Solar activity poses a range of real threats to life on Earth, from knocking out power grids and disabling satellites to increasing radiation exposure for air travelers. The Sun regularly produces bursts of energy and charged particles that interact with Earth’s magnetic field and atmosphere, and the effects scale dramatically depending on the intensity of the event. A severe solar storm could cost the U.S. economy alone between $6.2 billion and $42 billion per day in lost productivity.
Three Types of Solar Eruptions
Not all solar events are the same, and the distinction matters because each type of eruption travels at a different speed and causes different problems when it reaches Earth.
A solar flare is an intense burst of radiation, essentially a flash of light across the electromagnetic spectrum. Because it travels at the speed of light, it reaches Earth in about 8 minutes. Flares can immediately disrupt radio communications, particularly on the sunlit side of the planet.
A solar radiation storm sends charged particles (electrons and protons) streaming through space at extreme speeds. The fastest particles cover the 93 million miles from the Sun to Earth in roughly 30 minutes. These particles are the primary concern for human radiation exposure.
A coronal mass ejection (CME) is the heaviest hitter. It’s an enormous cloud of electrically charged plasma blasted from the Sun at over a million miles per hour. CMEs can reach Earth in as little as 15 hours, though slower ones take several days. When a CME’s magnetic field connects with Earth’s, it triggers geomagnetic storms that can cascade through power systems, satellites, and communications infrastructure.
Power Grid Failures and Blackouts
The most consequential risk from solar activity is its ability to damage electrical infrastructure. When a geomagnetic storm hits, it induces electric currents in long conductors on Earth’s surface, including power transmission lines and pipelines. During the most extreme storms (rated G5 on NOAA’s geomagnetic storm scale), widespread voltage control problems can occur, protective systems can malfunction, and entire grid sections may collapse. Transformers, which are expensive and take months to replace, can sustain permanent damage.
A 2017 study published in the journal Space Weather modeled what a severe geomagnetic storm would do to the U.S. economy. In a moderate scenario affecting about 8% of the population, the direct economic loss was $6.2 billion per day. In more extreme scenarios, that figure climbed to $42 billion per day. Critically, the direct cost within the blackout zone only represented about 49% of the total economic damage. The rest came from supply chain disruptions rippling outward to regions that never lost power, and even to other countries through trade linkages.
The 1859 Carrington Event remains the benchmark for worst-case scenarios. Measurements from a magnetic observatory in Colaba, India recorded a magnetic field disturbance of roughly negative 1,600 nanotesla, with researchers estimating the true storm intensity at around negative 1,760 nanotesla. For context, a typical strong geomagnetic storm might produce disturbances of a few hundred nanotesla. Telegraph systems across North America and Europe failed, with some operators reporting electric shocks and equipment catching fire. A storm of that magnitude hitting today’s interconnected grid would be far more disruptive.
Satellite Damage and Orbital Decay
Satellites face a double threat from solar activity. The first is direct damage: intense storms cause surface charging on satellite components, interfere with orientation systems, and disrupt communication links between satellites and ground stations. During extreme events, tracking satellites becomes difficult, and operators may lose the ability to send commands.
The second threat is subtler but affects every object in low Earth orbit. When solar activity increases, short-wavelength radiation and energetic particles heat the upper atmosphere through ionization. This causes the atmosphere to expand, pushing denser air up to altitudes where satellites orbit. The increased air density creates additional drag, pulling satellites lower and accelerating their orbital decay. During the solar maximum of 1989 to 1990, the effect was strong enough to cause a net decrease in the total number of cataloged objects in orbit, as debris and defunct satellites reentered the atmosphere faster than new objects were launched.
This atmospheric expansion also complicates space situational awareness. When drag changes unpredictably, satellites pass through tracking sensors at unexpected times, making it harder to predict conjunctions (close approaches) between objects. For the growing population of satellites in orbits below 800 kilometers, this is an increasing operational challenge during each solar maximum.
GPS Errors and Communication Blackouts
Solar activity warps the layer of the atmosphere that satellite navigation signals pass through. The ionosphere, a region of charged particles high above Earth’s surface, changes in density when hit by solar radiation and energetic particles. Those density changes bend and scatter GPS signals on their way to your receiver, introducing positioning errors of up to 100 meters. Single-frequency GPS receivers, including those in most consumer devices, are particularly vulnerable.
This isn’t just an inconvenience for drivers. Aviation relies on satellite-based augmentation systems for precision approaches and landings. Research tracking ionospheric disturbances over Canada from 2019 to 2023 found that as Solar Cycle 25 ramped up, both the intensity and duration of signal disruptions increased measurably. These disturbances degrade the accuracy and availability of the navigation services that aircraft depend on.
High-frequency radio communications, used by aviation over oceans, military operations, and emergency services, can fade or go completely dark during strong solar events. At the G5 level, HF radio may be unusable across large regions for one to two days. Low-frequency radio navigation can also fail for hours at a time.
Radiation Exposure for Air Travelers
Earth’s atmosphere normally shields people on the ground from solar radiation, but passengers and crew at cruising altitude lose some of that protection. During solar particle events, radiation levels at flight altitudes spike, especially on routes that pass near the poles where Earth’s magnetic shielding is weakest.
A study of flight attendant radiation exposure found that maximum doses during solar particle events reached 1.2 millisieverts on a single flight segment. Twenty flight segments recorded doses above 0.5 millisieverts. That 0.5 millisievert threshold is significant: it’s the monthly equivalent dose limit recommended for a developing fetus by the National Council on Radiation Protection and Measurements. A pregnant flight attendant working through a solar particle event could exceed that limit in a single shift.
For occasional travelers, a single elevated-dose flight is not a meaningful health risk. For crew members who fly frequently, especially on polar routes, cumulative exposure during active solar periods is a real occupational concern that airlines monitor.
Where We Are in the Current Solar Cycle
The Sun operates on roughly 11-year cycles of rising and falling activity. We are currently in Solar Cycle 25, which has turned out to be stronger than initially predicted. In 2019, an expert panel from NOAA, NASA, and the International Space Environment Services forecast a weak cycle peaking in July 2025 with a maximum sunspot number of 115. NOAA later revised that prediction significantly upward, calling for a peak between January and October 2024 with a sunspot number between 137 and 173. Even at the higher end, this cycle is still considered below the historical average, but it’s active enough to produce serious storms.
Higher solar activity means more frequent geomagnetic storms at every severity level. Over a typical 11-year cycle, G5 (extreme) storms occur about 4 times, while G1 (minor) storms happen around 1,700 times. The current cycle’s stronger-than-expected performance increases the probability of significant events over the next few years as activity remains elevated.
How Much Warning We Get
Earth’s primary early warning system for incoming solar storms is DSCOVR (Deep Space Climate Observatory), a satellite positioned at the L1 point, a gravitational balance point about one million miles from Earth toward the Sun. Solar wind and CMEs reach L1 before they reach Earth, giving DSCOVR a window to measure what’s coming and relay alerts.
The practical warning time is 15 to 60 minutes before a coronal mass ejection hits Earth. That’s enough time for power grid operators to take protective measures, like reducing load on vulnerable transformers, and for airlines to reroute flights away from polar regions. It is not enough time to fundamentally redesign infrastructure or evacuate affected areas. For solar flares, which travel at the speed of light, there is effectively no advance warning at all: the radiation arrives at the same time as the observation.
This narrow warning window is one reason space weather preparedness focuses heavily on building resilience into systems ahead of time, through hardened transformers, redundant satellite constellations, and backup navigation systems, rather than relying on real-time response.