SerpApi.Org
The Sun’s most extreme storms may be far more powerful than scientists currently plan for. New research led by physicists at NASA’s Goddard Space Flight Center, published in Nature on July 19, found that a persistent flaw in how space weather is measured has led scientists to assume there is a ceiling on how severe geomagnetic storms can get. There may not be one.
The 1859 Carrington Event — which knocked out telegraph networks across Europe and North America and sent auroras as far south as Florida — remains the benchmark for worst-case scenarios.
More recent events have also shown what is at stake. During the 2003 Halloween Storms, solar radiation disrupted an FAA navigation system for 26 hours, and the FAA issued its first advisory warning of excessive radiation doses on commercial flights. These events are rare. And that rarity, the researchers argue, is precisely the problem.
Why the measurements have been wrong all along
Spacecraft monitoring solar weather typically sit about one million miles from Earth at a gravitational sweet spot called Lagrange point 1, or L1. There, probes like NASA’s IMAP hover in a stable orbit where the gravitational pulls of Earth and the Sun cancel out. They measure the energy in the solar wind as it approaches Earth.
The problem is where these measurements are taken. Solar particles traveling from L1 to Earth pass through a turbulent layer called the magnetosheath, where the solar wind interacts with Earth’s magnetic field and loses energy. L1 measurements do not capture that loss. They record solar wind as it was, not as it arrives.
“We usually assume the truth may be around its measurement,” said Nithin Sivadas, the study’s lead author and a physicist at NASA Goddard. “But probability theory says it leans one way. That’s why space weather risks appear underestimated.”
This consistent one-directional bias has fed into models that appear to show a natural upper limit on how much energy can be transferred from the solar wind into Earth’s polar ionosphere. But that ceiling may simply be an artifact of flawed data, not a real physical boundary.
What satellites closer to Earth actually show
To test this, the team turned to spacecraft positioned much closer to Earth: NASA’s THEMIS all-sky imager, the Magnetospheric Multiscale (MMS) mission, and the DoubleStar satellite. Together, these allowed the team to compare over one million solar wind measurements with readings taken directly in the magnetosheath and magnetosphere.
The result was unambiguous. “There is currently no statistical evidence to suggest an upper limit to the energy transferred from the solar wind to the polar ionosphere,” the team concluded.
What this means for the next big storm
The implications are significant. If there is no ceiling, then the worst-case scenarios currently used in space weather planning may be systematically too mild.
“Our planet’s magnetic field does a really great job of protecting us against many space weather effects,” said Maria Walach of Lancaster University, the study’s co-author. “There are, however, extreme cases where satellites unexpectedly fall back to Earth, or we lose communication and GPS signals.”
A truly extreme storm — the kind that might occur once in a thousand years — could be more disruptive than current models predict. “If there is no upper limit to our planet’s response to the solar wind, modeling for extreme cases needs to take this into account,” Walach said, “and we should be vigilant of space weather effects.”
