Editing Voyager 2 (section)

=== Encounter with Uranus ===
{{Further|Exploration of Uranus}}
The closest approach to Uranus occurred on January 24, 1986, when ''Voyager 2'' came within {{convert|81,500|km|mi|sp=us|abbr=unit}} of the planet's cloudtops.<ref name="uranus approach">[https://voyager.jpl.nasa.gov/mission/science/uranus/ "Uranus Approach"] {{Webarchive|url=https://web.archive.org/web/20180909173736/https://voyager.jpl.nasa.gov/mission/science/uranus/ |date=September 9, 2018 }} NASA Jet Propulsion Laboratory, California Institute of Technology. Accessed December 11, 2018.</ref> ''Voyager 2'' also discovered 11 previously unknown moons: [[Cordelia (moon)|Cordelia]], [[Ophelia (moon)|Ophelia]], [[Bianca (moon)|Bianca]], [[Cressida (moon)|Cressida]], [[Desdemona (moon)|Desdemona]], [[Juliet (moon)|Juliet]], [[Portia (moon)|Portia]], [[Rosalind (moon)|Rosalind]], [[Belinda (moon)|Belinda]], [[Puck (moon)|Puck]] and [[Perdita (moon)|Perdita]].{{efn-ua|Some sources cite the discovery of only 10 Uranian moons by ''Voyager 2'',<ref name="elizabeth landau" /><ref name="voyager 2 mission team" /> but [[Perdita (moon)|Perdita]] was discovered in ''Voyager 2'' images more than a decade after they were taken.<ref>{{cite journal |doi=10.1006/icar.2001.6597 |title=Voyager's Eleventh Discovery of a Satellite of Uranus and Photometry and the First Size Measurements of Nine Satellites |journal=Icarus |volume=151 |issue=1 |pages=69–77 |year=2001 |last1=Karkoschka |first1=E. |bibcode=2001Icar..151...69K}}</ref>}} The mission also studied the planet's unique atmosphere, caused by its [[Uranus#Axial tilt|axial tilt]] of 97.8°; and examined the [[Rings of Uranus|Uranian ring system]].<ref name="uranus approach" /> The length of a day on Uranus as measured by ''Voyager 2'' is 17 hours, 14 minutes.<ref name="uranus approach" /> Uranus was shown to have a magnetic field that was misaligned with its rotational axis, unlike other planets that had been visited to that point,<ref name="elizabeth landau" /><ref>{{Cite journal |doi=10.1088/0034-4885/56/6/001 |title=Planetary magnetospheres |journal=Reports on Progress in Physics |volume=56 |issue=6 |pages=687–732 |year=1993 |last1=Russell |first1=C. T. |bibcode=1993RPPh...56..687R|s2cid=250897924 }}</ref> and a helix-shaped magnetic tail stretching 10 million kilometers (6 million miles) away from the Sun.<ref name="elizabeth landau" />

When ''Voyager 2'' visited Uranus, much of its cloud features were hidden by a layer of haze; however, false-color and contrast-enhanced images show bands of concentric clouds around its south pole. This area was also found to radiate large amounts of ultraviolet light, a phenomenon that is called "dayglow". The average atmospheric temperature is about {{Convert|60|K|F C|abbr=unit}}. The illuminated and dark poles, and most of the planet, exhibit nearly the same temperatures at the cloud tops.<ref name="elizabeth landau" />

The ''Voyager 2'' Planetary Radio Astronomy (PRA) experiment observed 140 lightning flashes, or Uranian electrostatic discharges with a frequency of 0.9-40 MHz.<ref name="aplin-2020">{{cite journal |last1=Aplin |first1=K.L. |last2=Fischer |first2=G. |last3=Nordheim |first3=T.A. |last4=Konovalenko | first4=A. |last5=Zakharenko |first5=V. |last6=Zarka |first6= P.|title=Atmospheric Electricity at the Ice Giants |journal=Space Science Reviews |date=2020 |volume=216 |issue=2 |page=26 |doi=10.1007/s11214-020-00647-0 |arxiv=1907.07151 |bibcode=2020SSRv..216...26A }}</ref><ref name="zarka-1986">{{cite journal |last1=Zarka |first1=P. |last2=Pederson |first2=B.M. |title=Radio detection of uranian lightning by Voyager 2 |journal=Nature |date=1986 |volume=323 |issue=6089 |page=605-608 |doi=10.1038/323605a0  |bibcode=1986Natur.323..605Z }}</ref> The UEDs were detected from 600,000&nbsp;km of Uranus over 24 hours, most of which were not visible.<ref name="aplin-2020" /> However, microphysical modeling suggests that Uranian lightning occurs in convective storms occurring in deep troposphere water clouds.<ref name="aplin-2020" /> If this is the case, lightning will not be visible due to the thick cloud layers above the troposphere.<ref name="zarka-1986" /> Uranian lightning has a power of around 10<sup>8</sup> W, emits 1×10^7 J – 2×10^7 J of energy, and lasts an average of 120 ms.<ref name="zarka-1986" />

