Geographical pole

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A geographical axis of rotation A (green), and showing the north geographical pole A1, and south geographical pole A2; also showing a magnetic field and the magnetic axis of rotation B (blue), and the north magnetic pole B2, and south magnetic pole B1. Geographical and Magnetic Poles.png
A geographical axis of rotation A (green), and showing the north geographical pole A1, and south geographical pole A2; also showing a magnetic field and the magnetic axis of rotation B (blue), and the north magnetic pole B2, and south magnetic pole B1.

A geographical pole is either of the two points on a rotating body (planet, dwarf planet, natural satellite, sphere...etc) where its axis of rotation intersects its surface. [1] As with Earth's North and South Poles, they are usually called that body's "north pole" and "south pole", one lying 90 degrees in one direction from the body's equator and the other lying 90 degrees in the opposite direction from the equator.

Planet Class of astronomical body directly orbiting a star or stellar remnant

A planet is an astronomical body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.

Dwarf planet planetary-mass object

A dwarf planet is a planetary-mass object that is neither a true planet nor a natural satellite. That is, it is in direct orbit of a star, and is massive enough for its gravity to compress it into a hydrostatically equilibrious shape, but has not cleared the neighborhood of other material around its orbit.

Natural satellite astronomical body that orbits a planet

A natural satellite or moon is, in the most common usage, an astronomical body that orbits a planet or minor planet.

Every planet has geographical poles. [2] If, like the Earth, a body generates a magnetic field, it will also possess magnetic poles. [3]

Earths magnetic field Magnetic field that extends from the Earths inner core to where it meets the solar wind

Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from the Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from the Sun. The magnetic field is generated by electric currents due to the motion of convection currents of molten iron in the Earth's outer core: these convection currents are caused by heat escaping from the core, a natural process called a geodynamo. The magnitude of the Earth's magnetic field at its surface ranges from 25 to 65 microteslas. As an approximation, it is represented by a field of a magnetic dipole currently tilted at an angle of about 11 degrees with respect to Earth's rotational axis, as if there were a bar magnet placed at that angle at the center of the Earth. The North geomagnetic pole, currently located near Greenland in the northern hemisphere, is actually the south pole of the Earth's magnetic field, and conversely.

Magnetic field spatial distribution of vectors allowing the calculation of the magnetic force on a test particle

A magnetic field is a vector field that describes the magnetic influence of electrical currents and magnetized materials. In everyday life, the effects of magnetic fields are often seen in permanent magnets, which pull on magnetic materials and attract or repel other magnets. Magnetic fields surround and are created by magnetized material and by moving electric charges such as those used in electromagnets. Magnetic fields exert forces on nearby moving electrical charges and torques on nearby magnets. In addition, a magnetic field that varies with location exerts a force on magnetic materials. Both the strength and direction of a magnetic field varies with location. As such, it is an example of a vector field.

Perturbations in a body's rotation mean that geographical poles wander slightly on its surface. The Earth's North and South Poles, for example, move by a few metres over periods of a few years. [4] [5] As cartography requires exact and unchanging coordinates, the averaged[ citation needed ] locations of geographical poles are taken as fixed cartographic poles and become the points where the body's great circles of longitude intersect.

Cartography The study and practice of making maps

Cartography is the study and practice of making maps. Combining science, aesthetics, and technique, cartography builds on the premise that reality can be modeled in ways that communicate spatial information effectively.

Great circle intersection of the sphere and a plane which passes through the center point of the sphere

A great circle, also known as an orthodrome, of a sphere is the intersection of the sphere and a plane that passes through the center point of the sphere. A great circle is the largest circle that can be drawn on any given sphere. Any diameter of any great circle coincides with a diameter of the sphere, and therefore all great circles have the same center and circumference as each other. This special case of a circle of a sphere is in opposition to a small circle, that is, the intersection of the sphere and a plane that does not pass through the center. Every circle in Euclidean 3-space is a great circle of exactly one sphere.

