Transpower has issued a precautionary grid emergency notice as the largest solar storm in two decades to affect Earth hits New Zealand this weekend.
Sixteen electricity assets across the country have been removed from service to prevent power cuts: seven in the North Island and nine in the South Island, Transpower said. The notice was expected to remain in place until midday tomorrow.
Transpower said in a statement earlier: "As part of our contingency plan we are removing some transmission lines from service across the South Island as a precaution. In order to do this, we have to issue a grid emergency notice, however this initial action should not impact supply of electricity to consumers."
Executive general manager John Clark told 1News 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."
The most recent event of similar or greater magnitude occurred in October 2003. (Source: 1News)
The severity of the geomagnetic storm – recently upgraded to a G5 – that sent multiple solar flares toward Earth could impact the power grid, radio signals, and satellite and communications systems, said the US National Oceanic and Atmospheric Administration.
Telecommunications company One NZ told 1News it was not anticipating any disruptions to its network but a team was monitoring developments.
The event had previously been classed as G4 but was upgraded this afternoon, with the effects expected to persist over the weekend.
The NOAA said a large sunspot cluster has produced several "moderate to strong" solar flares since Wednesday. Solar flares are eruptions of electromagnetic radiation in the Sun's atmosphere.
At least five coronal mass ejections of varying intensity and consisting of electromagnetic gas are expected to arrive at Earth over the next two days, prompting the first severe geomagnetic storm watch since 2005.
The solar storm emanates from a large sunspot cluster 16 times the diameter of Earth. A sunspot is a visibly darker region of the Sun's surface where surface temperature reduces due to high magnetic pressure.
The most recent event of similar or greater magnitude occurred in October 2003. That was a G5 level solar storm that wreaked havoc with power globally, notably in Sweden and South Africa where power outages occurred and transformers were destroyed.
The most intense event on record occurred in September 1859, known as the Carrington Event.
Aurorae were seen as close to the equator as Mexico and Hawaii and telegraph systems failed across North America and Europe, in some cases giving their operators electric shocks.
A storm of this magnitude occurring today would cause widespread electrical disruptions and blackouts worldwide.
The solar storm also brings a bonus for Kiwi skywatchers: "Vivid" auroras visible as far north as Auckland.
Astronomer Rob Davison told 1News that New Zealand could be in for some good aurorae over the weekend.
"Based on forecasts, the material is likely to arrive here sometime on Saturday, with the best chances for aurorae visible from New Zealand likely to be overnight from May 11 to May 12."
He said there were a few key things to remember for anyone hoping to catch a glimpse of an aurora.
"Increased solar activity improves the chances of a good auroral display, but it does not guarantee it.
"Aurorae can also peak and then disappear in a relatively short amount of time.
"Getting as far south and as far away from light pollution as possible will improve your chances.
"People should also remember to wrap up warm, as they may need to be outside for some time while their eyes adjust to the dark and while they wait for the peak of any display to appear."
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