Many Wairarapa residents were treated to the sight of the region’s sky lit up with ribbons of colour caused by a strong geomagnetic solar storm over the weekend – without any of the feared disruptions to the power grid.
The Aurora Australis is seen when charged particles from high-intensity solar flares and coronal mass ejections [CME, which are explosions of plasma] interact with the earth’s magnetosphere, with the vibrant colours caused by the particles interacting with different gases.
Although there were periods of cloud cover, many in Wairarapa witnessed the rare celestial light display, which was widely visible across New Zealand and
the Southern Hemisphere.
Under the Stars owner and astrophotographer Chris Murphy said the bright aurora started to “flare up” on Saturday night during his company’s monthly new moon stargazing experience at Luna Estate Winery in Martinborough.
“As soon as it was dark enough, it was quite obvious there was a pretty strong show, and the stargazers were obviously thrilled to see quite a rare event – as was I,” Murphy said.
“It was the first time I have been able to see obvious colour with the naked eye, and I have seen many aurora displays while working at Lake Tekapo.”
Murphy noted that location relative to the magnetic pole influenced the aurora’s intensity and height in the sky.
“For example, those down in the South Island were able to see it high overhead, whereas here, although we could still see a good show, it was all reaching into the southern sky.
“Wairarapa is in a great position in terms of its night sky quality – the dark skies already allow us to see the aurora in contrast.”
Murphy was aware that strong aurora activity had been forecast but noted that “we won’t ever get more than a few days warning”.
The sun goes through about an 11-year cycle and is nearing the peak of a solar maximum, which increases the likelihood of solar storms, he said.
“It’s definitely going to happen again at some point; it’s just a question of when.”
Wairarapa Dark Sky Reserve [WDSR] coordinator and Longbush resident Charlotte Harding said she saw “hints” of a red sky that was over by 7.30pm.
“My son and I jumped in the car and became aurora chasers, and we missed it,” she said.
WDSR committee member Tom Love said that for the first hour after dark at Dry River Rd the clouds were clear, allowing some “fantastic sights”.
“I’ve seen aurora before, but I’ve never seen such vivid colours,” he said.
“I also saw corona – that’s rays emanating from overhead.”
“This one has been extraordinary because it’s been so energetic that the Southern Lights have been seen as far north as southern Queensland, which never happens.”
Love said Wairarapa was well-positioned to see the aurora due to a clear view of the south right through to Antarctica.
The Space Weather Prediction Center at the National Oceanic and Atmospheric Administration in the United States issued a space weather warning for the G5 geomagnetic storm.
In response, Transpower said some circuits in the national electricity system were switched off on Saturday as a precaution to prevent damage to equipment, because CMEs f induce additional electrical currents down long electricity transmission lines.
In the end, there was no impact on New Zealand’s electricity supply, however.
Transpower has since been able to restore all electricity transmission circuits to service due to the subsiding of the G5 geomagnetic storm.
