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What are the variations of earth's magnetic field that have occurred with the passage of time?? |
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Answer» magnetic field changes on time scales from milliseconds to MILLIONS of years. Shorter time scales mostly arise from currents in the ionosphere (ionospheric dynamo region) and MAGNETOSPHERE, and some changes can be TRACED to geomagnetic storms or daily variations in currents. Changes over time scales of a year or more mostly reflect changes in the EARTH's interior, particularly the iron-rich core.[12]Frequently, the Earth's magnetosphere is hit by solar flares causing geomagnetic storms, provoking displays of aurorae. The short-term instability of the magnetic field is measured with the K-index.[29]Data from THEMIS show that the magnetic field, which interacts with the solar wind, is reduced when the magnetic orientation is ALIGNED between Sun and Earth – opposite to the previous hypothesis. During forthcoming solar storms, this could result in blackouts and disruptions in artificial satellites |
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