Space weather refers to the dynamic conditions in the near-Earth space environment driven primarily by the Sun’s activity. Solar flares, coronal mass ejections (CMEs), and high-speed solar wind streams can produce geomagnetic storms that disrupt satellite operations, endanger astronauts, degrade GPS accuracy, damage power grids, and interfere with radio communications. As modern civilisation becomes increasingly dependent on space-based and electronic infrastructure, understanding and predicting space weather has become a matter of national and economic security.
The Sun’s Influence on Earth
The Sun continuously emits a stream of charged particles — the solar wind — that flows outward through the solar system at speeds of 300 to 800 kilometres per second. Earth’s magnetic field normally deflects this stream, creating the magnetosphere — a protective bubble that shields the planet from most solar radiation. However, during periods of intense solar activity, the Sun produces disturbances powerful enough to temporarily overwhelm these defences.
Solar flares are sudden, intense bursts of electromagnetic radiation from the Sun’s surface, releasing energy equivalent to millions of nuclear weapons within minutes. The radiation travels at the speed of light, reaching Earth in about eight minutes. Coronal mass ejections are massive eruptions of magnetised plasma from the Sun’s corona, carrying billions of tonnes of charged particles outward at speeds of up to 3,000 kilometres per second. When a CME is directed toward Earth, it typically arrives in one to three days and can trigger severe geomagnetic storms.
Impacts on Modern Technology
Satellites are particularly vulnerable to space weather. Intense radiation can damage solar panels, degrade electronics, cause electrical charging that disrupts instruments, and alter satellite orbits by heating and expanding the upper atmosphere. During the February 2022 geomagnetic storm, SpaceX lost 38 of 49 newly launched Starlink satellites when the heated atmosphere increased drag beyond the satellites’ ability to compensate.
Power grids face risks from geomagnetically induced currents (GICs) — electrical currents that flow through the ground and enter power transmission lines during geomagnetic storms. In March 1989, a severe geomagnetic storm caused the collapse of Hydro-Québec’s power grid in Canada, leaving six million people without electricity for nine hours. Studies suggest that a storm of similar magnitude to the 1859 Carrington Event — the most intense geomagnetic storm in recorded history — could cause widespread, long-duration power outages affecting hundreds of millions of people.
Aviation is affected through disrupted high-frequency radio communications (the primary backup for transoceanic flights), degraded GPS navigation accuracy, and increased radiation exposure for crew and passengers on polar flight routes. Airlines routinely reroute polar flights during major space weather events, adding fuel costs and flight time.
Forecasting Space Weather
Space weather forecasting relies on a network of solar observatories and space-based monitors. NASA’s Solar Dynamics Observatory continuously images the Sun at multiple wavelengths, while the SOHO and STEREO spacecraft provide views from different vantage points. The DSCOVR satellite, positioned at the L1 Lagrange point 1.5 million kilometres sunward of Earth, provides approximately 15 to 60 minutes of warning before a CME arrives.
Forecasters at agencies like NOAA’s Space Weather Prediction Center and the European Space Agency’s Space Weather Service Centre use these observations combined with numerical models to predict geomagnetic storm intensity and timing. However, space weather forecasting remains less mature than terrestrial weather forecasting — accurately predicting the magnetic field orientation within a CME (the key factor determining storm severity) remains particularly challenging.
Preparing for Extreme Events
Machine learning is increasingly used to improve space weather predictions, identifying patterns in solar data that may precede major eruptions. International cooperation through organisations like the International Space Environment Service coordinates observations and warnings across nations. As society’s dependence on vulnerable technologies grows, investment in space weather monitoring, forecasting, and infrastructure resilience has become an urgent priority for governments and industries worldwide.
