Did You know: Auroras

This month . . . Auroras. Named for the Roman goddess of the dawn.

Auroras are caused by the collision of energetically charged particles with atoms in the high-altitude thermosphere of our atmosphere and are associated with the solar winds that flow past Earth. Auroras are known in the southern hemisphere as Aurora Australis or “Southern Lights” and in the northern hemisphere as Aurora Borealis or “Northern Lights”

Auroras in the southern hemisphere have been seen, on rare occasions, as far north as southern Queensland.

The most common colours in auroras are red and green. The colours depend on whether electrons collide with oxygen or nitrogen. As our night vision is most sensitive to green light, we are more likely to see the oxygen green line emissions.

While auroras are renowned for their spectacular light shows less well known are unexplained reports of sounds being heard during auroral displays including a hissing sound followed by a sharper crackling or clapping.

Earth is not the only planet with auroras. Auroras also occur on other planets in our solar system – Mars, Jupiter, Saturn, Uranus, Neptune. Like Earth's aurora, the lights have been seen close to the planets’ magnetic poles.

Photograph by Lex Huggett, Aurora Borealis, 28 May 2017.