Detailed images from ''Voyager 2''{{'}}s flyby of the Uranian moon [[Miranda (moon)|Miranda]] showed huge canyons made from [[Fault (geology)|geological faults]].<ref name="elizabeth landau">Elizabeth Landau (2016) [https://www.nasa.gov/feature/jpl/voyager-mission-celebrates-30-years-since-uranus "Voyager Mission Celebrates 30 Years Since Uranus"] {{Webarchive|url=https://web.archive.org/web/20170505052650/https://www.nasa.gov/feature/jpl/voyager-mission-celebrates-30-years-since-uranus/ |date=May 5, 2017 }} [[National Aeronautics and Space Administration]], January 22, 2016. Accessed December 11, 2018</ref> One hypothesis suggests that Miranda might consist of a reaggregation of material following an earlier event when Miranda was shattered into pieces by a violent impact.<ref name="elizabeth landau" />

''Voyager 2'' discovered two previously unknown Uranian rings.<ref name="elizabeth landau" /><ref name="voyager 2 mission team">Voyager 2 Mission Team (2012) [https://solarsystem.nasa.gov/news/184/1986-voyager-at-uranus/ "1986: Voyager at Uranus"] {{Webarchive|url=https://web.archive.org/web/20190524214544/https://solarsystem.nasa.gov/news/184/1986-voyager-at-uranus/ |date=May 24, 2019 }} NASA Science: Solar System Exploration, December 14, 2012. Accessed December 11, 2018.</ref> Measurements showed that the Uranian rings are different from those at Jupiter and Saturn. The Uranian ring system might be relatively young, and it did not form at the same time that Uranus did. The particles that make up the rings might be the remnants of a moon that was broken up by either a high-velocity impact or [[Roche limit|torn up by tidal effects]].<ref name="nasajpl"/><ref name="fastfacts"/>

In March 2020, NASA astronomers reported the detection of a large atmospheric magnetic bubble, also known as a [[plasmoid]], released into [[outer space]] from the planet [[Uranus]], after reevaluating old data recorded during the flyby.<ref>{{cite news |last=Hatfield |first=Miles |title=Revisiting Decades-Old Voyager 2 Data, Scientists Find One More Secret – Eight and a half years into its grand tour of the solar system, NASA's Voyager 2 spacecraft was ready for another encounter. It was Jan. 24, 1986, and soon it would meet the mysterious seventh planet, icy-cold Uranus. |url=https://www.nasa.gov/feature/goddard/2020/revisiting-decades-old-voyager-2-data-scientists-find-one-more-secret |date=March 25, 2020 |work=[[NASA]] |access-date=March 27, 2020 |archive-date=March 27, 2020 |archive-url=https://web.archive.org/web/20200327030510/https://www.nasa.gov/feature/goddard/2020/revisiting-decades-old-voyager-2-data-scientists-find-one-more-secret |url-status=live }}</ref><ref>{{cite news |last=Andrews |first=Robin George |title=Uranus Ejected a Giant Plasma Bubble During Voyager 2's Visit – The planet is shedding its atmosphere into the void, a signal that was recorded but overlooked in 1986 when the robotic spacecraft flew past. |url=https://www.nytimes.com/2020/03/27/science/uranus-bubble-voyager.html |date=March 27, 2020 |work=[[The New York Times]] |access-date=March 27, 2020 |archive-date=March 27, 2020 |archive-url=https://web.archive.org/web/20200327215013/https://www.nytimes.com/2020/03/27/science/uranus-bubble-voyager.html |url-status=live }}</ref>

{{Gallery| align = center
| style="width:175px;"|File:Uranus Voyager2 color calibrated.png|alt1=Uranus as viewed by ''Voyager 2'' | Uranus as viewed by ''Voyager&nbsp;2''
|File:Uranus Final Image.jpg|alt2=Departing image of crescent Uranus | Departing image of crescent [[Uranus]]
|File:Ariel Closest Approach.jpg|alt4=Ariel imaged from 130,000&nbsp;km | [[Ariel (moon)|Ariel]] as imaged from 130,000&nbsp;km
|File:Uranian rings PIA01977 modest.jpg|alt8=Voyager 2 photo of the Rings of Uranus | The [[rings of Uranus]] imaged by ''Voyager&nbsp;2''
}}