In 1859, the Carrington storm caused spectacular auroras and electrical disturbances in telegraph networks as far south as Cuba. 167 years later, a repeat could cripple key infrastructure while leaving some electronic devices surprisingly unaffected

On September 1, 1859, astronomer Richard Carrington watched an extraordinary flash erupt across a group of sunspots. Less than a day later, Earth was hit by one of the most powerful geomagnetic storms ever recorded. Auroras appeared far beyond their usual range, reaching places as far south as Cuba and Hawaii. Telegraph equipment malfunctioned, sparks flew and operators reported electric shocks.

A similar storm today would meet a world filled with power grids, satellites, navigation systems and communications networks. But it would not simply switch off every electronic device on Earth.

What happened during the Carrington Event?

Carrington was observing the Sun when he saw two patches of “intensely bright and white light.” Richard Hodgson independently witnessed the same flash. Carrington's report in the Monthly Notices of the Royal Astronomical Society became the first detailed account of what scientists now call a white-light solar flare.


The flare itself was a burst of electromagnetic radiation, which reaches Earth in roughly eight minutes. The much larger geomagnetic disturbance that followed was caused by magnetized material expelled from the Sun, now known as a coronal mass ejection, or CME.

The CME traveled far more slowly than light, although the 1859 event appears to have reached Earth exceptionally quickly.

What made the storm so memorable was what happened once it arrived. Earth's magnetic field underwent major disturbances, affecting electrical systems that were still in their early stages.

Why did telegraph systems go haywire?

Telegraph networks unintentionally became detectors of the storm. Long telegraph wires provided pathways for currents generated when Earth's magnetic field changed rapidly. Operators reported equipment producing sparks, electrical shocks and communication failures.

Some systems behaved in particularly strange ways. On a line between Boston and Portland, operators reportedly disconnected their batteries yet continued sending messages using the electrically induced current.

The current itself fluctuated with the auroral activity, sometimes becoming strong enough to interfere with relay magnets.

These reports, collected in the American Journal of Science, fit the same basic induction physics that concerns engineers studying modern power networks.

How far did the auroras spread?

The Carrington Event pushed auroras dramatically toward the equator. The US National Weather Service records sightings as far south as Cuba and Hawaii. Newspapers described unusually bright red skies, with some reports saying the light was strong enough to read by.

The important point is not simply how colorful the displays were. Their enormous geographic reach showed how severely the storm disturbed Earth's magnetosphere.

Scientists still face uncertainty when estimating the precise strength of the 1859 storm because measurements from that period were limited and much of the surviving evidence comes from eyewitness accounts.

Could another Carrington Event damage today's power grid?

A modern geomagnetic storm would create a very different technological problem. Rather than directly striking transformers like lightning, a major storm can rapidly change Earth's magnetic field across a large area. That changing field generates electric fields in the ground, which can push geomagnetically induced currents through long transmission lines and into grounded transformers.

Those currents can interfere with transformer operation, produce excess heating and complicate voltage control. Protective equipment can also be affected, while problems in one section of an interconnected grid can place additional pressure on another.

NOAA's G1-to-G5 scale classifies G5 as an extreme geomagnetic storm level capable of causing widespread voltage-control and protection problems. Some power systems could experience blackouts, while transformers could potentially be damaged.

But the outcome would not be identical everywhere. Storm duration, magnetic orientation, grid design, operating decisions and local ground conductivity would all matter.

A 2025 US Geological Survey study modeled a Carrington-class storm across the United States and found that some areas of the East and Midwest could experience particularly strong geoelectric fields. Conditions could also vary considerably within individual states because underground geology differs from place to place.

What would happen to satellites and navigation?

Satellites would face a different set of problems because they are not connected to the ground through long electrical transmission lines. Extreme geomagnetic storms can expose spacecraft to charged particles, radiation effects and surface charging. The upper atmosphere can also heat up and expand, increasing atmospheric drag on low-Earth-orbit satellites.

NOAA says extreme storms can interfere with satellite orientation, tracking, uplinks and downlinks. Operators may need to change spacecraft operating modes or make orbital corrections afterward.

Navigation and communications could also suffer. A disturbed ionosphere can degrade satellite navigation for days and make high-frequency radio communication impossible across many areas for one or two days.

That could affect aviation, maritime operations, surveying and precision agriculture, although the consequences would vary depending on available backups and operating procedures.

Would a Carrington storm really destroy the internet?

Not necessarily. The idea that a massive solar storm would instantly fry every computer, phone and electronic device is too simplistic. Fiber-optic cables themselves do not conduct geomagnetically induced currents. But modern networks rely on powered ground equipment, data centers, satellites, timing systems and electrical grids.

That means disruption could spread through interconnected infrastructure without every individual electronic device being directly damaged.

The G5 geomagnetic storm in May 2024 offered a recent demonstration of this vulnerability. It disrupted GPS-dependent operations and increased satellite drag, but it did not cause the universal technological collapse sometimes associated with stories about the Carrington Event.

Do we have better warning systems now?

Unlike the operators of 1859, modern utilities and satellite operators have warning systems. Solar observatories can identify an Earth-directed CME and provide broad warnings ranging from hours to days. Spacecraft positioned upstream from Earth can then measure the solar wind shortly before it reaches the magnetosphere, improving estimates of the storm's potential strength.

There is still a major limitation. The crucial magnetic orientation of incoming plasma may only become known around 15 to 45 minutes before impact, according to a NOAA space-weather fact sheet.

Even that short window can matter. Utilities can adjust grid configurations, while satellite operators can postpone risky operations and move spacecraft into safer modes.

A second Carrington Event would therefore be serious, but its effects would not be uniform. Some infrastructure could be badly disrupted while other systems continue operating.

The lesson from 1859 is not that modern civilization would simply switch off. It is that disturbances originating millions of miles away can travel through Earth's magnetic environment and eventually affect the long electrical networks on which modern life depends.

FAQs

Would another Carrington Event destroy every electronic device?
No. The effects would be serious but selective.

Could satellites be affected?
Yes. Satellites could face radiation, charging, tracking and atmospheric-drag problems.