Aurorae were witnessed as far north as Hamilton last night, as an additional atmospheric phenomenon with a peculiar name not entirely understood by scientists was visible to many lucky stargazers across the lower South Island.
The sun is supercharging aurora displays across the world this week due to a series of geomagnetic storms triggered by recent solar flare activity. Charged solar particles are expelled by the sun during coronal mass ejections and, when they reach Earth, they are funnelled over the poles by the planet’s magnetic field and interact with our atmosphere, causing aurora.
Humphrey Snorden witnessed the phenomenon known as STEVE over the Otago Peninsula at around 11pm on Monday night after looking for it for a number of years.
“I’ve always looked in the wrong direction previously. It was a big thrill to finally get it.”
Stardome astronomer Josh Aoraki told 1News that STEVE — an acronym for strong thermal emission velocity enhancement — is not entirely understood by science.
“STEVE is not an aurora, but it does occur simultaneously with regular aurora as the same process fuels both phenomena. That said, STEVE does not always appear when there is an aurora and no one quite knows why.”
Aoraki said STEVE is typically magenta in colour and differs from aurora in that it appears as a streak across the sky caused by heated gas.
“Both are a direct result of charged particles from our Sun interacting with the Earth’s magnetic field and atmosphere.”
The phenomenon was only discovered in 2015, but historical records show it may have been seen in the sky since the late 1800s, Aoraki said.
“It is likely not a very rare thing to see but the mechanics are not entirely understood so it is hard to predict when it will appear, unlike the aurora which is fairly easy to predict with satellites and Sun-observing telescopes.”
Sharine Gordon told 1News the aurora display last night in Otago was “amazing”.
“Early on in the evening, it was only visible once you had taken a photo, but by 3am, the evening sky was alight with dancing flashes of white and a glow of green behind the Remarkables,” she said.
“To see the sky dancing in the night is totally amazing.”
While last night’s light show was impressive, it paled compared with the aurorae displays seen across the country just three months ago.
On May 11, the National Space Weather Prediction Centre issued the first severe geomagnetic storm watch in 20 years following a series of solar flares and coronal mass ejections.
The G5 class storm was the largest to hit Earth in decades and forced Transpower to remove some electricity assets from service to prevent power cuts.
Executive general manager John Clark told 1News at the time the solar storm induced electrical currents through the Earth.
“Those electrical currents like to use our long transmission lines as an alternative route.”
The currents were “not good to have” through the grid so the flow of currents needed to be limited by turning off transmission circuits where possible, he said.
“This is a preemptive measure to make sure other more important equipment, namely transformers and generators, aren’t damaged.
“We’re able to supply everybody, but we haven’t got quite the same level of redundancy in the power system.”
