Editing Terminator (solar) (section)

==Lunar terminator==
[[File:Keeler crater AS13-60-8635.jpg|thumb|right|An oblique view of the large lunar crater [[Keeler (lunar crater)|Keeler]] at the terminator (from [[Apollo 13]])]]
[[File:Timocharis crater terminator AS15-P-9423.jpg|thumb|right|The east side of [[Timocharis (crater)|Timocharis]] crater while at the terminator (from [[Apollo 15]])]]
[[File:AS16-124-19897-19901 mosaic.jpg|thumb|right|Mosaic of [[Apollo 16]] photos along the terminator showing [[Darney (crater)|Darney]], [[Lubiniezky (crater)|Lubiniezky]], and [[Bullialdus (crater)|Bullialdus]] craters]]

The '''lunar terminator''' is the division between the illuminated and dark hemispheres of the [[Moon]].<ref>{{cite web |url=http://brahms.phy.vanderbilt.edu/a103/labs/tl_moon.shtml |title=List of basic lunar features |url-status=dead |archive-url=https://web.archive.org/web/20060203074721/http://brahms.phy.vanderbilt.edu/a103/labs/tl_moon.shtml |archive-date=2006-02-03 }}</ref> It is the lunar equivalent of the division between [[night]] and [[day]] on the Earth [[spheroid]], although the Moon's much lower rate of rotation<ref>The [[lunar day]] cycle is 29.53 Earth days in length (see [http://cseligman.com/text/sky/rotationvsday.htm]), so the terminator moves across the lunar surface at 15.4 kilometers per hour.</ref> means it takes longer for it to pass across the surface. At the equator, it moves at {{convert|15.4|kph|mph}}, as fast as an athletic human can run on earth.

Due to the angle at which [[sunlight]] strikes this portion of the Moon, shadows cast by [[impact crater|craters]] and other geological features are elongated, thereby making such features more apparent to the observer. This phenomenon is similar to the lengthening of shadows on Earth when the Sun is low in the sky. For this reason, much lunar photographic study centers on the illuminated area near the lunar terminator, and the resulting shadows provide accurate descriptions of the [[lunar terrain]].

===Lunar terminator illusion{{anchor|Lunar terminator}}===
The lunar terminator (or tilt) illusion is an [[optical illusion]] arising from the expectation of an observer on Earth that the direction of sunlight illuminating the Moon (i.e. a line [[perpendicular]] to the terminator) should correspond with the [[position of the Sun]], but does not appear to do so. The illusion results from misinterpreting the arrangement of objects in the sky according to intuition based on [[planar geometry]].<ref>{{cite web |last=Jones |first=Christopher B. |title=Lunar Terminator Illusion |url=http://chrisjones.id.au/MoonIllusion/|website=Ellipsis: unfinished thought... |access-date=21 May 2016|date=January 2014}}</ref><ref>{{cite web |first1=Andrea K. |last1=Myers-Beaghton |first2=Alan L. |last2=Myers |title=The Moon Tilt Illusion |url =http://www.seas.upenn.edu/~amyers/MoonPaper20June.pdf}}</ref>