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The same diagram may show the angle of grid north (the direction of the map's north–south grid lines), which may differ from true north. On the topographic maps of the U.S. Geological Survey (USGS), for example, a diagram shows the relationship between magnetic north in the area concerned (with an arrow marked "MN") and true north (a vertical ...
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]
Magnetic north versus ‘true north’ At the top of the world in the middle of the Arctic Ocean lies the geographic North Pole, the point where all the lines of longitude that curve around Earth ...
In surveying, bearings can be referenced to true north, magnetic north, grid north (the Y axis of a map projection), or a previous map, which is often a historical magnetic north. [citation needed] If navigating by gyrocompass, the reference direction is true north, in which case the terms true bearing and geodetic bearing are used.
True south is the direction opposite to the true north. It is important to make the distinction from magnetic north, which points towards an ever changing location close to the True North Pole determined Earth's magnetic field. Due to fundamental limitations in map projection, true north also differs from the grid north which is marked by the ...
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.
Maps typically include information on the declination as an angle or a small diagram showing the relationship between magnetic north and true north. Information on declination for a region can be represented by a chart with isogonic lines (contour lines with each line representing a fixed declination).
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.