Editing Navigation (section)

==Basic concepts==
{{longlat}}
In terrestrial navigation, the location of a person, ship, plane, etc is defined as a position using a reference point/coordinates (see [[Cartesian coordinate system]]). Positions can either be referenced as latitude/longitude or a distance and [[Cardinal direction|direction]] from a fixed reference point ([[Bearing (navigation)|bearing]]).<ref name="Smith1">{{cite book | last=Smith | first=Philip M. | title=Terrestrial Navigation | publisher=Routledge | publication-place=London ; New York | date=2017-10-16 | isbn=978-1-317-20046-8 | page=1}}</ref> Lines of position can be derived from a variety of methods and equipment. By determining and monitoring positions it is possible to find and direct a person, ship, plane, etc in a scientific way from one place to another.<ref name="r313">{{cite web | title=navigation | website=Cambridge Dictionary | date=2025-02-19 | url=https://dictionary.cambridge.org/dictionary/english/navigation | access-date=2025-02-24}}</ref> This often involves the use of [[maps]] or [[charts]] from which if desired, courses can be calculated or followed depending on the projection or methods used ([[Rhumb line]], [[Great circle]], etc).<ref name="Smith24">{{cite book | last=Smith | first=Philip M. | title=Terrestrial Navigation | publisher=Routledge | publication-place=London ; New York | date=2017-10-16 | isbn=978-1-317-20046-8 | page=24}}</ref>

===Latitude===
{{Further|Latitude}}
Roughly, the latitude of a place on Earth is its angular distance north or south of the [[equator]].<ref name="bow4">Bowditch, 2003:4.</ref> Latitude is usually expressed in [[degree (angle)|degrees]] (marked with °) ranging from 0° at the [[Equator]] to 90° at the North and South poles.<ref name="bow4"/> The latitude of the [[North Pole]] is 90° N, and the latitude of the [[South Pole]] is 90° S.<ref name="bow4" /> Mariners calculated latitude in the Northern Hemisphere by sighting the [[pole star]] ([[Polaris]]) with a [[sextant]] and using sight reduction tables to correct for height of eye and atmospheric refraction. The height of Polaris in degrees above the horizon is the latitude of the observer, within a degree or so.

===Longitude===
{{Further|Longitude}}
Similar to latitude, the longitude of a place on Earth is the angular distance east or west of the [[prime meridian]] or [[Greenwich meridian]].<ref name="bow4"/> Longitude is usually expressed in [[degree (angle)|degrees]] (marked with °) ranging from [[prime meridian|0°]] at the Greenwich meridian to [[180th meridian|180°]] east and west. [[Sydney]], for example, has a longitude of about [[151st meridian east|151° east]]. [[New York City]] has a longitude of [[74th meridian west|74° west]]. For most of history, mariners struggled to determine longitude. Longitude can be calculated if the precise time of a sighting is known. Lacking that, one can use a [[sextant]] to take a [[Lunar distance (navigation)|lunar distance]] (also called ''the lunar observation'', or "lunar" for short) that, with a [[nautical almanac]], can be used to calculate the time at zero longitude (see [[Greenwich Mean Time]]).<ref name="Norie 1828 pg 222">
 {{cite book
  | last =Norie
  | first =J.W.
  | title =New and Complete Epitome of Practical Navigation
  | year =1828
  | location =London
  | url =http://www.mysticseaport.org/library/initiative/ImPage.cfm?PageNum=3&BibId=13617&ChapterId=30
  | access-date =2007-08-02
  | page =222
  | url-status=dead
  | archive-url =https://web.archive.org/web/20070927203111/http://www.mysticseaport.org/library/initiative/ImPage.cfm?PageNum=3&BibId=13617&ChapterId=30
  | archive-date =2007-09-27
  }}</ref> Reliable [[marine chronometer]]s were unavailable until the late 18th century and not affordable until the 19th century.<ref name="Norie 1828 pg 221">
{{cite book
  | last =Norie
  | first =J.W.
  | title =New and Complete Epitome of Practical Navigation
  | year =1828
  | location =London
  | url =http://www.mysticseaport.org/library/initiative/ImPage.cfm?PageNum=2&BibId=13617&ChapterId=30
  | access-date =2007-08-02
  | page =221
  | url-status=dead
  | archive-url =https://web.archive.org/web/20070927202912/http://www.mysticseaport.org/library/initiative/ImPage.cfm?PageNum=2&BibId=13617&ChapterId=30
  | archive-date =2007-09-27
  }}</ref><ref name="Taylor 1851 pg 195">{{Cite book
| last = Taylor
| first = Janet
| title=An Epitome of Navigation and Nautical Astronomy
| publisher = Taylor
| edition = Ninth
| year = 1851
| url=https://archive.org/details/anepitomenaviga00taylgoog
| quote = Nautical Almanac 1849-1851.
| access-date=2007-08-02
| page = 295f
}}
</ref><ref name="Watchmakers and their Work, pg 230">
{{cite book
| first=Frederick James
| last=Britten
| title = Former Clock & Watchmakers and Their Work
| year = 1894
| publisher=Spon & Chamberlain
| location = New York
|url=https://archive.org/details/formerclockwatc00britgoog
| quote=Chronometers were not regularly supplied to the Royal Navy until about 1825
|access-date=2007-08-08
| page=[https://archive.org/details/formerclockwatc00britgoog/page/n242 230]
}}</ref> For about a hundred years, from about 1767 until about 1850,<ref>Lecky, Squire, ''Wrinkles in Practical Navigation''</ref> mariners lacking a chronometer used the method of lunar distances to determine Greenwich time to find their longitude. A mariner with a chronometer could check its reading using a lunar determination of Greenwich time.<ref name="Norie 1828 pg 221"/><ref name = "Roberts">{{cite book
|last= Roberts |first= Edmund |author-link= Edmund Roberts (diplomat)
|title=1837, Embassy to the Eastern courts of Cochin-China, Siam, and Muscat: in the U.S. sloop-of-war Peacock ... during the years 1832–3–4
|url=  https://books.google.com/books?id=aSgPAAAAYAAJ |publisher=   Harper & brothers  
|page=   373 |no-pp= <!-- 0 hides automatic 'p' or 'pp'.--> 
|chapter=   Chapter XXIV―departure from Mozambique
|isbn=9780608404066 |chapter-url= https://books.google.com/books?id=aSgPAAAAYAAJ&pg=PA365
|access-date=  April 25, 2012
|edition=   Digital
|quote= ...what I have stated, will serve to show the absolute necessity of having first rate chronometers, or the lunar observations carefully attended to; and never omitted to be taken when practicable.
}}</ref>

===Loxodrome===
{{Further|Rhumb line}}
In navigation, a rhumb line (or loxodrome) is a line crossing all meridians of longitude at the same angle, i.e. a path derived from a defined initial bearing. That is, upon taking an initial bearing, one proceeds along the same bearing, without changing the direction as measured relative to true or magnetic north.