See also

Antipodes diametrically opposite point on the Earths surface

In geography, the antipode of any spot on Earth is the point on Earth's surface diametrically opposite to it; the antipodes of a region similarly represent the area opposite it. A pair of points antipodal to each other are situated such that a straight line connecting the two would pass through Earth's center. Such points are as far away from each other as possible, a great-circle distance of up to 40,075.017 kilometres (24,901.461 mi) on the equator.

An equatorial bulge is a difference between the equatorial and polar diameters of a planet, due to the centrifugal force exerted by the rotation about the body's axis. A rotating body tends to form an oblate spheroid rather than a sphere.

Polar regions of Earth regions around the Earths geographical poles

The polar regions, also called the frigid zones, of Earth are the regions of the planet that surround its geographical poles, lying within the polar circles. These high latitudes are dominated by Earth's polar ice caps: the northern resting on the Arctic Ocean and the southern on the continent of Antarctica.

Related Research Articles

Longitude A geographic coordinate that specifies the east-west position of a point on the Earths surface

Longitude, is a geographic coordinate that specifies the east–west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees and denoted by the Greek letter lambda (λ). Meridians connect points with the same longitude. By convention, one of these, the Prime Meridian, which passes through the Royal Observatory, Greenwich, England, was allocated the position of 0° longitude. The longitude of other places is measured as the angle east or west from the Prime Meridian, ranging from 0° at the Prime Meridian to +180° eastward and −180° westward. Specifically, it is the angle between a plane through the Prime Meridian and a plane through both poles and the location in question.

Northern Hemisphere half of Earth that is north of the equator

The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's North Pole.

Celestial pole two imaginary points in the sky where the Earths axis of rotation, indefinitely extended, intersects the imaginary rotating sphere of stars called the celestial sphere

The north and south celestial poles are the two imaginary points in the sky where the Earth's axis of rotation, indefinitely extended, intersects the celestial sphere. The north and south celestial poles appear permanently directly overhead to an observer at the Earth's North Pole and South Pole, respectively. As the Earth spins on its axis, the two celestial poles remain fixed in the sky, and all other points appear to rotate around them, completing one circuit per day.

Geographic coordinate system Coordinate system

A geographic coordinate system is a coordinate system that enables every location on Earth to be specified by a set of numbers, letters or symbols. The coordinates are often chosen such that one of the numbers represents a vertical position and two or three of the numbers represent a horizontal position; alternatively, a geographic position may be expressed in a combined three-dimensional Cartesian vector. A common choice of coordinates is latitude, longitude and elevation. To specify a location on a plane requires a map projection.

Pole may refer to:

Circle of latitude Geographic notion

A circle of latitude on Earth is an abstract east–west circle connecting all locations around Earth at a given latitude.

Reference ellipsoid an ellipsoid that approximates the figure of the Earth

In geodesy, a reference ellipsoid is a mathematically defined surface that approximates the geoid, the truer figure of the Earth, or other planetary body. Because of their relative simplicity, reference ellipsoids are used as a preferred surface on which geodetic network computations are performed and point coordinates such as latitude, longitude, and elevation are defined.

Selenographic coordinates coordinate system

Selenographic coordinates are used to refer to locations on the surface of Earth's moon. Any position on the lunar surface can be referenced by specifying two numerical values, which are comparable to the latitude and longitude of Earth. The longitude gives the position east or west of the Moon's prime meridian, which is the line passing from the lunar north pole through the point on the lunar surface directly facing Earth to the lunar south pole. This can be thought of as the midpoint of the visible Moon as seen from the Earth. The latitude gives the position north or south of the lunar equator. Both of these coordinates are given in degrees.

The cataclysmic pole shift hypothesis is a fringe theory suggesting that there have been geologically rapid shifts in the relative positions of the modern-day geographic locations of the poles and the axis of rotation of the Earth, creating calamities such as floods and tectonic events.

Several vector diagrams are often used to demonstrate the physics underlying the Foucault pendulum.

Ground track path on the surface of the Earth or another body directly below an aircraft or satellite

A ground track or ground trace is the path on the surface of the Earth directly below an aircraft or satellite. In the case of a satellite, it is the projection of the satellite's orbit onto the surface of the Earth.

