, in the [[Plume (fluid dynamics)|plume]]s of Enceladus, of [[hydrogen cyanide]], a possible chemical essential for [[life]] as we know it, as well as other [[organic molecule]]s, some of which are yet to be better identified and understood. According to the researchers, "these [newly discovered] compounds could potentially support extant [[Microorganism|microbial communities]] or drive complex [[organic synthesis]] leading to the [[origin of life]]".{{r|NYT-20231214|Peter_2023}}

=== Radio occultations of Saturn's rings ===
In May 2005, ''Cassini'' began a series of [[radio occultation]] experiments, to measure the size-distribution of particles in [[Saturn's rings]], and measure the atmosphere of Saturn itself. For over four months, the craft completed orbits designed for this purpose. During these experiments, it flew behind the ring plane of Saturn, as seen from Earth, and transmitted radio waves through the particles. The radio signals received on Earth were analyzed, for frequency, phase, and power shift of the signal to determine the structure of the rings.

{{wide image|Saturn's rings in visible light and radio.jpg|1800px|Upper image: visible color mosaic of Saturn's rings taken on December 12, 2004. Lower image: simulated view constructed from a [[radio occultation]] observation on May 3, 2005. Color in the lower image represents ring particle sizes.}}
<!--
<gallery class="center" mode="packed-hover" heights="180px">
File:Saturn's rings in visible light and radio.jpg|Upper image: visible color mosaic of Saturn's rings taken on December 12, 2004. Lower image: simulated view constructed from a [[radio occultation]] observation on May 3, 2005. Color in the lower image represents ring particle sizes.
</gallery>
-->

=== Spokes in rings verified ===
In images captured September 5, 2005, ''Cassini'' detected spokes in Saturn's rings,<ref name=NASA-20061127/> previously seen only by the visual observer Stephen James O'Meara in 1977 and then confirmed by the [[Voyager program|Voyager]] space probes in the early 1980s.{{r|NASA-20040226|cassini.rings-spokes}}

=== Lakes of Titan ===
{{Main|Lakes of Titan}}
<!---[[File:Titan North Pole Lakes PIA08630.jpg|left|thumb|[[Lakes of Titan]]]]--->
[[File:PIA09184 -Titan Sea and Lake Superior.jpg|right|thumb|[[Ligeia Mare]], on the left, is compared at scale to [[Lake Superior]].]]
[[File:PIA18430-SaturnMoon-Titan-EvolvingFeature-20140821.jpg|thumb|left|upright=1.364|[[Titan (moon)|Titan]]: evolving feature in [[Ligeia Mare]] (August 21, 2014)]]
Radar images obtained on July 21, 2006, appear to show lakes of [[liquid hydrocarbon]] (such as [[methane]] and [[ethane]]) in Titan's northern latitudes. This is the first discovery of currently existing lakes anywhere besides on Earth. The lakes range in size from one to one-hundred kilometers across.<ref name=NASA-20110705/>

On March 13, 2007, the [[Jet Propulsion Laboratory]] announced that it had found strong evidence of seas of methane and ethane in the northern hemisphere of Titan. At least one of these is larger than any of the [[Great Lakes]] in North America.<ref name=NASA-20070313/>

=== Saturn hurricane ===
In November 2006, scientists discovered a storm at the south pole of Saturn with a distinct [[eyewall]]. This is characteristic of a [[hurricane]] on Earth and had never been seen on another planet before. Unlike a [[Earth|terrestrial]] hurricane, the storm appears to be stationary at the pole. The storm is {{cvt|8000|km|mi}} across, and {{cvt|70|km|mi}} high, with winds blowing at {{cvt|560|km/h|mph}}.<ref name=bbc4/>

=== Iapetus flyby ===
[[File:Iapetus equatorial ridge.jpg|thumb|right|Taken on September 10, 2007, at a distance of {{cvt|62,331|km}} Iapetus's equatorial ridge and surface are revealed. (CL1 and CL2 filters)]]
[[File:Inky stains on a frozen moon.jpg|thumb|right|Closeup of Iapetus surface, 2007]]
On September 10, 2007,  ''Cassini'' completed its flyby of the strange, two-toned, walnut-shaped moon, [[Iapetus (moon)|Iapetus]]. Images were taken from {{convert|1000|mi|km|-2|order=flip|abbr=on}} above the surface. As it was sending the images back to Earth, it was hit by a [[cosmic ray]] that forced it to temporarily enter [[safe mode (spacecraft)|safe mode]]. All of the data from the flyby was recovered.<ref name=foxnews1/>

=== Mission extension ===
<!--[[File:Two Halves of Titan.png|thumb|right|Titan in 2009, during the Equinox Mission]]-->
On April 15, 2008, ''Cassini'' received funding for a 27-month extended mission. It consisted of 60 more orbits of [[Saturn]], with 21 more close Titan flybys, seven of Enceladus, six of Mimas, eight of Tethys, and one targeted flyby each of [[Dione (moon)|Dione]], [[Rhea (moon)|Rhea]], and [[Helene (moon)|Helene]].<ref name=tps4/> The extended mission began on July 1, 2008, and was renamed the '''Cassini Equinox Mission''' as the mission coincided with Saturn's [[equinox]].<ref name=scidaily1/>

=== Second mission extension ===
A proposal was submitted to NASA for a second mission extension (September 2010 – May 2017), provisionally named the extended-extended mission or XXM.<ref name=tps3/> This ($60M pa) was approved in February 2010 and renamed the '''Cassini Solstice Mission'''.<ref name=NASA-20100203/> It included ''Cassini'' orbiting Saturn 155 more times, conducting 54 additional flybys of [[Titan (moon)|Titan]] and 11 more of Enceladus.

