Online Encyclopedia
North Pole
See also: town of North Pole, Alaska and village of North Pole, New York.
A North Pole is the northernmost point on any planet. There are various ways of defining a planet's North Pole. Earth's Pole, however it is defined, lies in the Arctic Ocean.
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Defining North Poles in astronomy
Astronomers define the north "geographic" pole of a planet in the solar system by the planetary pole that is in the same ecliptic hemisphere as the Earth's north pole. For the magnetic poles, their names are decided upon by the direction that their field lines emerge or enter the planet's crust. If they enter the same way as they do for Earth at the north pole, we call this the planet's north magnetic pole.
The axial tilt of the planet Uranus is very nearly 90 degrees relative to the ecliptic plane, so that labelling one pole or the other to be the "north" pole is still a matter of some dispute. When a body's axial tilt is greater than 90 degrees, either one of two interpretations can be considered equally valid; the axis could be tilted greater than 90 degrees, or the labelling of the poles could be reversed (north becomes south) and the body considered to be rotating in a retrograde direction.
Some bodies in the solar system, including Saturn's moon Hyperion and the asteroid Toutatis, lack a geographic north pole. They rotate chaotically because of their irregular shape and gravitational influences from nearby planets and moons.
The projection of a planet's north geographic pole onto the celestial sphere gives its north celestial pole.
Defining the North Pole of Earth
The North Pole, the northernmost point on the Earth, can be defined in four different ways. Only the first two definitions are commonly used. However it is defined, the North Pole lies in the Arctic Ocean.
- The Geographic North Pole, also known as True North, is the northernmost point on the Earth as determined by the planet's rotation. It has a known fixed position, at latitude 90° North. The national boundaries of Canada extend all the way to the Geographic North Pole. Therefore, the North Pole of the Earth may be said to be located in Canada. However, recently,Russia and Denmark are poised to contest this point. In the mid-20th Century, Canada made an official claim to the pole; if no compelling opposition is presented by the mid-21st Century, the pole will officially be considered part of Canada. There is no land at this location, which is usually covered by sea ice, and is also known as the North Pole, or polar ice cap .
- The Magnetic North Pole is the northern point at which the geomagnetic field points vertically, i.e. the dip is 90°. This definition was proposed by Sir William Gilbert, a courtier of Queen Elizabeth I, in 1600 and is still used. Despite its name, it is a south magnetic pole, because the north pole (labelled N) of every other magnet is attracted to it, and opposite magnetic poles attract each other. Its location (in 2003) is 78°18' North, 104° West, near Ellef Ringness Island , one of the Queen Elizabeth Islands, in Canada.
- The Geomagnetic North Pole is the pole of the Earth's geomagnetic field closest to true north. Like Magnetic North, it is a south magnetic pole. It is the centre of the region in the magnetosphere in which the Aurora Borealis can be seen. Its present location is 78°30' North, 69° West, near Thule in Greenland.
- The Northern Pole of Inaccessibility is defined as the point in the Arctic farthest from any coastline, and is at 84°03' North, 174°51' West. It is of interest mainly to explorers and conspiracy theorists, and was first visited in 1927.
Geographic North Pole
The Geographic North Pole, also known as true North, is the northern point at which the Earth's axis of rotation meets the surface. Geographic North has a known fixed position, at latitude 90° North. In whichever direction you travel from here, you are always heading south.
The boundaries of Canada extend all the way to the Geographic North Pole. There is no land at this location, which is usually covered by sea ice. The first expedition to the pole is generally accepted to have been made by Navy engineer Robert Edwin Peary and his employee, black American Matthew Henson and four Inuit men (Ootah , Seegloo, Egingway , and Ooqueah ) on April 6, 1909. Polar historians believe that Peary honestly thought he had reached the pole. However a 1996 analysis of a newly-discovered copy of Peary's record indicates that Peary must have been in fact 20 miles (32km) short of the Pole.
The first undisputed sight of the pole was in 1926 by Norwegian explorer Roald Amundsen and his American sponsor Lincoln Ellsworth from the airship Norge, designed and piloted by the Italian Umberto Nobile, in a flight from Svalbard to Alaska.
On May 3, 1952 U.S. Air Force Lieutenant Colonel Joseph O. Fletcher and Lieutenant William P. Benedict landed a plane at the geographic North Pole.
On April 6, 1992 Robert Schumann became the youngest person to visit the north pole.
In popular mythology, Santa Claus resides at the geographic North Pole.
Magnetic North
Magnetic North is one of several locations on the Earth's surface known as the "North Pole". Its definition, as the point where the geomagnetic field points vertically downwards, i.e. the dip is 90°, was proposed in 1600 by Sir William Gilbert, a courtier of Queen Elizabeth I, and is still used. It should not be confused with the less frequently used Geomagnetic North Pole. Magnetic North is the place to which all magnetic compasses point, although since the pole marked "N" on a bar magnet points north, and only opposite magnetic poles are attracted to each other, the Earth's magnetic north is actually a south magnetic pole.
Magnetic poles can flip flop from north to south and back again. The Earth's poles have done this repeatedly throughout history, and 500,000 years ago, the south magnetic pole was at the North Pole. It is thought that this occurs when the circulation of liquid nickel/iron in the Earth's outer core is disrupted and then reestablishes itself in the opposite direction. It is not known what causes these disruptions.
The first expedition to reach this pole was led by James Clark Ross, who found it at Cape Adelaide on the Boothia Peninsula on June 1, 1831. Roald Amundsen found Magnetic North in a slightly different location in 1903. The third observation of Magnetic North was by Canadian government scientists Paul Serson and Jack Clark, of the Dominion Astrophysical Observatory, who found the pole at Allen Lake on Prince of Wales Island. The Canadian government has made several measurements since, which show that Magnetic North is continually moving northwest. Its average speed between 2001 and 2003 was about 40 km per year. (See also Polar drift)
This movement is on top of a daily or diurnal variation in which Magnetic North describes a rough ellipse, with a maximum deviation of 80 km from its mean position. This effect is due to disturbances of the geomagnetic field by the sun.
The angular difference between Magnetic North and true North varies with location, and is called the magnetic declination.
Geomagnetic North Pole
The Geomagnetic North Pole is the pole of the Earth's geomagnetic field closest to true north.
Like the Magnetic North Pole, it is a south magnetic pole, because it attracts the north pole of a bar magnet. It is the centre of the region in the magnetosphere in which the Aurora Borealis can be seen. Its present location is 78°30' North, 69° West, near Thule in Greenland.
The first voyage to this pole was by David Hempleman-Adams in 1992.
The Northern Pole of Inaccessibility
The Northern Pole of Inaccessibility, located at 84°03' north, 174°51' west, is the point farthest from any northern coastline. It is located within the Arctic region. It is on the surface of the Arctic Ocean which is most distant from land, about 700 miles from the nearest coast. It is a geographic construct, not an actual physical phenomenon. It was first reached by Sir Hubert Wilkins , who flew by aircraft in 1927; in 1958 a Russian icebreaker reached this point.