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: http://www.cosmos.ru/mirrors/stern/Education/wms1.html
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The Earth is a huge magnet, and its magnetic influence extends far into space.
However, 60 miles (100 km) or more above the surface of the Earth, the natural environment is quite different. The fringes of the atmosphere at these heights are strongly heated by the Sun's x-rays and ultra-violet light (and by other causes as well), causing negative electrons to be torn off atoms and leaving the remainder of the atoms as positively charged "ions". These electrified fragments react strongly to the magnetic forces and can be steered and trapped by them.
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With a suitable input of energy, such fragments can also be accelerated to high speeds, can give rise to electic currents and emit a variety of radio-type waves.
![]() It can be shown that such free electrons and ions will be guided by the magnetic field lines (or "lines of force") which rise from near the southern (magnetic) pole and enter the Earth again near the northern pole. Electrons and ions tend to remain attached to field lines like beads on wires, though unlike beads they also slowly migrate ("drift") to neighboring "wires." It follows that the structure of field lines near Earth determines much of the motion and behavior of the free electrons and ions found there. Satellites observing magnetic forces in space have found (figure on right) that lines from most points on Earth are confined inside a fairly well-defined cavity, the magnetosphere of the Earth. The space outside it is dominated by the Sun, and by the fast "solar wind" of free ions and electrons emitted by the Sun.
Questions from Users: *** Reversals of the Earth's field (4 queries) *** How do Magnetic Reversals affect Animal Migrations? *** Can the Earth's field be used for spaceflight? *** Magnetic health products *** The strength of the Earth's field *** Measuring the Earth's magnetic field *** What is a "magnetic moment"? |
Next Stop: #2 Magnetic Fields
Author and Curator: Dr. David P. Stern
Mail to Dr.Stern: education("at" symbol)phy6.org
Co-author: Dr. Mauricio Peredo
Spanish translation by J. Méndez