Space & Science

Extreme Solar Storms May Be Far More Powerful Than Scientists Realized

The most violent solar storms — the kind that could knock out power grids, disable satellites, and ground flights across continents — may be significantly stronger than current models predict. A new study reveals that a hidden statistical bias has been hiding the true scale of the threat.

• Researchers at NASA's Goddard Space Flight Center and Lancaster University discovered that what scientists previously thought was a physical limit on geomagnetic storm intensity is actually a statistical illusion. The "saturation" effect seen in extreme storms disappears when measurement bias is corrected.
• The bias arises because solar wind monitors sit at the L1 Lagrange point, 1.5 million kilometres from Earth. When an extreme solar wind event is measured there, the wind that actually reaches Earth is typically weaker due to a statistical phenomenon called "regression to the mean," making storms appear less intense than they really are.
• Published in Nature on July 15, 2026, the study implies that a Carrington-class event — the 1859 superstorm that set telegraph wires on fire — could generate geomagnetic currents far exceeding the thresholds that modern power grids and satellite electronics are designed to withstand.

Every few centuries, the Sun fires off a storm of charged particles powerful enough to rewrite the rules of modern civilization. The 1859 Carrington Event is the most famous example: auroras were seen as far south as Cuba, and telegraph systems across Europe and North America sparked, failed, and in some cases electrocuted operators. If a storm of that magnitude hit Earth today, the damage to electrical infrastructure could run into trillions of dollars and take years to repair.

For decades, scientists believed there was a physical ceiling on how intense geomagnetic storms could become. Data from the past 50 years seemed to show that even as the solar wind driving the storms grew stronger, the Earth's magnetic response eventually plateaued. This apparent saturation was treated as a reassuring natural limit — a sign that the magnetosphere has built-in buffers.

The new study, led by Dr. Nithin Sivadas of NASA's Goddard Space Flight Center and co-authored by Dr. Maria Walach of Lancaster University, turns that assumption on its head. The team built an "error model" that accounts for the measurement uncertainty inherent in solar wind readings. The key insight is that the solar wind monitors — NASA's ACE and DSCOVR spacecraft — sit at the L1 point, a gravitational balance point 1.5 million kilometres sunward of Earth. The solar wind is turbulent and structured at scales smaller than that distance, so the wind measured at L1 is frequently not the same wind that hits Earth's magnetosphere 45 to 60 minutes later.

When the measured solar wind is extremely strong, the actual wind arriving at Earth is typically weaker due to regression to the mean — a statistical phenomenon where extreme values tend to be followed by less extreme ones. This creates a systematic bias: the strongest storms are systematically under-measured, making it look like the Earth's response saturates when in reality it does not. After correcting for this bias, the team found no evidence of a physical saturation limit. The most extreme storms may be capable of generating geomagnetic disturbances far beyond anything observed in the modern era.

The implications are significant. Power grid operators, satellite designers, and aviation authorities all rely on space weather models that assume a worst-case ceiling. If that ceiling does not exist, infrastructure built to withstand a one-in-100-year storm may be vulnerable to storms that are far rarer — and far more destructive. The study does not predict an imminent superstorm, but it warns that our understanding of the upper bound of space weather has been shaped by a statistical artifact rather than by physics.