Australian Weather Calendar: March 2017

March Photograph by Lydia Dobromilsky

The lights seen by Lydia Dobromilsky over Antarctica are aurora australis, or the southern lights. They are caused by streams of charged particles, produced by flares on the surface of the sun. After 150 million kilometres, these particles are directed by Earth's magnetic field to the plant's poles, where they collide with our atmosphere.

The effect is much like the process that occurs in neon lights: As a charged particle collides with an atom of gas in the atmosphere, it 'excites' the atom's electrons. The excited electrons then return to their normal state, releasing energy in the form of light. Green light, as Lydia saw, is produced by oxygen atoms.

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