The Carrington Event: A Glimpse into a Solar Storm’s Impact on Earth

The Carrington Event, which occurred in 1859, is the most powerful solar storm ever recorded. Named after Richard Carrington, the British astronomer who first observed it, this event had profound effects on Earth’s atmosphere and technological systems. Let’s delve into its impact on our planet.

Flares vs. CMEs

The lead time between a solar flare and its initial effects on Earth varies depending on the type and strength of the event:

1. Solar Flares: These are electromagnetic emissions from the Sun and can reach Earth within 8 minutes (at the speed of light) after their occurrence. The primary effects include disruptions in high-frequency communication channels and potential GPS disturbances.
2. Coronal Mass Ejections (CMEs): This is a massive burst of solar wind and magnetic fields rising above the solar corona or being released into space. Depending on the speed of the CME, it can take between 15 hours to several days to reach Earth. CMEs are responsible for the most intense geomagnetic storms which can lead to power grid disturbances, satellite issues, and intense auroras (northern and southern lights).

Near-Earth satellites and space stations have onboard instruments that monitor solar events and can issue warnings. This gives technicians on Earth time to take precautions, such as putting satellites into a “safe mode” or shutting down power grids to avoid damage.

Effects on Earth’s Atmosphere

1. Auroras: The Carrington Event caused brilliant auroras, or natural light displays in the sky, to be seen as far south as the Caribbean. These auroras were so bright that people in the northeastern U.S. could read newspapers by their light at night.
2. Expanding Atmosphere: Solar storms release an immense amount of energy, causing Earth’s outer atmosphere to heat up and expand. This expansion increases the drag on satellites in low Earth orbit, potentially altering their trajectories.

Krivolutsky, A. (2021). Disturbances of Ozone Layer and Radio Wave Absorption in D-Region of Ionosphere of the Earth During Solar Proton Event: Simulations with СHARM-I Model. Link to the article

Satellites and the Expanding Atmosphere

When the Earth’s atmosphere expands due to the energy from a solar storm, it increases the density of the thermosphere. Satellites orbiting in this region experience increased atmospheric drag. This drag slows them down, causing them to drop to a lower altitude. If not corrected, this can lead to a shortened satellite lifespan or even de-orbiting.

Piersanti, M., et al. (2022). On the Magnetosphere–Ionosphere Coupling During the May 2021 Geomagnetic Storm. Link to the article

Effects on the Ionosphere

1. Communication Disruptions: The ionosphere, a layer of the Earth’s atmosphere, plays a crucial role in radio wave propagation. The Carrington Event caused significant ionospheric disturbances, leading to the failure of telegraph systems across Europe and North America. Some telegraph operators even reported receiving shocks from their equipment!
   
   Barta, V., et al. (2022). Multi-instrumental investigation of the solar flares impact on the ionosphere on 05–06 December 2006. Link to the article
   
2. Energy Transport and Conversion: The ionosphere acts as a conduit for energy transport between the sun and the Earth. During the Carrington Event, the rapid influx of solar energy caused the ionosphere to become supercharged, leading to increased electric currents known as “geomagnetically induced currents” (GICs). These GICs can flow into power lines, potentially damaging transformers and other electrical infrastructure.

Regi, M., et al. (2022). Space Weather Effects Observed in the Northern Hemisphere during November 2021 Geomagnetic Storm: The Impacts on Plasmasphere, Ionosphere and Thermosphere Systems. Link to the article

Conclusion

The Carrington Event serves as a stark reminder of the sun’s potential to disrupt our technologically dependent society. While such powerful solar storms are rare, understanding their effects is crucial for preparing for future events. As we become more reliant on satellite-based technologies and power grids, safeguarding them from solar phenomena becomes increasingly vital.