Daytime period on any given point of the planets surface during which it experiences natural illumination from sunlight

On Earth, daytime is roughly the period of the day during which any given point in the world experiences natural illumination from especially direct sunlight. Daytime occurs when the Sun appears above the local horizon, that is, anywhere on the globe's hemisphere facing the Sun. During daytime, an observer sees indirect sunlight while in the shade, which includes cloud cover. 'Day' is sometimes used instead of 'daytime', in this case 'day' will mean 'the period of light between dawn and nightfall; the interval from sunrise to sunset', which is synonymous with daytime. However in this context, in order to be clear "daytime" should be used distinguish it from "day" which typically refers to a 24-hour period.

The poles of astronomical bodies are determined based on their axis of rotation in relation to the celestial poles of the celestial sphere. Astronomical bodies include stars, planets, dwarf planets and small Solar System bodies such as comets and minor planets, as well as natural satellites and minor-planet moons.

True polar wander Wandering of a planets pole of rotation

True polar wander is a solid-body rotation of a planet or moon with respect to its spin axis, causing the geographic locations of the north and south poles to change, or "wander". In a stable state, the largest moment of inertia axis is aligned with the spin axis, with the smaller two moments of inertia axes lying in the plane of the equator. When this is not the case, true polar wander will occur: the planet or moon will rotate as a rigid body to realign the largest moment of inertia axis with the spin axis.

Polar wander is the motion of a pole in relation to a fixed reference frame. It can be used, for example, to measure the degree to which Earth's magnetic poles have been observed to move relative to the Earth's rotation axis. It is also possible to use continents as a static entity and observe the relative motion of the magnetic pole on the different continents; by doing so, the relative motion of those two continents to each other can be observed over geologic time.

South Pole Southern point where the Earths axis of rotation intersects its surface

The South Pole, also known as the Geographic South Pole or Terrestrial South Pole, is one of the two points where the Earth's axis of rotation intersects its surface. It is the southernmost point on the surface of the Earth and lies on the opposite side of the Earth from the North Pole.

Apparent polar wander (APW) is the perceived movement of the Earth's paleo-magnetic poles relative to a continent while regarding the continent being studied as fixed in position. It is frequently displayed on the present latitude-longitude map as a path connecting the locations of geomagnetic poles, inferred at distinct times using paleomagnetic techniques.

This glossary of geography terms is a list of definitions of terms and concepts used in geography and related fields, which describe and identify natural phenomena, geographical locations, spatial dimension and natural resources. Geographical terms are classified according to their functions, such as description, explanation, analysing, evaluating and integrating.

North Magnetic Pole Wandering point on the Northern Hemisphere

The North Magnetic Pole is the wandering point on the surface of Earth's Northern Hemisphere at which the planet's magnetic field points vertically downwards. There is only one location where this occurs, near the Geographic North Pole and the Geomagnetic North Pole.

Geomagnetic pole The poles of a dipole approximation to the Earths field

The geomagnetic poles are antipodal points where the axis of a best-fitting dipole intersects the surface of Earth. This theoretical dipole is equivalent to a powerful bar magnet at the center of Earth and comes closer than any other model to accounting for the magnetic field observed at Earth's surface. In contrast, the magnetic poles of the actual Earth are not antipodal; that is, the line on which they lie does not pass through Earth's center.

References

  1. Kotlyakov, Vladimir; Komarova, Anna (2006). Elsevier's Dictionary of Geography: in English, Russian, French, Spanish and German. p. 557. Retrieved 22 June 2015.
  2. Hooper, William (2008). Aether and Gravitation. p. 224. Retrieved 22 June 2015.
  3. "20 Things You Didn't Know About... the North Pole". DiscoverMagazine.com. 2014-11-18. Retrieved 2015-06-26.
  4. Schar, Ray (2010). Wonderfully Weird World. p. 106. Retrieved 22 June 2015.
  5. Lovett, Richard A. (2013-05-14). "Climate Change Has Shifted the Locations of Earth's North and South Poles". Scientificamerican.com. Retrieved 2015-06-26.