Australians brace for rare weather event: 'No way to know how this will play out'

Australians could be in for another glimpse of a rare weather event.

Experts are keeping a close eye on increased activity on the sun, with RMIT School of Science associate professor Dr Brett Carter revealing auroras could be visible on Tuesday night.

Auroras, known as the Southern Lights, are usually seen from Tasmania.

However, May brought in the biggest geomagnetic storm in nearly 20 years, giving star gazers in Victoria, South Australia, and across the globe prime views of the rare event.

Hues of pink, purple and green lit up the sky, delighting regular Aussies and avid star gazers alike.

Now, another geomagnetic storm is expected to hit, with it forecast to be strongest on Tuesday evening.

This could give those in the southern parts of Victoria and Western Australia a chance at seeing the colourful phenomenon.

'If this storm ends up being as strong as it is forecast, there could be a possibility of visible auroras as far north as parts of NSW and South Australia,' Professor Carter said.

The weather event is caused by coronal mass ejections (CME's), which are clouds of charged particles and magnetic field that can interact with earth's magnetic field and atmosphere, bringing about colourful auroras.

'Since Saturday morning, both solar flares and coronal mass ejections - eruptions of solar material out into space - have been observed,' Professor Carter said.

'At least two coronal mass ejections are approaching Earth. 

'They are predicted to merge into one disturbance that is expected to arrive Tuesday morning onwards.

'The scale of the geomagnetic storm that these eruptions cause is expected to be largest the evening of Tuesday 30 July, giving Australians in southern parts of Victoria and Western Australia a chance at seeing some aurora - if conditions are right.'

It's unclear exactly what time the solar storm will arrive in Australia, and the likelihood of catching an aurora is 'highly uncertain'.

'The most significant issue in predicting the impact of such events on Earth is that we don't know the magnetic field within the eruption,' Professor Carter said. 

'Disturbances with southward magnetic field have significantly larger impacts than those that are northward.

'Currently, we don't have a reliable way to predict the magnetic field within solar eruptions.'

More research is needed, as well as more data and better models to predict the space environment, Professor Carter said.

'There's no way to know for sure how this space weather event is going to play out,' he said.

'We will just have to watch the data come in and see whether the conditions are suitable for aurora viewing or not.

'To know whether it's worth packing up the camera gear and heading for some dark, clear skies, keep an eye on the space weather data coming in and keep an eye on your social media feeds. 

'People are very quick to share their amazing aurora photos online.'