The largest solar storm on record hit the skies in the 1850s. Photo: HANDOUT / AFP / NASA
A hundred and sixty-five years ago, the largest solar storm on record lit up skies around the globe.
And while New Zealand was far enough behind the technological revolution for it to pass without incident, it did not go unnoticed.
The Carrington Event - named after its discoverer, British astronomer Richard Carrington - spanned August to September 1859.
A barrage of charged particles from the sun caused a flurry of activity in the Earth's atmosphere, causing auroras - usually only visible at the poles - to be spotted as far north as Chile and as far south as Cuba.
In countries with telegraph machines, the effects were damaging.
But as physics professor at the University of Otago, Craig Rodger, explained: "As far as New Zealanders were concerned, it would have been pretty lights in the sky, which basically puts us in exactly the same state as Elizabethan England, or Neanderthals, who would have just gone, 'Weird, what's that?'"
From the Taranaki Herald, 1859. Photo: Supplied / Papers Past
New Zealand newspapers from the time contain eyewitness accounts. The Taranaki Herald on 3 September, 1859, described it as a "gradually increasing light" which "was seen to quiver at intervals, and then vanish from the eyes like a dissolving view".
And then: "At last the aurora poured forth one vast and magnificent flood of rosy and half fiery light, sometimes hiding, sometimes only faintly concealing as with a gauze veil the stars around."
From the Taranaki Herald, 1859. Photo: Supplied / Papers Past
Not much was known about the phenomenon, as that same Taranaki Herald article noted:
"The cause of the aurora, even with our gigantic strides in physical science, is little known. Conjecture alone is left to us. It is generally attributed to electric and magnetic influences; and Dr [Michael] Faraday [a renowned English scientist] conceives that the earth's equilibrium is restored by the aurora conveying the electricity from the poles to the equator."
That explanation was very wrong, Rodger said, but the report was right when it said "in New Zealand... the Aurora Australis may be assumed of rare occurrence".
From the Lyttelton Times, 1859. Photo: Supplied / Papers Past
Since the Carrington event, only a handful of solar storms had come close - most recently in May 2024.
Solar storms present no direct threat to humans. They cannot hurt us, save for the ways they can affect the technology we rely on.
Overseas, the Carrington event had a noticeable effect on telegraph wires.
A snippet from the Nelson Examiner and New Zealand Chronicle, 'Notes of the Week' from New South Wales, reads: "The phenomena of Monday evening were preceeded [sic] by a palpable derangement of the telegraphic wires, which performed all sorts of odd freaks with the words committed to their charge."
From the Nelson Examiner and New Zealand Chronicle, 1859. Photo: Supplied / Papers Past
Rodger, who had trawled through the archives himself, said initially he was confused by the lack of local accounts of disruption to the telegraph system - until he realised why.
"We hadn't bloody installed it yet."
Similarly, the first powerlines would not go in until the late 1880s, three decades later.
From the New Zealander, 1859. Photo: Supplied / Papers Past
Nowadays, there is plenty that could go wrong.
In early December, the National Emergency Management Agency (NEMA) released an official plan for responding to space weather.
It detailed the risks across infrastructure and society, and said the electricity grid, satellite communications and cellular networks will all be disrupted, although AM radio was expected to remain operational throughout.
Some places may lose power for up to six days, and Transpower - which ran the national grid - was prepared to turn off sections to protect its transformers in the event of a future storm.
NEMA's report noted public awareness of the threat from space weather was low, and there could be increased crime and disorder, health impacts from an inability to heat and cool homes, and public health issues around food spoilage and access to clean water.
Experts announced in mid-October the sun had entered its solar maximum, a period of increased activity which takes place every 11 years or so.
With solar storms more likely during this period, NEMA's advice was to stock up on food, check emergency kits, and prepare to spend a few days off-grid.
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