Editing Day (section)

=== Sidereal day{{anchor|Extraterrestrial bodies}} ===
{{main|Earth's rotation#Stellar day|Sidereal time|Rotation period}}
[[File:PIA19547-Ceres-DwarfPlanet-Dawn-RC3-Animation-20150504.gif|thumb|Rotation of the dwarf planet [[Ceres (dwarf planet)|Ceres]]]]
A [[Sidereal time|sidereal day]] or [[stellar day]] is the span of time it takes for the Earth to make one entire [[rotation]]<ref>Certain authors caution against identifying "day" with rotation period. For example: {{cite web |first=Courtney |last=Seligman |title=Rotation Period and Day Length |url=http://cseligman.com/text/sky/rotationvsday.htm |url-status=live |archive-url=https://web.archive.org/web/20180929010908/http://cseligman.com/text/sky/rotationvsday.htm |archive-date=2018-09-29 |access-date=2011-06-03 |quote=A Cautionary Note: Because the rotation period of the Earth is almost the same as the length of its day, we sometimes get a bit sloppy in discussing the rotation of the sky, and say that the stars rotate around us once each day. In a similar way, it is not unusual for careless people to mix up the rotation period of a planet with the length of its day, or vice versa.}}</ref> with respect to the celestial background or a distant star (assumed to be fixed).<ref name=":1">{{Cite web |title=sidereal day |url=https://www.britannica.com/science/sidereal-day |access-date=2022-08-17 |website=[[Encyclopædia Britannica]] |language=en |archive-date=2022-09-26 |archive-url=https://web.archive.org/web/20220926003236/https://www.britannica.com/science/sidereal-day |url-status=live }}</ref> Measuring a day as such is used in [[astronomy]].<ref name=":1" /> A sidereal day is about 4 minutes less than a solar day of 24 hours (23 hours 56 minutes and 4.09 seconds), or 0.99726968 of a solar day of 24 hours.<ref name="Allen296">{{cite book |last1=Allen |first1=Clabon Walter |url=https://books.google.com/books?id=w8PK2XFLLH8C&pg=PA296 |title=Allen's Astrophysical Quantities |last2=Cox |first2=Arthur N. |date=2000 |publisher=[[Springer (publisher)|Springer]] |isbn=0-387-98746-0 |page=296 |author-link=Clabon Walter Allen |name-list-style=amp |access-date=2022-08-17 |archive-date=2011-12-09 |archive-url=https://web.archive.org/web/20111209062816/http://books.google.com/books?id=w8PK2XFLLH8C&pg=PA296 |url-status=live }}</ref> There are about 366.2422 stellar days in one mean tropical year (one stellar day more than the number of solar days).<ref>{{Cite web |last=Komhyr |first=Walter Dmyro |date=June 1980 |title=Operations Handbook – Ozone Observations with a Dobson Spectrophotometer |url=https://gml.noaa.gov/ozwv/dobson/papers/report6/appi.html |access-date=2022-08-17 |website=gml.noaa.gov |page=122 |archive-date=2021-06-12 |archive-url=https://web.archive.org/web/20210612111012/https://gml.noaa.gov/ozwv/dobson/papers/report6/appi.html |url-status=live }}</ref>

Besides a stellar day on [[Earth]], other bodies in the Solar System have day times, the durations of these being:<ref>{{cite web |title=Planetary Fact Sheet – Metric |url=https://nssdc.gsfc.nasa.gov/planetary/factsheet/ |archive-url=https://archive.today/20120719082605/http://nssdc.gsfc.nasa.gov/planetary/factsheet/ |archive-date=19 July 2012 |access-date=May 29, 2021 |work=nssdc.gsfc.nasa.gov [[NASA]]}}</ref><ref name="VRG-20190118">{{cite web |last=Griggs |first=Mary Beth |date=18 January 2019 |title=Shaky rings help scientists measure Saturn's days – Speedy planet |url=https://www.theverge.com/2019/1/18/18188429/rings-saturn-nasa-day-time-hours-duration |url-status=live |archive-url=https://web.archive.org/web/20190119035815/https://www.theverge.com/2019/1/18/18188429/rings-saturn-nasa-day-time-hours-duration |archive-date=19 January 2019 |access-date=18 January 2019 |work=[[The Verge]]}}</ref>
{| class="wikitable"
!Name
!Daylength (hours)
|-
|[[Mercury (planet)|Mercury]]
|{{val|4222.6}}
|-
|[[Venus]]
|{{val|2802}}
|-
|[[Moon|Earth's Moon]]
|708.7
|-
|[[Mars]]
|24.7
|-
|[[Ceres (dwarf planet)|Ceres]]
|9<ref>{{cite web |title=planets/dwarf-planets/ceres/in-depth |url=https://solarsystem.nasa.gov/planets/dwarf-planets/ceres/in-depth/ |url-status=live |archive-url=https://web.archive.org/web/20210602235747/https://solarsystem.nasa.gov/planets/dwarf-planets/ceres/in-depth/ |archive-date=June 2, 2021 |access-date=May 30, 2021 |work=nasa.gov}}</ref>–9.1<ref>{{cite web |author=Tate, Karl |date=21 November 2012 |title=Dwarf Planets of Our Solar System (Infographic) |url=https://www.space.com/18584-dwarf-planets-solar-system-infographic.html |url-status=live |archive-url=https://web.archive.org/web/20210518093249/https://www.space.com/18584-dwarf-planets-solar-system-infographic.html |archive-date=18 May 2021 |access-date=May 30, 2021 |work=www.[[space.com]]}}</ref>
|-
|[[Jupiter]]
|9.9
|-
|[[Saturn]]
|10.7
|-
|[[Uranus]]
|17.2
|-
|[[Neptune]]
|16.1
|-
|[[Pluto]]
|153.3
|}