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Aurora (the Aurora Borealis/Northern Lights or Aurora Australis/Southern Lights) are caused by 'space weather'.

The sun's magnetic field shoots billions of tons of charged particles across the Solar System, called a "Coronal Mass Ejection' or 'Solar Storm'. If Earth happens to be in the way, we collide with these particles

The Earth's magnetic field protects us from a lot of these particles, deflecting them around us, but some slide along the magnetic field lines down to the poles.

There, they excite atoms in the upper atmosphere, which causes them to glow (a bit like a fluorescent tube). Different atoms, at different altitudes, glow different colours.

Many different cultures had stories about the aurora. Māori spoke of them as the reflections of campfires from explorers who had gone to the icy lands in the south. The Norse people said they were a bridge to the heavens that gods used to travel to Earth. The Innuit of Canada thought they were ways to speak with their ancestors, and the Finnish people described it as a fox running across the sky and setting it on fire with his tail.

But other cultures closer to the equator didn't have any stories as they never saw the aurora!