Editing Minute and second of arc (section)

===Cartography===

Minutes (′) and seconds (″) of arc are also used in [[cartography]] and [[navigation]]. At [[sea level]] one minute of arc along the [[equator]] equals exactly one [[geographical mile]] (not to be confused with international mile or statute mile) along the Earth's equator or approximately {{convert|1|nmi|m mi|sigfig=4|spell=in|abbr=off|lk=on}}.<ref>{{cite web |url=http://www.oceannavigator.com/January-February-2003/Nautical-mile-approximates-an-arcminute/ |title=Nautical mile approximates an arcminute |date=1 January 2003 |first=George H. |last=Kaplan |magazine=Ocean Navigator |publisher=Navigator Publishing |access-date=2017-03-22}}</ref> A second of arc, one sixtieth of this amount, is roughly {{convert|30|m|abbr=off}}. The exact distance varies along [[meridian arc]]s or any other [[great circle]] arcs because the [[figure of the Earth]] is slightly [[Oblate spheroid|oblate]] (bulges a third of a percent at the equator).

Positions are traditionally given using degrees, minutes, and seconds of arcs for [[latitude]], the arc north or south of the equator, and for [[longitude]], the arc east or west of the [[Prime Meridian]]. Any position on or above the Earth's [[reference ellipsoid]] can be precisely given with this method. However, when it is inconvenient to use  [[radix|base]]-60 for minutes and seconds, positions are frequently expressed as decimal fractional degrees to an equal amount of precision. Degrees given to three decimal places ({{sfrac|1|{{val|1000}}}} of a degree) have about {{sfrac|1|4}} the precision of degrees-minutes-seconds ({{sfrac|1|{{val|3600}}}} of a degree) and specify locations within about {{convert|120|m|abbr=off}}.  For navigational purposes positions are given in degrees and decimal minutes, for instance, the [[Needles Lighthouse]] is at 50°39′44.2″N 1°35′30.5″W.<ref>{{cite web|author= The Corporation of Trinity House |title=1/2020 Needles Lighthouse|date=10 January 2020|series=Notices to Mariners|url=https://www.trinityhouse.co.uk/notice-to-mariners/1/2020-needles-lighthouse|access-date=24 May 2020}}</ref>