Australian Government - Antarctic Division
Australian Government Antarctic Division
Antarctica - Valued, Protected, Understood

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Poles

Southern poles from space

The three main South Poles

Poles

True Geographic Pole

Either of two points of intersection of the surface of the Earth with the Earth's axis of rotation. The location of this pole moves approximately 10m a year and is recalculated each year. The true south geographic pole is located near Amundsen-Scott South Pole Station. Here there are many markers representing the movement of the true geographic pole. The distance between the south geographic pole and the south magnetic pole is approximately 2,858 kilometres. The geographic pole is also sometimes referred to as the geodetic pole.

South Magnetic Pole

Is the point on the Earth's surface where the direction of the Earth's magnetic field is vertically upwards. The magnetic dip, the angle between the horizontal plane and the Earth's magnetic field lines, is 90° at the magnetic poles. The south magnetic pole is not fixed and its position moves about 5 kilometres a year presently in a north to northwesterly direction. The location of the south magnetic pole as at February 1998 was 64.59° S and 138.53° E.

Geomagnetic Pole

Either of two points of intersection of the surface of the Earth with the extended axis of a magnetic dipole which is assumed to be located at the centre of the Earth and approximates the source of the Earth's magnetic field. It should not be confused with the magnetic pole which relates to the actual magnetic field of the Earth. The south geomagnetic pole is at 78° 30' S and 111° E which is near Russia's Vostok Station.

Pole of Inaccessibility

The furthest point from any Antarctic coasts. It is located at approximately 83° S and 55° E, approximately 870 kilometres from the South Pole. The pole of inaccessibility was reached by a Soviet Antarctic Expedition for International Geophysical Year research work in 1958. Today a building, plaque and bust of Vladimir Lenin still remain. They are protected as an historic site. When the site was visited in January 2007, only the bust and plaque were visible.

Ceremonial Pole

Located near Amundsen-Scott South Pole Station. A red and white striped barber pole capped with a metallic chromium globe. Surrounding the barber pole are 12 flags representing the original Antarctic Treaty signatories. The barber pole was placed on the Geographic Pole, but this pole moves 10m per year.

Directions

Geographic or true directions

North-south is along any meridian and east-west is along any parallel, because of the way the graticule has been defined. These lines are perpendicular except at the poles. The direction determined by the orientation of the graticule is called geographic or true direction. True north is therefore the direction towards the north geographic pole.

Magnetic North

The direction indicated by the north seeking pole of a magnetic needle influenced only by the Earth's magnetic field. The direction of the magnetic pole is not usually parallel to the meridian. The difference between true north and magnetic north is called magnetic declination.

Grid North

The northwards direction of a line of constant easting on a grid projection. When a rectangular grid is placed over the graticule of a map, the north direction of the grid will generally not coincide with true north. For example, when a UTM projection is used, grid north and true north only coincide at the central meridian. Away from the central meridian the difference between true north and grid north is known as the grid convergence.

Meridian

A line approximating the surface of the Earth, from the north pole to the south pole and connecting points of equal longitude. The prime meridian, located at Greenwich, England, is the origin from which the numbering begins for identifying lines of longitude.

Parallel

A circle approximating the surface of the Earth, parallel to the equator and connecting points of equal latitude.

Great Circle distance

The shortest distance between two points on the surface of the Earth, assuming the Earth is spherical.

Other Information

Geodetic Datum

A geodetic datum forms the basis for horizontal control surveys where the curvature of the Earth is considered. The datum generally consists of the position of an origin point (latitude, longitude and elevation above the reference spheroid) , an orientation (an azimuth from this point or other points of known position) and two constants which define the reference spheroid.

Map Projections Information about three map projections commonly used in Antarctica.

Conversion Calculators eg a calculator that returns a distance and direction for two points stored in a UTM projection.

Written by Ursula Ryan, AADC