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Somewhat more formally, Bowditch defines variation as "the angle between the magnetic and geographic meridians at any place, expressed in degrees and minutes east or west to indicate the direction of magnetic north from true north. The angle between magnetic and grid meridians is called grid magnetic angle, grid variation, or grivation." [1] By ...
A magnet's North pole is defined as the pole that is attracted by the Earth's North Magnetic Pole, in the arctic region, when the magnet is suspended so it can turn freely. Since opposite poles attract, the North Magnetic Pole of the Earth is really the south pole of its magnetic field (the place where the field is directed downward into the ...
If the reference direction is north (either true north, magnetic north, or grid north), the bearing is termed an absolute bearing. In a contemporary land navigation context, true, magnetic, and grid bearings are always measured in this way, with true north, magnetic north, or grid north being 0° in a 360-degree system. [5]
The magnetic azimuth is the arc between the point on the horizon below the heavenly body and the direction of magnetic north. [ 1 ] When the latitude and date are known, the bearing of the sun at sunrise or sunset relative to true north can be readily determined. [ 2 ]
The local angular difference between magnetic north and true north is called the magnetic declination. Most map coordinate systems are based on true north, and magnetic declination is often shown on map legends so that the direction of true north can be determined from north as indicated by a compass. [28]
The magnetic pole moved along the northern Canadian shore for centuries, Dr Brown said. It drifted into the Arctic Ocean in the 1990s, and after that, it accelerated and headed towards Siberia.
The angle between the magnetic and the true meridian is the magnetic declination, which is relevant for navigating with a compass. [13] Navigators were able to use the azimuth (the horizontal angle or direction of a compass bearing) [14] of the rising and setting Sun to measure the magnetic variation (difference between magnetic and true north ...
Compass needles in the Northern Hemisphere point toward the magnetic North Pole, although the exact location of it changes from time to time as the contours of Earth’s magnetic field also change.