Aurora Australis? At this time of year, at this time of day, in this part of the country?

By Joshua Sibbing, class of 2020.

Every now and then, southern Australia is blessed with a spectacular light display called Aurora Australis. In the northern hemisphere, where auroras are more common, indigenous cultures associate the aurora with celebration. However in Australia, many ancient oral traditions describe the lights as an evil omen due to its rareness and red colour.

Auroras over Kangaroo Island in South Australia have a unique interpretation that reflects the island’s mysterious history. Although the island was uninhabited at the time of European colonisation, archaeological evidence shows that this wasn’t always the case. People had lived on Kangaroo Island for a continuous 14 000 years until mysteriously disappearing just 2 000 years ago. The Narringeri people consider auroras to be campfires of spirits from the people that lived the island.

Aurora Australis appearing in Gunai country (Swift’s Creek, Victoria) in August 2005. Image by Fir0002/Flagstaffotos via Wikimedia Commons.

In Gippsland, Victoria, the Gunai people have a different interpretation of the aurora. Some Gunai people consider the aurora to be “bushfires in the spirit world”, while others consider it to be the anger of Mungan Ngour – a god who lives in the sky. The aurora is believed to be a fire sent by Mungan Ngour for breaking rules and for drifting away from tradition.

Despite the rareness of these events on the Australian mainland, they are well-documented through oral tradition. The science behind these ancient light displays is just as fascinating.

From the sun to our skies

Our aurora journey starts at the sun, where hydrogen and helium burn on its surface at an extremely high temperature of 5 600 °C. The intense heat causes parts of the burning fuel to separate and fly off into space. These separated particles (protons and electrons) become like a wind and move through the solar system – this is called the “solar wind”. Large disturbances on the sun can create even stronger winds called “solar storms”.

When the solar wind reaches the Earth, something strange happens. Instead of colliding with the Earth, the solar wind is repelled away from the Earth like a magnet. This is due to the Earth’s invisible “magnetosphere”. The deflected particles then become attracted to the Earth’s magnetic poles and funnel down to the Arctic and Antarctic.

Earth’s invisible magnetosphere and the incoming solar winds. Image by Frédéric Michel via Wikimedia Commons

When passing through the Earth’s atmosphere, these particles release energy. The energy that they release helps the nitrogen and oxygen gases in our atmosphere vibrate and shine light. The different vibrating gases in the atmosphere are what create the green, red, and purple colours.

Why is Aurora Australis so rare?

Auroras actually aren’t that rare at all. It just so happens that most of the auroras in the southern hemisphere form over the ocean and Antarctica. This is because Earth’s southern magnetic pole is in a pretty isolated location – just slightly off the coast of Antarctica. The brightest lights shine around the latitude of the magnetic pole, so from Australia we can only see the tip of the iceberg.

Schematic diagram of an observer watching Aurora Australis from Victoria. Author’s image.

To see an aurora in Australia, you need to be in a very dark place far from any lights. Nights without a moon are even better! Light pollution from cities like Melbourne will hide an aurora, so your best bet is to go out into the country. Larger solar storms create more intense auroras, so pay attention to solar forecasts for special events.

Other useful resources

Bureau of Meteorology – Space Weather Services

Here you can see geomagnetic activity, aurora forecasts, maps, and soon, a live sky camera from Tasmania. You can also subscribe to alerts via SMS or email for possible aurora events in your area.

Aurora | NASA

Learn all about auroras and see fantastic images on NASA’s aurora website.