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The World Digital Magnetic Anomaly Map (WDMAM) was first made available by the Commission for the Geological Map of the World in 2007. Compiled with data from governments and institutes, [1] the project was coordinated by the International Association of Geomagnetism and Aeronomy, and was presented by Mike Purucker of NASA and Colin Reeves of the Netherlands. [2]
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 magnetic field has behaved even more dramatically in the past, with the magnetosphere weakening so much that its polarity reversed. This flips the magnetic north and south poles, and the ...
The Bangui magnetic anomaly in central Africa and the Kursk magnetic anomaly in eastern Europe (both in red) In geophysics, a magnetic anomaly is a local variation in the Earth's magnetic field resulting from variations in the chemistry or magnetism of the rocks. Mapping of variation over an area is valuable in detecting structures obscured by ...
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 WMM, IGRF, and GUFM models only describe the magnetic field as emitted at the core-mantle boundary. In practice, the magnetic field is also distorted by the Earth crust, the distortion being magnetic anomaly. For more precise estimates, a larger crust-aware model such as the Enhanced Magnetic Model may be used.
A telluric current (from Latin tellūs ' earth '), or Earth current, [1] is an electric current that flows underground or through the sea, resulting from natural and human-induced causes. These currents have extremely low frequency and traverse large areas near or at Earth 's surface.
Google has updated it's aerial maps of Ukraine for the first time since the start of Russia's attack - with images now revealing the full scale of devastation. The contrast is stark in Mariupol.