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True north
 
 
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True north is the direction along the earth's surface towards the geographic North Pole
North Pole

The North Pole, also known as the Geographic North Pole or Terrestrial North Pole is, subject to the caveats explained below, defined as the point in the northern hemisphere where the Earth's axis of rotation meets the Earth's surface....
.

True north usually differs from magnetic north (the direction of the magnetic north pole) and grid north
Grid north

Grid north is a navigational term referring to the direction northwards along the grid lines of a map projection. It is contrasted with true north and magnetic north ....
 (the direction northwards along the grid lines of a map projection
Map projection

A map projection is any method of representing the surface of a sphere or other shape on a Plane . Map projections are necessary for creating maps....
).

The direction of true north is marked in the skies by the north celestial pole. For most practical purposes, this is the position of Polaris
Polaris

Polaris is the brightest star in the constellation Ursa Minor. It is very close to the north celestial pole , making it the current northern pole star....
. However, due to the precession
Precession

Precession refers to a change in the direction of the axis of a rotation object. In physics, there are two types of precession, torque-free and torque-induced, the latter being discussed here in more detail....
 of the Earth's axis, true north rotates in an arc that takes approximately 25,000 years to complete.






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True north is the direction along the earth's surface towards the geographic North Pole
North Pole

The North Pole, also known as the Geographic North Pole or Terrestrial North Pole is, subject to the caveats explained below, defined as the point in the northern hemisphere where the Earth's axis of rotation meets the Earth's surface....
.

True north usually differs from magnetic north (the direction of the magnetic north pole) and grid north
Grid north

Grid north is a navigational term referring to the direction northwards along the grid lines of a map projection. It is contrasted with true north and magnetic north ....
 (the direction northwards along the grid lines of a map projection
Map projection

A map projection is any method of representing the surface of a sphere or other shape on a Plane . Map projections are necessary for creating maps....
).

The direction of true north is marked in the skies by the north celestial pole. For most practical purposes, this is the position of Polaris
Polaris

Polaris is the brightest star in the constellation Ursa Minor. It is very close to the north celestial pole , making it the current northern pole star....
. However, due to the precession
Precession

Precession refers to a change in the direction of the axis of a rotation object. In physics, there are two types of precession, torque-free and torque-induced, the latter being discussed here in more detail....
 of the Earth's axis, true north rotates in an arc that takes approximately 25,000 years to complete. In 2102 Polaris will make its closest approach to the celestial north pole. 5,000 years ago, the closest star to the celestial north pole was Thuban
Thuban

Thuban is a star in the constellation of Draco . A relatively inconspicuous star in the night sky of the Northern Hemisphere, it is historically significant as having been the north pole star in ancient times....
.

On maps issued by the United States Geological Survey
United States Geological Survey

The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it....
, and the U.S. military, true north is marked with a line terminating in a five-pointed star. Maps issued by the United Kingdom
United Kingdom

The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom , the UK or Britain,is a sovereign state located off the northwestern coast of continental Europe....
 Ordnance Survey
Ordnance Survey

Ordnance Survey is an executive agency of the United Kingdom government. It is the national mapping agency for Great Britain, and one of the world's largest producers of maps....
 contain a diagram showing the difference between true north, grid north and magnetic north at a point on the sheet.