The most powerful solar radiation storm in 20 years: what threatens technology and people

When the Sun changes the rules for satellites, aviation, and the night sky in a matter of minutes.

In the second half of January, the Earth was hit by the strongest solar radiation storm in more than two decades: the level of the charged particle flux reached S4 on the NOAA five-point scale - a "serious" event, the likes of which the planet has not seen since 2003.^{2 7} . Streams of high-energy protons, ejected during a powerful flare and coronal mass ejection, covered the distance from the Sun to the Earth in a matter of tens of minutes, hit the magnetosphere and sharply increased the radiation load in space and in the polar latitudes.^{2 3} For most people on the surface, this went unnoticed — but for satellites, astronauts, airlines, and energy workers, it's no longer just a good story about the northern lights, but a high-alert operating mode.

What exactly happened: S4 storm and G4 geomagnetic storm

The US National Space Weather Prediction Center (NOAA Space Weather Prediction Center, SWPC) reported that on January 19, a powerful coronal mass ejection (CME) flare occurred on the Sun, triggering one of the strongest solar radiation storms in the last 20+ years.^{7 2} . The stream of high-energy protons recorded by the GOES-19 satellite reached the S4 level — a “severe radiation storm,” exceeding the intensity of the famous “Halloween storms” of 2003, long considered the benchmark extreme example of space weather.^{7 9} .

In parallel with the radiation storm, a powerful geomagnetic storm hit the Earth: according to NOAA and Live Science, the magnetosphere disturbance reached the G4 ("strong") level twice during the day - at around 14:38 p.m. and 3:23 a.m. Eastern Time.⁴ This is the second strongest level out of five possible (maximum - G5): under such conditions, temporary disruptions in the operation of satellites, radio communications, as well as local impact on power systems in sensitive regions are possible.^{4 6} .

Where did the storm come from: a solar flare and a coronal mass ejection

According to Space.com and NOAA, the storm was triggered by a powerful X-class flare on the Sun, which occurred in an active region near the solar equator on January 18, accompanied by the release of plasma and magnetic fields into interplanetary space.^{2 4} The coronal mass ejection (CME) was moving towards Earth as a high-speed cloud of charged particles, which in about a day reached the planet's magnetosphere and sharply "shaken" it, causing a geomagnetic storm.⁴ .

A radiation storm is not the same as a geomagnetic storm: the former is associated with a powerful stream of fast protons that travel at nearly the speed of light and can reach Earth in tens of minutes, while a geomagnetic storm is usually associated with a slower, denser plasma cloud called a CME.^{2 10} In this case, both factors coincided: first the Earth was "covered" with a radiation attack, and then came a blow to the magnetosphere.

How the S1–S5 scale works and why S4 is serious

NOAA classifies solar radiation storms on a scale from S1 to S5, where S1 is a minor event and S5 is an extreme event, with widespread disruptions to space technology and serious restrictions on aviation and spaceflight.¹¹ The current storm has reached S4 level: this means that the flow of protons with energies above 10 MeV (megaelectronvolts) has exceeded the threshold of hundreds of “particles per square centimeter per second per steradian” - a figure that engineers and astrophysicists consider a real threat to electronics and people outside the protection of the atmosphere.⁷ .

According to the official classification, an S4 storm has the following typical consequences: a significant increase in radiation doses for astronauts in orbit, high risk for crews and passengers of flights passing through high latitudes, degradation of data from satellite sensors, problems with navigation systems, as well as temporary failures in radio communications in polar regions.^{7 11} All this is no longer a theoretical scenario, but a working environment for dispatchers and operators.

What the satellites experienced: data failures and risks to electronics

As Space.com notes, citing NOAA data, during the storm's peak, some satellite systems experienced temporary data blackouts, likely because the proton flux was so dense that it "stitched up" or overloaded sensors that measure particle fluxes and electromagnetic radiation.² In such conditions, satellite operators are forced to switch to protected modes: change the orientation of the devices, turn off sensitive devices, and postpone maneuvers to reduce the risk of damage to electronics.

Strong radiation storms can cause so-called "single event upsets" - random errors in the operation of microcircuits caused by the ingress of a cosmic particle into a sensitive memory element or processor. At best, this means a temporary failure, at worst - permanent damage to the module^{2 9} That is why such events pose a much greater threat to space technology than to people on the surface of the Earth.

Aviation: What a storm means for flights over the poles

According to the SWPC, the main risk from S4 storms concerns flights passing through polar trajectories - over the North or South Pole, where the Earth's magnetic shield is weaker and charged particles more easily penetrate the atmosphere.⁷ . In such conditions, crews and passengers may receive an increased dose of cosmic radiation, and high-frequency (HF) radio communications, which are often used in these latitudes, will experience serious interference or a complete "blackout" for a certain time.^{3 10} .

International airlines in such storms usually consider rerouting flights to more southerly routes, which increases flight time and fuel consumption, but reduces radiation exposure and risks to communications. So far, there have been no reports of mass flight cancellations, but the SWPC has explicitly warned air carriers to be prepared for "significant interference with radio communications in the polar regions."^{7 6} .

Is this dangerous for people on Earth?

