24 Apr 2017

Spectacular Aurora display not over yet

9:19 am on 24 April 2017

Aurora hunters were treated to an unusually intense and widespread display of the Southern Lights over the weekend, and it's not over yet, says Otago University astronomer Ian Griffin.

The Aurora Australis near Cape Saunders on the Otago Peninsula.

The Aurora Australis near Cape Saunders on the Otago Peninsula. Photo: Supplied / Ian Griffin

The Aurora Australis, or the Southern Lights, were spotted all over the country - and as far north as Auckland.

Dr Griffin - who is also the Otago Museum director - told Morning Report it was a particularly intense display in Otago on Sunday night.

"This was quite an interesting display, I saw mostly greens, but other people who have got better eyes than me were seeing reds, but the photographs showed all the colours much better and there were some lovely purples in there as well. So it was a pretty stunning display, all told."

The Aurora Australis near Cape Saunders on the Otago Peninsula.

The Aurora Australis near Cape Saunders on the Otago Peninsula. Photo: Supplied / Ian Griffin

This week's display was caused by a large coronal hole on the sun, said Dr Griffin.

"It's basically a gap in the sun's magnetic field that starts spewing material towards the Earth - and it races towards the Earth at between 600 and 800 kilometres per second - and it's that material that interacts with the Earth's magnetic field and causes the atmosphere to glow.

"And that glow is the aurora, and the colour of the glow is different gases in the atmosphere, so the green glow is mainly oxygen and if you can see the red colour, that's nitrogen."

The Aurora Australis near Cape Saunders on the Otago Peninsula.

The Aurora Australis near Cape Saunders on the Otago Peninsula. Photo: Supplied / Ian Griffin

He said Sunday was unfortunately cloudy in Otago, but that he had seen some "brilliant' pictures of lights in Christchurch and Wellington, and even further north.

"One of the most amazing things was that somebody photographed it in Auckland, which is pretty incredible really, because to see the aurora that far north is very unusual. You may only see it in Auckland once every couple of years."

Dr Griffin said the current round of lights could continue for a few more days.

"It'll probably tail off, but if it's clear tonight, I would nip out and have a look."

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