Magnetic north in the context of "Compass rose"

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⭐ Core Definition: Magnetic north

The north magnetic pole, also known as the magnetic north pole, is a point on the surface of Earth's Northern Hemisphere at which the planet's magnetic field points vertically downward (in other words, if a magnetic compass needle is allowed to rotate in three dimensions, it will point straight down). There is only one location where this occurs, near (but distinct from) the geographic north pole. The Earth's Magnetic North Pole is actually considered the "south pole" in terms of a typical magnet, meaning that the north pole of a magnet would be attracted to the Earth's magnetic north pole.

The north magnetic pole moves over time according to magnetic changes and flux lobe elongation in the Earth's outer core. In 2001, it was determined by the Geological Survey of Canada to lie west of Ellesmere Island in northern Canada at 81°18′N 110°48′W / 81.300°N 110.800°W / 81.300; -110.800 (Magnetic North Pole 2001). It was situated at 83°06′N 117°48′W / 83.100°N 117.800°W / 83.100; -117.800 (Magnetic North Pole 2005 est) in 2005. In 2009, while still situated within the Canadian Arctic at 84°54′N 131°00′W / 84.900°N 131.000°W / 84.900; -131.000 (Magnetic North Pole 2009), it was moving toward Russia at between 55 and 60 km (34 and 37 mi) per year. In 2013, the distance between the north magnetic pole and the geographic north pole was approximately 800 kilometres (500 mi). As of 2021, the pole is projected to have moved beyond the Canadian Arctic to 86°24′00″N 156°47′10″E / 86.400°N 156.786°E / 86.400; 156.786 (Magnetic North Pole 2021 est).

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👉 Magnetic north in the context of Compass rose

A compass rose or compass star, sometimes called a wind rose or rose of the winds, is a polar diagram displaying the orientation of the cardinal directions (north, east, south, and west) and their intermediate points. It is used on compasses (including magnetic ones), maps (such as compass rose networks), or monuments. It is particularly common in navigation systems, including nautical charts, non-directional beacons (NDB), VHF omnidirectional range (VOR) systems, satellite navigation devices ("GPS").

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Magnetic north in the context of Magnetic declination

Magnetic declination (also called magnetic variation) is the angle between magnetic north and true north at a particular location on the Earth's surface. The angle can change over time due to polar wandering.

Magnetic north is the direction that the north end of a magnetized compass needle points, which corresponds to the direction of the Earth's magnetic field lines. True north is the direction along a meridian towards the geographic North Pole.

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Magnetic north in the context of Rhumb line

In navigation, a rhumb line (also rhumb (/rʌm/) or loxodrome) is an arc crossing all meridians of longitude at the same angle. It is a path of constant azimuth relative to true north, which can be steered by maintaining a course of fixed bearing. When drift is not a factor, accurate tracking of a rhumb line course is independent of speed.

In practical navigation, a distinction is made between this true rhumb line and a magnetic rhumb line, with the latter being a path of constant bearing relative to magnetic north. While a navigator could easily steer a magnetic rhumb line using a magnetic compass, this course would not be true because the magnetic declination—the angle between true and magnetic north—varies across the Earth's surface.

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Magnetic north in the context of Geomagnetic reversals

A geomagnetic reversal is a change in the Earth's dipole magnetic field such that the positions of magnetic north and magnetic south are interchanged (not to be confused with geographic north and geographic south). The Earth's magnetic field has alternated between periods of normal polarity, in which the predominant direction of the field was the same as the present direction, and reverse polarity, in which it was the opposite. These periods are called chrons.

Reversal occurrences appear to be statistically random. There have been at least 183 reversals over the last 83 million years (thus on average once every ~450,000 years). The latest, the Brunhes–Matuyama reversal, occurred 780,000 years ago with widely varying estimates of how quickly it happened. Some sources estimate the most recent four reversals took on average 7,000 years to occur. Clement (2004) suggests that this duration is dependent on latitude, with shorter durations at low latitudes and longer durations at mid and high latitudes. Others estimate the duration of full reversals to vary from between 2,000 to 12,000 years.

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