NASA-led researchers have challenged a decades-old scientific belief by suggesting that Earth may not have an upper limit to how strongly it responds to powerful solar storms. The findings, published in the journal Nature , indicate that extreme space weather could have a greater impact on satellites, communication systems and navigation technologies than scientists previously believed.
For years, scientists thought that electric currents generated in Earth's upper atmosphere during solar storms increased only up to a certain level, even if the incoming solar wind became stronger. This apparent "saturation" had been accepted as a natural limit in Earth's response to space weather.
However, the new study, led by NASA Goddard Space Flight Center space physicist Nithin Sivadas, argues that this limit may not actually exist.
Why scientists may have been wrong
According to the researchers, the long-held conclusion resulted from how solar wind has traditionally been measured.
Most observations of the solar wind are made by spacecraft positioned about one million miles closer to the Sun than Earth. By the time the solar wind reaches Earth's magnetic field, its strength often changes. As a result, researchers were comparing Earth's response with solar wind measurements that were stronger than what actually interacted with the planet.
This measurement uncertainty created the false impression that Earth's electric currents stopped increasing during stronger solar storms.
NASA analysed more than one million observations
To test the theory, the research team examined more than one million solar wind measurements collected by NASA spacecraft operating much closer to Earth, including the Magnetospheric Multiscale (MMS) mission and the Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission.
Unlike earlier observations, the new data showed a direct relationship between solar wind strength and electric currents in Earth's upper atmosphere. As the solar wind became stronger, the atmospheric currents also continued to increase, with no evidence of reaching a maximum limit.
Why the findings matter
Electric currents generated during solar storms can interfere with satellites, GPS navigation, radio communications and other technologies that rely on space-based infrastructure.
If Earth's response to solar storms has no upper limit, as the study suggests, future extreme solar storms could have more severe effects on technological systems than current models predict.
The researchers said additional observations of powerful solar wind events will be needed to determine conclusively whether any physical upper limit exists. For now, the findings challenge decades of scientific understanding and could reshape how scientists assess the risks posed by severe space weather.
