New Zealand / Science

Explainer: Why it's prime time to be an aurora-chaser

19:30 pm on 26 April 2023

The Aurora Australis, as seen near Dunedin, on Monday night. Photo: Ian Griffin / Supplied

The Aurora Australis put on a spectacle in a rare solar storm on Monday night, with purple, orange and green flares seen in the sky as far north as Auckland.

Astronomers say this hints towards an upcoming solar maximum - a period of increased activity, with more frequent visibility of auroras.

What is an Aurora Australis?

An Aurora Australis, also known as the Southern Lights, is caused by magnetically driven explosions on the sun, which shoot material at high speed away from the sun, called Coronal Mass Ejections (CME).

It results in an array of colours lighting up the night sky.

"I think this whole aurora-chasing thing in catching on." Otago Museum director and astronomer Dr Ian Griffin

How did Monday's display compare to others seen in New Zealand?

According to Otago Museum director and astronomer Dr Ian Griffin, the most recent display was "brilliant".

"I've sort of been looking at Aurora Australia from New Zealand for about a decade now and this was in the top two, I reckon, of displays."

Griffin said the aurora was "really bright" and a "really rare form of aurora" known as 'Steve' was also on display.

He said 'Steve' was a "fantastic river of gas" that was sometimes generated during strong aurora storms - and seeing one was quite rare.

Is aurora-chasing a thing now?

Griffin said one of the best things about Monday's display was the sheer number of people who turned out to see it. Griffin said he was watching from Hoopers Inlet near Dunedin and "the number of cars that were there was pretty astonishing".

"I think this whole aurora-chasing thing in catching on."

Why is it a good time to chase auroras?

It was a good time to chase auroras as the sun was near to its next peak, Griffin said.

The astronomer said the sun goes through a cycle every 11 years when there are "peaks and troughs in activity".

Griffin said it was about two years out from the next peak, so he expected to see more displays of the aurora in coming weeks and months that were "hopefully as good, maybe even better, than the one we saw on Monday".

More displays of the Aurora Australis are expected in the coming weeks and months. Photo: Ian Griffin / Supplied

How will we know an aurora is coming?

Some auroras were caused by big explosions on the sun, Griffin said, and then the material starts moving towards Earth.

"We do get a few days warning, but even then, there is uncertainty of what time the aurora will flare up."

Griffin said chasing auroras was bit like fishing. Sometimes people go out and do not quite known what will happen, but sometimes "you catch the enormous great big fish, and that happened to me on Monday night".

What if I am all set to see the aurora and it doesn't happen?

Sometimes the aurora display was not quite what was expected, but regardless, Griffin said New Zealand has a "stunning night sky".

"Even if you do go out and don't see the aurora, there's so much out there to see if you get a really dark spot," he said.

"While the auroras can be a bit fickle, the night sky is always beautiful and it's worth spending a couple hours underneath it."