What would happen if a massive coronal mass ejection from the Sun hit us directly today? The question is not science fictionBecause something like this has already happened and turned the planet upside down: we're talking about the so-called Carrington event, considered the largest solar storm of which we have instrumental and testimonial record.
That cosmic shock was no minor anecdote. From the end of August to the beginning of SeptemberIn the heart of the 19th century, the sky lit up with colors, telegraphs burned out in several countries, and the Earth's magnetosphere warped like Play-Doh. And be warned: recent research suggests it was even more intense than we thought, with changes in the magnetic field at a rate that would threaten our world today. most critical infrastructures.
What was the Carrington Event and how did it unfold?
To put things in perspective, we have to travel back to September 1, 1859. Richard C. CarringtonA British astronomer was observing a huge group of sunspots when he saw a flash of white light on the solar disk: an exceptional flare, visible even in continuous daylight. Just 17 hours and 40 minutes later, the material ejected by the Sun (a coronal mass ejection) reached Earth in an unusually fast way.
The episode was preceded by days of turmoil on the solar surface. Numerous stains were counted from August 28th onwards. and flashes of light; in fact, they were already recorded that night unusual auroras throughout North America. The climax came between September 1 and 2, when the Sun-Earth interaction became fierce and the geomagnetic storm unleashed its full force.
The investigations point to a sequence of two ejections. The first one took between 40 and 60 hours (normal), while the second, which traveled through the “open plasma corridor"Because of the previous one, it only needed 17 hours to cover the 150 million kilometers. That second impact came with a magnetic field oriented to the south, ideal for coupling and shaking the ground field, and it was the one that raised the real geomagnetic gale.
Within minutes, the upper atmosphere was heated by the X-rays and UV rays from the flare, It expanded and increased the "drag" on low Earth orbitThe magnetosphere, which normally extends up to about 60,000 km from Earth, was dramatically compressed, with estimates placing it at around 7000 km. There were reports that the Van Allen radiation belt temporarily weakened. discharge protons and electrons towards the atmosphere and fueling auroras at unimaginable latitudes.
The Carrington flare may have reached temperatures of tens of megakelvin. Not just visible light: also X-rays and even gamma radiationProtons with energies on the order of tens of MeV arrived and penetrated deep into the polar atmosphere. Modern studies have linked these particle showers to an approximate 5% reduction in stratospheric ozone, which would have taken several years to recover.
This is how it was experienced on Earth: auroras, telegraphs, and fiery nights
The "human" part of the event was as spectacular as it was unsettling. There were auroras galore in mid-latitudes and even tropical regionsFrom Madrid and Rome, through Santiago de Chile and Concepción, to Havana, Hawaii, and northern Colombia (with reports from Montería and also Costa Rica). In Australia, the Moreton Bay Courier described “beautiful red tones” for several consecutive nights.
The scene was repeated all over the world: You could read the newspaper at midnight With the reddish-green glow of the sky. In the Rocky Mountains, the miners got up, lit their fires, and ate breakfast, thinking it was dawn, when it was actually one in the morning. Some interpreted that blazing sky as an apocalyptic sign, understandable if you'd never seen an aurora in your life.
But beyond the spectacle, the damage was real. Telegraph systems, then the global communications networkNetworks collapsed in Europe and North America; there were power surges affecting operators, fires in offices, and cascading failures. Reports indicate widespread outages lasting approximately 14 hours. Paradoxically, some links heavily charged with atmospheric electricity... The messages traveled without batteries., taking advantage of the energy induced by the storm itself. How is technological defense being prepared?
The electrical infrastructure of the time was incipient, so the technological impact was limited compared to today. Imagine a similar episode in the 21st century.With satellites, interconnected power grids, GPS, aviation and digital banking: the damage would be in the billions and the recovery, long and complex.
What the records say: more intense than we thought
Much of what we know comes from observatories of the time, such as Kew and Greenwich (London). Their “photographic” magnetometers They used beams of light reflected from mirrors to trace the evolution of the field on photosensitive paper. The problem: the storm was so powerful that the light went beyond the scale of the paper, saturating the recording at critical moments.
A modern digitization of those bands has allowed for extracting more value. Measuring stroke speed before and after saturationsIt has been estimated that the magnetic field changed at a minimum rate of about 500 nT per minute at latitudes like that of London, an enormous figure. To put this in perspective, at that latitude, reaching 350–400 nT/min once a century is considered extraordinary; so Carrington might fit better within the range of ancient events.
In addition to magnetometers, “chemical fingerprints” support the magnitude of the event. In ice cores from Greenland and Antarctica A nitrate spike was detected, associated with intense bursts of solar particles, the largest in five centuries. This all fits with a truly extreme geomagnetic storm by historical standards.
Beyond 1859: Miyake events and other notable episodes
The Carrington Event is the largest geomagnetic storm directly observed, but It's not the worst thing the Sun has done If we look back thousands of years, radiocarbon (C-14) studies of tree rings have identified "Miyake Events": abrupt spikes caused by bursts of solar particles. Nine have been found in the last 15,000 years, with notable episodes in 774 and 993 AD
A recent study of subfossils of trees found in the Drouzet River (French Alps) detected a gigantic peak dating back some 14,300 yearsapproximately twice the number of events in the 8th and 10th centuries. Comparing carbon-14 with beryllium in ice cores, the evidence points to an extreme solar storm as the cause. Such events, if they were to occur today, could damage transformers on a large scale and cause blackouts for months, in addition to affecting satellites and posing radiation risks to astronauts.
