The Earthly Impacts of Solar Storms

In the early hours of 19 January 2026, NASA’s Solar Dynamic Observatory - a spacecraft pointed towards our local star since 2010 - observed a powerful solar flare erupting from the Sun. Solar events of this magnitude are uncommon, but not unprecedented. On this day, the X1.9-class flare originated in the large sunspot region 4341, and produced a coronal mass ejection (CME) - a large cloud of magnetised solar plasma - that hurled towards the Earth. This triggered global space-weather agencies, such as the Australian Bureau of Meteorology (BoM), to issue a G4 geomagnetic storm warning. 

Online, astronomers and space-weather enthusiasts around the world excitedly noted the eruption, predicting that it would create a dazzling light show - the aurora borealis and aurora australis once the solar storm arrived at Earth. High-frequency radio, which relies on Earth’s ionosphere, was also expected to be disturbed.

Then, a few days later, around 8:30 am on the 20th January, the CME arrived, delivering on the predictions. Spectacular auroral shows lit up the northern hemisphere skies, where nighttime and clear sky conditions aligned with the storm’s arrival.

Curiously, on the other side of the world and at roughly the same time, four major powerlines in western Victoria suddenly tripped, impacting almost 8,000 households in the Charlton, Hamilton, Maryborough and Ararat regions. Whilst power to these regions was restored within 30 minutes, the company responsible for infrastructure, CitiPower, confirmed it was investigating whether this outage was linked to the geomagnetic storm that was triggered by the X1.9 flare. The company stated that the timing of the network disturbances - in particular, that all four were tripped at the same timestamp - closely aligns with the arrival of the space-weather event. So how does a solar storm create a risk for critical terrestrial infrastructure, such as the power grid? Dr Richard Marshall -  Principal Research Scientist at the BoM Space Weather - breaks down this complex, yet important, field of science and how it impacts our planet.

The Sun, our local star, is an enormous hydrogen fusion reactor. Deep within its interior (in its core), hydrogen atoms are fused into helium, releasing enormous amounts of energy. This is emitted across the electromagnetic spectrum - from radio waves to gamma rays. While our eyes are sensitive to only a small portion of this spectrum (‘visible light’), our skin can feel infrared radiation and be tanned by ultraviolet radiation. Radio telescopes can pick up radio waves from solar activity, and orbiting X-ray telescopes can keep their eyes on the solar disc.

When we observe the solar disc, we often see small, irregularly shaped dark patches on it. These are known as sunspots and are tied to the complex solar magnetic field, which is shaped by many tangled north and south magnetic poles threaded through its surface.

“The Sun has a large-scale magnetic field which is somewhat poloidal in shape, like a doughnut,” said Dr Marshall. “Differential rotation of the Sun's outer layers, whereby the equatorial region rotates faster than the high latitude regions or poles, results in the Sun's magnetic field lines being wrapped around the Sun, creating a toroidal field.”

“The differential rotation leads to the magnetic field being wound up and clustered. Clustered magnetic fields are driven to the surface by buoyancy forces, which emerge from the surface as solar active regions and sunspots. The increased appearance of active regions signals the ascending phase of the solar cycle towards solar maximum, a period where solar flares and CMEs are more common.”

Solar flares and CMEs are related, but distinct phenomena. Solar flares unleash intense bursts of radiation that travel at the speed of light, reaching the Earth quickly in just over eight minutes. Whereas CMEs, on the other hand, are the ejection of magnetised plasma that takes time to traverse the 150 million km between the Earth and the Sun. Additionally, in the background, the Sun is constantly emitting the solar wind, a continuous stream of charged particles that radiate outwards across the Solar System and shape space weather even during non-event activity.

“It is generally considered that solar flares and coronal mass ejections (CMEs) are typically driven by magnetic reconnection of twisted magnetic fields emanating from solar active regions that are visible in white light images of the sun as sunspots,” he said.

