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The dipole magnetic moment of Neptune is about 2.2 × 10 17 T·m 3 (14 μT·R N 3, where R N is the radius of Neptune). Neptune's magnetic field has a complex geometry that includes relatively large contributions from non-dipolar components, including a strong quadrupole moment that may exceed the dipole moment in strength. By contrast, Earth ...
Earth's magnetic field deflects most of the solar wind, whose charged particles would otherwise strip away the ozone layer that protects the Earth from harmful ultraviolet radiation. [4] One stripping mechanism is for gas to be caught in bubbles of the magnetic field, which are ripped off by solar winds. [5]
Earth's two main belts extend from an altitude of about 640 to 58,000 km (400 to 36,040 mi) [3] above the surface, in which region radiation levels vary. The belts are in the inner region of Earth's magnetic field. They trap energetic electrons and protons. Other nuclei, such as alpha particles, are less prevalent.
It took 4.5 billion years before humanity appeared on Earth, and life as we know it will see suitable conditions for 1 [94] to 2.3 [95] billion years more. Red dwarfs, by contrast, could live for trillions of years because their nuclear reactions are far slower than those of larger stars, meaning that life would have longer to evolve and survive.
The equatorial magnetic field strengths of Uranus and Neptune are respectively 75 percent and 45 percent of Earth's 0.305 gauss. [16] Their magnetic fields are believed to originate in an ionized convecting fluid-ice mantle.
If the Earth's magnetic fields were exactly dipolar, the north pole of a magnetic compass needle would point directly at the North Geomagnetic Pole. In practice, it does not because the geomagnetic field that originates in the core has a more complex non-dipolar part, and magnetic anomalies in the Earth's crust also contribute to the local ...
The dense clusters of lines are within the Earth's core. [24] The magnetic field of the Earth, and of other planets that have magnetic fields, is generated by dynamo action in which convection of molten iron in the planetary core generates electric currents which in turn give rise to magnetic fields. [12]
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.