What causes the aurora?
Why and how do aurora get created in the night sky of the arctic and antarctic? Why are they usually green in color or occasionally also red or pink or purple. What gives them different colors, and can we see them on other planets?
The aurora are caused by charged particles from the solar wind hitting atoms in the Earth's upper atmosphere. The Sun emits a stream of electrons and protons called the solar wind. These particles interact with the Earth's magnetic field and are funneled towards the magnetic poles, which is why aurora are visible at high latitudes.
The different colors in the aurora come from different atoms being excited. Green aurora come from the excitation of oxygen. Red and blue aurora come from the excitation and ionization of nitrogen atoms.
Just for fun, here is a beautiful video of the aurora viewed from the International Space Station.
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