“These twisted magnetic field lines, often referred to as flux ropes, rise through the Sun's gaseous outer layers due to buoyancy forces and expand through the surface and into the solar atmosphere. Convective motion continues to move the footprints of these flux ropes and sometimes brings magnetic fields of opposite polarity together, resulting in magnetic reconnection.”

“The energy stored in the stressed magnetic fields being contorted over many hours to days is suddenly released, expelling magnetised plasma into the solar system as a CME and accelerating particles down remanent magnetic fields into the lower solar atmosphere, generating x-ray emissions, observed as a solar flare,” he said.

Sunspots also allow scientists to measure the solar cycle, a periodic, 11-year variation in the Sun’s activity, counted by the number of observed sunspots on the solar surface.

“Slow drift meridional motion migrates the sunspot magnetic field lines of opposing polarity towards the Sun's equator and poles over long timescales of years, returning the Sun's magnetic field to a more poloidal shape, signalling solar minimum. This process takes around 11 years and is referred to as the solar cycle. Solar active regions are most commonly observed during solar maximum,” said Dr Marshall.

“The process of magnetic reconnection that is often considered the source of solar flares and CMEs provides the driving energy to accelerate plasma, originally constrained to the Sun's atmosphere by magnetic fields, into the Solar System.”

“The plasma is intrinsically connected to the magnetic fields and propagates with the ejected magnetic fields, and hence the plasma cloud or CME carries a magnetic field structure. This material propagates and interacts with a background stream of plasma, referred to as the solar wind, as it propagates into the solar system,” he said.

Fortunately for life on Earth, our planet has a powerful natural shield. As charged particles from the incoming solar wind and CMEs arrive, they interact with an invisible force field: Earth’s magnetic field. This ensures that these particles don’t hit our atmosphere directly, deflecting much of this energy and redistributing it around the planet through the magnetosphere.

The magnetic field itself is generated deep below our feet, in the liquid outer core, where the motion of molten, electrically conducting material produces this field. It is broadly dipolar in shape, which means it has a north and south magnetic pole where field lines converge with the surface.

Near these polar regions, charged particles from the solar wind can become trapped and guided along the field lines towards the upper atmosphere. When these particles collide with atmospheric gases such as nitrogen and oxygen, they transfer energy and cause them to become excited. Soon enough, this energy is released, emitting as the shimmering light display of the aurora. Different gases have different energy levels, which in turn generate different colours.

During powerful geomagnetic storms, this process can intensify and cause a large disturbance in the magnetosphere, triggering an avalanche of excited particles in the atmosphere, expanding auroral activity to regions that are far from the magnetic poles. Recently, there have been two major storms, one in May 2024 and one in November 2025. So powerful, these storms produced this auroral activity at low latitudes and disrupted GPS signals globally.

“The Earth's magnetic field, generated by the motion of the Earth's outer core, is elongated from a dipole shape into a tear-drop shape due to its interaction with the background solar wind, and this cavity is referred to as the magnetosphere,” said Dr Marshall.

“The magnetosphere contains a number of different electrical current systems in near-Earth space that are significantly enhanced during solar storms (typically referred to as geomagnetic storms).”

“During these events, the magnetosphere may connect with the magnetic field of the CME, resulting in a build-up of the magnetic field on the night-side of the Earth. The contorted and stressed magnetic field configurations are sometimes favourable for magnetic reconnection, resulting in explosive release of this stored energy that accelerates particles and increases electrical current systems in the magnetosphere environment.”

“The accelerated particles can travel along geomagnetic field lines and precipitate into the Earth's upper atmosphere, creating aurora and increasing winds at high altitudes of hundreds of kilometres,” he said. “This precipitation expands the upper atmosphere and can increase the density of the atmosphere at altitudes where low-Earth-orbit satellites operate.” 

“The energised currents and particles can also have an impact on the ionised region of the Earth's upper atmosphere known as the ionosphere, creating issues for radio signals that travel through this region such as high-frequency radio and satellite positioning signals (e.g., GPS).”

However, geomagnetic storms don’t just affect the atmosphere; they can also induce electrical currents on the ground that interfere with energy infrastructure.

