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Physics LibreTexts

2.10: Aurora

At the interface between the atmosphere and the Solar wind, magnetic fields shape the appearance of striking natural light shows. Here on the Earth, these light shows colloquially go by the names the Northern and Southern Lights, and are more technically called aurora. These events occur when solar storms blast ionized particles toward the Earth. These particles can get captured by the Earth's magnetic field and accelerated down field lines. In the process, they may collide with and ionize atoms in the Earth's ionosphere. Over time, these ions will recapture an electron, and release energy in the characteristic greens (oxygen), reds and blues (nitrogen) of aurora. These events also give off light in non-visible wavelengths, including ultraviolet and even X-Ray.
 


Images of the aurora australis and aurora borealis from around the world, including those with rarer red and blue lights. Click here for original source URL.


Aurora are seen on Saturn and Jupiter as well as over Earth. While Saturn's aurora are similar in nature to Earth's, Jupiter's aurora are also driven by interactions between Jupiter and its moons. The moon Io, in particular, releases a steady stream of material as it undergoes continual volcanic eruptions. As Io passes in and out of Jupiter's magnetosphere, these ions get captured and accelerated along Jupiter's magnetic field lines to generate aurora.

The relationship between aurora and planetary magnetic fields causes the aurora to be richest at the magnetic poles of each planet. In the polar regions of the planet Earth, aurora are seen regularly at night during solar maxima and sporadically at all other times. When a particularly large storm of particles hits the Earth's atmosphere aurora may actually span from polar regions to mid-latitudes.