A Carrington-class solar storm today could knock out power grids for months

Every so often, the sun unleashes a burst of charged particles powerful enough to light up the sky far from the poles and scramble electrical equipment across entire continents. The best-documented example struck in 1859, decades before electrical grids existed, so the damage was limited mostly to telegraph lines. Scientists at the National Oceanic and Atmospheric Administration have spent years modeling what a storm of that same magnitude would do to a modern, grid-dependent society, and the estimates are sobering enough to shape how satellites are built and monitored today.

The 1859 Storm That Set the Benchmark

According to a NOAA educational account of the event, English astronomer Richard Carrington was observing a group of sunspots on the morning of September 1, 1859, when he witnessed a sudden flash of intense white light near them. Roughly 17 hours later, the night sky over North America, and as far south as Panama, lit up with aurora so bright that people could read newspapers by it outdoors. Gold miners in the Rocky Mountains reportedly woke up and started making breakfast, mistaking the glow for sunrise.

The storm’s more disruptive effects showed up in the era’s only continent-spanning electrical network: the telegraph system. NOAA notes that spikes of electricity surged into telegraph wires, shocking operators and igniting small fires in some offices, even as the lines themselves stopped carrying messages. Solar storms of this scale blast electrified gas and dust away from the sun at speeds up to 2 million miles per hour, and when that material slams into Earth’s magnetic field, it can distort and disrupt it for hours or days.

The activity did not come entirely without warning signs. In the days before Carrington’s observation, NOAA’s account describes an aurora appearing over Florida, an extraordinary sight so far south that residents mistook the glowing sky for a swamp fire. Auroras of that kind form when charged particles from the sun, mostly electrons and protons, collide with gases high in Earth’s atmosphere, and their appearance at such low latitudes is itself a signal of how energetic the underlying solar activity had become.

What a Repeat Would Do to the Grid

NOAA has cited estimates from the National Academies of Sciences suggesting that a Carrington-scale storm striking today could cost the country nearly $2 trillion, with cascading disruption to telecommunications, banking systems, GPS navigation, and the electrical grid itself, according to a NOAA feature on space weather and infrastructure. The same estimates put the U.S. population at risk of an extended power outage from such a storm at between 20 million and 40 million people, with restoration potentially taking anywhere from 16 days to as long as one to two years in the hardest-hit areas.

NOAA’s own research places storms on the scale of the 1859 event at roughly once every 500 years, while storms carrying half that intensity occur closer to once every 50 years. Solar activity itself runs on an 11-year cycle, with the years around solar maximum producing the most sunspots and the greatest likelihood of a severe storm reaching Earth.

The 1989 Quebec Blackout Previewed the Danger

A smaller-scale preview of that vulnerability already happened once. On a cold night in March 1989, a geomagnetic storm knocked Hydro-Québec’s electricity transmission system offline within about 90 seconds, cutting power to roughly six million people across Quebec and the surrounding region for about nine hours, with some areas going without electricity for days. Because the outage struck during the Cold War, NOAA notes that many residents initially feared it signaled the start of a nuclear strike rather than a burst of activity from the sun.

The 1989 event was driven by the same underlying mechanism as the Carrington storm: a coronal mass ejection sent billions of tons of electrically charged particles toward Earth, where they drove strong currents across the planet’s surface that overwhelmed grid equipment. NOAA has said such currents can also accelerate corrosion in oil and gas pipelines and disrupt the high-frequency radio signals used in aviation and search-and-rescue operations.

How NOAA Watches the Sun for the Next One

To reduce the chances of being caught off guard, NOAA operates a network of satellites built specifically to watch the sun. The GOES-R series of geostationary weather satellites orbits about 22,300 miles above Earth, generally outside the planet’s protective magnetic field, so engineers equipped them with a graduated system of shielding to blunt the radiation and charged particles they encounter during solar storms. NOAA has described the satellites as needing to be unusually tough because they serve as the lookouts warning other, less-hardened spacecraft.

NOAA supplemented that coverage in February 2015 with the launch of DSCOVR, the agency’s first deep-space climate observatory, which now orbits about one million miles from Earth and continuously monitors the solar wind for early signs of an incoming storm. That advance warning gives grid operators, satellite controllers, and airlines a window to take protective steps, such as postponing risky satellite maneuvers or bracing transformers, before a storm’s particles actually arrive.

Satellite operators in particular have learned to treat solar-storm warnings as an operational routine rather than a rare emergency. NOAA has noted that spacecraft controllers can choose to delay orbit-adjustment maneuvers or other tasks that would expose a satellite to elevated radiation once a warning is issued, shrinking the window in which a spacecraft is vulnerable. Because the sun’s output rises and falls on that predictable 11-year cycle, forecasters can also give utilities and satellite operators a general sense of which years carry the greatest risk, even though the exact timing and strength of any individual storm remains difficult to forecast more than a few days out.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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