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The Earth and most of the planets in the Solar System, as well as the Sun and other stars, all generate magnetic fields through the motion of electrically conducting fluids. [54] The Earth's field originates in its core. This is a region of iron alloys extending to about 3400 km (the radius of the Earth is 6370 km).
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 ...
World Magnetic Model. Magnetic declination map at sea-level for the year 2010 derived from WMM2010. The World Magnetic Model (WMM) is a large spatial-scale representation of the Earth's magnetic field. It was developed jointly by the US National Geophysical Data Center and the British Geological Survey. The data and updates are issued by the US ...
A geomagnetic reversal is a change in a planet'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 ...
Magnetic declination. Angle on the horizontal plane between magnetic north and true north. Example of magnetic declination showing a compass needle with a "positive" (or "easterly") variation from geographic north. N g is geographic or true north, N m is magnetic north, and δ is magnetic declination. Magnetic declination (also called magnetic ...
South Atlantic Anomaly. The South Atlantic Anomaly (SAA) is an area where Earth 's inner Van Allen radiation belt comes closest to Earth's surface, dipping down to an altitude of 200 kilometres (120 mi). This leads to an increased flux of energetic particles in this region and exposes orbiting satellites (including the ISS) to higher-than-usual ...
The PHI instrument also enabled scientists to take a magnetic map, or magnetogram, which shows concentrations of the sun’s magnetic field within its sunspot regions.
The magnetic field of a magnetic dipole has an inverse cubic dependence in distance, so its order of magnitude at the earth surface can be approximated by multiplying the above result with (R outer core ⁄ R Earth) 3 = (2890 ⁄ 6370) 3 = 0.093 , giving 2.5×10 −5 Tesla, not far from the measured value of 3×10 −5 Tesla at the equator.