l The Northern Lights - aurora borealis - are caused by charged particles colliding in the Earth's atmosphere.

l They are seen above the magnetic poles of the northern and southern hemispheres.

l Green and pink are the most common colours, but there are also reds, blues, and yellows. The rare red aurora is caused by high-altitude oxygen, which can be as high as 200 miles above ground.

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l Electrons and protons are hurled from the Sun's atmosphere, with some entering Earth's to collide with gas particles, causing the display.