What causes the Aurora Australis here in Hobart, Tasmania?
The sun releases particles of plasma (which we call “solar wind”) through sunspots and coronal holes. They strike the earth’s magnetosphere at hundreds of km/s. Contained within the plasma are electrons. When these electrons collide with the gases in Earth’s upper atmosphere it ‘excites’ them into a higher energy state. When they move back down to their natural energy state, they emit a photon of light. Collisions with oxygen produce green and yellow auroras while collisions with nitrogen produce pink, red, purple and blue auroras.
The sun goes through an 11 year cycle of solar maximum and solar minimum. During solar maximum there are many more solar flares, resulting in a higher frequency of auroras. Hobart, Tasmania is at 42 degrees south latitude and typically experiences the Aurora Australis at least several times or more a year, dependent upon the solar cycle. Tasmania has also got some of the darkest skies in the world, especially facing south, so we are blessed to have fantastic views of the Southern Lights.
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