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  2. Earth's magnetic field - Wikipedia

    en.wikipedia.org/wiki/Earth's_magnetic_field

    The remaining terms predict that the potential of a dipole source (ℓ=1) drops off as 1/r 2. The magnetic field, being a derivative of the potential, drops off as 1/r 3. Quadrupole terms drop off as 1/r 4, and higher order terms drop off increasingly rapidly with the radius. The radius of the outer core is about half of the radius of the Earth.

  3. History of geomagnetism - Wikipedia

    en.wikipedia.org/wiki/History_of_geomagnetism

    The earliest ideas on the nature of magnetism are attributed to Thales (c. 624 BC – c. 546 BC). [1] [2] In classical antiquity, little was known about the nature of magnetism. No sources mention the two poles of a magnet or its tendency to point northward. There were two main theories about the origins of magnetism.

  4. Terrestrial magnetism - Wikipedia

    en.wikipedia.org/?title=Terrestrial_magnetism&...

    This page was last edited on 13 July 2016, at 01:13 (UTC).; Text is available under the Creative Commons Attribution-ShareAlike 4.0 License; additional terms may ...

  5. Magnetic dip - Wikipedia

    en.wikipedia.org/wiki/Magnetic_dip

    Isoclinic lines for the year 2020. Magnetic dip results from the tendency of a magnet to align itself with lines of magnetic field. As Earth's magnetic field lines are not parallel to the surface, the north end of a compass needle will point upward in the Southern Hemisphere (negative dip) or downward in the Northern Hemisphere (positive dip).

  6. Telluric current - Wikipedia

    en.wikipedia.org/wiki/Telluric_current

    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.

  7. A Treatise on Electricity and Magnetism - Wikipedia

    en.wikipedia.org/wiki/A_Treatise_on_Electricity...

    A Treatise on Electricity and Magnetism at Internet Archive. 1st edition 1873 Volume 1, Volume 2; 2nd edition 1881 Volume 1, Volume 2; 3rd edition 1892 (ed. J. J. Thomson) Volume 1, Volume 2; 3rd edition 1892 (Dover reprint 1954) Volume 1, Volume 2; Original Maxwell Equations – Maxwell's 20 Equations in 20 Unknowns – PDF

  8. Magnetopause - Wikipedia

    en.wikipedia.org/wiki/Magnetopause

    Venus and Mars do not have a planetary magnetic field and do not have a magnetopause. The solar wind interacts with the planet's atmosphere [12] and a void is created behind the planet. In the case of the Earth's moon and other bodies without a magnetic field or atmosphere, the body's surface interacts with the solar wind and a void is created ...

  9. K-index - Wikipedia

    en.wikipedia.org/wiki/K-index

    The official planetary K p-index is derived by calculating a weighted average of K-indices from a network of 13 geomagnetic observatories at mid-latitude locations.Since these observatories do not report their data in real-time, various operations centers around the globe estimate the index based on data available from their local network of observatories.