When an arriving CME impacts Earth’s magnetosphere, it compresses and distorts the magnetic field, causing it to rapidly change. When magnetic fields change, they induce electric currents (this is known as Faraday’s law). In turn, these rapid changes in the magnetic field generate geomagnetically induced currents (GICs) within the Earth’s crust and along long conductors structures on its surface, such as power transmission lines, pipelines and rail networks.

High-voltage transmission lines effectively act as giant conductors, and during strong geomagnetic storms, the GICs can flow into transformers, causing them to saturate, triggering overheating, voltage instability, automatic protective shutdowns or even permanent damage in extreme cases. 

“The currents in the ionosphere and magnetosphere generate electromagnetic fields that propagate to Earth and penetrate the Earth's crust and mantle. This can establish electric fields in the Earth's surface that drive currents in long conductors such as power networks and pipelines. These are just some of the changes in the near-Earth environment, and subsequent impacts on technological systems, that can occur during a solar/geomagnetic storm,” said Dr Marshall.

While severe space-weather events are rare, history has shown several notable examples. The strongest solar storm on record - the Carrington Event of 1859 - caused telegraph systems to spark, shocked operators, and produced even aurora near the equator. An event of this magnitude, should it occur today, would result in trillions of dollars in global economic damage.

More recently, a moderate geomagnetic storm in 1989 triggered the Quebec power grid to collapse, plunging six million people into having no power for several hours. Additionally, in 2003, the Halloween solar storms caused several large transformers in South Africa, Sweden and North America to surge, resulting in infrastructure damage.

“The Bureau is aware that during the May 2024 and November 2025 storms, several operational disruptions were reported across Australia. Both storms were among the largest of the current solar cycle, though perhaps not the most historically significant.”

“They caused measurable impacts to aviation operations, HF radio systems, and navigation accuracy, with limited but noteworthy effects on ground‑based electrical infrastructure,” said Dr Marshall.

Ironically, modern grids are much more vulnerable and sensitive than earlier systems because transmission lines are longer, operating voltages are higher, and networks are more interconnected. At the same time, energy utilities and governments are more aware of space-weather risks and have been developing monitoring and mitigation strategies designed to reduce the impact of these events. These effects, however, are much more dominant towards the poles and away from most populations.

“The geometry of the Earth's magnetic field is such that it concentrates towards higher latitudes that tend to be more exposed to many of the impacts of space weather than low-middle latitudes; however, there are certain current systems in near-Earth space which have larger impacts at low-middle latitudes than at high latitudes, so Australia is susceptible to space weather.”

The Bureau of Meteorology is the national provider of space weather information for Australia and operates the Australian Space Weather Forecasting Centre (ASWFC) all year round. The role of the ASWFC is to support industry and the community through the delivery of timely and reliable space weather information on events in the space weather environment likely to have an impact on our region.

Whether the Victorian power outages are ultimately confirmed to be linked to the January storm or not, the timing of the event reminds us all of an uncomfortable reality: our communities and energy infrastructure are at times exposed to forces that originate far beyond Earth’s atmosphere. Satellites, navigation systems, aviation routes, communications networks and power grids all operate within an environment shaped by the Sun’s changing behaviour, and at the mercy of the solar cycle.

Space weather is not often thought about as much as it should be. Yet, it is present in our everyday lives, manifesting as the phenomenon that produces captivating auroras, the observation of distant solar flares, or sudden technical warnings issued by scientists of an incoming geomagnetic storm. But when disruptions ripple into everyday systems, from electricity supply to GPS reliability, it becomes clear that the effects are not confined to space.

This incident in Victoria highlights the importance of continually monitoring space weather events, being prepared and the important coordination between scientists, industry and government.

It would be impossible to think we, a feeble species on a small rocky planet, could control the violent dynamics of our local star.

It is smart, however, if we choose how ready we are when it reminds us that Earth does not exist in isolation.

Video credits: NASA, NASA Goddard Space Flight Centre, NOAA