{{Short description|Direction on Earth's surface}}
{{Other uses}}
{{redirect|True south|the flag used to represent Antarctica|Flag of Antarctica}}
{{refimprove|date=May 2012}}

'''True north''' is the direction along [[Earth]]'s surface towards the place where the imaginary rotational axis of the Earth intersects the surface of the Earth on its [[Northern Hemisphere|northern half]], the True [[North Pole]]. '''True south''' is the direction opposite to the true north. 

It is important to make the distinction from ''magnetic'' north, which points towards [[North magnetic pole|an ever changing location]] close to the True North Pole determined by [[Earth's magnetic field]]. Due to fundamental limitations in [[map projection]], true north also differs from the [[grid north]] which is marked by the direction of the grid lines on a typical printed map. However, the [[geographic coordinate system|longitude lines]] on a [[globe]] leads to the true poles, because the three-dimensional representation avoids those limitations.

The [[celestial pole]] is the location on the imaginary [[celestial sphere]] where an imaginary extension of the rotational axis of the Earth intersects the celestial sphere. Within a margin of error of 1°, the true north direction can be approximated by the position of the [[pole star]] [[Polaris]] which would currently appear to be very close to the intersection, [[star trail|tracing]] a tiny circle in the sky each [[sidereal time|sidereal day]]. Due to the [[axial precession]] of Earth, true north rotates in an arc with respect to [[fixed stars|the stars]] that takes approximately 25,000 years to complete. Around 2101–2103, Polaris will make its closest approach to the celestial north pole (extrapolated from recent Earth [[precession]]).{{sfn|Meeus|1997|p=305}}{{sfn|McClure|2013}}{{sfn|Smiley|Khan|1959|p=250}} The visible star nearest the north celestial pole 5,000 years ago was [[Thuban]].{{sfn|Ridpath|2004|p=5|ps= : "Around 4800 years ago Thuban ({{GreekFont|α}} Draconis) lay a mere 0°.1 from the pole. Deneb ({{GreekFont|α}} Cygni) will be the brightest star near the pole in about 8000 years' time, at a distance of 7°.5."}}   The radius of the circle traced out by the north pole in the sky over the 25,000 year cycle is 23.5°.<ref>{{Cite web |last=Walker |first=John |date=4 April 2026 |title=Your Sky Help: Precession |url=https://www.fourmilab.ch/yoursky/help/precession.html |website=Your Sky}}</ref>

On maps published by the [[United States Geological Survey]] (USGS) and the [[United States Armed Forces]], true north is marked with a line terminating in a five-pointed star.<ref>{{Cite web|url=https://www.usgs.gov/faqs/what-do-different-north-arrows-a-usgs-topographic-map-mean|title=What do the different north arrows on a USGS topographic map mean?|website=United States Geological Survey}}</ref> The east and west edges of the USGS topographic quadrangle maps of the United States are [[meridian (geography)|meridian]]s of [[longitude]], thus indicating true north (so they are not exactly parallel). Maps issued by the [[United Kingdom]] [[Ordnance Survey]] contain a diagram showing the difference between true north, grid north, and magnetic north at a point on the sheet; the edges of the map are likely to follow grid directions rather than true, and the map will thus be truly rectangular/square.{{cn|date=October 2022}}

==References==
{{Reflist}}

==Sources==
* {{cite web |last=McClure |first=Bruce |year=2013 |url=http://earthsky.org/brightest-stars/polaris-the-present-day-north-star |title=Polaris is the North Star |work=Astronomy Essentials |publisher=[[EarthSky]] |access-date=2014-04-28 |archive-url=https://web.archive.org/web/20140309155804/http://earthsky.org/brightest-stars/polaris-the-present-day-north-star |archive-date=2014-03-09 |url-status=live }}
*{{cite book |last=Meeus |first=Jean |year=1997 |title=Mathematical Astronomy Morsels |location=[[Richmond, VA]] |publisher=Willmann-Bell |isbn=0-943396-51-4 }}
*{{cite book |editor-last=Ridpath |editor-first=Ian |date=2004 |title=Norton's Star Atlas |publisher=[[Pearson Education]] |location=New York |isbn=0-13-145164-2 |url-access=registration |url=https://archive.org/details/nortonsstaratlas00ianr }}
* {{cite journal |last1=Smiley |first1=C. H. |last2=Khan |first2=A. Majid|title=Polaris and Precession |journal=Journal of the Royal Astronomical Society of Canada |year=1959 |volume=53 |page=249 |bibcode=1959JRASC..53..249S }}

[[Category:Geography of the Arctic]]
[[Category:Cartography]]
[[Category:Chinese discoveries]]
[[Category:Navigation]]
[[Category:Orientation (geometry)]]

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