A solar storm can disrupt technology on Earth in minutes, but the chain of events begins 93 million miles away on the Sun.
This article explains what happens during a solar storm, why some storms are minor and others are dangerous, and how space weather affects modern life.
What Is a Solar Storm?
A solar storm is a disturbance in space weather caused by activity on the Sun, usually from a solar flare, a coronal mass ejection (CME), or both.
These events release radiation and charged particles that can travel through interplanetary space and interact with Earth’s magnetic field.
Scientists track solar storms because they can affect satellites, radio communications, navigation systems, aviation, electric power grids, and even astronauts.
The severity depends on the speed, direction, and magnetic structure of the solar eruption.
What Happens During a Solar Storm?
What happens during a solar storm depends on the type of solar event and whether it is aimed at Earth.
A flare produces intense electromagnetic radiation that reaches Earth in about eight minutes, while a CME can take one to several days to arrive.
When the storm reaches Earth, it can compress the magnetosphere, inject energy into near-Earth space, and create electric currents in the upper atmosphere and on the ground.
Those currents are what make solar storms disruptive to technology.
The Sun Releases Energy and Plasma
Solar storms usually start in active regions on the Sun where magnetic fields are twisted and unstable.
When the field rearranges suddenly, it can trigger a solar flare, a CME, or both.
- Solar flare: A burst of X-rays and ultraviolet radiation.
- Coronal mass ejection: A massive cloud of plasma and magnetic field.
- Solar energetic particles: High-speed particles that can pose radiation risks.
Not every flare causes major damage, and not every CME hits Earth.
The most serious storms occur when a fast CME carries a magnetic field orientation that couples strongly with Earth’s magnetic field.
Radiation Reaches Earth First
If the event includes a strong flare, Earth receives a surge of electromagnetic radiation almost immediately.
This can disturb the ionosphere, the charged layer of the upper atmosphere that reflects and absorbs radio waves.
The result may include shortwave radio blackouts, degraded high-frequency communications, and noisy or unreliable signals used in aviation and maritime operations.
These effects often occur before the CME itself arrives.
The Magnetosphere Responds
When a CME arrives, it collides with Earth’s magnetosphere, the protective region shaped by our planet’s magnetic field.
If the CME’s magnetic field points southward, it can transfer energy efficiently into the magnetosphere and trigger geomagnetic storms.
This interaction can cause the aurora borealis and aurora australis, which are visible signs of charged particles entering the upper atmosphere.
In stronger events, the same process can create geomagnetically induced currents that affect infrastructure.
How Solar Storms Affect Technology
Modern society relies on systems that are vulnerable to space weather.
Even a moderate solar storm can cause operational issues, while a severe event can create widespread disruptions.
Satellites and GPS
Solar storms can heat and expand Earth’s upper atmosphere, increasing drag on low-Earth-orbit satellites.
That extra drag can alter satellite trajectories and increase fuel use for station-keeping.
Radiation can also damage satellite electronics, upset onboard sensors, and interfere with timing systems.
GPS and other global navigation satellite systems may become less accurate because solar activity distorts signals as they pass through the ionosphere.
Radio Communications
High-frequency radio is especially sensitive to solar flares and ionospheric disturbances.
Pilots, emergency responders, ships, and remote operations sometimes rely on these bands when other communications are unavailable.
During a solar storm, signals can fade, skip unpredictably, or drop out entirely.
This is one reason space weather alerts matter for aviation and maritime safety.
Power Grids
Power grids are vulnerable to geomagnetically induced currents, which can flow through long transmission lines during a strong geomagnetic storm.
These currents can interfere with transformers, relays, and grid stability.
In rare but severe cases, grid operators may need to redistribute loads, reduce risk, or temporarily take equipment offline.
The 1989 Quebec blackout is one of the best-known examples of how space weather can affect electric infrastructure.
Astronauts and High-Altitude Flights
Astronauts face the greatest exposure because they are outside much of Earth’s atmospheric shielding.
Strong solar energetic particle events can increase radiation levels in space stations and spacecraft.
At high altitudes and near polar routes, airline crews and passengers may also experience slightly higher radiation exposure during intense storms.
Airlines and regulators may reroute flights to avoid communication and radiation issues.
How Scientists Measure Solar Storm Severity
Space weather agencies use several scales and measurements to describe storm intensity.
The most widely referenced include flare classes, CME speed, geomagnetic storm indices, and radiation storm levels.
- Solar flare classes: A, B, C, M, and X, with X being the strongest.
- Kp index: Measures geomagnetic disturbance on a scale from 0 to 9.
- NOAA space weather scales: Summarize impacts on radio, radiation, and geomagnetic conditions.
Forecasters at NOAA’s Space Weather Prediction Center and other observatories use satellite data, solar telescopes, and magnetometer readings to estimate whether a storm will arrive and how severe it may be.
What Are the Warning Signs of a Solar Storm?
There are no visible warning signs from the ground before most solar storms.
Detection depends on instruments that monitor the Sun and the solar wind.
Potential indicators include:
- A strong solar flare seen in X-ray and ultraviolet observations
- A halo CME moving toward Earth in coronagraph images
- Rising solar proton activity
- Space weather alerts from NOAA, NASA, ESA, or national meteorological agencies
Because flares arrive quickly and CMEs can take days, forecasts matter.
Early alerts help operators protect satellites, power systems, and communication networks.
Can a Solar Storm Cause a Blackout?
Yes, a severe solar storm can contribute to a blackout if it drives strong geomagnetic currents into the power grid.
However, a blackout is not automatic, and grid resilience varies by region, equipment age, and operator preparedness.
The most likely sequence is not a city-wide sudden failure but a series of technical problems, alarms, voltage fluctuations, transformer stress, and protective shutdowns.
In the worst cases, these problems can cascade into broader outages.
How to Prepare for Solar Storm Impacts
Most people do not need emergency supplies specifically for solar storms, but basic preparedness helps.
The main risks are to technology, not direct physical harm on the ground.
- Keep backup charging options for phones and essential devices.
- Use offline maps or printed directions when traveling.
- Follow NOAA space weather alerts during major solar activity.
- Expect temporary GPS or radio disruptions if traveling by air, sea, or in remote areas.
- For critical operations, maintain redundant communications and power systems.
Organizations that depend on satellites, timing systems, or long-distance power transmission often have dedicated space weather procedures to reduce exposure.
Why Solar Storms Matter More in the Modern Era
Solar storms have existed for as long as the Sun has had an active magnetic field, but their consequences are greater today because society depends on interconnected technology.
A storm that might once have been a curiosity can now affect navigation, banking, logistics, emergency response, and power delivery.
That is why solar physics, heliophysics, magnetosphere research, and space weather forecasting remain important fields in 2026.
Better monitoring improves warning time, and better infrastructure design reduces the impact when the Sun becomes active.