"True south" redirects here. For the flag used to represent Antarctica, see Flag of Antarctica.
True north (also called geodetic north or geographic north) is the direction along Earth's surface towards the geographic North Pole or True North Pole.
The direction of astronomical true north is marked in the skies by the north celestial pole. This is within about 1° of the position of Polaris, meaning the star would appear to trace a tiny circle in the sky each sidereal day. Due to the axial precession of Earth, true north rotates in an arc with respect to 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).[1][2][3] The visible star nearest the north celestial pole 5,000 years ago was Thuban.[4]
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.[5] The east and west edges of the USGS topographic quadrangle maps of the United States are meridians of longitude, thus indicating true north (so they are not exactly parallel). Maps issued by the United KingdomOrdnance 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.[citation needed]
^Ridpath 2004, p. 5: "Around 4800 years ago Thuban (α Draconis) lay a mere 0°.1 from the pole. Deneb (α Cygni) will be the brightest star near the pole in about 8000 years' time, at a distance of 7°.5."
^"What do the different north arrows on a USGS topographic map mean?". United States Geological Survey.
Sources
McClure, Bruce (2013). "Polaris is the North Star". Astronomy Essentials. EarthSky. from the original on 2014-03-09. Retrieved 2014-04-28.
Smiley, C. H.; Khan, A. Majid (1959). "Polaris and Precession". Journal of the Royal Astronomical Society of Canada. 53: 249. Bibcode:1959JRASC..53..249S.
true, north, other, uses, disambiguation, true, south, redirects, here, flag, used, represent, antarctica, flag, antarctica, this, article, needs, additional, citations, verification, please, help, improve, this, article, adding, citations, reliable, sources, . For other uses see True north disambiguation True south redirects here For the flag used to represent Antarctica see Flag of Antarctica This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources True north news newspapers books scholar JSTOR May 2012 Learn how and when to remove this template message True north also called geodetic north or geographic north is the direction along Earth s surface towards the geographic North Pole or True North Pole Geodetic north differs from magnetic north the direction a compass points toward the Magnetic North Pole and from grid north the direction northwards along the grid lines of a map projection Geodetic true north also differs very slightly from astronomical true north typically by a few arcseconds because the local gravitational field may not point at the exact rotational axis of Earth citation needed The direction of astronomical true north is marked in the skies by the north celestial pole This is within about 1 of the position of Polaris meaning the star would appear to trace a tiny circle in the sky each sidereal day Due to the axial precession of Earth true north rotates in an arc with respect to 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 1 2 3 The visible star nearest the north celestial pole 5 000 years ago was Thuban 4 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 5 The east and west edges of the USGS topographic quadrangle maps of the United States are meridians 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 citation needed References Edit Meeus 1997 p 305 McClure 2013 Smiley amp Khan 1959 p 250 Ridpath 2004 p 5 Around 4800 years ago Thuban a Draconis lay a mere 0 1 from the pole Deneb a Cygni will be the brightest star near the pole in about 8000 years time at a distance of 7 5 What do the different north arrows on a USGS topographic map mean United States Geological Survey Sources EditMcClure Bruce 2013 Polaris is the North Star Astronomy Essentials EarthSky Archived from the original on 2014 03 09 Retrieved 2014 04 28 Meeus Jean 1997 Mathematical Astronomy Morsels Richmond VA Willmann Bell ISBN 0 943396 51 4 Ridpath Ian ed 2004 Norton s Star Atlas New York Pearson Education ISBN 0 13 145164 2 Smiley C H Khan A Majid 1959 Polaris and Precession Journal of the Royal Astronomical Society of Canada 53 249 Bibcode 1959JRASC 53 249S This article about geography terminology is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title True north amp oldid 1116803987, wikipedia, wiki, book, books, library,
