The aurora borealis, often called the Northern Lights, is a mesmerizing natural light display visible in polar regions. This spectacular phenomenon is a visible light emission created high in the Earth’s atmosphere, making viewing the lights entirely harmless to human health. The true risk lies not with the light show itself but with the underlying space weather event that creates it, which can severely disrupt global technology.
Viewer Safety and Radiation Exposure
The fear that watching the aurora exposes a person to harmful radiation is unfounded because Earth’s natural defenses are exceptionally effective. The charged particles from the sun, primarily electrons and protons, that cause the light show never reach the ground. These high-energy particles are intercepted high above the surface, typically between 60 and 250 miles up, where they collide with atmospheric gases like oxygen and nitrogen.
The collision process converts the particles’ kinetic energy into the visible light of the aurora. The resulting glow is a form of non-ionizing radiation, no different from the light emitted by a household lamp. The planet’s magnetic field (the magnetosphere) and the atmosphere work in tandem to shield ground-level viewers. Standing outside to watch the aurora exposes a person to less radiation than the background level absorbed from the natural world, such as from concrete or flying commercially.
Understanding the Cause: Solar Flares and Geomagnetic Storms
The spectacular light of the aurora results from immense energy released from the sun through specific events. These events include solar flares (powerful bursts of electromagnetic radiation) and Coronal Mass Ejections (CMEs), which are vast clouds of plasma and magnetic field material. CMEs are particularly important because they hurl billions of tons of superheated gas into space, forming an intensified stream known as the solar wind.
When this energized solar wind reaches Earth, it collides with the magnetosphere, the planet’s magnetic shield. This interaction compresses and distorts the magnetosphere, which can lead to a geomagnetic storm if the solar material’s magnetic field is aligned correctly with Earth’s. During a storm, charged particles gain access to the atmosphere near the magnetic poles, spiraling down along the magnetic field lines. This influx of particles excites the atoms and molecules of the upper atmosphere, causing them to glow and creating the colorful, dynamic forms of the aurora.
The Real Risks: Impact on Global Technology
While the lights are safe to watch, the intense geomagnetic storms that cause the most brilliant displays pose a genuine threat to modern infrastructure. A rapidly changing magnetic field at the Earth’s surface can induce electrical currents in long conductors, a phenomenon known as Geomagnetically Induced Currents (GICs). GICs flow through power transmission lines and grounded systems, including oil and gas pipelines.
The quasi-direct current from a GIC can push large power transformers into a state called half-cycle saturation. This current causes transformers to overheat, draw excessive reactive power, and potentially suffer permanent damage, leading to widespread power outages. A well-documented example is the 1989 storm that caused the collapse of the Hydro-Québec power grid, leaving millions without electricity for hours.
Beyond the power grid, severe space weather events disrupt satellite operations and communication systems. High-energy particles can penetrate satellite electronics, causing memory errors or even permanent hardware failure, especially for spacecraft in Low Earth Orbit. The storm-driven energy also dramatically alters the ionosphere, the layer of the atmosphere through which radio signals travel. This disturbance causes “scintillation,” a rapid fluctuation in the amplitude and phase of radio waves.
For navigational tools, this ionospheric distortion significantly degrades the accuracy of Global Positioning System (GPS) and other Global Navigation Satellite System (GNSS) signals. The positioning error can increase from typical centimeter-level precision to tens of meters or more. This loss of reliable positioning affects critical activities like commercial aviation, precision agriculture, and financial network timing. The actual danger of the aurora’s cause is an indirect, technological vulnerability.