As we approach our technological age, there is no shortage of scares. In 1989, a “minor” storm collapsed Quebec’s power grid for more than nine hours, with losses amounting to millions. In 1994, problems with communications satellites (ANIK E1 and E2) disrupted services in Canada, and in 1997 Telstar 401 was damaged. The effects of atmospheric expansion from X-rays on a Japanese satellite were also cited in July 2000.
Adding to the intrigue, on July 23, 2012, a coronal mass ejection occurred which, according to various analyses, grazed Earth's orbit days after Earth had passedIf they coincided, some studies have described it as much larger than Carrington's. In any case, it serves as a reminder: superstorms are not a myth.
Without going that far, In May 2024 we saw auroras at unusual latitudes and disruptions to HF radio communications. NOAA went so far as to categorize the levels as severe and issued warnings to infrastructure operators to mitigate potential impacts. A preliminary analysis by MIT suggested that up to half of the satellites in LEO They recorded storm-related anomalies, including the temporary deactivation of anti-collision safety systems.
If it happened today: real risks and how we are preparing
The ESA has tested “worst case” scenarios. A class X45 flare (radiation in 8 minutes), followed by a barrage of particles in 10–20 minutes and, after about 15 hours, a CME at 2000 km/s. The perfect recipe for GPS/Galileo outages, radar disruptions, electronic failures in satellites (bit flips, resets) and, in low orbit, an increase in atmospheric drag of up to 400%.
On land, geomagnetically induced currents can saturate and damage transformers, distorting the 50/60 Hz waves and forcing shutdowns. Pipelines, long cables, and rail networks are also vulnerable. Decision-making is complicated because, with degraded data, an evasive maneuver Taking steps to avoid a collision with a satellite can increase the risk of collisions with other objects.
To buy time and reduce damage, there is global surveillance. DSCOVR provides on-site data of the solar wind; NASA's Parker Solar Probe and ESA's Solar Orbiter are studying the origin of eruptions; and new tools are arriving: Surya, an AI powered by IBM and NASA, promises improve the prediction of lightning flashes in less time. ESA is also deploying the D3S network and preparing the Vigil mission to L5 to view the Sun "edge-on" and issue early warnings.
When the warning arrives on time, there is room for maneuver. Operators can reconfigure satellitesDisconnecting sensitive loads, rerouting aircraft to safer paths with respect to radiation, reducing transformer power, or sectioning the grid to contain damage. It doesn't prevent the event, but mitigates the bill and speeds up recovery.
Why can the Sun put on such a show?
Behind every storm there is magnetism. Sunspots are regions of intense magnetic fieldThere, flares (bursts of radiation) and coronal mass ejections (plasma clouds with their own field) occur. If the CME field reaches "southward," it couples better with the magnetosphere and The geomagnetic storm breaks out.
Ultimate energy comes from nuclear fusion in the solar core. In each reaction, approximately 0,7% of the mass It is transformed into energy (E=mc²). This energy travels first through the radiative zone (about 500,000 km thick) and then through the convective zone (about 200,000 km), emerging as the granules. that boils in the photosphere. Each “granule” changes in 10–15 minutes, evidence of unstoppable convective transport.
The Sun has cycles of about 11 years, with peaks of activity. Thousands of phenomena were recorded during the 2008–2019 cycle.On the order of 13,000 plasma clouds and some 21,000 flares, which gives an idea of the occasional hyperactivity of our star. Most pass by unnoticed by us; Sometimes, howeverThe shot goes straight and it's on goal.
Documented technological impacts and lessons learned
The list of modern damage grows with each cycle. Power grids, satellites, radio, GPS…all have shown vulnerabilities. Cases like ANIK E1/E2 (1994) and Telstar 401 (1997) illustrate that storms can knock out critical services. In 1989, Quebec learned the hard way how a poorly managed GIC It becomes a massive blackout.
The upper atmosphere also plays its part: when X-rays heat the thermosphere, Density increases at high altitude And satellites in low Earth orbit slow down more, consume fuel adjusting their orbits, and increase the risk of collisions. If you add it all up degraded measurements And with more objects "crossing" each other, managing space traffic becomes an odyssey.
Key concepts for orientation
- Space weather: set of conditions of the Sun and the interplanetary medium that affect the Earth and technology.
- Coronal mass ejection (CME): plasma cloud and magnetic field that can cause severe geomagnetic storms.
- Solar flare: burst of radiation (X-rays/UV) that arrives in minutes and alters the ionosphere.
- Blazing star: behavior of the Sun as a star capable of emitting flares of great intensity.
It's worth talking about probabilities. Recent mathematical estimates They place the possibility of another storm of Carrington's magnitude in the coming decades between 0,46% and 1,88%. It's not cause for panic, but it is something to be aware of. have plans and redundanciesIf the Kew and Greenwich records, the nitrate spikes in the ice, or the tree rings in the Alps teach us anything, it's that the Sun, from time to time, plays games. in a big wayAnd the more we depend on electronics, the more it behooves us to be ready for the next challenge.
