Editing Solar time (section)

{{Short description|Calculation of elapsed time by the apparent position of the sun}}
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{{Use American English|date = April 2019}}
{{Use mdy dates|date=June 2022}}
[[Image:Sidereal day (prograde).svg|right|thumb|300px|On a [[Direct motion|prograde]] planet like the [[Earth]], the [[sidereal time|sidereal day]] is shorter than the '''solar day'''. At time 1, the [[Sun]] and a certain distant [[star]] are both overhead. At time 2, the planet has rotated 360° and the distant star is overhead again (1→2 = one sidereal day). But it is not until a little later, at time 3, that the Sun is overhead again (1→3 = one solar day).  More simply, 1→2 is a complete [[rotation of the Earth]], but because the revolution around the Sun affects the [[angle]] at which the Sun is seen from the Earth, 1→3 is how long it takes [[noon]] to return. [Note that in this diagram, the relative motion, and corresponding angles, are highly exaggerated for illustrative purposes.] ]]

'''Solar time''' is a calculation of the passage of [[time]] based on the [[position of the Sun]] in the [[sky]]. The fundamental unit of solar time is the [[day]], based on the [[synodic rotation period]]. Traditionally, there are three types of time reckoning based on astronomical observations: [[#Apparent solar time|'''apparent solar time''']] and [[#Mean solar time|'''mean solar time''']] (discussed in this article), and ''[[sidereal time]]'', which is based on the apparent motions of [[star]]s other than the Sun.<ref>For the three kinds of time, see (for example) the explanatory section in the almanac [http://gallica.bnf.fr/ark:/12148/bpt6k210143f.image.f740.langFR ''Connaissance des Temps'' for 1902, page 759] {{webarchive|url=https://web.archive.org/web/20110810025808/http://gallica.bnf.fr/ark:/12148/bpt6k210143f.image.f740.langFR |date=August 10, 2011 }}.</ref>