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The magnetic field is generated by a feedback loop: current loops generate magnetic fields (Ampère's circuital law); a changing magnetic field generates an electric field (Faraday's law); and the electric and magnetic fields exert a force on the charges that are flowing in currents (the Lorentz force). [58]
Study of Earth's magnetosphere began in 1600, when William Gilbert discovered that the magnetic field on the surface of Earth resembled that of a terrella, a small, magnetized sphere. In the 1940s, Walter M. Elsasser proposed the model of dynamo theory, which attributes Earth's magnetic field to the motion of Earth's iron outer core.
The Brunhes–Matuyama reversal, named after Bernard Brunhes and Motonori Matuyama, was a geologic event, approximately 781,000 years ago, when the Earth's magnetic field last underwent reversal. [ 1 ] [ 2 ] Estimations vary as to the abruptness of the reversal.
Their field strengths are intermediate between those of the gas giants and those of the terrestrial planets, being 50 and 25 times that of Earth's, respectively. The equatorial magnetic field strengths of Uranus and Neptune are respectively 75 percent and 45 percent of Earth's 0.305 gauss. [ 16 ]
The transition from the normal field to the reversed field lasted approximately 250 years, while the magnetic field remained reversed for approximately 440 years. During the transition, Earth's magnetic field declined to a minimum of 5% of its current strength, and was at about 25% of its current strength when fully reversed.
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 ...
Illustration of the coordinate systems used for representing the Earth's magnetic field. The coordinates X,Y,Z correspond to north, east, and down; D is the declination and I is the inclination. At a given location, a full representation of the Earth's magnetic field requires a vector with three coordinates (see
A new study posits that the shifting of the magnetic poles possibly spelled the end of Neanderthals. Neanderthals died out 42,000 years ago as Earth’s magnetic poles flipped, scientists claim ...