Despite the loud headlines, for people on the surface of the planet, even such a strong radiation storm does not pose a direct threat. As CNN, Space.com and NOAA point out, the Earth's atmosphere and magnetosphere effectively absorb the bulk of the stream of charged particles, preventing them from reaching levels that would be dangerous to health.^{1 2 3} Radiation exposure can only increase at high latitudes and mainly at the altitude of airliner cruise flights or in orbit, where protection is much weaker.

Therefore, for an ordinary resident of Ukraine or any other mid-latitude country, the most noticeable consequence of the storm will not be health problems, but rather short-term disruptions in GPS, mobile communications, or satellite television — if they occur at all.^{2 6} The main risks of this event are technical and strategic, not medical.

Auroras over Europe and Ukraine

Already in the early hours of the storm, social media was flooded with photos of the aurora borealis in places where you wouldn't normally see it. According to Deutsche Welle and other European media, bright curtains of the northern lights were observed in the United States, Canada, Germany, Switzerland, as well as in a number of Eastern European countries.^{4 5} Ukrainian resources reported the appearance of auroras over the northern and western regions — in particular, over Lviv, Volyn, and partly Kyiv regions, where in clear weather you could see pink-green hues in the sky.^{3 5} .

Such phenomena become possible when a geomagnetic storm is so strong that charged particles "push through" the magnetic field and penetrate deeper into the atmosphere, causing it to glow at unusually low latitudes.⁴ For many, this is a fascinating sight, but for space weather experts, it is more of an indicator that the magnetosphere is undergoing serious stress.

Possible impact on power systems and communications

Powerful geomagnetic storms like the current one could theoretically affect power systems by causing induced currents in long power lines, transformers and pipelines. NOAA warns that G4 levels could cause voltages that “require corrective action by power companies” to avoid damage to equipment.^{4 6} The most sensitive systems are in high latitudes and regions with specific geology, where currents are more easily induced in the soil.

Regarding communications, SWPC and Newsweek note the risks of temporary disruptions to satellite navigation (GPS) and high-frequency radio communications, especially at high latitudes and over oceans.^{5 6} However, at the time of publication, there were no reports of large-scale outages or accidents: probably due to the warnings of operators and the preventive measures taken.

Why this is happening right now: the solar activity cycle

The Sun goes through roughly 11-year activity cycles, during which the number of sunspots, flares, and coronal ejections increases, peaks, and then declines. Astronomers estimate that the current cycle (the 25th on record) is entering a maximum phase, so the frequency and strength of such storms are naturally increasing.^{2 10} Already in 2024–2025, the Earth experienced a series of strong geomagnetic storms, causing spectacular auroras and local failures in satellite systems.

The current event stands out for combining a very high level radiation storm (S4) with a strong geomagnetic storm (G4), making it one of the most intense complex space events in the last two decades.^{2 7} And this is clearly not the last episode: scientists expect that by the peak of the cycle, the Sun will demonstrate similar "flashes of character" more than once.

Ukrainian context: satellites, communications, energy and war

For Ukraine, which is waging war in a context of high technological dependence on satellite communications, navigation, and energy infrastructure, such events have an additional dimension. Any disruptions in satellite systems—from reconnaissance to commercial platforms like Starlink—could complicate troop control, fire control, logistics, and civilian services if they overlap at critical moments in combat.^{3 6} That is why Ukrainian military and energy experts are closely monitoring reports from SWPC and other space weather centers.

At the same time, strong space storms are a reminder that the whole world has to build security taking into account factors that no state controls. For Ukraine, which already lives in the reality of combined threats — from missiles to cyberattacks — adding space weather to this list seems almost ironic. However, for now, the main effect of the current storm for Ukrainians is, rather, a chance to see the northern lights with their own eyes and an occasion to remember that our rear begins not only at the border, but also in orbit.

What to do and what not to be afraid of

Experts from SWPC and scientists quoted by CNN and ABC7 insist: there is no point in panicking about the S4 storm. It will not make the air "radioactive", will not cause massive communication outages across the planet, and even more so will not "burn" electronics in smartphones or cars^{1 6} Satellites, polar flights, specialized radio systems, and individual elements of power systems in risk regions remain potentially vulnerable.

For ordinary people, the main recommendations are reduced to a minimum: do not panic, follow the reports of scientific institutions with interest and, if you are lucky with the sky, go out at night to see the aurora borealis. All more complex decisions — from switching satellites to safe mode to the possible redirection of flights — are made by specialists who have access to operational data on space weather.^{2 7} .

Sources

1. CNN: "Sun releases largest solar radiation storm 'in over 20 years'" — explanation of the nature of the storm, SWPC comments, risk assessment for the population and technology.
2. Space.com / LiveScience: "Earth was just hit by the strongest solar radiation storm in over 20 years" / "Earth hit by biggest 'solar radiation storm' in 23 years" — details about the S4 level, the storm mechanism, the impact on satellites and aviation.
3. NV English: material about powerful solar activity and auroras over Europe and Ukraine.
4. Deutsche Welle: report on the northern lights over the US and Europe against the backdrop of an intense solar storm.
5. The Hill / Newsweek: reports on "largest solar radiation storm in 20 years", SWPC quotes on possible technical failures.
6. NOAA SWPC: official bulletins on S4 storm and G4 geomagnetic storm, description of expected impacts on satellites, aviation and power systems.
7. NOAA SWPC, Solar Radiation Storm help page: description of the S1–S5 scale and criteria for classifying solar radiation storms.