=== Great Storm of 2010 and aftermath ===
[[File:Saturn Storm.jpg|thumb|left|Northern hemisphere storm in 2011]]
On October 25, 2012, ''Cassini'' witnessed the aftermath of the massive [[Great White Spot]] storm that recurs roughly every 30 years on Saturn.<ref name=NASA-20121025/> Data from the composite infrared spectrometer (CIRS) instrument indicated a powerful discharge from the storm that caused a temperature spike in the stratosphere of Saturn {{convert|83|K-change|C-change F-change}} above normal. Simultaneously, a huge increase in [[ethylene]] gas was detected by NASA researchers at Goddard Research Center in Greenbelt, Maryland.  Ethylene is a colorless gas that is highly uncommon on Saturn and is produced both naturally and through man-made sources on Earth. The storm that produced this discharge was first observed by the spacecraft on December 5, 2010, in Saturn's northern hemisphere. The storm is the first of its kind to be observed by a spacecraft in orbit around Saturn as well as the first to be observed at thermal infrared wavelengths, allowing scientists to observe the temperature of Saturn's atmosphere and track phenomena that are invisible to the naked eye. The spike of ethylene gas that was produced by the storm reached levels that were 100 times more than those thought possible for Saturn. Scientists have also determined that the storm witnessed was the largest, hottest stratospheric vortex ever detected in the Solar System, initially being larger than Jupiter's [[Great Red Spot]].

=== Venus transit ===
On December 21, 2012, ''Cassini'' observed a [[transit of Venus]] across the Sun. The VIMS instrument analyzed sunlight passing through the Venusian atmosphere. VIMS previously observed the transit of exoplanet [[HD 189733 b]].<ref name=NASA-20121220/>

=== ''The Day the Earth Smiled'' ===
{{Main|The Day the Earth Smiled}}
<!-- "The Day the Earth Smiled" is the official name of the image - see http://photojournal.jpl.nasa.gov/catalog/PIA17171 -->
[[File:The Day the Earth Smiled PIA17172.jpg|right|thumb|''The Day the Earth Smiled'' – [[Saturn]] with some of its moons, [[Earth]], [[Venus]], and [[Mars]] as visible in this ''Cassini'' montage (July 19, 2013)<ref name=NYT-20131112/>]]
On July 19, 2013, the probe was pointed towards Earth to capture an image of the Earth and the [[Moon]], as part of a natural light, multi-image portrait of the entire Saturn system. The event was unique as it was the first time NASA informed the public that a long-distance photo was being taken in advance.{{r|NYT-20131112|bbc2}} The imaging team said they wanted people to smile and wave to the skies, with ''Cassini'' scientist [[Carolyn Porco]] describing the moment as a chance to "celebrate life on the [[Pale Blue Dot#Reflections|Pale Blue Dot]]".<ref name=bbc3/>

=== Rhea flyby ===
On February 10, 2015, the ''Cassini'' spacecraft visited [[Rhea (moon)|Rhea]] more closely, coming within {{convert|47000|km|mi|abbr=on}}.<ref name=cassini.tour-2015/> The spacecraft observed the moon with its cameras producing some of the highest resolution color images yet of Rhea.<ref name=ciclops.pia19057/>

=== Hyperion flyby ===
''Cassini'' performed its latest flyby of Saturn's moon [[Hyperion (moon)|Hyperion]] on May 31, 2015, at a distance of about {{convert|34000|km|abbr=on}}.<ref name=NASA-20150528/>
{{Clear}}
{{Multiple image|direction=horizontal|align=center|caption_align=center|width=190
|image1=PIA17193-SaturnMoon-Hyperion-20150531.jpg
|caption1=Hyperion – context view from {{convert|37,000|km|mi|abbr=on}} (May 31, 2015)
|image2=PIA17194-SaturnMoon-Hyperion-20150531.jpg
|caption2=Hyperion – close-up view from {{convert|38,000|km|mi|abbr=on}} (May 31, 2015)
}}

=== Dione flyby ===
''Cassini'' performed its last flyby of Saturn's moon [[Dione (moon)|Dione]] on August 17, 2015, at a distance of about {{convert|295|mi|km|order=flip|abbr=on}}. A previous flyby was performed on June 16.<ref name=NASA-20150813/>

=== Hexagon changes color ===
{{Main|Saturn's hexagon}}
Between 2012 and 2016, the persistent hexagonal cloud pattern at Saturn's north pole changed from a mostly blue color to more of a golden color.<ref name=NASA-20161021/> One theory for this is a seasonal change: extended exposure to sunlight may be creating haze as the pole swivels toward the Sun.<ref name=NASA-20161021/> It was previously noted that there was less blue color overall on Saturn between 2004 and 2008.<ref name=tps2/>

<gallery mode=packed heights=180>
File:PIA21049 Changing Colors in Saturn's North.jpg|2012 and 2016: hexagon color changes
File:PIA21611 - Saturn's Hexagon as Summer Solstice Approaches.gif|2013 and 2017: hexagon color changes
</gallery>