Auroras from Space
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Auroras from Space

January 5, 2004
Where does the auroral light come from? Most of the light is emitted by oxygen atoms excited from bombardment by charged solar particles. Charged particles consisting of atomic fragments released by the sun stream through space and run into Earth’s magnetic field. When a charged particle moves through a magnetic field, a force perpendicular to the motion is created and that force diverts the particle into a spiral path until it collides with atoms in the upper atmosphere. In a sense, auroras are the neon lights of the Earth’s poles. The upper atmospheric collisions excite the atoms (oxygen and nitrogen) into emitting light, in much the same way that electrons pumped inside of a glass tube filled with neon gas create a neon light. The green light emitted from excited oxygen is centered around a wavelength of 558 nanometers, while the rarer red light is emitted around wavelengths in the 630 nanometer region.

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