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polar lights [Q&A]


Sathwika of SDM PU College asks, what is the mechanism of the formation of aurora?

Aurorae, aka polar lights, form when plasma from the solar wind gets funneled into the Earth’s atmosphere around the magnetic poles, and collide with Oxygen and Nitrogen atoms and ions in the upper atmosphere. The collision causes the electrons in the species to jump to a higher excitation state, from which it decays spontaneously, releasing the energy as visible light. The auroras become prominent whenever there is a mass ejection from the solar corona and that material hits the Earth’s magnetosphere, wraps around, “shorts out” (reconnects) the fields at the downwind side, and whips back “down the chute” to the magnetic poles. Here is an animation from the SoHO team that depicts that:

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